Neurophysiological mechanisms of electroacupuncture in regulating pancreatic function and adipose tissue expansion

Figure 1 Electroacupuncture modulates the trophic influence of peripancreatic adipose tissue on the pancreatic intrinsic nervous system. A: Histological alterations in pancreatic tissue and ectopic fat deposition in the pancreas across experimental groups (200 × magnification). Blue arrows indicate vacuolar-like changes; B: Comparative analysis of peripancreatic adipose tissue (PAT) blood perfusion between the control and model groups; C: Immunohistochemical staining for NGF in PAT under high magnification for the different groups (400 × magnification). Scale bar represents 50 μm; D: Illustrative immunofluorescence images showing co-expression of NGF and tyrosine hydroxylase (TH) in all groups (200 × magnification). Red fluorescence denotes NGF, while green fluorescence indicates TH. A uniform scale bar is applied to all groups; D: Pearson correlation analysis between NGF and TH expression (n = 5); E: Illustrative immunofluorescence images showing co-expression of NGF and TH in all groups (200 × magnification); F and G: Representative Western blot bands for NGF; F and H: Vascular endothelial growth factor (VEGF) in PAT. Vinculin served as a loading control; I-L: PAT blood flow changes during electroacupuncture stimulation at acupoints ST25, LI11, and ST37 in normal rats, respectively. ^aP < 0.05 compared to the normal control group; ^bP < 0.05 compared to the model or alternative treatment group. TH: Tyrosine hydroxylase; ST25: Tianshu acupoint; LI11: Quchi acupoint; ST37: Shangjuxu acupoint.

Figure 2 Electroacupuncture modulates inflammatory mediators in peripancreatic adipose tissue, enhancing metabolic function. A and B: Electroacupuncture (EA)'s impact on the expression of F4/80 (also known as EGF-like module-containing mucin-like hormone receptor-like 1); A and C: Influence of EA on MCP-1 levels; A and D: Changes in interleukin (IL)-1β expression due to EA treatment; A and E: EA's effect on IL-10 expression; F and G: Expression levels of PPAR-γ following EA intervention; F and H: Adipose tissue expression of FABP4 in response to EA; F and I: TRPV1 expression in PAT after EA treatment. Vinculin served as a loading control; J: Representative immunofluorescence images of co-expression of FABP4 and TRPV1 in the pancreas of the model group (200 × magnification). Blue fluorescence representing FABP4, and TRPV1 is represented by purple fluorescence; K: Quantitative analysis of the co-localization of FABP4 and TRPV1 immunofluorescence, indicating a correlation between the two proteins. ^aP < 0.05 compared to the normal control group; ^bP < 0.05 compared to the model or another treatment group.

Figure 3 TRPV1-mediated acupuncture modulates the discharge patterns of the pancreatic intrinsic nervous system. A and B: The impact of manual acupuncture (MA) at Tianshu (ST25) acupoint on pancreatic intrinsic nervous system (PINS) activity and the corresponding discharge frequency in wild-type (WT) mice; C and D: The influence of MA at ST25 on PINS activity and discharge frequency in TRPV1 knockout (TRPV1^-/-) mice; E and F: The effect of MA at ST25 on peripancreatic adipose tissue (PAT) activity and associated discharge frequency in WT mice; G and H: The alteration in PAT activity and discharge frequency following MA at Tianshu (ST25) acupoint in TRPV1^-/- mice (n = 7). ^aP < 0.01 compared to the dur-MA group; ^bP < 0.01 compared to the pre-MA group and MA, manual acupuncture. TRPV1: Transient receptor potential vanilloid subfamily member 1; MA: Manual acupuncture.

Figure 4 TRPV1-mediated enhancement of metabolic function by electroacupuncture. A: Representative immunofluorescence images of pancreatic tissue across experimental groups. The nuclei are visualized in blue by 4',6-diamidino-2-phenylindole (DAPI), with green immunofluorescence indicating the presence of TRPV1. Islets were examined at 630 × magnification. A uniform scale bar of 25 μm applies to all groups; B: Representative immunofluorescenc images of the dorsal root ganglion across groups. Nuclei are stained blue by DAPI, with green immunofluorescence representing TRPV1 and red immunofluorescence representing insulin; C: Percentage of pancreatic TRPV1+ nerve fibers in each group; D: Illustrative immunofluorescence images showing co-expression of TRPV1 and INS in all groups. ^aP < 0.05 compared to the normal control group; ^bP < 0.05 compared to the model group. TRPV1: Transient receptor potential vanilloid subfamily member 1; INS: Insulin; DAPI: 4',6-diamidino-2-phenylindole.

Figure 5 Modulation of pancreatic function by TRPV1 neuronal pathways in electroacupuncture-treated t10 dorsal root ganglion. A: Representative immunofluorescence images illustrating co-expression of insulin (INS) and CGRP in the pancreas at 200 × magnification. Nuclei are stained blue with 4',6-diamidino-2-phenylindole, with red representing INS and green representing CGRP immunofluorescence; B-D: Electrophysiological activity measurements of the T10 DRG in model mice under different conditions: Untreated model, TRPV1 knockout (TRPV1^-/-) in T10 DRG, and TRPV1^-/- in T10 DRG followed by electroacupuncture (EA) at the ST25 acupoint; E: Discharge frequency associated with the groups mentioned in B-D; F-H: Impact of EA on the expression levels of TRPV1 and INS in the pancreas following capsazepine injection into the T10 DRG. GAPDH served as an internal reference protein. ^aP < 0.05 compared to the model or another treatment group. INS: Insulin; DAPI: 4',6-diamidino-2-phenylindole; ST25: Tianshu acupoint.

Figure 6 TRPV1 knockout preserves immunometabolic homeostasis in peripancreatic adipose tissue and pancreas. A-F: Impact of electroacupuncture (EA) on the levels of insulin receptor, EGF-like module-containing mucin-like hormone receptor-like 1 (F4/80), interleukin (IL)-10, IL-1β, and insulin in peripancreatic adipose tissue following TRPV1 knockout; G-I: Influence of EA on the expression levels of TRPV1 and calcitonin gene-related peptide-receptor component protein (CGRP) in the pancreas. Vinculin served as loading controls; J: Representative immunofluorescence images of co-expression of TRPV1 and CGRP in the islets of the ST25 group (200 × magnification). Nuclei were stained with 4',6-diamidino-2-phenylindole (blue), TRPV1 is represented by red immunofluorescence, and CGRP by green immunofluorescence; K: Correlation between TRPV1 and CGRP expression as revealed by quantitative analysis of the co-localization of TRPV1 and CGRP immunofluorescence. ^aP < 0.05 compared to the normal control group; ^bP < 0.05 compared to the model or another treatment group. IL: Interleukin; EA: Electroacupuncture