Effect of ethanol infusion on the pituitary-testicular responsiveness to gonadotropin releasing hormone and thyrotropin releasing hormone in normal males and in chronic alcoholics presenting with hypogonadism

Nine chronic male alcoholics presenting with hypogonadism but without overt liver failure were examined under baseline conditions and after acute injection of gonadotropin releasing hormone (GnRH, 100 μg iv) and thyrotropin releasing hormone (TRH, 200 μg iv), performed at 60 min of a 3-h infusion of saline and 0.4 g/kg ethanol, respectively. Controls were 10 male adult volunteers examined under the same conditions. Six alcoholics and six controls underwent a third test with the infusion of 0.8 g/kg ethanol. Subjects were hospitalized and the infusion was started after a 48-h period of abstinence from alcohol. Tests were performed in random order at intervals of at least three weeks, always at 15:00 following a standard meal in the morning. Plasma levels of FSH, LH, prolactin (PRL) and testosterone (T) were measured by radioimmunoassay. Significantly higher levels of FSH, LH and PRL, and significantly lower levels of T were recorded in alcoholics vs. controlson plasma samples drawn at about 08:00 for three consecutive days. Ethanol infusion at the dose of 0.4 g/kg did not change the pattern of response to GnRH and TRH of controls and alcoholics. Doubling the alcohol dosage yielded a significant reduction of LH response in normal subjects whereas did not result in a similar effect in alcoholics. The mean LH increment of alcoholics was significantly less than that of normals at all times during saline and infusion of 0.4 g/kg ethanol; significance was not attained when the dose of ethanol was 0.8 g/kg. The mean FSH and PRL increments of alcoholics were significantly different from controls only during saline and only at some times of the sampling sequence. The mean TSH increment was similar in controls and alcoholics. Ethanol infusion per se did clearly lower T levels in controls but not in alcoholics. The data obtained in normal subjects as well as the impaired LH responsiveness and enhanced morning levels of FSH, LH and PRL observed in alcoholics are compatible with a dual effect of ethanol, at the hypothalamo-pituitary and testicular level.