Involvement of opioid receptors in nucleus tractus solitarii in modulating endotoxic hypotension in rats.
Opioid antagonists selective for the mu-receptor (naltrexone) and kappa-receptor (nalmefene), respectively, were unilaterally microinjected into the nucleus tractus solitarii (NTS) of the pentobarbital anaesthetized (50 mg/kg, i.p.) rat subjected to E. coli endotoxin (15 mg/kg, i.v.). Naltrexone (0.5 microgram) ameliorated or totally abolished the endotoxic hypotension and tachycardia, and nalmefene at a dose of 1/25 (0.02 microgram) that of naltrexone showed a similar effect. The results suggest that the kappa- and mu-opioid receptors in NTS are actively involved in mediating the hypotensive and tachycardiac effects induced by systemic endotoxin in rats.
Xu
T
T
Department of Physiology, Beijing Medical University, China.
Wang
T
T
Han
J
J
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004731:Endotoxins; D006339:Heart Rate / Q000187:drug effects; D007022:Hypotension / Q000139:chemically induced / Q000503:physiopathology*; D008297:Male; D008526:Medulla Oblongata / Q000503:physiopathology*; D008845:Microinjections; D009271:Naltrexone / Q000031:analogs & derivatives / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D009475:Neurons, Afferent / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D011957:Receptors, Opioid / Q000502:physiology*; D013238:Stereotaxic Techniques
D004731:Endotoxins; D009292:Narcotic Antagonists; D011957:Receptors, Opioid; D009271:Naltrexone; C038981:nalmefene