The spinal cord dorsal horn is pivotal for primary afferent signal transmission and modulation. Primary afferent fibers from each dorsal root arrive at the dorsal horn and travel 1-2 segments caudally and rostrally. Usually, in vitro spinal cord slices or in vivo preparations are employed for primary afferent stimulation and patch-clamp recordings to assess input signals. However, the spinal cord slices lose "intact" cross-segmental pathways, and in vivo studies are technically challenging.

Here, we describe the preparation of a spinal cord trunk for analyzing afferent signal cross-segmental transmission in adult rats. By combining patch-clamp recording, Lissauer's tract stimulation, and ambient temperature manipulation, our methods enable accessing primary afferent pathways within several segments.

Our present spinal trunk preparation can be maintained healthy for about 5 h. Lissauer's tract stimulation induced evoked excitatory postsynaptic currents (eEPSCs) recorded in 6-10 mm rostrally in the ipsilateral dorsal horn. The eEPSCs, spontaneous EPSCs (sEPSCs), and neural excitability can be modulated by ambient temperature rise. Neuropharmacological studies can also be conducted on this spinal trunk preparation.

Compared with conventional in vitro spinal cord slices, our present method maintains a relatively intact cross-segment pathway in the dorsal horn; compared with in vivo study, it avoids mechanical vibration and other technical challenges in living animals.

The rodent spinal cord trunk can be maintained for an extended period in a fully submerged chamber; combined with patch clamp recordings, our protocol facilitates the study of primary afferent transmission and modulation in the dorsal horn within adjacent segments.

Temperature is closely linked to the life history of organisms, and thus thermoception is an important sensory mechanism. Transient receptor potential (TRP) ion channels are the key mediators of thermal sensation. In this study, we analyzed the sequence characteristics of TRPs in gecko Hemiphyllodactylus yunnanensis and compared the phylogenetic relationships of TRP family members among different Squamata species. In addition, we sequenced the transcriptome of skin and brain tissues of H. yunnanensis exposed to 12 °C (cold), 20 °C (cool), 28 °C (warm), and 36 °C (hot). The results showed that a total of 591 TRPs were identified in the genomes of 21 Squamate species, and these genes were classified into six subfamilies. Among them, 26 TRP genes were identified in H. yunnanensis and distributed on 13 chromosomes. Overall, TRP genes were conserved in squamates. Based on the transcriptome results, we found a total of 9 TRP genes expressed in the brain and skin of H. yunnanensis, of which six TRP genes were under positive selection. TRPP1L2, TRPP1L3, and TRPV1 were involved in heat-sensitive responses (> 36 °C), and TRPV3, TRPA1, and TRPM8 were involved in cold-sensitive responses (< 20 °C). TRPM8 and TRPP1L2 were important cold and heat sensors in H. yunnanensis, respectively.

Behavioral models have served a key role in understanding nociception, the sensory system by which animals detect noxious stimuli in their environment. Developing zebrafish (Danio rerio) are a powerful study organism for examining nociceptive pathways, given the vast array of genetic, developmental, and neuroscience tools available for these animals. However, at present there are few widely-adopted behavioral models for nociception in developing zebrafish. This study examines the locomotor response of hatching-stage zebrafish embryos to dilute solutions of the noxious chemical and TRPA1 agonist allyl isothiocyanate (AITC). At this developmental stage, AITC exposure induces a robust uniphasic hyperlocomotion response. This behavior was thoroughly characterized by determining the effects of pre-treatment with an array of pharmacological agents, including anesthetics, TRPA1 agonists/antagonists, opioids, NSAIDs, benzodiazepines, SSRIs, and SNRIs. Anesthetics suppressed the response to AITC, pre-treatment with TRPA1 agonists induced hyperlocomotion and blunted the response to subsequent AITC exposures, and TRPA1 antagonists and the opioid buprenorphine tended to reduce the response to AITC. The behavioral responses of zebrafish embryos to a noxious chemical were minimally affected by the other pharmacological agents examined. The feasibility of using this behavioral model as a screening platform for drug discovery efforts was then evaluated by assaying a library of natural product mixtures from microbial extracts and fractions. Overall, our results indicate that irritant-evoked locomotion in embryonic zebrafish is a robust behavioral model for nociception with substantial potential for examining the molecular and cellular pathways associated with nociception and for drug discovery efforts.

Asthma is an inflammatory airway disease characterized by excessive bronchoconstriction and airway hyperresponsiveness. Airway nerves play a crucial role in regulating these processes. In asthma, interactions between inflammatory cells and nerves result in nerve dysfunction, which worsens airway function. This review discusses new insights regarding the role of airway nerves in healthy lungs and examines how communication between nerves and leukocytes, including eosinophils, mast cells, dendritic cells, and innate lymphoid cells, contributes to nerve dysfunction and the worsening of airway disease. Clinical implications and therapeutic opportunities presented by neuroimmune interactions are also addressed.

The neural mechanisms of the affective-motivational symptoms of chronic pain are poorly understood. In chronic pain, our innate coping mechanisms fail to provide relief. Hence, these behaviors are manifested at higher frequencies. In laboratory animals, such as mice and rats, licking the affected areas is a behavioral coping mechanism and it is sensitized in chronic pain. Hence, we have focused on delineating the brain circuits mediating licking in mice with chemotherapy-induced peripheral neuropathy (CIPN). Mice with CIPN develop intense cold hypersensitivity and lick their paws upon contact with cold stimuli. We studied how the lateral parabrachial nucleus (LPBN) neurons facilitate licking behavior when mice are exposed to noxious thermal stimuli. Taking advantage of transsynaptic viral, optogenetic, and chemogenetic strategies, we observed that the LPBN neurons become hypersensitive to cold in mice with CIPN and facilitate licks. Furthermore, we found that the expression of licks depends on competing excitatory and inhibitory inputs from the spinal cord and lateral hypothalamus (LHA), respectively. We anatomically traced the postsynaptic targets of the spinal cord and LHA in the LPBN and found that they synapse onto overlapping populations. Activation of this LPBN population was sufficient to promote licking due to cold allodynia. In sum, our data indicate that the nociceptive inputs from the spinal cord and information on brain states from the hypothalamus impinge on overlapping LPBN populations to modulate their activity and, in turn, regulate the elevated affective-motivational responses in CIPN.

