Premenstrual dysphoric disorder is associated with the longer length from clitoris to urethra – BMC Blogs Network

The PMDD is triggered at times of hormonal fluctuations, in particular exposure to progesterone [1], and does not occur in the women during pregnancy and after menopause (without hormone replacement). The suppression of ovulation and suppression of the cyclical hormonal changes by the hormone therapy is the most effective treatment for PMDD [1, 18]. These evidences highlight that the direct activating effect of hormones plays an essential role in the pathogenesis of PMDD, at least sexual steroid hormones, such as progesterone, may precipitate the presentation of PMDD. Moreover, the very early organizational effect of prenatal sex hormones that may contribute to the PMDD has recently got attentions. The previous work using the 2D:4D ratios as a marker of prenatal sex hormones exposure, indicated that the prenatal sex hormones exposure might influence individual differences in the severity of premenstrual symptoms [9], and could be a factor in the development of PMDD. A recent preclinical animal study clearly showed that prenatal androgenization induced anxiety-like behavior in adult female rats, implying that prenatal exposure to high concentration of testosterone might influence the development of neural networks and impose the risk of anxiety-like behavior later in life [19]. We measured the 2D:4D ratios, AGD-AC, AGD-AF, and CUMD of the subjects, and found that the left/right 2D:4D ratios, AGD-AC and AGD-AF did not show any difference between PMDD patients and controls, but a significant longer CUMD was seen in the patients with PMDD. The CUMD, as well as the 2D:4D ratios, AGD-AC and AGD-AF, is supposed to be positive association with prenatal androgen levels, therefore, our results supported that atypical high prenatal androgen exposure might predispose individuals to be susceptible to PMDD.

We did not detect the current level of androgens in the patients with PMDD. An early research reported that serum levels of androgens were higher in women with premenstrual irritability and dysphoria than in controls [20], but other studies had shown that plasma testosterone in women with premenstrual symptoms was not different from that in non-symptomatic controls [21, 22]. A recent study which carefully investigated the level of androgens in women with cyclical mood changes and premenstrual syndrome demonstrated that plasma testosterone was significantly lower in women with luteal phase symptoms compared with those with additional follicular phase symptoms [23]. The PCOS is a hyperandrogenic, oligomenorrhea/amenorrhea, fertility problems and metabolic disorder found in 67% of reproductive-aged women [24]. Therefore, the clinical features and pathophysiological processes of the PMDD should be totally different from ones of the PCOS. Recently, several studies demonstrated that AGD in adult patients with PCOS was longer than that in control, implying that extreme prenatal androgen exposure might contribute to PCOS [16, 25, 26]. Whereas, our PMDD patients showed elongated CUMD, rather than extended AGD. It seems that both of PMDD and PCOS are probably involved in the higher prenatal androgen exposures. But, why did PMDD patients have a longer CUMD and PCOS patents have a longer AGD? Future studies are awaited to help delineate the difference. At present, it can be inferred that there are other factors led to discrepant perineum appearances, in addition to prenatal androgen hormones.

Several reports demonstrated that the presence of premenstrual symptoms correlated negatively with sexual satisfaction [23, 27,28,29]. Sexual pleasure and orgasm during copulation in women depends on many factors, such as past experience, stimulation of one or all of these triggering zones, autonomic arousal, and partner- and contextual-related cues, etc. [30]. The clitoral complex in relation to the urethra, vulva, and vagina is the essential sensory triggering zone [29]. A longer CUMD in a woman decrease her likelihood of experiencing orgasm in sexual intercourse, as the longer CUMD may decrease penile-clitoral contact during sexual intercourse or decrease penile stimulation of internal aspects of the clitoris [12]. Therefore, the longer CUMD might contribute to the sexual difficulties of women with premenstrual symptoms, according to our results.

There are some major defects in the present studies. This is a preliminary study with limited samples that were not chosen randomly, the way of collecting cases could lead the bias to some extent. Moreover, we did not study the association of individual differences in the severity of premenstrual symptoms with the left/right 2D:4D ratios, AGD-AC, AGD-AF and CUMD, and did not collect data about the sexual function/satisfaction of subjects, at same time.

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