ANDROGENIC REGULATION OF EXPRESSION OF BETA-TUBULIN MESSENGER-RIBONUCLEIC-ACID IN MOTONEURONS OF THE SPINAL NUCLEUS OF THE BULBOCAVERNOSUS

Expression of beta-tubulin mRNA was examined in androgen-sensitive mot oneurons of the spinal nucleus of the bulbocavernosus (SNB) in adult m ale rats by in situ hybridization histochemistry using cDNA encoding m ouse beta-tubulin. Hybridizable beta-tubulin mRNA was localized in the somata and proximal dendrites of SNB motoneurons. Removal of androgen by castration significantly reduced the expression level of beta-tubu lin mRNA in the SNB motoneurons, whereas the change was prevented by t estosterone treatment. On the contrary, castration or testosterone tre atment did not induce any changes in the expression level of beta-tubu lin mRNA in the androgen-insensitive motoneurons of the retrodorsolate ral nucleus. These results suggest that androgen regulates the express ion of beta-tubulin gene in the SNB motoneurons and may provide eviden ce for the molecular mechanisms of hormonally-induced neuronal plastic ity in the SNB motoneurons.