Giagulli V A, Carbone D
O.U. Internal Medicine, Sub. Endocrinology, Ospedale Putignano-Noci-Gioia del Colle, 270015 Noci, Bari, Italy.
J Endocrinol Invest. 2006 Sep;29(8):706-13. doi: 10.1007/BF03344180.
Serum inhibin B (IB) and testosterone (T) levels, secreted by Sertoli cells (SC) and Leydig cells (LC), respectively, are parameters of the functional state of these cells. Whereas LC activity and, consequently, T secretion are regulated by serum LH, factors regulating IB secretion by SC are still partially unknown. There is evidence that under certain conditions such as puberty, aging or some spermatogenesis defects, LH levels or Gn-independent factors might contribute to regulating SC activity and IB secretion. Among these factors, GH and IGF-I as well as PRL might have a role. Therefore, in order to explore the possible effects of either LH alone and FSH alone or a combination of both Gn, respectively, on SC function, IB plasma levels and spermatogenesis, we studied their effects in 6 patients with hypogonadotropic hypogonadism (HH), whereas the effects of GH on these parameters were studied in 6 men with panhypopituitarism (PH). Finally, the possible effects of PRL on SC function and spermatogenesis were studied in 6 patients with hyperprolactinemia (HPRL); 24 normal, fertile adults served as control group. In men with HH, neither human chorionic Gn (hCG) nor FSH, respectively, were able to increase serum IB after 3 months of therapy, whereas combined Gn therapy for 24 months increased IB plasma levels and stimulated spermatogenesis in 4 out of 6 hypogonadal men. In panhypopituitaric men, GH added to the classical Gn therapy did not have an additional effect on serum IB levels or spermatogenesis. Surprisingly, in our hyperprolactemic men, IB plasma levels were increased and positively correlated (p<0.01) with serum PRL levels, whereas normalization of the latter by cabergoline treatment caused a decrease of IB levels and a moderate increase in T, LH and FSH. In conclusion, the lack of SC response to FSH therapy alone, as opposed to the response to combined Gn therapy, might indicate that normalization of serum T by hCG is required to obtain IB secretion by SC. Addition of GH did not affect SC function, serum IB levels or spermatogenesis. Finally, our data suggest that PRL plasma levels might have a direct role on IB secretion, suggesting that the hypogonadism found in patients with HPRL might be a consequence of both central (inhibition of Gn secretion) and peripheral (stimulation of IB secretion) origin.
分别由支持细胞（SC）和间质细胞（LC）分泌的血清抑制素B（IB）和睾酮（T）水平，是这些细胞功能状态的参数。虽然LC活性以及因此的T分泌受血清促黄体生成素（LH）调节，但调节SC分泌IB的因素仍部分未知。有证据表明，在某些情况下，如青春期、衰老或一些精子发生缺陷，LH水平或不依赖Gn的因素可能有助于调节SC活性和IB分泌。在这些因素中，生长激素（GH）、胰岛素样生长因子-I（IGF-I）以及催乳素（PRL）可能起作用。因此，为了分别探究单独的LH、单独的促卵泡生成素（FSH）或两者联合对SC功能、血浆IB水平和精子发生的可能影响，我们研究了它们对6例低促性腺激素性性腺功能减退（HH）患者的影响，而对GH对这些参数的影响则在6例全垂体功能减退（PH）男性中进行了研究。最后，在6例高催乳素血症（HPRL）患者中研究了PRL对SC功能和精子发生的可能影响；24名正常、有生育能力的成年人作为对照组。在HH男性中，治疗3个月后，人绒毛膜促性腺激素（hCG）和FSH均不能增加血清IB，而联合Gn治疗24个月可使6例性腺功能减退男性中的4例血浆IB水平升高并刺激精子发生。在全垂体功能减退男性中，在经典Gn治疗基础上加用GH对血清IB水平或精子发生没有额外影响。令人惊讶的是，在我们的高催乳素血症男性中，血浆IB水平升高且与血清PRL水平呈正相关（p<0.01），而通过卡麦角林治疗使后者恢复正常导致IB水平下降以及T、LH和FSH适度升高。总之，与联合Gn治疗的反应相反，单独FSH治疗时SC缺乏反应可能表明需要通过hCG使血清T正常化才能使SC分泌IB。加用GH不影响SC功能、血清IB水平或精子发生。最后，我们的数据表明PRL血浆水平可能对IB分泌有直接作用，提示HPRL患者中发现的性腺功能减退可能是中枢性（抑制Gn分泌）和外周性（刺激IB分泌）共同作用的结果。
