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 < or = 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 < or = 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 < or = 0.01) inhibited immunoreactive LH release in both sexes, but there were no measurable changes in FSH values at any time.(ABSTRACT TRUNCATED AT 250 WORDS)