Effects of acute and repeated alcohol ingestion on hypothalamic-pituitary-gonadal and hypothalamic-pituitary-adrenal functioning in normal males

We investigated the effects of acute and repeated alcohol ingestion on plasma levels of hormones associated with the functioning of the hypothalamic-pituitary-gonadal (HPG) and hypothalamic-pituitary-adrenal (HPA) systems in normal males. In the first experiment, 7 normal male subjects were given ethanol (1.3 g/kg) in the form of a 43% alcohol solution of whiskey and water over a 30-min period (from 19:00 h to 19:30 h); blood samples were collected 30 min and immediately before the beginning of alcohol ingestion and then at intervals of 30 min for 180 min. Blood ethanol levels rose sharply and reached their maximum at 60 min, remaining above 1.0 mg/ml until 180 min. Prolactin levels increased, reaching a peak at 60 min, gradually returning to the initial value at 180 min. Decreased testosterone levels were observed only at 30 min. Luteinizing hormone (LH), adrenocorticotrophic hormone (ACTH) and cortisol levels did not show any increases. In the second experiment, 9 normal males were given the same dose of alcohol, but this was given on 7 consecutive evenings and the hormonal changes were examined on the 1st and 7th days, only at 30 and 60 min after alcohol ingestion began (during the period that blood ethanol levels were ascending to their peak). The results on the 1st day reconfirmed the findings in the first experiment and on the 7th day, the last alcohol ingestion produced increases in prolactin levels and decreases in testosterone levels at 30 and 60 min, but did not change other hormone levels. The present findings indicate that (1) acute alcohol ingestion produces increases in plasma prolactin levels and decreases in plasma testosterone levels; (2) these changes in hormone levels occur during the period when blood ethanol levels are ascending, but hormone levels return to their respective initial values even when the level of blood ethanol remains high (above 1.0 mg/ml); (3) increases in prolactin levels appear to be induced by the pharmacological action of alcohol, but not by non-specific factors such as stress; (4) alcohol may reduce testosterone levels by acting on peripheral sites, but not by suppressing LH secretion; (5) alcohol at doses sufficient to affect plasma prolactin and testosterone levels does not produce any increases in plasma ACTH and cortisol levels; (6) repeated alcohol ingestion over 7 consecutive evenings did not lead to the development of any tolerance with regard to these hormonal changes. The present study thus suggests that