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Alcohol‐Induced Inhibition of LH Secretion in Intact and Gonadectomized Male and Female Rats: Possible Mechanisms
Author(s) -
Rivier Catherine,
Rivest Serge,
Vale Wylie
Publication year - 1992
Publication title -
alcoholism: clinical and experimental research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.267
H-Index - 153
eISSN - 1530-0277
pISSN - 0145-6008
DOI - 10.1111/j.1530-0277.1992.tb01896.x
Subject(s) - medicine , endocrinology , luteinizing hormone , alcohol , hormone , follicle stimulating hormone , hypothalamus , radioimmunoassay , gonadotropin , ethanol , chemistry , biochemistry , organic chemistry
Alcohol (EtOH) is reported to decrease gonadotropin secretion, but the mechanisms mediating these changes are not fully understood. The present study examined the ability of acutely or chronically administered EtOH to alter plasma luteinizing hormone (LH) and follicle stimulating hormone (FSH) levels in both male and female rats, and correlated these changes with blood EtOH levels (BALs); investigated possible changes in the pituitary responsiveness of animals exposed to EtOH; and probed the role of the paraventricular nucleus (PVN) of the hypothalamus in mediating alcohol‐induced decreases in plasma LH levels. The injection of 0.5 g EtOH/kg was accompanied by significantly higher BALs in females compared with males. This dose of alcohol did not alter rectal temperature, and only significantly ( p ≤ 0.01) decreased plasma LH levels in female rats. These findings were not altered by removal of gonadal steroids. Administration of 2.0 g EtOH/kg was followed by BALs that were comparable in both groups of rats at the 1‐ and 2‐hr time‐points, but were significantly ( p ≤ 0.01) higher in females 3 hr after treatment. Rectal T measurably decreased in all rats injected with 2 g EtOH/kg, though intact females showed the greatest change. This alcohol treatment also significantly ( p ≤ 0.01) inhibited immunoreactive LH release in both sexes, but there were no measurable changes in FSH values at any time. Using alcohol regimens which significantly lowered LH values in both sexes, we then showed that neither acute nor prolonged (7 days) treatment of male or female rats with alcohol measurably altered the LH response to 10, 30, or 100 ng gonadotropin‐releasing hormone (GnRH). Finally, we observed that in male rats, destruction of the PVN did not prevent the inhibitory effect of acute alcohol administration on LH secretion. These results indicate that alcohol‐induced decreases in plasma LH levels are not primarily mediated by changes in pituitary responsiveness to GnRH, and that the PVN is not necessary for the inhibitory effect of alcohol on LH secretion. It is therefore probable that alcohol acts outside the PVN to alter brain neurotransmitters that impact on GnRH‐secreting neurons.