The anxiolytic effect of pregnancy in rats is reversed by finasteride.

Several studies have shown the influence of the oestrous cycle on anxiety levels and the important role of progesterone in this effect. The metabolism of this steroid hormone yields neuroactive steroids among them allopregnanolone (alloP) and allotetrahydrodeoxycorticosterone (alloTHDOC), which bind to GABAA receptors and have anxiolytic effects. Considering that during pregnancy there is an increase in levels of both progesterone and its metabolites, the main objectives of this work were: (1) to assess changes in anxiety levels during pregnancy and (2) to verify the role of alloP and alloTHDOC in this process using finasteride, an inhibitor of 5alpha-reductase, the enzyme responsible for their synthesis. The results showed a significant reduction in anxiety levels on the 19th day of pregnancy, which was reversed by finasteride, suggesting a role for alloP and alloTHDOC in the anxiolytic process.