Premium
Involvement of Neurosteroids in the Effect of the Endogenous Benzodiazepine Receptor Ligand Octadecaneuropeptide (ODN) on Gonadotropin‐Releasing Hormone Gene Expression in Rat Brain
Author(s) -
Li S.,
Givalois L.,
Pelletier G.
Publication year - 1997
Publication title -
journal of neuroendocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.062
H-Index - 116
eISSN - 1365-2826
pISSN - 0953-8194
DOI - 10.1046/j.1365-2826.1997.00574.x
Subject(s) - neuroactive steroid , medicine , endocrinology , pregnenolone , receptor , pregnenolone sulfate , endogeny , gabaa receptor , antagonist , chemistry , pregnanolone , inhibitory postsynaptic potential , gonadotropin releasing hormone , hormone , biology , steroid , luteinizing hormone
We have recently demonstrated that different activators of the GABA A receptor complex including reduced progesterone metabolites and the endozepine octodecaneuropeptide (ODN) exert an inhibitory influence on GnRH gene expression. In order to investigate the possible involvement of neurosteroids, especially progesterone metabolites in the effect of ODN, we have evaluated in adrenalectomized and castrated male rats the influence of pretreatment with an inhibitor of 3 β ‐hydroxysteroid dehydrogenase (3 β ‐HSD) trilostane (TRIL) and an inhibitor of 5 α ‐reductase MK‐906 on GnRH mRNA levels in ODN‐treated rats. TRIL completely prevented the inhibitory influence of ODN on GnRH mRNA. It was also found that the inhibitor of 3 β ‐HSD as well as pregnenolone sulfate (PREG‐S), which has been shown to be increased following TRIL treatment, could induce an increase in GnRH mRNA. MK‐906 could also completely reverse the negative influence of ODN. When administered alone, this antagonist of 5 α ‐reductase induced an increase in GnRH mRNA. These results clearly indicate that the inhibition of two key enzymes for the synthesis of reduced progesterone metabolites can completely prevent the inhibitory influence of the endozepine ODN, suggesting that the effect of this endogenous ligand might be completely or partially mediated by an activation of the synthesis of active progesterone metabolites. On the other hand, it remains possible that, as a consequence of enzymatic inhibition, an increase in some precursors known as antagonists of GABA A may play a role in the prevention of the ODN effect by the two enzyme antagonists.