Hall P F, Osawa S, Mrotek J
Endocrinology. 1981 Nov;109(5):1677-82. doi: 10.1210/endo-109-5-1677.
Two approaches were used to study the possible role of calmodulin in the regulation of synthesis of testosterone by Leydig cells: trifluoperazine was used as an inhibitor of calmodulin and liposomes were used to deliver calmodulin into the cells. The inhibitor prevented the expected responses of Leydig cells to LH and to cAMP. First the increase in synthesis of testosterone produced when these agents are added to Leydig cells was inhibited by the drug. Second, increased transport of cholesterol to mitochondria produced by LH and cAMP was inhibited by trifluoperazine. Third, increased side-chain cleavage of cholesterol (cholesterol leads to pregnenolone) produced by these agents in isolated mitochondria was also inhibited by the drug. When Leydig cells were incubated with liposomes containing calmodulin, production of testosterone, transport of cholesterol to mitochondria, and side-chain cleavage of cholesterol were all stimulated. The effect of calmodulin is greater if Ca2+ is added before incorporation into liposomes than if calmodulin and Ca2+ are introduced into the Leydig cells from separate liposomes. Stimulation of testosterone synthesis does not occur if calmodulin is dialyzed against EGTA, if calmodulin with excess anticalmodulin is present in the liposomes, if either calmodulin or Ca2+ is added to the medium (no liposomes), or if Ca2+ alone is present in liposomes. These observations suggest that calmodulin is involved in regulating the transport of cholesterol to mitochondria, a process that is stimulated by LH and cAMP and one that may account for the increased steroid synthesis produced by these agents.
使用三氟拉嗪作为钙调蛋白抑制剂，并使用脂质体将钙调蛋白递送至细胞内。该抑制剂可阻止睾丸间质细胞对促黄体生成素（LH）和环磷酸腺苷（cAMP）的预期反应。首先，当将这些物质添加到睾丸间质细胞中时所产生的睾酮合成增加被该药物抑制。其次，LH和cAMP所引起的胆固醇向线粒体转运增加被三氟拉嗪抑制。第三，这些物质在分离的线粒体中所引起的胆固醇侧链裂解（胆固醇转化为孕烯醇酮）也被该药物抑制。当睾丸间质细胞与含有钙调蛋白的脂质体一起孵育时，睾酮的产生、胆固醇向线粒体的转运以及胆固醇的侧链裂解均受到刺激。如果在将钙调蛋白掺入脂质体之前添加Ca2+，则钙调蛋白的作用比从单独的脂质体中将钙调蛋白和Ca2+引入睾丸间质细胞时更大。如果钙调蛋白用乙二醇双四乙酸（EGTA）透析、脂质体中存在过量抗钙调蛋白的钙调蛋白、将钙调蛋白或Ca2+添加到培养基中（无脂质体）或脂质体中仅存在Ca2+，则不会发生睾酮合成的刺激。这些观察结果表明，钙调蛋白参与调节胆固醇向线粒体的转运，这一过程受到LH和cAMP的刺激，并且可能是这些物质所导致的类固醇合成增加的原因。
