Interleukin-1 beta acts at hypothalamic sites to inhibit gastric acid secretion in rats

It has been established that interleukin-1 beta (IL-1 beta) injected into the cerebrospinal fluid inhibits gastric acid secretion in rats. Brain sites of action of IL-1 beta were investigated in conscious rats implanted unilaterally with chronic hypothalamic cannula. Gastric acid secretion was monitored 2 h after pylorus ligation. Human recombinant IL-1 beta (10 ng) microinjected into the medial preoptic area, anterior hypothalamus, and paraventricular nucleus inhibited gastric acid secretion by 76-83%. IL-1 beta microinjected into the ventromedial hypothalamus and other hypothalamic sites outside of responsive sites had no effect. IL-1 beta inhibitory action in the medial preoptic area was dose related (0.1-10 ng), prevented by indomethacin (5 mg/kg ip), and mimicked by prostaglandin E2. These results show that IL-1 beta acts in the medial preoptic area/anterior hypothalamus and paraventricular nucleus to inhibit acid secretion in pylorus-ligated rats and that IL-1 beta action is likely to involve prostaglandin E2.