Noradrenaline release in hypothalamus and ACTH secretion induced by central interleukin-1β

Abstract

THE effect of interleukin-lβ (IL-1β, 10 ng per 5μl i.c.v.) on noradrenaline release in the hypothalamus of freely moving rats and on plasma ACTH levels has been studied, respectively by intracerebral microdialysis and radioimmunoassay. IL-1β induced an early increase in noradrenaline (NA) release in the paraventricular nucleus (PVN) followed by a second long-lasting enhancement starting from 80 min, with a maximum at 140 min (187 ± 14%). Heat-denatured IL-1β induced only the early increase without any other change at later times. IL-1β did not significantly affect NA release in the area surrounding the PVN at any time. IL-1β increased ACTH levels at 2 and 3 h. Indomethacin (10 mg kg-1, i.p.) prevented the noradrenergic and ACTH responses. The NA system in the PVN plays a part in the mechanism controlling the ACTH response induced by IL-1.