Altered Sensitivity to an Opiate Antagonist, Naloxone, in Hyperprolactinemic Male Rats
作者:
Cynthia . Sweeney,
William . Morgan,
M. Susan Smith,
Andrzej Bartke,
期刊:
Neuroendocrinology
(Karger Available online 1985)
卷期:
Volume 41,
issue 1
页码: 1-6
ISSN:0028-3835
年代: 1985
DOI:10.1159/000124145
出版商: S. Karger AG
关键词: Luteinizing hormone;Endorphins;Hyperprolactinemia
数据来源: Karger
摘要:
An increase in endogenous opiatergic tone has been suggested as a mechanism for suppression of gonadotropin release in hyperprolactinemia (hyperPRL). In an attempt to evaluate this possibility in hyperprolactinemic males, we have examined the effects of a specific opiate antagonist, naloxone, on plasma LH levels in adult male rats rendered hyperprolactinemic by transplanting two pituitary glands underneath the kidney capsule. Naloxone was adminstered intravenously (i.v.) at different dose levels (0.2, 2, or 20 mg/kg body weight) and blood samples were collected at intervals ranging from 15 to 60 min after naloxone administration. In all experiments, plasma LH levels in the sham-operated controls were significantly increased after naloxone administration, while those in the pituitary-grafted group remained unaltered. Injecting naloxone daily for 3 or for 10 days failed to alter plasma LH levels in both sham-operated and pituitary-grafted animals. Administration of LHRH induced a 7-fold increase in plasma LH levels in both the pituitary-grafted animals and the sham-operated controls. These studies demonstrate that hyperPRL interferes with the naloxone-induced rise in circulating LH levels in the male rat.
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