Lejeune H, Chuzel F, Thomas T, Avallet O, Habert R, Durand P, Saez J
INSERM-INRA U418, Hôpital Debrousse, Lyon.
Ann Endocrinol (Paris). 1996;57(1):55-63.
In addition to the endocrine control of Leydig cell functions by LH, paracrine control of Leydig cell functions has been suspected from the indirect stimulatory effect of FSH on Leydig cells. Coculture experiments of Leydig and Sertoli cells and the effect of Sertoli cell conditioned media on Leydig cells confirmed the production by Sertoli cells of acute steroideogenic factor(s) and factors involved in the positive or negative control of Leydig cell differenciated functions. Characterization and purification of these paracrine factors has been until recently unsuccessful. Another approach has been to investigate whether compounds of known biological activities in other systems, were produced within the testis and act on leydig cells. IGF-I is produced by Sertoli and Leydig cells under the control of their respective gonadotropin, LH and FSH. IGF-I enhanced hCG responsiveness of Leydig cells by increasing both LH receptor and steroidogenic enzymes. On the contrary TGF-beta which is also produced by Sertoli and Leydig cells is a potent inhibitor of Leydig cell functions. Its production by Sertoli cells is inhibited by FSH. Inhibin enhanced Leydig cell differentiated cell functions. Activin has, conversely to what has been published in the rat, a stimulatory effect on Leydig cell functions in the immature porcine Leydig cell model. The effects of these growth factors or related molecules mainly consist in positive (IGF-I, Inhibin, Activin) or negative (TGF-beta, TGF-alpha/EGF, bFGF) trophic effects regulating LH/hCG receptor number and mRNAs and steroidogenic enzyme mRNAs and activites, allowing regulation of the responsiveness of Leydig cells to LH. Thus both gonadotropins contribute, directly for LH and indirectly, through paracrine mecanisms, for FSH, to testosterone production.
除了促黄体生成素（LH）对睾丸间质细胞功能的内分泌控制外，从促卵泡激素（FSH）对睾丸间质细胞的间接刺激作用来看，人们怀疑存在对睾丸间质细胞功能的旁分泌控制。睾丸间质细胞与支持细胞的共培养实验以及支持细胞条件培养基对睾丸间质细胞的作用，证实了支持细胞产生急性类固醇生成因子以及参与睾丸间质细胞分化功能正性或负性控制的因子。直到最近，这些旁分泌因子的鉴定和纯化都未成功。另一种方法是研究在其他系统中具有已知生物活性的化合物是否在睾丸内产生并作用于睾丸间质细胞。胰岛素样生长因子-I（IGF-I）在其各自的促性腺激素LH和FSH的控制下，由支持细胞和睾丸间质细胞产生。IGF-I通过增加LH受体和类固醇生成酶，增强了睾丸间质细胞对人绒毛膜促性腺激素（hCG）的反应性。相反，同样由支持细胞和睾丸间质细胞产生的转化生长因子-β（TGF-β）是睾丸间质细胞功能的有效抑制剂。支持细胞产生TGF-β受到FSH的抑制。抑制素增强了睾丸间质细胞的分化细胞功能。与在大鼠中发表的情况相反，激活素在未成熟猪睾丸间质细胞模型中对睾丸间质细胞功能具有刺激作用。这些生长因子或相关分子的作用主要包括正向（IGF-I、抑制素、激活素）或负向（TGF-β、TGF-α/表皮生长因子（EGF）、碱性成纤维细胞生长因子（bFGF））营养作用，调节LH/hCG受体数量和信使核糖核酸（mRNAs）以及类固醇生成酶的mRNAs和活性，从而调节睾丸间质细胞对LH的反应性。因此，两种促性腺激素都对睾酮的产生有贡献，LH直接起作用，FSH则通过旁分泌机制间接起作用。
