Pyrogens enhance beta-endorphin release in hypothalamus and trigger fever that can be attenuated by buprenorphine.
At first, we investigated whether both beta-endorphin release level in the hypothalamus and body temperature can be altered after intracerebroventricular (i.c.v.) injection of either lipopolysaccharide (LPS), interleukin-1beta (IL-1beta), or prostaglandin E(2) (PGE(2)) in rats. It was found that in the rat, i.c.v. administration of either LPS (0.5 microg in 10 microl), IL-1beta (10 ng in 10 microl), or PGE(2) (200 ng in 10 microl), in addition to producing fever, upregulated the immunoreactivity of beta-endorphin in the preoptic anterior hypothalamus of rat brain. Secondarily, we assessed whether the fever induced by either LPS, IL-1beta, or PGE(2) can be altered by pretreatment with buprenorphine (an opioid receptor antagonist). The results revealed that i.c.v. administration of buprenorphine (1 - 10 microg in 10 microl) alone had an insignificant effect on the body temperature. However, the fever induced by i.c.v. injection of either LPS, IL-1beta, or PGE(2) was significantly attenuated by pretreatment with i.c.v. injection of buprenorphine 1 h before the pyrogen injection in rats. The results suggest that pyrogens enhance beta-endorphin release in the hypothalamus and trigger fever which can be attenuated by buprenorphine, an opioid receptor antagonist.
Institute of Physiology, National Yang-Ming University Medical School, Taipei, Taiwan.
Shu-Ming
SM
Tsai
Mao-Tsun
MT
Lin
Jhi-Joung
JJ
Wang
Wu-Tein
WT
Huang
D000818:Animals; D002047:Buprenorphine / Q000008:administration & dosage / Q000494:pharmacology*; D015232:Dinoprostone / Q000008:administration & dosage / Q000494:pharmacology; D005334:Fever / Q000139:chemically induced* / Q000517:prevention & control*; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism*; D007150:Immunohistochemistry; D007276:Injections, Intraventricular; D007375:Interleukin-1 / Q000008:administration & dosage / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000008:administration & dosage / Q000494:pharmacology; D008297:Male; D009292:Narcotic Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D011749:Pyrogens / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D001615:beta-Endorphin / Q000378:metabolism*
D007375:Interleukin-1; D008070:Lipopolysaccharides; D009292:Narcotic Antagonists; D011749:Pyrogens; D002047:Buprenorphine; D001615:beta-Endorphin; D015232:Dinoprostone