The Regulation of Gonadotropin-Releasing Hormone-Induced Calcium Signals in Male Rat Gonadotrophs by Testosterone Is Mediated by Dihydrotestosterone
endo.endojournals.org/cgi/conten … 139/3/1038
PDF: endo.endojournals.org/cgi/reprint/139/3/1038.pdf
Tidbits:
“…The 5a-reduction of T appears to be a critical step in the regulation of GnRH-induced Ca2+ signals.”
“…Finasteride treatment of intact male rats did, however, mimic the effect of castration on GnRH-induced Ca2+ signals.”
"…The anterior pituitary and gonadotrophs in particular have [b]very high levels of 5a-reductase activity /b, suggesting that the metabolism of T plays a role in gonadotroph function.
“…The present study, therefore, hints at a possible function of the 5-reductase in the pituitary, viz. the regulation of GnRH-induced Ca2+ signaling.”
The effectiveness of finasteride treatment was established by the resulting decrease in the weight of the ventral prostate and in prostatic DHT concentrations, and [b]we assume that a similar inhibition of 5a-reductase activity would be observed in the pituitary, as has been previously reported /b.
"In summary, this study has demonstrated the importance of the conversion of T to DHT in the regulation of GnRH-induced Ca2+ signals in anterior pituitary gonadotrophs. As such, they hint at an important function of the abundant 5-reductase activity found in the anterior pituitary gland.
As the changes in GnRH-induced Ca2+ signaling observed after finasteride treatment appear separate from the regulation of LH secretion, the present findings leave open the precise role of the Ca2+ signals in gonadotroph function and suggest that the modulation of GnRH-induced Ca2+ signals by T is not an important element in its negative feedback control of LH secretion.
The findings of the present study provide new avenues for investigation of the importance of 5-reduction of T and Ca2+ signaling in the regulation of reproductive function in males. "