Po gene expression is modulated by androgens in the sciatic nerve of adultmale rats

The present results show that androgens are able to modulate the Po gene ex pression in different models. In particular,we have shown that: (1) the mes senger for the androgen receptor (AR) is present in the rat sciatic nerve b ut not in cultured Schwann cells; (2) castration induces a decrease of Po m RNA levels in the sciatic nerve of male rats, which is counteract by the su bsequent treatment with dihydrotestosterone (DHT), the 5 alpha-reduced meta bolite of testosterone; (3) castration is also able to significantly decrea se in the sciatic nerve the activity of the enzyme 5 alpha-reductase (which converts testosterone into DI-); and (4) DHT is able to stimulate Po gene expression in cultured Schwann cells. These observations seem to indicate t hat androgens may exert their effect on Po gene expression via: indirect me chanisms; modulation of neuronal influences reaching the Schwann cells thro ugh the binding of the androgen to the AR present in neurons may be postula ted. However, alternative mechanisms may also be taken in consideration. Th e data presented suggest indeed that androgens might act on Schwann cells v ia the progesterone receptor (PR) rather than the AR. It has been observed that: (1) the messenger for PR is present in Schwann cells; (2) DHT may act ivate the transcriptional activity of a PR-responsive gene by binding to th e PR; and (3) putative steroid responsive elements have been described in t his paper to be present in the Po promoter region. (C) 1999 Elsevier Scienc e B.V. All rights reserved.