ACTIVATION OF GALANIN PATHWAYS ACROSS PUBERTY IN THE MALE-RAT - GALANIN GENE-EXPRESSION IN THE BED NUCLEUS OF THE STRIA TERMINALIS AND MEDIAL AMYGDALA

Galanin and vasopressin are coexpressed in the bed nucleus of the stri a terminalis and medial amygdala of the male rat. In adult males, the level of gene expression for both peptides in these regions is depende nt on circulating levels of testosterone. We hypothesized that galanin messenger RNA levels would be enhanced in adult males compared with p repubertal males due to the rise in plasma testosterone levels. We use d in situ hybridization and quantitative autoradiography to measure ga lanin messenger RNA in cells of the bed nucleus of the stria terminlis and medial amygdala of prepubertal and adult male rats. Our results s how that significantly (P less than or equal to 0.05) more galanin mes senger RNA expressing neurons are detectable in the bed nucleus of the stria terminalis of adult compared with prepubertal male rats. In con trast, no differences were observed between the groups in the number o f labeled neurons detected within the medial amygdala. However, the av erage labeling intensity was significantly enhanced in both the bed nu cleus of the stria terminalis (P less than or equal to 0.001) and medi al amygdala (P less than or equal to 0.001) of adult compared with pre pubertal animals. The present findings are consistent with the hypothe sis that gonadal hormones regulate galanin gene expression in some bra in regions and suggest that the activation of the hypothalamic-pituita ry-gonadal axis which occurs naturally with puberty is associated with activation of galanin pathways in the bed nucleus of the stria termin alis and medial amygdala.