Previous studies have driven the notion that the cannabis constituent cannabidiol could be an effective adjunct to opioid administration for managing pain. Most of these studies have used experimental rodents with routes of administration, such as subcutaneous and intraperitoneal, that do not correspond with the routes used in clinical practice. In response to this, we tested the ability of cannabidiol co-administration to augment opioid analgesia via the more clinically-relevant oral route of administration. To this end, male and female rats were orally gavaged with cannabidiol (25 mg/kg), oxycodone (1.4 mg/kg), or a combination of both, after which they were tested in an operant thermal orofacial pain assay in which they voluntarily exposed their faces to cutaneous thermal pain to receive a palatable reward. All three drug conditions produced analgesic effects of varying degrees, being most profound in the combination group where a statistically significant enhancement over oxycodone-induced analgesia alone was evident. Additionally, oxycodone administration decreased lick frequencies - a measure of motor coordination of rhythmic movements - which too was magnified by co-administration of cannabidiol. Together these studies provide further support of an ability of cannabidiol to augment opioid effects, particularly analgesia, when administered by a route relevant to human pain management. As such, they encourage the notion that cannabidiol could find utility as an opioid-sparing approach to treating pain.

Chronic constipation is a prevalent, burdensome gastrointestinal disorder whose etiology and pathophysiology remain poorly understood. Differences in the composition of the intestinal microbiota have been shown between constipated patients and healthy people. Data indicate that these microbial differences contribute to the disorder.

Preclinical studies in mice examined the effects of Lactobacillus gasseri on intestinal motility ex vivo, the reversal of motility inhibition by μ-opioid receptor agonists ex vivo and in vivo in mice, and the effects on capsaicin-stimulated transient receptor potential vanilloid 1 (TRPV1) in Jurkat cells. Thereafter, a clinical study of 40 women with functional constipation was conducted to investigate the effects of Lactobacillus gasseri with a randomized parallel design. After 14 days of baseline recording, treatment with Lactobacillus gasseri or placebo was given over 28 days, with 14 days of follow-up. Outcomes with complete spontaneous bowel movements (CSBM), spontaneous bowel movements, emptying frequency, abdominal pain, time spent for defecation, Bristol stool form scale, use of rescue laxatives, and impact on sex life were investigated.

In preclinical studies, Lactobacillus gasseri increased intestinal motility in an ex vivo model, reversed the motility inhibition caused by μ-opioid receptor agonist ex vivo and in vivo in mice, and counteracted capsaicin-stimulated activity of TRPV1 in Jurkat cells. In the clinical trial, Lactobacillus gasseri showed a significant reduction in abdominal pain, along with a correlation and tendency for an increased number of CSBM. Few adverse events were encountered.

Treatment with Lactobacillus gasseri can alleviate pain sensations in functional constipation, possibly with an improved bowel-emptying function.

The perception of innocuous temperatures is crucial for thermoregulation. The TRP ion channels TRPV1 and TRPM2 have been implicated in warmth detection, yet their precise roles remain unclear. A key challenge is the low prevalence of warmth-sensitive sensory neurons, comprising fewer than 10% of rodent dorsal root ganglion (DRG) neurons. Using calcium imaging of >20,000 cultured mouse DRG neurons, we uncovered distinct contributions of TRPV1 and TRPM2 to warmth sensitivity. TRPV1's absence - and to a lesser extent absence of TRPM2 - reduces the number of neurons responding to warmth. Additionally, TRPV1 mediates the rapid, dynamic response to a warmth challenge. Behavioural tracking in a whole-body thermal preference assay revealed that these cellular differences shape nuanced thermal behaviours. Drift diffusion modelling of decision-making in mice exposed to varying temperatures showed that TRPV1 deletion impairs evidence accumulation, reducing the precision of thermal choice, while TRPM2 deletion increases overall preference for warmer environments that wildtype mice avoid. It remains unclear whether TRPM2 in DRG sensory neurons or elsewhere mediates thermal preference. Our findings suggest that different aspects of thermal information, such as stimulation speed and temperature magnitude, are encoded by distinct TRP channel mechanisms.

Somatosensory pathways convey crucial information about pain, touch, itch and body part movement from peripheral organs to the central nervous system1,2. Despite substantial needs to understand how these pathways assemble and to develop pain therapeutics, clinical translation remains challenging. This is probably related to species-specific features and the lack of in vitro models of the polysynaptic pathway. Here we established a human ascending somatosensory assembloid (hASA), a four-part assembloid generated from human pluripotent stem cells that integrates somatosensory, spinal, thalamic and cortical organoids to model the spinothalamic pathway. Transcriptomic profiling confirmed the presence of key cell types of this circuit. Rabies tracing and calcium imaging showed that sensory neurons connect to dorsal spinal cord neurons, which further connect to thalamic neurons. Following noxious chemical stimulation, calcium imaging of hASA demonstrated a coordinated response. In addition, extracellular recordings and imaging revealed synchronized activity across the assembloid. Notably, loss of the sodium channel NaV1.7, which causes pain insensitivity, disrupted synchrony across hASA. By contrast, a gain-of-function SCN9A variant associated with extreme pain disorder induced hypersynchrony. These experiments demonstrated the ability to functionally assemble the essential components of the human sensory pathway, which could accelerate our understanding of sensory circuits and facilitate therapeutic development.

Music traditions worldwide are subject to remarkable diversity but the origins of this variation are not well understood. Musical behaviour is the product of a multicomponent collection of abilities, some possibly evolved for music but most derived from traits serving nonmusical functions. Cultural evolution has stitched together these systems, generating variable normative practices across cultures and musical genres. Here, we describe the cultural evolution of musical distortion, a noisy manipulation of instrumental and vocal timbre that emulates nonlinear phenomena (NLP) present in the vocal signals of many animals. We suggest that listeners' sensitivity to NLP has facilitated technological developments for altering musical instruments and singing with distortion, which continues to evolve culturally via the need for groups to both coordinate internally and differentiate themselves from other groups. To support this idea, we present an agent-based model of norm evolution illustrating possible dynamics of continuous traits such as timbral distortion in music, dependent on (i) a functional optimum, (ii) intra-group cohesion and inter-group differentiation and (iii) groupishness for assortment and social learning. This account illustrates how cultural transmission dynamics can lead to diversity in musical sounds and genres, and also provides a more general explanation for the emergence of subgroup-differentiating norms.This article is part of the theme issue 'Nonlinear phenomena in vertebrate vocalizations: mechanisms and communicative functions'.

Sensitive skin is a dermatologic condition with variable prevalence. Universally established cutoff scores for the sensitive scale (SS) and burden of sensitive skin (BoSS) questionnaires are lacking in general populations.

