INHIBITION OF BRAIN 5-ALPHA-REDUCTASE IN PREGNANT RATS - EFFECTS ON ENZYMATIC AND BEHAVIORAL ACTIVITY

Medial basal hypothalamic (MBH) 5 alpha-reductase activity was signifi cantly blocked with a known inhibitor, Proscar (Finasteride), in pregn ant rats while their open-field behavior was quantified during the las t week of pregnancy. In control animals, open-field behavior significa ntly decreased (in a stair-step fashion) as a function of increasing g estational age. Conversely, in Proscar-treated animals open-field valu es significantly increased on day 15 and 17 of gestation compared to c ontrol values. These data indicate that inhibition of MBH 5 alpha-redu ctase during pregnancy significantly increased open-field activity lev els during late gestation in rats and provides evidence for a link bet ween the production of 5 alpha-reduced metabolites of progesterone in brain in behavioral activity during pregnancy.