Published online Sep 7, 2017. doi: 10.3748/wjg.v23.i33.6088
Peer-review started: April 27, 2017
First decision: June 8, 2017
Revised: July 21, 2017
Accepted: August 2, 2017
Article in press: August 2, 2017
Published online: September 7, 2017
Processing time: 133 Days and 13.2 Hours
Influence of chronic hyperglycemia on chemical coding of enteric neurons in stomach using pig as a model for human diabetic complications.
Ten pigs were divided into two groups: diabetic (D group, n = 5) and control (C group, n = 5). Pigs constituting the experimental group were given streptozotocin (150 mg/kg). Animals were euthanized six weeks after the induction of diabetes. The samples of stomach were collected from animals of both groups. The cryostat sections were processed for double immunofluorescence staining using primary antisera directed towards pan-neuronal marker (Hu C/D) proteins and/or neuronal isoform of nitric oxide synthase (nNOS), vasoactive intestinal peptide (VIP) and galanin (GAL).
In the control group in the myenteric ganglia (MG) of the corpus we have noted 22.28% ± 1.19% of nNOS positive neurons, while in diabetic group we have found 40.74% ± 2.22% of nNOS immunoreactive perikarya (increase by 82.85 %). In turn in the pylorus we have observed 15.91% ± 0.58% nNOS containing neurons in control animals and 35.38% ± 1.54% in the diabetes group (increase by 122.37%). In the MG of the antrum and submucosal ganglion (SG) in the corpus hyperglycemia did not cause statistically significant changes. With regard to VIP-positive cell bodies in the antrum MG in the control animals we have noted 18.38 ± 1.39% and 40.74% ± 1.77% in the experimental group (increase by 121.65%). While in the corpus we have observed 23.20% ± 0.23% in the control and 30.93% ± 0.86% in the diabetes group (increase by 33.31%). In turn in the pylorus VIP positive cells bodies constituted 23.64% ± 1.56% in the control group and 31.20% ± 1.10% in the experimental group (increase by 31.97%). In the submucosal ganglion in the corpus we have noted 43.61% ± 1.06% in the control animals and 37.00% ± 1.77% in the experimental group (decrease by 15.15%). Expression of GAL-positive perikarya showed statistically significant changes only in the MG of the antrum and pylorus. In the antrum GAL positive perykarya constituted 26.53% ± 1.52% in the control and 36.67% ± 1.02% in the experimental animals (increase by 38.22%). While in the pylorus GAL positive neurons in the control group constituted 16.32% ± 0.92% and 17.99% ± 0.38% in the experimental animals (increase by 10.23%).
Our results support the hypothesis that in the course of diabetes, long term episodes of high glucose serum level may influence the chemical phenotyping of enteric neurons.
Core tip: Our results revealed the neuronal plasticity of enteric neurons within porcine stomach in response to chronic hyperglycemia. We used the pig as a model for human gastrointestinal disorders occurring in people with diabetes. Our study highlights the important role of the enteric nervous system in response to high glucose serum level. We observed a substantial increase in the expression of nitric oxide, galanin and vasoactive intestinal peptide inside the enteric neurons. Since all of the investigated molecules have inhibitory properties, they may be involved in the impairment of the motor function of the stomach occurring in people with long-term diabetes.