To determine the prevalence of and the associated risk factors for sensitive skin among Thais and to establish cutoff values for diagnosing mild, moderate, and severe cases of sensitive skin.

A cross-sectional study involving 621 participants aged ≥ 18 years was conducted using an online questionnaire disseminated via various social platforms. Participants completed the SS-14, SS-10, and BoSS questionnaires to assess sensitive skin severity. Cutoff scores for these instruments were determined.

Sensitive skin was reported by 86.9% of participants, with 57.5% indicating moderate to severe sensitive skin. Significant risk factors for sensitive skin included female sex, underlying dermatologic conditions, history of atopic dermatitis, and dry skin type. The following cutoff points for diagnosing mildly, moderately, and severely sensitive skin were established for each questionnaire: SS-14 (6/16/25), SS-10 (5/13/22), and BoSS (13/19/24), respectively. The SS-10 questionnaire demonstrated greater diagnostic accuracy than the BoSS questionnaire.

This pioneering study elucidated the prevalence of and risk factors for sensitive skin in Thais. The established cutoff values will facilitate sensitive skin diagnosis and guide patient management strategies.

Persistent or chronic pain is the primary reason people seek medical care, yet current therapies are either limited in efficacy or cause intolerable side effects. Diverse mechanisms contribute to the basic phenomena of nociceptor hyperexcitability that initiates and maintains pain. Two prominent players in the modulation of nociceptor hyperexcitability are the transient receptor potential vanilloid type 1 (TRPV1) ligand-gated ion channel and the voltage-gated potassium channel, Kv7.2/3, that reciprocally regulate neuronal excitability. Across many drug development programs targeting either TRPV1 or Kv7.2/3, significant evidence has been accumulated to support these as highly relevant targets; however, side effects that are poorly separated from efficacy have limited the successful clinical translation of numerous Kv7.2/3 and TRPV1 drug development programs. We report here the pharmacological profile of 3 structurally related small molecule analogues that demonstrate a novel mechanism of action (MOA) of dual modulation of Kv7.2/3 and TRPV1. Specifically, these compounds simultaneously activate Kv7.2/3 and enable unexpected specific and potent inhibition of TRPV1. This in vitro potency translated to significant analgesia in vivo in several animal models of acute and chronic pain. Importantly, this specific MOA is not associated with any previously described Kv7.2/3 or TRPV1 class-specific side effects. We suggest that the therapeutic potential of this MOA is derived from the selective and specific targeting of a subpopulation of nociceptors found in rodents and humans. This efficacy and safety profile supports the advancement of dual TRPV1-Kv7.2/3 modulating compounds into preclinical and clinical development for the treatment of chronic pain.

Recent evidence suggests that the gut microbiota can influence pain sensitivity, highlighting the potential for microbiota-targeted pain interventions. During early life, both the microbiota and nociceptors are fine-tuned and respond to environmental factors, however, little is known about how they interact with each other. Using germ-free and gnotobiotic models, we demonstrate that microbiota colonization controls nociceptor sensitivity, partly by modulating mast cell production of nerve growth factor (NGF). We report that germ-free mice respond less to thermal and capsaicin-induced stimulation, which correlates with reduced trafficking of TRPV1 to the cell membrane of nociceptors. In germ-free mice, mast cells express lower levels of NGF. Hyposensitivity to thermal and capsaicin-induced stimulation, reduced TRPV1 trafficking, and decreased NGF expression are reversed when mice are colonized at birth, but not when colonization occurs after weaning. Inhibition of mast cell degranulation and NGF signaling during the first weeks of life in colonized mice leads to a hyposensitive phenotype in adulthood, demonstrating a role for mast cells and NGF signaling in linking early life colonization with nociceptor sensitivity. These findings implicate the early life microbiota in shaping mast cell NGF production and nociceptor sensitivity later in life. SIGNIFICANCE STATEMENT: Nociceptors are specialized sensory neurons that detect and transduce painful stimuli. During the early postnatal period, nociceptors are influenced by sensory experiences and the environment. Our findings demonstrate that gut microbiota colonization is essential in setting the threshold of nociceptor responses to painful stimuli. We show that early-life bacterial colonization controls the production of nerve growth factor by mast cells, affecting our sensitivity to pain later in life. Our study highlights the potential for developing new pain treatments that target the gut microbiome.

Preclinical studies suggested that Transient Receptor Potential Vanilloid 1 (TRPV1) channels contribute to neuropathic pain in animal models of diabetic polyneuropathy. Patients with painful diabetic polyneuropathy commonly experience ongoing burning pain. This study aimed at evaluating the association between this specific type of pain and TRPV1 intraepidermal nerve fibers in patients with painful diabetic polyneuropathy. We consecutively enrolled 70 patients with diabetic polyneuropathy. Each patient completed the Neuropathic Pain Symptom Inventory (NPSI) to identify the various types of neuropathic pain. All patients underwent a distal leg skin biopsy, with immunostaining of skin nerve fibers using antibodies for the pan-axonal marker Protein Gene Product 9.5 (PGP9.5), TRPV1, Calcitonin Gene-Related Peptide (CGRP), and Substance P. We found that 57% of patients (n = 40) had neuropathic pain symptoms, with ongoing burning pain being the most frequently reported type of pain at the NPSI (70% of patients with pain, n = 28). Patients with ongoing burning pain had higher TRPV1 intraepidermal nerve fiber density and TRPV1/PGP9.5 ratio compared with those with painless polyneuropathy ( P = 0.014, P = 0.013) and painful polyneuropathy with other types of pain ( P < 0.0001, P = 0.024); they also had increased CGRP dermal nerve fiber density compared with patients with painless polyneuropathy ( P = 0.005). Our study showed that ongoing burning pain is associated with an increased expression of intraepidermal TRPV1 fibers, as well as an increased dermal representation of CGRP fibers. These findings suggest that TRPV1 contributes to ongoing burning pain, possibly in conjunction with elevated CGRP expression, highlighting its significance as a therapeutic target for patients with painful diabetic polyneuropathy.

