Fabbri A, Ciocca D R, Ciampani T, Wang J, Dufau M L
Section on Molecular Endocrinology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA.
Endocrinology. 1995 May;136(5):2303-8. doi: 10.1210/endo.136.5.7720679.
GH-releasing hormone (GHRH) is present in the interstitial and germ cells of the rat testis. In previous studies we found that GHRH is secreted from rat adult Leydig cells, in which it stimulates basal and LH-induced cAMP formation and steroidogenesis. In other studies cAMP production in Sertoli cells was found to be stimulated by GHRH. In the present report, we describe a potential paracrine action of GHRH in the Sertoli cell, with stimulation of cAMP formation in cultured adult and pubertal Sertoli cells. GHRH increased FSH-stimulated cAMP production in adult and pubertal cultures in a time-dependent manner. GHRH stimulation of basal and FSH-induced extracellular cAMP formation was more prominent in pubertal than in adult cultures. Immunocytochemical studies demonstrated the presence of GHRH-like immunoreactivity in rat interstitial cells from day 4 to adult life and in the acrosomal region of early and intermediate spermatids at stages III-VI of the seminiferous epithelium cycle. Immunoreactive GHRH was not observed in late spermatids and mature sperm or in Sertoli cells at any age. These results indicate that GHRH acts synergistically with FSH to promote cAMP production in Sertoli cells in culture. Testicular GHRH of Leydig and germ cell origin may be an important paracrine regulator of Sertoli cell function. Alternatively, GHRH present in germ cells may exert stage-specific intracrine functions.
生长激素释放激素（GHRH）存在于大鼠睾丸的间质细胞和生殖细胞中。在先前的研究中，我们发现GHRH由成年大鼠睾丸间质细胞分泌，它能刺激基础状态下以及促黄体生成素（LH）诱导的环磷酸腺苷（cAMP）生成和类固醇生成。在其他研究中，发现GHRH能刺激支持细胞中的cAMP生成。在本报告中，我们描述了GHRH在支持细胞中的一种潜在旁分泌作用，即刺激成年和青春期支持细胞培养物中的cAMP生成。GHRH以时间依赖性方式增加成年和青春期培养物中促卵泡生成素（FSH）刺激的cAMP生成。与成年培养物相比，GHRH对基础状态下以及FSH诱导的细胞外cAMP生成的刺激在青春期培养物中更为显著。免疫细胞化学研究表明，从出生后第4天到成年期，大鼠间质细胞以及生精上皮周期III - VI阶段早期和中期精子细胞的顶体区域存在GHRH样免疫反应性。在晚期精子细胞、成熟精子或任何年龄的支持细胞中均未观察到免疫反应性GHRH。这些结果表明，GHRH与FSH协同作用，促进培养的支持细胞中的cAMP生成。来自睾丸间质细胞和生殖细胞的睾丸GHRH可能是支持细胞功能的重要旁分泌调节因子。或者，生殖细胞中存在的GHRH可能发挥阶段特异性的内分泌功能。
