Effect of intracerebroventriculary- injected glucagon-like peptide-1 on gastric mucosal blood flow in rats

In this study, the effects of intracerebroventricularly (i.c.v) injected glucagon like peptide-1 (GLP-1) on gastric mucosal blood flow (GMBF) the role of its central-specific receptors in this effect, and also its effects on changes in GMBF induced by intragastric absolute ethanol were investigated in rats. A total of-64 male Sprague-Dawley rats weighing 200-300 g were used throughout the experiments. Under isoflurane (4%) anesthesia, cannulas for i.s.v. injections were placed on the skull of rats. GMBF was measured by Laser Doppler flowmeter, and the data was collected by computer using "MP30 Data Acquisition" System. After preparation of the stomach for GMBF recording, a probe was placed in the gastric mucosa and basal GMBF recordings were obtained after 30-minute stabilization period. Rats were treated with GLP-1 (3, 10 and 30 µg/10 µl; i.c.v.) or saline (10 µl; i.c.v.) to find out the effective dose of i.c.v. GLP-1 on GMBF. Then specific receptor antagonist exendin- (9-39) (1 µg/10 µl; i.c.v.) was injected before the effective dose of i.c.v. GLP-1. Subsequent to those injections saline was introduced into the gastric chamber and GMBF was recorded every fifth minute during the next 30 min. In order to confirm the effect of GLP-1 on intraluminal absolute-ethanol-induced changes in GMBF, ethanol (1,5 ml) was administrated into the gastric chamber in rats following 5 min of GLP-1 injection. 10 µg i.c.v. GLP-1 increased the GMBF and i.c.v. exendin- (9-39) antagonized this effect. In addition, GLP-1 reduced the inhibition of absolute ethanol on GMBF. Consequently, we suggest that, i.c.v. GLP-1 increases GMBF and its central specific receptors mediate this effect. İn addition i.c.v. GLP-1 reduced the intraluminal ethanol-induced inhibition of GMBF.