Changes in Expression of the Neuropeptide Y Y1 Receptor Gene in the Medial Amygdala of Transgenic Mice During Pregnancy and After Delivery

The study investigated the effects of pregnancy-related fluctuations in neuroactive steroids on Y 1 receptor gene expression in the medial amygdala of transgenic mice. It was found that concentrations of progesterone and its metabolites increased on day 18 of pregnancy and returned to normal 2 days after delivery, paralleling changes in Y 1 receptor gene expression. The use of finasteride, a 5α-reductase inhibitor, prevented these increases, indicating that endogenous neuroactive steroid fluctuations during pregnancy were linked to changes in Y 1 receptor gene expression. This suggested a functional interaction between the GABAergic and NPY–Y 1 receptor systems.