The neuroactive steroid 3α-5α-tetrahydroprogesterone (allopregnanolone), a metabolite of progesterone, is a positive allosteric modulator of GABAA receptors, and low levels have been implicated in the etiology of mood disorders. However, it is not known whether metabolism of progesterone to allopregnanolone varies across the menstrual cycle or is low after menopause. We hypothesized that the allopregnanolone/progesterone ratio would decrease from the follicular to luteal phase. We also hypothesized that postmenopausal women would have lower levels of progesterone and allopregnanolone but similar allopregnanolone/progesterone ratios as premenopausal women in the follicular phase. Serum fasting allopregnanolone and progesterone levels were measured by gas chromatography-mass spectrometry in ten premenopausal women at the follicular, mid-cycle, and luteal phases of the menstrual cycle and in twenty-four postmenopausal women. Although allopregnanolone and progesterone levels increased from the follicular to luteal phase, the allopregnanolone/progesterone ratio decreased 8-fold [0.33 ± 0.08 (follicular) vs 0.16 ± 0.09 (mid-cycle) vs 0.04 ± 0.007 (luteal), p = 0.0003]. Mean allopregnanolone and progesterone levels were lower in postmenopausal than premenopausal women at all menstrual cycle phases (p < 0.01). The mean allopregnanolone/progesterone ratio was similar in postmenopausal and premenopausal women in the follicular phase (0.39 ± 0.08 vs 0.33 ± 0.08, p = 0.94) but was significantly lower at mid-cycle and in the luteal phase than in postmenopausal women (p < 0.01). In conclusion, the serum allopregnanolone/progesterone ratio decreases 8-fold from the follicular to luteal phase and is lower at mid-cycle and the luteal phase than in postmenopausal women. Whether these data have implications for luteal phase and other mood disorders merits further study.

中文翻译：

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整个月经周期和更年期的别孕酮与黄体酮的比率

神经活性类固醇 3α-5α-四氢孕酮 (allopregnanolone) 是孕酮的一种代谢物，是 GABAA 受体的正变构调节剂，低水平与情绪障碍的病因有关。然而，尚不清楚黄体酮到别孕酮的代谢是否随月经周期变化或绝经后低。我们假设从卵泡期到黄体期，别孕酮/孕酮的比例会降低。我们还假设绝经后妇女的孕酮和别孕酮水平较低，但与处于卵泡期的绝经前妇女的别孕酮/孕酮比例相似。通过气相色谱-质谱法测量了 10 名绝经前妇女在卵泡、月经中期、和月经周期的黄体期以及 24 名绝经后妇女。尽管别孕酮和黄体酮水平从卵泡期到黄体期增加，但别孕酮/黄体酮比率下降了 8 倍 [0.33 ± 0.08（卵泡期）vs 0.16 ± 0.09（周期中期）vs 0.04 ± 0.007（黄体期）]，p =0.00 . 在所有月经周期阶段，绝经后妇女的平均别孕酮和孕酮水平均低于绝经前妇女（p < 0.01）。在卵泡期，绝经后和绝经前妇女的别孕酮/黄体酮平均比率相似（0.39 ± 0.08 vs 0.33 ± 0.08，p = 0.94），但在周期中期和黄体期显着低于绝经后妇女（p < 0.01）。综上所述，从卵泡期到黄体期，血清别孕酮/黄体酮比值下降了 8 倍，并且在周期中期和黄体期比绝经后妇女更低。这些数据是否对黄体期和其他情绪障碍有影响值得进一步研究。