The alterations in the swallowing cortical network associated with taste stimulation in patients with post-stroke dysphagia remain unclear. The aim of the study was to investigate the alterations in brain functional activity among individuals with post-stroke dysphagia under taste stimuli using functional near-infrared spectroscopy (fNIRS). We recruited 28 patients with post-stroke dysphagia and 24 age-matched healthy controls in this study. Each of them completed swallowing evaluation, resting-state and swallowing task-related fNIRS test. We found that the brain activation of patients significantly decreased in the left and right supplemental motor area (SMA) for water swallowing task and the left SMA and right primary sensory area (S1) for salty water swallowing, compared with healthy controls, only the left SMA remained significant for salty water swallowing after False Discovery Rate (FDR) correction. Fourteen healthy controls and 13 patients were included in the subgroup analysis, to explore the influences of preferred taste on swallowing network, we observed that the brain activation in the right S1 was significantly reduced during water swallowing in patient group (p = 0.008, with FDR corrected), all channels showed similar strengths in the activation under preferred taste stimulus between the groups. Functional connectivity (FC) between hemispheric sensorimotor areas were significantly decreased in patients compared with healthy controls. Our investigation revealed a noteworthy reduction in the activation of the left SMA during the salty water swallowing task in patients with dysphagia when compared to the healthy control group. The dysphagic patients following stroke exhibited impaired interaction between hemispheric sensorimotor areas associated with swallowing. Sour, sweet, and preferred taste stimulation have the potential to enhance brain plasticity, which may offer new insights for developing novel strategies for post-stroke dysphagia.

To advance the exploration of mechanisms underlying natural multi-gated ion channels, a novel butterfly-shaped biomimetic K+ channel GnC7 (n = 3, 4) is developed with dual mechanical and pH responsiveness, exhibiting unprecedented K+/Na+ selectivity (G3C7: 34.4; G4C7: 41.3). These channels constructed from poly(propylene imine) dendrimer and benzo-21-crown-7-ethers achieve high K+ transport activity (EC50: 0.72 µm for G3C7; 0.9 µm for G4C7) due to their arc-like mechanical rotation. The dynamic mode relies on butterfly-shaped topology derived from the highly symmetrical core and multiple intramolecular hydrogen bonds. GnC7 can sense mechanical stimulus applied to liposomes/cells and then adapt the K+ transport rate accordingly. Furthermore, reversible ON/OFF switching of K+ transport is realized through the pH-controllable host-guest complexation. G4C7-induced ultrafast cellular K+ efflux (70% within only 9 min) efficiently triggers mitochondrial-dependent apoptosis of cancer cells by provoking endoplasmic reticulum stress accompanied by drastic Ca2+ sparks. This work embodies a multi-dimensional regulation of channel functions; it will provide insights into the dynamic behaviors of biological analogs and promote the innovative design of artificial ion channels and therapeutic agents.

CRISPR-Cas9 is now the leading method for genome editing and is advancing for the treatment of human disease. CRIPSR has promise in treating neurological diseases, but traditional viral-vector-delivery approaches have neurotoxicity limiting their use. Here we describe a simple method for non-viral transfection of primary human DRG (hDRG) neurons for CRISPR-Cas9 editing. We edited TRPV1, NTSR2, and CACNA1E using a lipofection method with CRISPR-Cas9 plasmids containing reporter tags (GFP or mCherry). Transfection was successfully demonstrated by the expression of the reporters two days post-administration. CRISPR-Cas9 editing was confirmed at the genome level with a T7-endonuclease-I assay; protein level with immunocytochemistry and Western blot; and functional level through capsaicin-induced Ca2+ accumulation in a high-throughput compatible fluorescent imaging plate reader (FLIPR) system. This work establishes a reliable, target specific, non-viral CRISPR-Cas9-mediated genetic editing in primary human neurons with potential for future clinical application for sensory diseases.

The crystal structure of capsaicin (C18H27NO3), or trans-8-methyl-N-vanillylnon-6-enamide, the natural product responsible for the spiciness of chilli peppers, was determined using low-temperature single-crystal X-ray diffraction. The reported crystal structure is in good agreement with previous determinations based on powder X-ray diffraction data. The localization and free refinement of all H atoms revealed that each capsaicin molecule is hydrogen bonded to four other molecules, with the O-H and N-H groups acting as hydrogen-bond donors, and the C=O group serving as a bifurcated hydrogen-bond acceptor.

Porcine enteric coronaviruses, including transmissible gastroenteritis virus (TGEV), porcine epidemic diarrhea virus (PEDV) and porcine deltacoronavirus (PDCoV), have caused enormous economic losses to the global pig industry. Unfortunately, new variants emerge of these viruses will make it difficult for pigs vaccinated with the appropriate vaccine to develop protective immunity. Hence, it is urgent to explore effective therapeutic agents and targets against these viruses. Capsaicin is an active compound found in plants of the Capsicum genus (prevention and/or treatment of pain, hypertension and inflammation), but little is known about its effects on enterovirus infections. Herein, we used porcine enteric coronavirus TGEV as a model to evaluate the antiviral activity of capsaicin and discovered that capsaicin inhibited the replication phase of TGEV. Mechanistically, calcium signaling pathway participates in the capsaicin-mediated antiviral function. Importantly, capsaicin treatment impaired the viral replication by attenuating cytosolic calcium, and supplementation with CaCl2 reduced the inhibitory effect of capsaicin on TGEV infection. Finally, we revealed that TRPV4 plays an essential role in modulating calcium ion influx in IPEC-J2 cells, and capsaicin inhibits TGEV replication by decreasing calcium ion influx through inhibition of TRPV4. Overall, our data suggest that capsaicin is a promising small molecular drug candidate for strengthening host resistance to porcine enteric coronavirus infection.

The Felidae exhibits remarkable diversity in body size, with lengths ranging from 50 to 370 cm and weights from 1.1 to 423 kg. However, the underlying mechanisms driving this variation remain poorly understood. Here, we focused on the Siberian tiger (Panthera tigris altaica), the largest of the six extant tiger subspecies, and revealed the surprising expression of nicotinic acetylcholine receptors (nAChRs) in pituitary somatotrophs, which are crucial for regulating growth hormone (GH) secretion. Single-nucleus RNA sequencing of Siberian tiger pituitary cells exhibited the coexpression of CHRNA3, CHRNB4, and CHRNA5 genes in somatotrophs, a finding confirmed by electrophysiological experiments demonstrating the formation of functional nAChRs. Activation of these receptors elevated intracellular Ca2+ levels, thereby enhancing GH secretion in somatotrophs. Notably, nAChRs were absent in the pituitary glands of mice, domestic cats, and rats, both in early life and adulthood, despite high acetylcholine levels during early life. These results suggest that nAChRs in Siberian tiger somatotrophs play a pivotal role in GH release, offering new insights into the molecular mechanisms regulating body size in these terrestrial giants.

