Abstract: KA8 is a C-terminal octapeptide (30-37) of oxyntomodulin and glicentin. KA8 could inhibite gastric secrection. But it is not clear if KA8 is able to inhibite gastric secrection induced by cold-restraint and TRH administration in intracerebroventricle. We designed two experiments. All the rats were fasted for 24 h before experiment. The rats with light ether anaesthesia were undertook the operation of pylorus and cardia ligation. After the rats remained consciousness, the rats were divided into two groups. One Was injected by iv KA8 (60μg/kg), another was gaven NS as control, then the rats were sxposed 4 C enviroment for 2 hours. In the second experiment, the rats were implanted with tube in cerebro-ventricle before one week. The rats were administrated TRH (60μg/kg) through the tube and divided into two groups. One was injected by iv KA8, another Was received NS as a control. Each rat was placed in separated cage for 4 hours. All rats were decapitated and plasmas were stored in -20℃ for gastrin determination. The resoults shown that KA8 could significantly inhibited gastric secretion not only for rats exposed to cold, but also for TRH icy administration. But KA8 was not able to infulence the plasma concentration of pentogastrin. It suggest that KA8 inhibit gastric secretion but the biologica activity of KA8 is not associated with pentogastrin.

Key words: KA8, oxyntomodulin, cold-restraint, TRH, Gastric acid