Decreased Postnatal Testosterone Surge in Male Rats Exposed to Ethanol During the Last Week of Gestation

Prenatal alcohol exposure in the rat is known to interfere with the neurobehavioral sexual differentiation of the male brain. Because normal sexual differentiation of the male brain requires adequate levels of perinatal testosterone, we examined the effect of prenatal ethanol exposure on (1) the postnatal surge of testosterone and (2) the in vitro secretion of testosterone in response to luteinizing hormone (LH) stimulation of testes from fetal alcohol exposed (FAE) animals and controls. Sprague‐Dawley dams were administered a fortified liquid diet containing 35% ethanol‐derived calories, a pair‐fed (PF) isocaloric liquid diet, or given ad libitum access to dry lab chow (CF). Dams were administered the liquid diets from days 7 or 14 through parturition. The postnatal surge of testosterone in FAE males was studied only in animals exposed to ethanol from day 14 through parturition. In the first experiment, FAE and PF males and females were delivered by cesarian section on day 22 of gestation (E22) and trunk blood collected at 0, 60, 120, and 240 min after parturition. Experiment 2 measured plasma testosterone in male pups that were killed at 0, 60, 120, 240, 360, and 480 min after delivery. Results showed that the postnatal testosterone surge of FAE males in both experiments was significantly attenuated compared with PF controls. No effect of prenatal ethanol was observed in female offspring. Female testosterone levels were several fold lower than male littermates, and no evidence of a postnatal testosterone surge was observed. Production of testosterone from testes was studied using an automated perfusion system. The secretory testosterone response to LH stimulation of testes on day 18 (E18) of gestation and at birth (E22) was similar in testes from FAE animals to that observed in testes from PF and CF controls. The response of all testes to a pulse of LH (5 nM) delivered over a 5‐min period (flow rate = 200 μl/min) from animals at E18 was significantly greater than the response observed at day 22. No morphological abnormalities were detected by visual inspection of electron photomicrographs of testes from FAE animals at E18 or E22. The in vitro response to LH of testes from FAE animals indicates that the reduction in the postnatal testosterone surge in FAE animals is not due to a decrease in testicular sensitivity to LH.