抄録
The central part of the bed nucleus of the stria terminalis was shown to be sexually dimorphic, i.e., smaller in women, with a female volume and neuron number in male-to-female transsexuals. The interstitial nuclei of the anterior hypothalamus (INAH) 3 was also sexually dimorphic, i.e., more than twice as large in heterosexual men than in homosexual men. These findings indicate that each sexual identity and sexual orientation has a different biological substrate. We studied the gonadotropin secretory pattern in 4 21-27 year-old female-to-male transsexual women (FTMs). In 2 FTMs, the surge secretion of LH was atypical, showing extremely low amplitudes, in accord with the clinical diagnosis of anovulatory menstrual cycles based on the basal body temperature (BBT), whereas pulsatile secretions of LH in both follicular and luteal phases were typical. One of these FTMs was bisexual and another homosexual. Two other FTMs showed almost typical LH secretory patterns and BBT during the cycle, being homosexual. Although it is controversial whether the control mechanism for gonadotropin secretion in the human hypothalamus is sexually dimorphic, we assume that FTMs are atypical not only in sexual identity, but also in sexual orientation and the control of gonadotropin secretion, suggesting that they have a general hypothalamic sexual differentiation disorder (GHSDD). [Jpn J Physiol 54 Suppl:S41 (2004)]