The transient receptor potential vanilloid 1 receptor (TRPV1) is a calcium-sensitive membrane receptor activated by capsaicin and the endocannabinoid, anandamide (AEA). Once activated in vitro, endometrial cancer (EC) cell growth appears to be inhibited through increased apoptosis, but the mechanism remains unclear. Our aim was to investigate the expression and distribution of TRPV1 in normal and cancerous endometria and to determine the precise in vitro mechanism of decreased EC cellular growth. TRPV1 expression in patients with endometrial carcinoma (15 Type 1 EC, six Type 2 EC) and six normal patients (atrophic endometria) was assessed using quantitative RT-PCR and immunohistochemistry (IHC). Additionally, immunohistochemical staining for the proliferation marker Ki-67, the pro-apoptotic marker BAX and the anti-apoptotic marker Bcl-2 were explored. TRPV1 transcript (p = 0.0054) and immunoreactive protein (p < 0.0001) levels were significantly reduced in all EC tissues when compared to control (atrophic) endometria. The almost 50% reduction in TRPV1 transcript levels was mirrored by an almost complete loss of immunoreactive TRPV1 protein. The increased proliferation (Ki-67) of EC tissues correlated with the expression of mutated BAX and inversely correlated to Bcl-2, but only in Type 2 EC samples. In vitro, AEA caused a decrease in Ishikawa cell numbers, whilst capsaicin did not, suggesting the anti-proliferative effect of AEA in EC cells is not via the TRPV1 receptor. In conclusion, the loss of TRPV1 expression in vivo plays a role in the aetiopathogenesis of EC. Activation of cells by AEA also probably promotes EC cell loss through a pro-apoptotic mechanism not involving TRPV1.

Two-thirds of patients with Fabry disease suffer debilitating pain attacks triggered by exercise, fever, and exposure to environmental heat. These patients face an even greater risk of heat-related episodic pain in the face of global climate change. Almost nothing is known about the biological mechanisms underlying heat-induced pain crises in Fabry disease, and there is no preclinical model available to study Fabry crises. Here, we established the first model of heat-induced pain attacks in Fabry disease by exposing transgenic Fabry rats to environmental heat. Heat exposure precipitated robust mechanical hypersensitivity, closely matching temporal features reported by patients with Fabry disease. At the cellular level, heat exposure sensitized Fabry dorsal root ganglia (DRG) neurons to agonists for transient receptor potential cation channel A1 (TRPA1), but not TRPV1. The heat shock response, which normally confers heat-resilience, was impaired in Fabry disease, and we demonstrated that heat shock proteins (HSP70 and HSP90) regulate TRPA1. Strikingly, pharmacologically inhibiting HSP90 completely prevented cellular and behavioral sensitization by environmental heat in Fabry disease. Together, this work establishes the first model of episodic pain in Fabry disease, implicates the heat shock response in heat-evoked pain episodes, and identifies a novel heat shock protein-TRPA1 regulatory axis.

Some thermosensitive transient receptor potential (TRP) channels form a protein complex with anoctamin 1 (ANO1, also called TMEM16A). TRP channels have high calcium permeability, and the calcium entering cells through TRP channel activation activates ANO1, a calcium-activated chloride channel, involved in many physiological and pathological conditions. The physiological significance of TRP channels is often mediated by their ability to activate ANO1, which controls chloride flux across the plasma membrane. This review summarizes the latest understanding on the interactions between ANO1 and thermosensitive TRP channels, including TRPV1, TRPV3, and TRPV4, which are involved in pain sensitization in primary sensory neurons, proliferation and migration of human keratinocytes, and fluid secretion such as sweat, respectively.

Optogenetics and chemogenetics are relatively new biomedical technologies that emerged 20 years ago and have been evolving rapidly since then. This has been made possible by the combined use of genetic engineering, optics, and electrophysiology. With the development of optogenetics and thermogenetics, the molecular tools for cellular control are continuously being optimized, studied, and modified, expanding both their applications and their biomedical uses. The most notable changes have occurred in the basic life sciences, especially in neurobiology and the activation of neurons to control behavior. Currently, these methods of activation have gone far beyond neurobiology and are being used in cardiovascular research, for potential cancer therapy, to control metabolism, etc. In this review, we provide brief information on the types of molecular tools for optogenetic and thermogenetic methods─microbial rhodopsins and proteins of the TRP superfamily─and also consider their applications in the field of activation of non-neuronal tissues and mammalian cells. We also consider the potential of these technologies and the prospects for the use of optogenetics and thermogenetics in biomedical research.

Obesity is a significant contributor to various metabolic diseases such as heart disease and diabetes. Due to the adverse effects of synthetic anti-obesity drugs, natural products from functional food plants, which mimic the effects of synthetic chemicals, present promising alternatives. However, many natural plant-derived compounds are poorly soluble in water, resulting in low bioavailability within the gastrointestinal tract, a key limitation for the effectiveness of many hydrophobic substances. In this study we developed a microemulsion-based drug delivery system in Drosophila, which effectively enhanced the solubility of hydrophobic compounds without noticeable effects on food intake or survival in fruit flies. This system consisted of cremophor EL, ethanol and ethyl oleate (7:6:1), which enabled the establishment of an emulsion-based liquid high-fat diet (LHFD) model, followed by a pilot screening of 161 standard substances from traditional Chinese medicine. We found that piperine (PIP), an alkaloid derived from black pepper, significantly decreased triacylglycerol (TAG) levels in both the intestine and in whole flies. We demonstrated that piperine (1 mg/ml) significantly elevated cytosolic Ca2+ levels in enterocytes by activating Transient receptor potential (TRP) channels. TRPV1 agonists such as capsaicin and evodiamine (another alkaloid identified during the screening) also exhibited anti-obesity effects. Increased Ca2+ levels resulted in the suppression of dietary lipase Magro expression through the activation of the transcription factor cAMP response element binding protein (CREB). Furthermore, hydrophobic compounds in the microemulsion were successfully delivered to distal tissues including liver and brain blood vessels in mice, and PIP in the microemulsion was sufficient to reduce body weight in mice. In conclusion, we have developed a microemulsion-based U-GLAD platform for drug delivery, and piperine is identified as a weight-controlling compound, providing a novel approach to the treatment of obesity and its associated symptoms.

