Intracisternal injection of apolipoprotein A-IV inhibits gastric secretion in pylorus-ligated conscious rats.

BACKGROUND/AIMS: Fat feeding increases not only serum but also cerebrospinal fluid concentration of apolipoprotein (apo) A-IV, a protein produced mainly by the small intestine in the rat. We hypothesized that apo A-IV may have a central effect on gastric secretion.

METHODS

Gastric juice was collected by the pylorus ligation method. Rats underwent pylorus ligation and received intracisternal injection of apo A-IV under brief isoflurane anesthesia. Two hours after the injection, gastric juice was collected and gastric acid output determined.

RESULTS

Intracisternal injection of 0.5 microgram apo A-IV had no effect on gastric secretion. However, gastric acid secretion was significantly inhibited by intracisternal injection of 1 microgram apo A-IV. Furthermore, intracisternal administration of higher doses of apo A-IV (2.0 and 4.0 microgram) resulted in greater inhibition of gastric acid secretion in a dose-dependent manner. On the contrary, 4 micrograms of apo A-I intracisternally injected failed to inhibit gastric acid secretion. Intraperitoneal administration of 15 micrograms of apo A-IV did not alter gastric secretion.

CONCLUSIONS

These results suggest that apo A-IV may act in the brain to inhibit gastric acid secretion. Apo A-IV might be a central enterogastrone, which is a gastric inhibitor produced by the small intestine in response to fat feeding.