Effects of Prenatal Alcohol Exposure on the Sexually Dimorphic Nucleus of the Preoptic Area of the Hypothalamus in Male and Female Rats

Prenatal alcohol exposure can produce a variety of behavioral and physiological alterations, including changes in sexually dimorphic behaviors. It has been proposed that alcohol alters these behaviors by altering prenatal androgen and/or other steroid levels. This study was designed to examine the effects of prenatal alcohol exposure on a sexually dimorphic neuroanatomical structure, namely, the sexually dimorphic nucleus of the preoptic area of the hypothalamus (SDN‐POA). This nucleus is larger in males than females and is sensitive to perinatal sex steroid exposure. The SDN‐POA was examined in 70–80‐day‐old male and female rats whose mothers received on days 6–20 of pregnancy either a liquid diet containing 35% ethanol‐derived calories (EDC) or a 0% EDC isocaloric pair‐fed liquid diet. An ad libitum lab chow control group was also included (LC). Both volume and average cell size of the SDN‐POA were markedly smaller in alcohol‐exposed males relative to 0% EDC and LC controls. In contrast, prenatal alcohol exposure did not appear to affect SDN‐POA volume or cell size in females. Prenatal alcohol exposure did not significantly alter the volume of a nearby nucleus, the nucleus of the anterior commissure, in either sex. These findings support the hypothesis that prenatal alcohol exposure alters sexual differentiation in males, perhaps by altering some aspect of the prenatal androgen environment. The absence of any effect in 35% EDC females suggests that males and females may be differentially sensitive to alcohol's effects on this nucleus.