Phytocannabinoids (pCBs) from Cannabis sativa represent an important class of bioactive molecules, potentially useful for the treatment of a wide range of diseases. Their efficacy is due to their ability to interact with multiple targets of the endocannabinoid system, including the thermosensitive transient receptor potential (Thermo-TRPs), namely TRPV1-4, TRPA1, and TRPM8 channels. Previously, we demonstrated a shift in selectivity toward TRPA1 in the activity profile of the main pCBs, that is, CBD, ∆8-THC, CBG, CBC, and CBN, by swapping the pentyl chain with the α,α-dimethylheptyl (DMH) one. Using these derivatives as a starting point, here we investigate the effects on the thermo-TRPs activity profile of the integration of a quinone group into the resorcinol scaffold. We found that, while the activity on TRPA1 is substantially retained, an increase in potency/efficacy on the TRPV3 modulation is observed. Docking studies were used to elucidate the binding modes of the most active compounds toward this receptor, providing a rationale for this biological activity. In summary, we show that the quinone derivatives of DMH-pCBs are endowed with a TRPA1/TRPV3 desensitizing activity, potentially useful for the treatment of skin diseases sustained by inflammatory conditions.

Acute pain, a critical aspect of patient care, presents a challenge due to its subjective nature and complex biological underpinnings. Biomarkers for acute pain promise a paradigm shift in how pain is perceived, diagnosed, and managed. The study of genetic, inflammatory, and neurotransmission markers associated with pain experience may hold the key for the development of personalized and effective pain management strategies. This narrative review explores the neurobiological pathways of acute pain, encompassing inflammatory responses and neurotransmission mechanisms. It synthesizes current research on the identification and clinical application of biomarkers, emphasizing their potential to enhance diagnostic precision, treatment effectiveness, and risk prediction. We underscore the promising role of acute pain biomarkers in identifying patients at risk for developing acute and potentially chronic pain, predicting patients' response to pharmacological interventions, and aiding in the development of novel therapeutic and pain preventive strategies. The evolving landscape of biomarker research not only deepens our understanding of pain mechanisms but also lays the foundation for more tailored and patient-specific healthcare interventions.

The human brain has a remarkable ability to learn and update its beliefs about the world. Here, we investigate how thermosensory learning shapes our subjective experience of temperature and the misperception of pain in response to harmless thermal stimuli. Through computational modeling, we demonstrate that the brain uses a probabilistic predictive coding scheme to update beliefs about temperature changes based on their uncertainty. We find that these expectations directly modulate the perception of pain in the thermal grill illusion. Quantitative microstructural brain imaging further revealed that individual variability in computational parameters related to uncertainty-driven learning and decision-making is reflected in the microstructure of brain regions such as the precuneus, posterior cingulate gyrus, cerebellum, as well as basal ganglia and brainstem. These findings provide a framework to understand how the brain infers pain from innocuous thermal inputs, with important implications for the etiology of thermosensory symptoms under chronic pain conditions.

The classic formulation, Coptis cream, is widely used in clinical practice to treat allergic skin conditions, including eczema and urticaria. Through extraction screening, Coptis cream extract obtained with 75% ethanol (referred to as RPTCA) demonstrated optimal anti-allergic effects. However, the underlying mechanism of its anti-allergic action remains unexplored.

To investigate the anti-allergic effects of RPTCA and to explore its possible mechanism of action.

The anti-allergic effects of RPTCA were investigated in C48/80-induced allergy models, namely, RBL-2H3 cells in vitro and foot-swelling mouse models in vivo. The underlying mechanisms and the monomer composition of RPTCA were explored.

Results demonstrated that RPTCA significantly reduced C48/80-induced foot swelling, vascular permeability, mast cell count, and cytokine secretion in mice. Mechanistic analysis revealed that C48/80 activated TRPV1 and TRPV4, with TRPV1 inhibition suppressing cell degranulation. RPTCA downregulated MRGPRB3 overexpression and degranulation levels, while MRGPRB3 inhibition markedly suppressed C48/80 activation and degranulation. RPTCA also decreased PLC phosphorylation through MRGPRB3, reduced intracellular Ca2+ and CaMKII phosphorylation, inhibited PKC phosphorylation, suppressed TRPV1 activation, and ultimately limited mast cell degranulation. Furthermore, RPTCA downregulated NF-κB and ERK/JNK signaling pathways, inhibiting inflammatory factor release. The component analysis identified nine main components in RPTCA, each capable of inhibiting cell degranulation.

RPTCA inhibits TRPV1 activation and reduces cell degranulation through the PLC/Ca2+/PKC pathway, while also suppressing the secretion of inflammatory factors through the NF-κB signaling pathway and ERK/JNK proteins.

Many drugs preferred for pain relief are insufficient against oxaliplatin (OX) induced neuropathic pain (OX-IN). Studies have shown that such pain mediators as the TRPV1 channel play a critical role in triggering high-sensitivity pain response in the dorsal root ganglia (DRG). TRPV1 activated by oxidative stress increases cytosolic free Ca2+ levels and leads to apoptotic cell damage. The key factors involved in the pathophysiology of OX-IN, which involves many components, are mitochondrial dysfunction and oxidative stress, both triggered by excessive Ca2+ influx across the neuronal membrane. Selenium (Se), an essential trace element, prevents the harmful effects of this oxidative stress through glutathione peroxidase. This study is based on understanding the neuroprotective role of Se, a cofactor for glutathione peroxidase, against TRPV1-mediated oxidative damage, mitochondrial dysfunction and apoptosis in OX-IN using molecular techniques such as patch clamp. The primary target in this study was DRGs as the initial station of OX-induced peripheral pain isolated in adult rats. In addition to the SN (sciatic) neurons isolated from the same animals, in vitro breast cancer cell (MCF-7) was also used to confirm the results. The study was conducted with four groups: control (5% dextrose), OX (4 mg/kg OX twice a week), Se (1.5 mg/kg Se every other day) and finally OX + Se, all of which were administered to the animals intraperitoneally for 4 weeks. The OX (50 μM for 24 h) and Se (200 nM for 2 h) were applied to MCF-7 cells in vitro. Although an excessive increase was observed in Tumour necrosis factor α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6), as well as mitochondrial oxidative stress, apoptosis and TRPV1 channel overactivations in DRG and SN neurons under OX treatment, Se suppressed these negative effects. While OX reduced glutathione peroxidase and significantly increased malondialdehyde level (LP) in DRG neurons, Se reversed this situation. In conclusion, the TRPV1-mediated efficacy of Se in suppressing OX-induced pain symptoms was demonstrated and we concluded that Se should be considered in future therapeutic approaches in the treatment of OX-IN.

