The Effects of Dutasteride on Mood, HPA Axis, and Serum Allopregnanolone Levels in Women With Menstrual-Related Mood Disorders and Controls

Studies of premenstrual syndrome (PMS) to date have demonstrated that the syndrome represents an abnormal response to normal physiological events. Specifically patients with PMS experience a dysphoric mood state in response to normal luteal phase levels of progesterone and additionally fail to demonstrate the augmentation of the hypothalamic-pituitary-adrenal (HPA) axis normally seen in the luteal phase. A parsimonious explanation for the dysregulation of both mood and HPA axis function in PMS is that both are mediated by abnormal levels of or response to the progesterone neurosteriod metabolite, allopregnanolone. Both exposure to and withdrawal from allopregnanolone have been shown to precipitate adverse mood states in animal studies, presumably consequent to induced conformational changes in the GABA(A) receptor (increased alpha-4 subunit) that impair GABA receptor function. This impairment of GABA receptor function may also be associated with loss of restraint of HPA axis activity and hence may underlie the luteal phase increases in HPA activity in normal women. In this protocol, we propose to block conversion of progesterone to allopregnanolone in women with menstrual-related mood disorder (MRMD; equivalent in most reports to a severe form of PMS called premenstrual dysphoric disorder (PMDD)) and in normal (control) women. We will block progesterone metabolism (and hence exposure to allopregnanolone) with a newly approved 5 alpha-reductase inhibitor, dutasteride. We hypothesize the following: 1) Elimination of exposure to allopregnanolone in women with MRMD will eliminate dysphoric mood in the luteal phase; 2) Elimination of exposure of normal control women to allopregnanolone will eliminate the luteal phase enhancement of stimulated stress axis activity response. These hypotheses, if confirmed, will increase the precision with which we can dissect the pathophysiological mechanisms involved in MRMD and in menstrual-related stress physiology. In this protocol, our study objectives are as follows: Primary Objectives: 1) Determine whether suppression of neurosteroid synthesis will diminish mood symptoms in women with MRMD. 2) Determine if suppression of neurosteroid synthesis will eliminate luteal phase-related increases in stimulated HPA axis activity in control women. Secondary Objectives: 1) Determine whether differences in response to allopregnanolone account for the divergent effects of menstrual cycle phase on HPA axis activity in patients with MRMD and controls. 2) Determine if the Dex-CRH test, like the graded stressor treadmill test, can reveal the effects of menstrual cycle phase on HPA axis function.