Guillou F, Martinat N, Combarnous Y
Biochim Biophys Acta. 1986 Jul 11;887(2):196-203. doi: 10.1016/0167-4889(86)90055-8.
We have previously shown that equine follicle-stimulating hormone (FSH) stimulates plasminogen activator secretion in Sertoli cells at much lower concentrations than would be expected from its relative binding activity. We have introduced the term 'superactivity' to designate this particular behavior. In the present study, we show that equine FSH triggers a long-lasting (20 h) plasminogen activator secretion, whereas rat, porcine and ovine FSH as well as equine LH and equine choriogonadotropin (CG) provoke a short-term response (2.5 h). Moreover, equine FSH was also shown to be superactive in the stimulation of estradiol secretion and cyclic AMP production. This indicates that the step responsible for the long-term stimulation by equine FSH is not located beyond cAMP accumulation. Equine and porcine FSH were found to be equally stable during incubation with the cells demonstrating that equine FSH superactivity was not due to higher stability. Besides, phosphodiesterase inhibition led to a similar increase in the responses to both hormones. This rules out the possibility that equine FSH superactivity is due to less stimulation of phosphodiesterase activity. All these data strongly suggest that equine FSH exhibits superactivity in rat Sertoli cells by stimulating adenylate cyclase activity for a much longer period of time than do all other gonadotropins. The molecular mechanism of this outstanding behavior remains to be elucidated.
我们之前已经表明，马促卵泡激素（FSH）刺激支持细胞分泌纤溶酶原激活物时所需的浓度，比根据其相对结合活性预期的浓度要低得多。我们引入了“超活性”这一术语来描述这种特殊行为。在本研究中，我们发现马FSH引发了持久（20小时）的纤溶酶原激活物分泌，而大鼠、猪和羊的FSH以及马促黄体生成素（LH）和马绒毛膜促性腺激素（CG）则引发短期反应（2.5小时）。此外，马FSH在刺激雌二醇分泌和环磷酸腺苷（cAMP）产生方面也表现出超活性。这表明，马FSH长期刺激的步骤并不位于cAMP积累之后。在与细胞孵育过程中，发现马FSH和猪FSH的稳定性相同，这表明马FSH的超活性并非源于更高的稳定性。此外，磷酸二酯酶抑制导致对两种激素的反应出现类似增加。这排除了马FSH超活性是由于对磷酸二酯酶活性刺激较少的可能性。所有这些数据都强烈表明，与所有其他促性腺激素相比，马FSH通过更长时间地刺激腺苷酸环化酶活性，在大鼠支持细胞中表现出超活性。这种突出行为的分子机制仍有待阐明。
