TY - JOUR
T1 - Effects of naloxone on vasopressin secretion in conscious rats
T2 - Evidence for inhibitory role of endogenous opioid peptides in vasopressin secretion
AU - Yamada, Takayuki
AU - Nakao, Kazuwa
AU - Itoh, Hiroshi
AU - Shirakami, Gotaro
AU - Sugawara, Akira
AU - Saito, Yoshihiko
AU - Mukoyama, Masashi
AU - Arai, Hiroshi
AU - Hosoda, Kiminori
AU - Shiono, Shozo
AU - Eigyo, Masami
AU - Matsushita, Akira
AU - Imura, Hiroo
PY - 1989/8
Y1 - 1989/8
N2 - The effects of naloxone, an opioid antagonist, on arginine vasopressin (AVP) secretion were examined in conscious unrestrained rats under both basal and stimulated conditions. Intravenous injection of naloxone in a dose of 0.1 mg/kg did not significantly affect the basal plasma AVP level. However, 0.5 or 2.5 mg/kg naloxone significantly raised the basal AVP level in euhydrated rats. Naloxone (0.5 mg/kg) significantly enhanced AVP secretion after 72-h water deprivation. However, the enhancement was more prominent in euhydrated rats than in dehydrated rats. Pretreatment with naloxone (0.5 mg/kg) also significantly prolonged AVP secretion induced by intracerebroventricular injection of angiotensin-II (100 ng). Moreover, naloxone (0.5 mg/kg) significantly increased AVP secretion induced by intracerebroventricular injection of carbachol (10 ng). Naloxone (0.5 mg/kg) altered neither basal blood pressure nor the angiotensin-II-induced pressor response, but augmented the carbachol-induced pressor response. This suggests that facilitation of AVP secretion by naloxone is not due to a reflex mechanism resulting from decreased blood pressure. These results indicate that endogenous opioid peptides exert a tonic inhibitory control on AVP secretion in rats.
AB - The effects of naloxone, an opioid antagonist, on arginine vasopressin (AVP) secretion were examined in conscious unrestrained rats under both basal and stimulated conditions. Intravenous injection of naloxone in a dose of 0.1 mg/kg did not significantly affect the basal plasma AVP level. However, 0.5 or 2.5 mg/kg naloxone significantly raised the basal AVP level in euhydrated rats. Naloxone (0.5 mg/kg) significantly enhanced AVP secretion after 72-h water deprivation. However, the enhancement was more prominent in euhydrated rats than in dehydrated rats. Pretreatment with naloxone (0.5 mg/kg) also significantly prolonged AVP secretion induced by intracerebroventricular injection of angiotensin-II (100 ng). Moreover, naloxone (0.5 mg/kg) significantly increased AVP secretion induced by intracerebroventricular injection of carbachol (10 ng). Naloxone (0.5 mg/kg) altered neither basal blood pressure nor the angiotensin-II-induced pressor response, but augmented the carbachol-induced pressor response. This suggests that facilitation of AVP secretion by naloxone is not due to a reflex mechanism resulting from decreased blood pressure. These results indicate that endogenous opioid peptides exert a tonic inhibitory control on AVP secretion in rats.
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U2 - 10.1210/endo-125-2-785
DO - 10.1210/endo-125-2-785
M3 - Article
C2 - 2546748
AN - SCOPUS:0024389381
SN - 0013-7227
VL - 125
SP - 785
EP - 790
JO - Endocrinology
JF - Endocrinology
IS - 2
ER -