Pain and itch are unpleasant and distinct sensations that give rise to behaviors such as reflexive withdrawal and scratching in humans and mice. Interestingly, it has been observed that pain modulates itch through the neural circuits housed in the brain and spinal cord. However, we have yet to fully understand the identities and mechanisms by which specific neural circuits mediate pain-induced modulation of itch. Independent studies indicate that brainstem nuclei such as the lateral parabrachial nucleus (LPBN), and rostral ventromedial medulla (RVM) are important for suppressing itch by noxious somatosensory stimuli. Here, using mouse and viral genetics, rabies tracing, chemogenetics, and calcium imaging, we show that the synaptic connections between LPBN and RVM play an instrumental role in the interactions between pain and itch. Notably, we found that the LPBN neurons that express the gene encoding the substance P receptor, Tacr1 (LPBNTacr1), synapse onto Tacr1-expressing RVM neurons (RVMTacr1). The RVMTacr1 neurons were found to be nociceptive, sufficient for inhibiting itch, and necessary for pain-induced itch suppression. Moreover, through brain-wide anterograde and retrograde viral tracing studies, we found that the RVMTacr1 neurons are bidirectionally connected with LPBN, periaqueductal gray (PAG), and lateral hypothalamic area (LHA). Thus, together, our data indicate that the RVMTacr1 neurons integrate nociceptive information to mediate itch-induced scratching and can mediate the physiological effects of itch through their downstream targets.

Moxibustion is a form of therapy that to warm the acupoints located skin by using dried mugwort leaves. It is widely used to treat gouty arthritis (GA). However, the mechanism of moxibustion on improving GA has not been fully revealed. In this study, we explore the mechanism of moxibustion on GA via metabolomics combined with traditional Chinese medicine (TCM) theory.

Three days before model induction, the rats of moxibustion groups were treated with moxibustion in the ST36 and SP6, and then, a GA rat model induced by monosodium urate (MSU) was established. Biological samples, including joint synovial tissue and serum samples, were collected and measured by histopathological staining, molecular biology assays and liquid chromatography-mass spectrometry (LC-MS)-based metabolomics.

We found that moxibustion could reduce the ankle edema induced by MSU crystals, decrease the expression of related proinflammatory genes, decrease the levels of serum IL-18 and IL-1β, and restore the metabolism of glycerol phospholipids, niacin and nicotinamide in GA model rats.

Moxibustion can regulate the metabolism of GA model rats widely to inhibit inflammation. Our research deepens our understanding of the complex mechanisms of moxibustion and promotes the application of moxibustion in the clinical practice.

Homeostasis and survival of various animal species have been affected by changes in environmental temperature, causing animals to evolve physiological systems for sensing ambient and body temperature. Temperature-sensitive transient receptor potential (TRP) channels have multimodal properties that are activated by physical stimuli such as temperature, as well as by various chemical substances. Our goal is to understand the diversity of the vertebrate thermosensory system by characterizing the temperature-sensitive TRPV channels of the elephant shark, which belongs to the Holocephali of the cartilaginous fishes. Since elephant sharks are basal jawed vertebrates, analysis of elephant shark TRPs is critical to understanding the evolution of thermosensory systems in vertebrate lineages. We found that temperature stimulation activated elephant shark TRPVs in an electrophysiological analysis similarly to the mammalian ortholog. The thermal activation threshold of elephant shark TRPV1 (31°C) was similar to the thresholds reported for several other fish species, but was much lower than that of mammalian orthologs. Strikingly, the elephant shark TRPV4 was a cooling-activated channel with a threshold of 20°C, whereas, in several tetrapods, it is activated by warmth. These results suggest that the temperature sensitivity of TRPV4 has changed in vertebrate evolutionary lineages. Furthermore, we also found the elephant shark possesses heat-evoked TRPV3 with a threshold of 42°C, which is absent in more derived teleost fishes. Taken together, our findings elucidate that the vertebrate-type thermosensory system has already emerged in the common ancestor of jawed vertebrates, although their temperature-sensing ranges were different from those of mammals.

In this review, we introduce the concept of "dual thermosensing mechanisms," highlighting the functional collaboration between G protein-coupled receptors (GPCRs) and transient receptor potential (TRP) channels that enable sophisticated cellular thermal responsiveness. GPCRs have been implicated in thermosensory processes, with recent findings identifying several candidates across species, including mammals, fruit flies, and nematodes. In many cases, these GPCRs work in conjunction with another class of thermosensors, TRP channels, offering insights into the complex mechanisms underlying thermosensory signaling. We examine how GPCRs function as thermosensors and how their signaling regulates cellular thermosensation, illustrating the complexity of thermosensory systems. Understanding these dual thermosensory mechanisms would advance our comprehension of cellular thermosensation and its regulatory pathways.

While benzodiazepines have been a mainstay of the pharmacotherapy of anxiety disorders, their short-term efficacy and risk of abuse have driven the exploration of alternative treatment approaches. The endocannabinoid (eCB) system has emerged as a key modulator of anxiety-related processes, with evidence suggesting dynamic interactions between the eCB system and the GABAergic system, the primary target of benzodiazepines. According to the existing literature, the activation of the cannabinoid receptors has been shown to exert anxiolytic effects, while their blockade or genetic deletion results in heightened anxiety-like responses. Moreover, studies have provided evidence of interactions between the eCB system and benzodiazepines in anxiety modulation. For instance, the attenuation of benzodiazepine-induced anxiolysis by cannabinoid receptor antagonism or genetic variations in the eCB system components in animal studies, have been associated with variations in benzodiazepine response and susceptibility to anxiety disorders. The combined use of cannabinoid-based medications, such as cannabinoid receptor agonists and benzodiazepine co-administration, has shown promise in augmenting anxiolytic effects and reducing benzodiazepine dosage requirements. This article aims to comprehensively review and discuss the current evidence on the involvement of the eCB system as a key modulator of benzodiazepine-related anxiolytic effects, and further, the possible mechanisms by which the region-specific eCB system-GABAergic connectivity modulates the neuro-endocrine/behavioral stress response, providing an inclusive understanding of the complex interplay between the eCB system and benzodiazepines in the context of anxiety regulation, to inform future research and clinical practice.

