Reduced sensitivity of hypothalamic-preoptic area norepinephrine and dopamine to testosterone feedback in adult fetal ethanol-exposed male rats

Endocrine feedback of testosterone (T) in regulation of the hypothalamus is via the effects of T on the noradrenergic system. The current experiment was performed to determine the effects of fetal ethanol exposure (FEE) on the norepinephrine (NE) and dopamine (DA) content in the hypothalamic-preoptic area (HPOA) of adult male rats, and the response of NE and DA to T administration. Pregnant rats were exposed to diets containing either a liquid diet containing ethanol, a liquid diet containing sucrose isocalorically substituted for ethanol, or a chow and water diet. Male offspring were castrated or sham-operated at 45 days of age. The animals received either testosterone propionate (TP) or an oil vehicle. HPOA was collected at 55 days of age from each animal and NE and DA content was measured by HPLC-EC. There was no significant alteration of NE or DA content in the HPOA in FEE animals compared to catecholamine levels in animals derived from dams on the control diets. Castration had no significant effect on NE and DA content in the chow-fed or pair-fed animals. TP administration significantly reduced NE content only in the chow- and pair-fed animals but not in the FEE animals. DA content in the HPOA was not affected by castration, but TP administration also resulted in significantly reducing DA content in chow- and pair-fed castrate male rats but not in FEE castrate male rats. The results indicate that FEE alters the response of the noradrenergic and dopaminergic neurons in the HPOA to T administration. The inhibition of HPOA NE and DA content in castrated rats given high doses of TP is significantly diminished in fetal ethanol-exposed rats that is indicative of a reduction of neuronal responsiveness to steroid feedback regulation of the hypothalamus.