Kumanov Philip, Tomova Analia, Isidori Aldo, Nordio Maurizio
Clinical Center of Endocrinology, Medical University, Sofia, Bulgaria.
Int J Androl. 2005 Aug;28(4):234-40. doi: 10.1111/j.1365-2605.2005.00534.x.
The pineal gland, through the rhythmic production of melatonin, seems to play an important role in the control of the reproductive function of many vertebrate species. In contrast, the effects of the pineal gland in humans and the relationship between gonadotropins and melatonin secretion are not yet clarified. On the basis of these considerations, the aim of the present study was to clarify whether melatonin serum concentrations were altered in males with different hypothalamo-pituitary-gonadal disturbances, in comparison to normal individuals. We have studied 36 individuals divided into three groups according to their gonadotropin status: normals, hypogonadotropic hypogonadism and hypergonadotropic hypogonadism. They were submitted to blood sample withdrawal at 03.00, 11.00 and 19.00 h for melatonin determination according to a radioimmunological method, without extraction of the sample. The results obtained in the present study suggest the existence of an interaction between the pituitary and the pineal gland. In fact, in the case of hypersecretion of gonadotropins, nocturnal melatonin release is reduced, while night melatonin secretion is increased in the opposite situation (hypogonadotropic hypogonadism). Both these endocrine pathologies are characterized by a reduced sexual steroid secretion; for that reason, this reduction cannot be regarded as responsible for the two opposite dysfunctions of melatonin release. In conclusion, our study shows that darkness-dependent release of melatonin in males with hypogonadotropic hypogonadism is significantly higher in comparison with the healthy men, while it is significantly reduced in patients with hypergonadotropic hypogonadism. A strong significant negative correlation is also found between gonadotropins and melatonin release.
松果体通过有节律地分泌褪黑素，似乎在许多脊椎动物物种生殖功能的控制中发挥着重要作用。相比之下，松果体在人类中的作用以及促性腺激素与褪黑素分泌之间的关系尚未明确。基于这些考虑，本研究的目的是明确与正常个体相比，患有不同下丘脑 - 垂体 - 性腺功能紊乱的男性血清褪黑素浓度是否发生改变。我们根据促性腺激素状态将36名个体分为三组：正常人、低促性腺激素性性腺功能减退和高促性腺激素性性腺功能减退。按照放射免疫法，在凌晨3点、上午11点和晚上7点采集他们的血样以测定褪黑素，样本无需提取。本研究获得的结果提示垂体与松果体之间存在相互作用。事实上，在促性腺激素分泌过多的情况下，夜间褪黑素释放减少，而在相反情况下（低促性腺激素性性腺功能减退）夜间褪黑素分泌增加。这两种内分泌疾病均以性类固醇分泌减少为特征；因此，这种减少不能被视为导致褪黑素释放这两种相反功能障碍的原因。总之，我们的研究表明，与健康男性相比，低促性腺激素性性腺功能减退男性中依赖黑暗的褪黑素释放显著更高，而在高促性腺激素性性腺功能减退患者中则显著降低。促性腺激素与褪黑素释放之间也存在强烈的显著负相关。
