Influence of LHRH on sex hormone receptors in the amygdala of the male rat

Abstract

Autoradiography was used to localize estrogen-accumulating cells in the amygdala (AMY), of male rats. with LHRH hormones of seven adult male rats (86 days old). Seven mail rats were each treated with an injection of luteinizing hormone-releasing hormone (LHRH, 25 μg) at 83 days old and 3 days later with 250 μCi 3H-estradiol (E2). A control group of male rats was also treated with 250 μCi 3H-E2, two hours before sacrifice. Both groups were sacrificed at 86 days old. In the control group of male rats, the nuclei of the AMY with the highest density of estrogen binding (receptors) were nucleus medialis (NM), nucleus corticalis (NCO), nucleus centralis (NCE) and massa intercalata (MI) of pars corticomedialis of AMY. These nuclei belong to the phylogenetically older corticomedial part of the AMY. Light to moderate labeling was present in the phylogenetically younger nucleus basomedialis (NBM) and nucleus basolateralis (NBL). Weak labeling was present in nucleus lateralis anterior (NLA) and nucleus lateralis posterior (NLP) both from the phylogenetically younger basolateral part of the adult male rat AMY. This distribution of estrogen receptors could be related to the biologically more significant influence of estrogen on the regions of response divergence than on regions of sensory convergence of AMY. In the male rats treated with LHRH 3H-E2, we noticed different a distribution of estrogen receptors, in the different types nuclei of neurons (nucleus of AMY). We observed a smaller number of estrogen receptors in the nucleus of pyramidal neurons, while in fusiform and stellate neurons, a similar number of receptors was present as in the control group for NM, NCO, and NCE. In massa intercalata we found a large numberof receptors in the nuclei of neurons, in the older pars AMY. In younger pars AMY, NBL and NLP, we noticed a significant decrease of receptors for estradiol in the nuclei of pyramidal and fusiform neurons.