Effects of neuroendocrine peptides on gastric dysmotility in diabetic mellitus

Objective To investigate the relationship between contractive activity of isolated gastric antrum smooth muscle and the change of somatostatin(ss), vasoactive intestinal peptide (VIP), motilin(MTL), substance P (SP) in diabetic mellitus rats. Methods Twenty male Sprague-Dawley rats were divided into two groups: the control(n=10) and the experimental(n=10). The resting tension, the mean contractile amplitude and frequency of spontaneous changes of isolated longitudinal, circular gastric antrum smooth muscle strips were measured by transducer, and SS, VIP, MTL, SP levels in plasma and gastric antrum tissue extracts were measured by radioimmunoassay. Results In isolated gastric antrum smooth muscle strips, the motility parameters were significantly decreased in diabetic rats than those in control(P0.01). In diabetic rats, the plasma levels of SS, VIP and MTL were higher than those in control(P0.01, P0.05), while SP level was decreased(P0.05). In the gastric antrum, the level of SS was significantly higher than in the controls (P0.01). The levels of SP and MTL were lower than those of the controls (P0.05, P0.01). The level of VIP did not differ from that in the controls (P0.05). In diabetic rats, there were negative correlations between the plasma, tissue SS levels and the motility parameters of gastric antrum strips, and the plasma VIP and MTL had negative correlations with the motility parameters of gastric antrum strips, but the VIP and MTL level of gastric tissue had no correlation with strip motility parameters. The plasma and tissue SP level had no excellent correlation with gastric strip motility parameters. Conclusion Diabetic rats have gastrointestinal dysfunction and it is related with the disturbed neuroendocrine peptides. The changes of these peptides' levels in plasma and gastric tissue may play some roles in the gastric motility disorders of diabetes mellitus.