Allopregnanolone concentrations and premenstrual syndrome

OBJECTIVE: To evaluate basal allopregnanolone and progesterone in both phases of the menstrual cycle in women suffering from premenstrual syndrome (PMS) and their response to a GnRH test. DESIGN: We selected 56 women (28 patients with PMS and 28 controls) aged between 18 and 32 years. Blood samples were drawn in both follicular and phases. Twenty-eight women (14 patients with PMS and 14 controls) underwent a GnRH test in the luteal phase. METHODS: We evaluated allopregnanolone by RIA, using a specific antibody. Serum progesterone and oestradiol were determined using a commercially available RIA kit. RESULTS: Luteal phase allopregnanolone concentrations were significantly lower in patients with PMS than in controls. Progesterone concentrations were significantly lower in patients with PMS in both the follicular and the luteal phase. Serum oestradiol concentrations were in the normal range in both groups of women, although slightly greater in those with PMS. Allopregnanolone and progesterone responses to a GnRH test were significantly blunted in women with PMS. CONCLUSIONS: Diminished concentrations of allopregnanolone and progesterone, its precursor, and a blunted response to the GnRH test lead us to hypothesise that patients with PMS may suffer from an inadequate production of ovarian neuroactive steroids, especially in the luteal phase. This would lead to an impaired anxiolytic GABA(A)-mediated response in stressful physiological and psychological conditions, and may in part explain various psychoneuroendocrine symptoms that arise during PMS.