EFFECTS OF AREA POSTREMA LESION AND ABDOMINAL VAGOTOMY ON INTERLEUKIN-1-BETA-INDUCED NOREPINEPHRINE RELEASE IN THE HYPOTHALAMIC PARAVENTRICULAR NUCLEUS REGION IN THE RAT

Peripherally administered interleukin-1 beta (IL-1 beta) has been show n to increase extracellular norepinephrine (NE) concentration in the p araventricular nucleus (PVN) of the hypothalamus. The present study wa s carried out using an in vivo microdialysis technique in conscious ra ts in order to examine the possible involvement of the area postrema ( AP) and the abdominal vagal afferent nerves in this effect. Extracellu lar NE concentrations in the PVN region were measured by high performa nce liquid chromatography with electrochemical detection. In AP-lesion ed or abdominal-vagotomized rats, the NE increase was significantly at tenuated compared to that in sham-operated rats; this reduction was gr eater in abdominal-vagotomized rats than in AP-lesioned rats. The resu lts suggest that the AP as well as the abdominal vagal afferent nerves is involved in intraperitoneal (i.p.) administered IL-1 beta-induced NE release in the PVN region. (C) 1997 Elsevier Science Ireland Ltd.