The effects of highly selective opioid receptor antagonists on the release of arginine vasotocin induced by hyperosmotic stimulation and angiotensin II injection.
The effects of highly selective antagonists to mu-, delta-, and kappa-opioid receptor subtypes on hyperosmotic- or angiotensin II (AII)-induced arginine vasotocin (AVT) release were investigated in chicks. Plasma levels of AVT increased about 1.5-fold after the administration of 1.5 M NaCl (200 microl, ip) or 100 ng AII (5 microl, icv). The administration of the mu-antagonist naloxonazine and the kappa-antagonist nor-Binaltorphimine further elevated plasma levels of AVT stimulated by hypertonic NaCl or AII. These effects of mu- and kappa-opioid receptor antagonists on AVT release were dose dependent. Nor-Binaltorphimine enhanced hyperosmotically stimulated plasma levels of AVT at a lower dose than that of naloxonazine. Conversely, the delta-selective antagonist naltrindole did not significantly affect AVT secretion. None of the opioid receptor antagonists influenced basal plasma levels of AVT. Therefore, these results suggest that mu- and kappa-opioid receptors are involved in hyperosmotic- and AII-induced AVT release, and the effect of the kappa-opioid receptor antagonist in the AVT release stimulated by hyperosmolality is strong compared to that of the mu-opioid receptor antagonist.
Sasaki
T
T
Laboratory of Animal Physiology, Nagoya University, Chikusa, Japan.
Arakawa
K
K
Shimada
K
K
Saito
N
N
D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D002645:Chickens; D008297:Male; D009270:Naloxone / Q000031:analogs & derivatives / Q000494:pharmacology; D009271:Naltrexone / Q000031:analogs & derivatives / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology*; D011957:Receptors, Opioid / Q000502:physiology; D017465:Receptors, Opioid, delta / Q000037:antagonists & inhibitors / Q000502:physiology; D017473:Receptors, Opioid, kappa / Q000037:antagonists & inhibitors / Q000502:physiology; D017450:Receptors, Opioid, mu / Q000037:antagonists & inhibitors / Q000502:physiology; D012462:Saline Solution, Hypertonic; D014668:Vasotocin / Q000378:metabolism*
D009292:Narcotic Antagonists; D011957:Receptors, Opioid; D017465:Receptors, Opioid, delta; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu; D012462:Saline Solution, Hypertonic; D000804:Angiotensin II; D009270:Naloxone; C051844:norbinaltorphimine; D009271:Naltrexone; C034643:naloxonazine; C055382:naltrindole; D014668:Vasotocin