Target neurons of endogenous androgens immunocytochemically localized in male rat hypothalamus.

A polyclonal antiserum against androgens, i.e., testosterone, 5alpha-dihydrotestosterone and androstenedione, was tested to reveal target neurons of endogenous androgens in the hypothalamus of both intact and castrated male rats. Paraffin sections of hypothalamus and testis were immunostained by using Avidin-Biotin Complex method and 3-3' diaminobenzidine to visualize the immunoperoxidase complex. Conventional control experiments for method and antiserum specificity were performed. The antiserum proved to be specific for androgens, i.e., testosterone, 5alpha-dihydrotestosterone and androstenedione. The nuclear labeling observed in tissues stained by this procedure is consistent with the hypothesis that the labeled neurons contained DHT, which is the main testosterone metabolite active in the cell nucleus. The antiserum was effective in staining not only the hypothalamic neurons of intact males with normal serum levels of testosterone but also the hypothalamic neuron of castrated males with very low serum levels of testosterone. Evidence is presented indicating that the immunostaining technique represents a more specific and sensitive method to identify target neurons of endogenous androgens than autoradiography.

Hypothalamic target cells of endogenous sexual steroids in female rat. An immunocytochemical approach utilizing antiestradiol antiserum.

The immunostaining proposed in this study identifies cells containing endogenous estrogens in the Central Nervous System, in the presence of both very high and very low serum estrogen levels. Ten adult rats, seven normal and three ovariectomized females, were used for this study. Paraffin sections of hypothalamus and ovary of each female were stained using Avidin-Biotin Complex method and antiestradiol antiserum. Two different antiestradiol antisera were tested in this work: tests for method and antisera specificity are described. The immunostaining used here shows to be specific and sensitive revealing a higher number of labeled hypothalamic areas than those revealed by other techniques.