Effects of ARC-hippocampus obestatin neural pathway on gastric motility and gastric emptying in diabetic rats

Abstract

Objective: To investigate the obestatin neural projections from arcuate nucleus (ARC) to hippocampus in diabetic rats, and its effects on gastric motility and gastric emptying of rats. Methods: Diabetic model was established by fructose intake combined with streptozotocin injected intraperitoneally in healthy male Wistar rats. Diabetic rats were randomly divided into five groups: control group (NS group), 0.1, 1 and 10 pmol obestatin group, and obestatin + NBI27914 group, with 7 rats in each group. 0.5 μl saline (NS), obestatin (0.1 pmol, 1 pmol, 10 pmol) or the mixture (10 pmol obestatin + 60 pmol NBI27914) was injected into the hippocampus respectively, the gastric motility was recorded immediately after administration, and the gastric emptying was studied 15 min later. ARC-hippocampus obestatin neural pathway and ARC obestatin mRNA expression were compared between normal and diabetic rats with fluorogold (FG) retrograde tracing and immunofluorescence histochemical staining. Results: Compared with normal rats, the number of ARC FG/obestatin double labeled neurons and the expression level of ARC obestatin mRNA were decreased significantly in diabetic rats (P＜0.05); Obestatin could inhibit gastric motility and gastric emptying in a dose-dependent manner (P＜0.05~0.01) and the effects of obestatin could be partially blocked by NBI27914, an antagonist of corticotropin releasing factor receptor 1 (CRFR1) (P＜0.05). Compared with normal rats, the inhibitory effects of obestatin on gastric motility and gastric emptying were significantly decreased in diabetic rats (P＜0.05). Conclusion: There is an obestatin neural pathway between ARC and hippocampus, which participates in the regulation of gastric motility and gastric emptying in diabetic rats, and CRFR1 signal pathway is involved in this process. The damage of this neural pathway may participate in gastric motility dysfunction in early stage of diabetes.