Allopregnanolone in women with premenstrual syndrome.

5Alpha-reduced metabolites of progesterone, especially 3alpha-hydroxy-5alpha-pregnan-20-one (allopregnanolone) are now listed to neurosteroids. Their anesthetic properties can be explained by their allosteric interaction with GABA(A) receptors. A woman's organism is provided with an abundance of progesterone during the luteal phase of the menstrual cycle and its level falls down sharply with the first day of menses. The level of allopregnanolone follows that of progesterone. Many women suffer from so called premenstrual syndrome (PMS) during the luteal phase. In this study we have determined allopregnanolone and progesterone levels and their ratios in order to assess the over-all activity of C21-steroid 5alpha-reductase in these patients and in controls. Significantly lower levels of both progesterone and allopregnanolone than in controls have been found in PMS patients in the follicular phase only.