CRF IN THE PARAVENTRICULAR NUCLEUS MEDIATES GASTRIC AND COLONIC MOTOR RESPONSE TO RESTRAINT STRESS

The role of corticotropin-releasing factor (CRF) in the paraventricular nucleus of the hypothalamus (PVN) in the control of gastric emptying of a nonnutrient meal and colonic transit was investigated in conscious fasted rats chronically implanted with hypothalamic cannulas and catheters in both the stomach and proximal colon. CRF (0.06-0.6 nmol) microinfused unilaterally into the PVN resulted in a dose-dependent inhibition of gastric emptying (0-51%) and stimulation of colonic transit (0-93%). CRF (0.6 nmol)-induced delay in gastric emptying was inhibited by 50% by subdiaphragmatic vagotomy or atropine methyl nitrate (1 mg/kg ip), whereas the stimulation of colonic transit was completely abolished by atropine methyl nitrate and reduced by 19% by vagotomy. Microinfusion of CRF (0.6 nmol) into the lateral hypothalamus or central amygdala had no effect. Restraint exposure for 1 h delayed gastric emptying and stimulated colonic transit by 28 and 78%, respectively. Bilateral microinfusion of the CRF antagonist alpha-helical CRF-(9-41) (13 nmol) into the PVN before restraint abolished stress-induced alterations of gastric and colonic transit. The CRF antagonist did not alter basal gastric and colonic transit under basal conditions. These data indicate that the PVN is a specific responsive site for central CRF-induced alterations of gastric and colonic transit and suggest that endogenous CRF in the PVN plays a role in mediating restraint stress-related alterations of gastrointestinal transit.