Androgen regulates gene expression of cytoskeletal proteins in adult rat motoneurons.

Expression of beta-actin and beta-tubulin mRNA was examined in androgen-sensitive motoneurons of the spinal nucleus of the bulbocavernosus (SNB) in adult male rats by in situ hybridization histochemistry using complementary DNAs encoding chick beta-actin and mouse beta-tubulin, respectively. Both hybridizable beta-actin and beta-tubulin mRNAs were localized in the somata and proximal dendrites of SNB motoneurons. Removal of androgen by castration significantly reduced the expression levels of both beta-actin and beta-tubulin mRNAs in the SNB motoneurons, whereas the changes were prevented by testosterone treatment. In contrast, castration or testosterone treatment induced little or no change in the expression levels of these mRNAs in the much less androgen-sensitive motoneurons of the retrodorsolateral nucleus (RDLN). These results suggest that androgen regulates the expression of beta-actin and beta-tubulin genes in the SNB motoneurons and may provide evidence for the molecular mechanisms of hormonally induced neuronal plasticity in the SNB motoneurons.