INTERLEUKIN-1-BETA IN THE DORSAL VAGAL COMPLEX INHIBITS TRH ANALOG-INDUCED STIMULATION OF GASTRIC CONTRACTILITY

The effect of murine interleukin-1 beta (mIL-1 beta) microinjected int o the dorsal vagal complex (DVC) on thyrotropin-releasing hormone (TRH ) analogue (RX-77368)-induced stimulation of gastric contractility was examined in fasted, urethan-anesthetized rats. Gastric corpus contrac tions were measured with extraluminal force transducers and analyzed b y computer. Microinjection of RX-17368 (30 ng) into the right DVC with mIL-1 beta microinjected either into the right (100, 250 pg) or into the left (100, 500 pg) DVC inhibited gastric contractility for 30-120 min postinjection. Peak suppression of gastric contractility (64-78%) occurred at 50-60 min postinjection. Microinjedion of mIL-1 beta into the DVC at a lower dose (10 pg) or into sites adjacent to the DVC (100 -500 pg) did not suppress the stimulated gastric contractility pattern . Injection of mIL-1 beta (250 pg) or 0.1% bovine serum albumin into t he DVC alone did not alter basal gastric contractlity. Intracisternal injection of the IL-1 receptor antagonist (250 ng/10 mu l) abofished t he inhibitory effect of mIL-1 beta (250 pg) on gastric contractility. These results demonstrate that mIL-1 beta acts in the DVC to inhibit v agally stimulated gastric contractility, and its action is mediated by IL-1 receptors.