Effects of sex steroids on the growth of neuronal processes in neonatal rat hypothalamus-preoptic area and cerebral cortex in primary culture.

Dissociated cells of neonatal rat hypothalamus-preoptic area and cerebral cortex were grown in primary culture, and the effects of sex steroids on neurons were morphometrically studied. In cultures of the hypothalamus-preoptic area estradiol-17β or testosterone propionate significantly increased the total neuronal process length as compared with control cultures given no steroids in the medium. Significant stimulatory effects were detected on 1, 2 and 3 days after plating, while, 5a-dihydrotestosterone failed to show any stimulatory influence. In contrast, none of these steroids was effective in cultures of cerebral cortical cells. Based on the number of processes arising from the soma, neurons were divided into unipolar, bipolar and multipolar neurons. Percentage of multipolar neurons of the hypothalamus-preoptic area was more in cultures treated with estradiol-17β or testosterone propionate than the controls. Significant effect was not noted in cultures with 5α-dihydrotestosterone, while, in cultures of the cerebral cortical cells, effects on sprouting of these steroids were far less marked than in cultures of the hypothalamus-preoptic area. The present findings substantiate the importance of aromatization of androgen to exert its influence on neuronal process growth in cell culture.