GALANIN IN THE BED NUCLEUS OF THE STRIA TERMINALIS AND MEDIAL AMYGDALA OF THE RAT - LACK OF SEXUAL DIMORPHISM DESPITE REGULATION OF GENE-EXPRESSION ACROSS PUBERTY

Neurons in the bed nucleus of the stria terminalis (BNST) and the medi al amygdala (AMe) coexpress vasopressin and galanin (GAL) in the adult male rat. Here, we have asked whether GAL gene expression, like vasop ressin gene expression in these same neurons, exhibits sexual dimorphi sm and whether GAL pathways in the BNST and AMe are activated with pub erty in female rats as we have previously observed in male rats. In Ex p I, in situ hybridization histochemistry and quantitative autoradiogr aphy were used to compare GAL gene expression in the BNST and AMe of p repubertal (24-day-old) and adult (90-day-old) male and female rats. I n the BNST, both the number of GAL mRNA-expressing neurons (F = 41.98; P less than or equal to 0.0001; males, P less than or equal to 0.007; females, P less than or equal to 0.001) and the intensity of labeling (F = 40.35; P less than or equal to 0.0001; males, P less than or equ al to 0.004; females, P less than or equal to 0.002) were significantl y increased in adult compared to prepubertal animals of both sexes. In the AMe of both males (P less than or equal to 0.001) and females (P less than or equal to 0.001), the intensity of labeling was significan tly enhanced across puberty (F = 66.29; P less than or equal to 0.0001 ); however, the number of GAL mRNA-expressing neurons in this region d id not change. We found no evidence for sexual dimorphism of GAL gene expression in either brain region. In Exp 2, we replicated our observa tions of a lack of sexual dimorphism of GAL gene expression in the BNS T of adult male and female rats. These findings are consistent with th e hypothesis that GAL neurons in the BNST and AMe are steroid sensitiv e in both sexes. However, our failure to detect any differences in eit her the number of GAL mRNA-expressing neurons or the level of expressi on between male and female rats at either age indicates that these pat hways do not exhibit sexual dimorphism.