INTRACISTERNAL INJECTION OF APOLIPOPROTEIN A-IV INHIBITS GASTRIC-SECRETION IN PYLORUS-LIGATED CONSCIOUS RATS

Background/Aims: Fat feeding increases not only serum but also cerebro spinal fluid concentration of apolipoprotein (apo) A-IV, a protein pro duced mainly by the small intestine in the rat. We hypothesized that a po A-IV may have a central effect on gastric secretion. Methods: Gastr ic juice was collected by the pylorus ligation method. Rats underwent pylorus ligation and received intracisternal injection of apo A-IV und er brief isoflurane anesthesia. Two hours after the injection, gastric juice was collected and gastric acid output determined. Results: Intr acisternal injection of 0.5 mu g apo A-IV had no effect on gastric sec retion. However, gastric acid secretion was significantly inhibited by intracisternal injection of 1 mu g apo A-IV. Furthermore, intracister nal administration of higher doses of apo A-IV (2.0 and 4.0 mu g) resu lted in greater inhibition of gastric acid secretion in a dose-depende nt manner. On the contrary, 4 mu g of apo A-I intracisternally injecte d failed to inhibit gastric acid secretion. Intraperitoneal administra tion of 15 mu g of apo A-IV did not alter gastric secretion. Conclusio ns: These results suggest that apo A-IV may act in the brain to inhibi t gastric acid secretion. Apo A-IV might be a central enterogastrone, which is a gastric inhibitor produced by the small intestine in respon se to fat feeding.