4TH VENTRICLE INJECTION OF CORTICOTROPIN-RELEASING FACTOR AND GASTRIC-EMPTYING OF GLUCOSE DURING GASTRIC FILL

The effect of corticotropin-releasing factor (CRF) administered into t he fourth ventricle on the gastric emptying of a 12-ml intragastric in fusion of 12.5% D-glucose was examined in nondeprived male rats. All t hree CRF doses tested (10, 100, and 1,000 pmol) significantly reduced (by 28, 29, and 44%, respectively) the amount of glucose emptied from the stomach at the end of the 12-min (1.0 ml/min) gastric infusion int erval. The 10 pmol effective dose is the lowest yet reported to influe nce gastric emptying. The receptor specificity of the exogenous CRF (1 ,000 pmol) effect was demonstrated by its complete blockade by preinje ction of alpha-helical CRF-9-41 (10 nmol) into the fourth ventricle. I njection of the antagonist alone, however, did not affect glucose empt ying, indicating little activation of the targeted receptors under the present nonstressful, baseline conditions. Our results suggest that o f the central CRF receptor systems that influence gastric emptying, th ose in the caudal brain stem, targeted by fourth ventricular injection , may be of particular importance.