Caffeic acid phenethyl ester (CAPE) is a hydrophobic phytochemical typically found in propolis that acts as an antioxidant, anti-inflammatory and cardiovascular protector, among several other properties. However, the molecular entity responsible for recognising CAPE is unknown, and whether that molecular interaction is involved in developing an antioxidant response in the target cells remains an unanswered question. Herein, we hypothesized that a subfamily of TRP ion channels works as the molecular entity that recognizes CAPE at the plasma membrane and allows a fast shift in the antioxidant capacity of intact endothelial cells (EC). By monitoring cytoplasmic Ca2+ in a microvascular EC model, we compared the calcium responses evoked by three structurally related compounds: caffeic acid phenethyl ester, neochlorogenic acid and caffeic acid. Only CAPE induced rapid and transient calcium responses at nanomolar concentrations together with a gradual increase in cytoplasmic sodium levels, suggesting the activation of a non-selective cationic permeation at the plasma membrane. Electrophysiological as well as pharmacological, and RNA silencing assays confirmed the involvement of TRPV1 in the recognition of CAPE by ECs. Finally, we demonstrated that Ca2+ influx by TRPV1 was necessary for recording CAPE-induced cytoplasmic redox changes, a phenomenon captured in real-time in ECs expressing the HyPer biosensor. Our data depict a molecular mechanism behind the antioxidant effect of CAPE in endothelial cells, connecting the activation of TRPV1 ion channels, cytoplasmic calcium increase, and a reduction of disulfide bonds on a redox biosensor. This phenomenon occurs within seconds to minutes and contributes to a better understanding of the mechanisms underlying the vasodilatory effect of CAPE and other compounds that interact with TRPV1 in the vascular bed.

Mouthfeel is vital in consumer acceptance of foods and beverages. Despite the critical role mouthfeel plays in product development, the concept is often poorly understood and subject to various interpretations. Within this review, five topics of interest are discussed to provide a better understanding of the mouthfeel attribute-the definition, the perception, the importance, the influencing factors, and the methods of measurement of mouthfeel. Mouthfeel encompasses multiple attributes. Although mouthfeel attributes perceived through physical and chemical perceptions, such as cooling and heating, are understood as mouthfeel, attributes perceived through mechanoreceptors, such as creaminess and thickness, are more challenging due to varying opinions on texture and mouthfeel. Other factors, like food composition and temperature, are also vital in understanding the overall effect of mouthfeel in food and beverages. Including all perceived attributes and factors is important for consumer acceptance of products and for developing consistent evaluation of products. Other topics to consider include the dynamic aspects of oral processing and cultural backgrounds as these topics create additional intricacies in defining and understanding mouthfeel perception. Despite the lack of instrumental methodology available to measure mouthfeel attributes, trained panelists can be used to predict facets of mouthfeel in the eating experience. When designing sensory testing for trained panelists, experimental conditions and a product-specific lexicon are important factors to consider. Overall, understanding of the mouthfeel attributes and their role in consumer preference for different types of food and beverages continues to evolve.

SUMOylation is a post-translational modification that attaches a small ubiquitin-like modifier (SUMO) group to a target protein via SUMO ligases, while deSUMOylation refers to the removal of this SUMO group by sentrin-specific proteases (SENPs). Although the functions of these processes have been well described in the nucleus, the role of SUMOylation and deSUMOylation in regulating ion channels is emerging as a novel area of study. Despite this, their contributions to pain signaling remain less clear. Therefore, this review consolidates the current evidence on the link(s) between SUMOylation, deSUMOylation, and pain, with a specific focus on ion channels expressed in the sensory system. Additionally, we explore the role of SUMOylation in the expression and function of kinases, vesicle proteins, and transcription factors, which result in the modulation of certain ion channels contributing to pain. Altogether, this review aims to highlight the relationship between SUMOylation and deSUMOylation in the modulation of ion channels, ultimately exploring the potential therapeutic role of these processes in chronic pain.

Transient receptor potential melastatin 2 (TRPM2) is a non-selective cation channel with high Ca2+ permeability. TRPM2 exhibits temperature sensitivity, detecting warm to noxious high temperatures. This temperature sensitivity is regulated by several endogenous factors, including reactive oxygen species, adenosine diphosphate ribose, Ca2+ ions, and TRPM2 phosphorylation by protein kinase C, which alter TRPM2 activity at body temperature. Consequently, at core body temperature, TRPM2 regulates the physiological functions of TRPM2-expressing cells and tissues, such as immunocytes, pancreatic β cells, and the brain. In contrast, TRPM2 in sensory neurons detects warm temperatures. The current review summarizes the regulatory mechanisms of TRPM2 and its roles in physiological processes, focusing on temperature-dependent phenomena.

The prevalence of gastrointestinal disorders caused by alcohol, Helicobacter pylori, non-steroidal anti-inflammatory drugs, chronic stress and sedentary lifestyle is on the rise. Calcitonin gene-related peptide (CGRP), a 37-amino acid neuropeptide, has emerged as a protective factor against various gastrointestinal issues. Despite its known benefits, the dual role of CGRP in gastrointestinal damage remains unclear. Discovered 30 years ago through alternative RNA processing of the calcitonin gene, CGRP is known to be a potent vasodilator involved in crucial defensive mechanisms for both physiological and pathological conditions. Promising evidences from preclinical research have attracted the interest of scientists for the exploration of CGRP as a therapeutic neuropeptide. Numerous evidences suggest that this neuropeptide is secreted by the neurons under the influence of endogenous as well as exogenous stimuli. CGRP repairs the gastric mucosal barrier and maintain mucosal integrity by suppressing NF-κB activation, thereby reducing tumour necrosis factor-alpha expression. In addition, recent studies suggest that CGRP modulates immune responses and enhances epithelial cell proliferation, further contributing to its cytoprotective effects. Consequently, CGRP and the CGRP secretagogues represent promising novel targets for clinical applications. This review aims to elucidate the role of CGRP and CGRP secretagogues in the management of gastrointestinal disorders, highlighting its potential as a therapeutic agent in the context of evidence-based modern gastroenterology.

Broad-range thermal receptor 1 (BRTNaC1), activated by heat at low extracellular pH, was recently identified in myriapods. Although the overexpression of BRTNaC1 leads to robust heat-activated current with a cation selectivity profile, the structure of this receptor and how it is gated by proton and heat remain to be investigated. Here we determine cryogenic electron microscopy structures of BRTNaC1 in the apo, proton-induced and heated states. Based on these structures, patch-clamp recordings and molecular dynamic simulations, we found that a 'twist the wrist' mechanism is used for proton activation of BRTNaC1, while heat induces broad conformational changes in BRTNaC1, including rotation and shift in the transmembrane helices to open this channel. Moreover, as testosterone inhibited BRTNaC1 activation, we identified four clustered residues important for such inhibition. Therefore, our study has established the structural basis for ligand and temperature gating in the BRTNaC1 ion channel.