Influence of chronic alcohol administration on representative indices of puberty and sexual maturation in male rats and the development of their progeny

The effects of chronic alcohol administration on reproductive endocrinology in the developing male rat were examined. Prepubescent male rats (25 days of age) were maintained on an alcohol liquid diet or were pair-fed a control diet until early adulthood and selected indices of sexual maturation were examined at weekly intervals. To determine whether sexually immature animals were more sensitive to the effects of alcohol than adults, fully mature male animals were exposed to an identical period of alcohol exposure and comparisons were made between the two groups. The results demonstrated that alcohol significantly affected many of the primary indices of puberty and sexual maturation. The normal pubertal increases in serum testosterone levels, the weights of the testes and secondary sex organs and β-endorphin levels in the hypothalamus were substantially reduced in alcohol-exposed animals compared with controls. In contrast to these results, the effects of alcohol on reproductive endocrinology in the fully mature animal were transitory and of considerably less magnitude. After a 2-week alcohol-free period, male rats exposed to alcohol during development were bred with drug-naive primiparous females. Although the same number of pregnancies resulted from matings between alcohol-exposed males and drug-naive females compared with controls, litter sizes were significantly smaller in alcohol-derived offspring than in controls. In all other respects, such as body weights, sex ratios, mortality rates and gross developmental features (eye opening, incisor eruption and testes descent), alcohol-derived offspring were identical with controls. Upon closer examination, however, significant disturbances were detected in alcohol-derived male offspring. Serum testosterone levels, seminal vesicle weights and β-endorphin levels in the hypothalamus were significantly lower in 60-day-old alcohol-derived offspring than in controls. These disturbances appeared to be relatively selective, inasmuch as no other abnormalities in reproductive endocrine status or in any other hormone level were observed. In conclusion, it has been shown that chronic alcohol administration markedly disrupts reproductive endocrinology in the developing male rat, that chronic exposure to alcohol has greater effects in the sexually immature animal than in the adult and, finally, that male offspring sired by male rats exposed to alcohol during adolescence have selective, but significant, endocrine abnormalities.