Febrile effects of polyriboinosinic acid: polyribocytidylic acid and interferon: relationship to somatostatin in rat hypothalamus.
The changes in thermoregulatory effectors produced by an injection of polyriboinosinic acid: polyribocytidylic acid (Poly I:C) or interferon were assessed and compared in control rats, in rats with hypothalamic somatostatin (SS) receptor blockade and in rats with hypothalamic SS depletion. Intrahypothalamic (i.h., 0.05-0.50 microgram) or intraperitoneal (i.p., 100-600 micrograms) administration of Poly I:C caused a dose-related rise in colon temperature in control rats at all ambient temperatures (Ta) studied. A Poly I:C-induced fever was produced by increased metabolism at a Ta of 8 degrees C, whereas at 30 degrees C, it was caused by cutaneous vasoconstriction. At a Ta of 22 degrees C, the fever was caused by increased metabolism and cutaneous vasoconstriction. On the other hand, i.h. administration of SS-14 antagonist (0.1-0.5 ng) caused a dose-related fall in colon temperature at Ta of 8 degrees C or 22 degrees C. At a Ta of 8 degrees C, the hypothermia was caused by decreased metabolism, whereas at 22 degrees C, it was caused by decreased metabolism and cutaneous vasodilation. At a Ta of 30 degrees C, the thermoregulatory effectors were not affected by SS-14 antagonist treatment. Furthermore, the fever induced by Poly I:C or interferon was significantly reduced by pretreatment of rats with an i.p. dose of cysteamine (30 mg. kg-1) or an i.h. dose of SS-14 antagonist (0.1 ng). The results indicate that a somatostatinergic pathway in rat hypothalamus may mediate the fever induced by interferon or its inducer Poly I:C.
Chuang
J
J
Department of Physiology, National Cheng Kung University Medical College, Taiwan, Republic of China.
Lin
M T
MT
Chan
S A
SA
Won
S J
SJ
D000818:Animals; D001833:Body Temperature Regulation; D005334:Fever / Q000139:chemically induced*; D007031:Hypothalamus / Q000378:metabolism*; D007267:Injections; D007274:Injections, Intraperitoneal; D007369:Interferon Inducers; D007372:Interferons; D008297:Male; D011070:Poly I-C; D051381:Rats; D011919:Rats, Inbred Strains; D013004:Somatostatin / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology
D007369:Interferon Inducers; D013004:Somatostatin; C043820:cyclo(7-aminoheptanoylphenylalanyl-tryptophyl-lysyl-benzylthreonyl); D007372:Interferons; D011070:Poly I-C