Dendritic branching features of Golgi-impregnated neurons from the “ventral” medial amygdala subnuclei of adult male and female rats

Abstract

The anterodorsal (MeAD) and posteroventral (MePV) subnuclei would form the proposed "ventral" division of the rat medial nucleus of the amygdala (MeA). These parts receive chemosensorial inputs, have gonadal hormone receptors and modulate hypothalamic neuroendocrine secretion and defensive/reproductive behaviors. The aims of this study were: (1) to provide further data on the morphology of Golgi-impregnated dendrites from the MeAD and the MePV of adult rats; and (2) to compare the results obtained for dendritic branching and predominant dendritic spatial distribution in both these subnuclei in males and diestrus females. Dendritic arborization levels, number of branches in each level, distribution of dendrites around the cell body and distally from it, and the preferred spatial distribution of dendritic branches were studied using different techniques and compared between sexes. MeAD and MePV multipolar neurons had spiny dendrites with sparse ramifications. The main statistically significant differences were found in the predominant dendritic spatial distribution in the MeAD (rather medially and laterally in males and ventromedially in females, p<0.02) and in the MePV (rather medially and mediodorsally in males and ventrally in females, p<0.01). Results suggest that synaptic information might be processed and integrated differently in the dendrites of males and females in these sex steroid-responsive MeA subnuclei. The inclusion of the MeAD and the MePV in one single "ventral" MeA division is further discussed.