PRENATAL STRESS ALTERS THE SIZE OF THE ROSTRAL ANTERIOR COMMISSURE INRATS

In rodents and other mammals, prenatal stress disrupts both sexual dif ferentiation and sexual behavior. The present study examined the area of the anterior division of the anterior commissure (the Aca) in coron al, thionin-stained sections of prenatally stressed (P-S), and control male and female rats. Pregnant rats were exposed to thrice-daily heat , light, and restraint stress or left undisturbed during days 15-22 of pregnancy. Adult P-S and control males and females were killed, perfu sed, and their brains removed. Serial coronal sections (total of appro ximately 200 mu m) through the rostral portion of the Aca (the rAca) w ere taken and stained with thionin. The sections were examined and tra ced under x25 using computerized microscopy to obtain the area in mm(2 ). The data revealed that control females had a larger rAca compared t o control males, and that P-S males had a larger rAca compared to cont rol males; further, control males and P-S females were not significant ly different, nor were control females and P-S males. These results su ggest that, in rats, the Ac may be sexually dimorphic (in a direction similar to that described in humans) and that prenatal stress an event that modifies sex-typical behavior, physiology, and neuroanatomy reve rses that sex difference. (C) 1997 Elsevier Science Inc.