Interferon-a acts at the preoptic hypothalamus to reduce natural killer
cytotoxicity in rats.
Take, Sachiko, Daisuke Uchimura, Yoshio Kanemitsu, Toshihiko Katafuchi, and
Tetsuro Hori.
Department of Physiology, Faculty of Medicine, Kyushu University,
Fukuoka
APStracts 2:0018R, 1995.
Interferon-a acts at the preoptic hypothalamus to reduce natural killer
cytotoxicity in rats. Am. J. Physiol. (Regulatory Integrative Comp. Physiol.
): --We previously demonstrated that an intracerebroventricular (icv)
injection of recombinant human interferon-a (rhIFN-a) reduced the
cytotoxicity of splenic natural killer (NK) cells in rats and mice. In the
present study, we investigated the brain sites at which rhIFN-a acts to
suppress the splenic NK activity in unanesthetized rats implanted
unilaterally with chronic hypothalamic cannula. A microinjection of rhIFN-a
at a dose of 200 U into the medial part of the preoptic hypothalamus (MPO)
reduced the NK activity to about 60% of the control 30 min after the
injection. 50 U of rhIFN-a also decreased the NK activity to about 80%. The
injection of rhIFN-a at a dose of 200 U into other hypothalamic areas (the
lateral preoptic hypothalamus, ventromedial hypothalamus, lateral
hypothalamus, and paraventricular nucleus) had no effect. The MPO-rhIFN-a
-induced immunosuppression was completely blocked by splenic denervation, but
not by an adrenalectomy. These results suggest that IFN-a suppresses the
splenic NK activity predominantly through the MPO-sympathetic pathway.
Received 12 September 1994; accepted in final form 17 January 1995.
APS Manuscript Number R514-4.
Article publication pending Am. J. Physiol. (Regulatory Integrative Comp.
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 25 February 1995.