Neuropharmacology - Premenstrual steroids?

The symptoms of premenstrual syndrome include depressed mood and anxiety, and the molecular mechanisms behind this are now becoming clear. During menstruation, levels of progesterone fall, and, as a result, so do levels of the progesterone metabolite allopregnanolone. Using a rat model, the authors have found that when production of allopregnanolone is blocked, increased levels of the α4 subunit of the GABAAreceptor are produced. This changes the sensitivity of the receptor to endogenous ligands, resulting in the symptoms associated with premenstrual syndrome.