Eikvar L, Levy F O, Attramadal H, Hansson V
Institute of Medical Biochemistry, University of Oslo, Norway.
J Steroid Biochem Mol Biol. 1995 May;52(5):431-6. doi: 10.1016/0960-0760(95)00002-h.
In the present study we have examined the effects of islet activating protein (IAP) on the regulatory effects of FSH, glucagon and (-)N6-(R)-phenyl-isopropyladenosine (PIA), an adenosine A1 receptor agonist, on the formation of cAMP and estradiol-17 beta (E2) in Sertoli cell cultures isolated from immature (19-day-old) rats. FSH (NIH-FSH-S-15) (1.25 micrograms/ml) caused a more than 10-fold stimulation of the level of both cAMP and E2 in the spent media from Sertoli cell cultures during an 18 h incubation. Both responses were reduced by 80% in the presence of PIA (10(-6) M). When the cultures were preincubated for 24 h with increasing concentration of IAP, the inhibitory effects of PIA were counteracted in a concentration-dependent manner. Moreover, preincubation with IAP (> 20 ng/ml) caused a significant stimulation of FSH-stimulated cAMP production even in the absence of PIA. PIA inhibited FSH-stimulated cAMP production in a concentration dependent manner. However, when the cells were preincubated with IAP (100 ng/ml) for 24 h, the inhibitory effects of PIA were completely abolished, and PIA now actually caused a slight stimulation of cAMP production. Both FSH and glucagon stimulated cAMP production in a concentration-dependent manner. Preincubation with IAP (100 ng/ml for 24 h) resulted in an increase in maximal stimulation of cAMP production for both FSH and glucagon. When adenylyl cyclase (AC) activity was measured directly in isolated membrane particles from Sertoli cells cultured in the presence of IAP (100 ng/ml) for 24 h, both basal and FSH-stimulated AC activity were significantly higher than in membrane particles from control cells. These results provide a further characterization of the functional Gi component coupled to the AC complex in cultured rat Sertoli cells, mediating the inhibitory effects of adenosine and possibly other endogenous substances on cAMP production.
在本研究中，我们检测了胰岛激活蛋白（IAP）对促卵泡激素（FSH）、胰高血糖素以及腺苷A1受体激动剂（-）N6-（R）-苯基异丙基腺苷（PIA）在从未成熟（19日龄）大鼠分离的支持细胞培养物中对环磷酸腺苷（cAMP）和雌二醇-17β（E2）形成的调节作用的影响。在18小时的孵育过程中，FSH（美国国立卫生研究院FSH-S-15）（1.25微克/毫升）使支持细胞培养物的消耗培养基中cAMP和E2水平的刺激增加了10倍以上。在存在PIA（10^-6 M）的情况下，这两种反应均降低了80%。当培养物用浓度递增的IAP预孵育24小时时，PIA的抑制作用以浓度依赖性方式被抵消。此外，用IAP（>20纳克/毫升）预孵育即使在没有PIA的情况下也会显著刺激FSH刺激的cAMP产生。PIA以浓度依赖性方式抑制FSH刺激的cAMP产生。然而，当细胞用IAP（100纳克/毫升）预孵育24小时时，PIA的抑制作用完全被消除，并且PIA现在实际上导致cAMP产生略有刺激。FSH和胰高血糖素均以浓度依赖性方式刺激cAMP产生。用IAP（100纳克/毫升，24小时）预孵育导致FSH和胰高血糖素对cAMP产生的最大刺激增加。当在存在IAP（100纳克/毫升）的情况下培养24小时的支持细胞分离的膜颗粒中直接测量腺苷酸环化酶（AC）活性时，基础和FSH刺激的AC活性均显著高于对照细胞的膜颗粒。这些结果进一步表征了与培养的大鼠支持细胞中的AC复合物偶联的功能性Gi成分，介导腺苷以及可能其他内源性物质对cAMP产生的抑制作用。
