Estradiol and the addition of progesterone increase the sensitivity to a neurosteroid in postmenopausal women

Abstract

The aim of this study was to compare the pharmacodynamic response to a neuroactive steroid, pregnanolone, before and during different hormonal settings of postmenopausal hormone replacement therapy (HRT), using natural progesterone. A second aim was to investigate whether the response to pregnanolone was associated with cyclicity in negative mood symptoms during treatment. Twenty six postmenopausal women with climacteric symptoms were administered HRT in a randomized, double blinded, placebo-controlled, crossover study. The women received 2 mg oral estradiol (E(2)) continuously during two 28-day cycles and 800 mg of vaginal progesterone or placebo sequentially for the last 14 days of each treatment cycle. Pharmacodynamic response to pregnanolone was assessed before treatment, and during the last week of each treatment cycle, by comparing the effects of intravenous pregnanolone (3alpha-hydroxy-5beta-pregnan-20-one) on saccadic eye velocity (SEV), saccade acceleration, saccade latency and self-rated sedation. Throughout the study daily symptom rating scales were kept. According to the daily symptom rating scales, patients were divided into two groups; one group who displayed a significant variance in negative mood symptoms during HRT (cyclicity) and one group with no cyclical changes in negative mood symptoms during treatment. During treatment with either E(2) alone or E(2)+progesterone the response in saccadic eye movement parameters and in self-rated sedation to pregnanolone was enhanced compared to pretreatment values. The SEV, saccade acceleration and sedation responses to pregnanolone was also increased in women expressing cyclicity in negative mood symptoms compared to women with no cyclical changes in negative mood during HRT. In conclusion, during treatment with either E(2) alone, or E(2)+progesterone, pregnanolone sensitivity was increased. Women expressing cyclicity in negative mood symptoms were more sensitive to pregnanolone than women without symptom cyclicity during HRT.