Steroid effects on the gene expression of peripheral myelin proteins

The present article summarizes recent observations obtained in our laborato ry which clearly indicate that sex steroids exert relevant effects on the p eripheral nervous system. In particular, the following important points hav e emerged: (1) Steroids exert stimulatory actions on the synthesis of the p roteins proper of the peripheral myelin (e.g., glycoprotein Po and peripher al myelin protein 22) in vivo and on the Schwann cells in culture; (2) in m any cases the actions of hormonal steroids are not due to their native mole cular forms but rather to their metabolites (e.g., dilhydroprogesterone and tetrahydroprogesterone in the case of progesterone; dihydrotestosterone an d 5 alpha -androstane-3 alpha ,17 beta -diol in the case of testosterone); (3) the mechanism of action of the various steroidal molecules may involve both classical (progesterone and androgen receptors) and nonclassical stero id receptors (GABA,, receptor); and finally, (4) the stimulatory action of steroid hormones on the proteins of the peripheral myelin might have clinic al significance in cases in which the rebuilding of myelin is needed (e.g., aging, peripheral injury, demyelinating diseases, and diabetic neuropathy) . (C) 2001 Academic Press.