Comparative study on anorexigenic effect of glucagon-like peptide-1 receptor agonists in rats.

Glucagon-like peptide-1 (GLP-1) expression is shared by both intestinal cells and neurons of brainstem, which plays anorexigenic role on food intake. However, the exact source of physiological GLP-1 influencing food intake and pertinent mechanism of GLP-1 receptor agonists (GLP-1RA) remain unelucidated. In this study, the immediate early gene product c-Fos was chosen as the specific antigen for immunohistochemistry to show the certain areas of central nervous system (CNS) activation by the GLP-1RA. Thirty normal SD rats were randomly assigned to 3 groups, which were single intraperitoneally injected with Liraglutide (200 µg/kg), Exenatide (10 µg/kg) and saline, respectively. After injection, the amount of food intake and acute glycemic variation were assessed for comparison. The results showed that acute pharmacological dosage of GLP-1RA (Liraglutide or Exenatide) could significantly influence food intake. However, glycemic change indicated that the anorexic effect was dissociated with change in blood glucose in normal rats. Moreover, c-Fos was expressed significantly higher in major critical nuclei related to food intake in GLP-1RA groups when compared with the control group, and its expression was also found in spinal cord. The results suggested that acute administration of pharmacological doses of GLP-1 influences CNS via circulation and vagal pathways, especially on the arcuate nucleus (ARC) and the nucleus of solitary tract (NTS), and GLP-1 modulates autonomic nervous activities.

[Relationship between gastrointestinal dyskinesis and gastrointestinal neurons in diabetic mellitus: experiment with rats].

OBJECTIVE: To investigate the relationship between gastrointestinal dyskinesis and histologic changes of gastrointestinal myenteric plexus cholinergic and nitrergic neurons in STZ-induced diabetic rats. METHODS: 45 SD rats were randomly divided into control group, diabetic group and insulin group. 16 weeks after diabetic model established, gastrointestinal motility of rats was measured and histologic changes of myenteric plexus cholinergic neuron and nitrergic neuron was observed. RESULTS: Compared with control group, gastrointestinal motility of diabetic group was markedly slow (P < 0.01), the myenteric plexus cholinergic neuron counting of gastric antrum and small intestine were significantly decreased (6.6 +/- 2.9 vs 15.7 +/- 3.8 15.6 +/- 10.3 vs 22.6 +/- 7.4, P < 0.01), yet the number of nitrergic neuron only markedly reduced in gastric antrum (5.3 +/- 1.2 vs 11.8 +/- 2.2, P < 0.01). The gastrointestinal mobility, gastric antrum nitrergic neuron and small intestine cholinergic neuron counting of insulin group were markedly higher than that of diabetic group (P < 0.05), yet lower than that of control group (P < 0.01). CONCLUSION: The gastrointestinal dyskinesis of STZ-induced diabetic rats might be associated with lesions of gastrointestinal myenteric plexus cholinergic neuron and nitrergic neuron. Insulin intensive therapy can partly ameliorate diabetic gastrointesternal dyskinesis.