Reproductive Endocrinology and Signaling Group, Dept. of Biology and Ecology, Faculty of Sciences at Univ. of Novi Sad, Dositeja Obradovica Square 2, 21000 Novi Sad, Serbia.
Am J Physiol Endocrinol Metab. 2012 May 1;302(10):E1239-51. doi: 10.1152/ajpendo.00554.2011. Epub 2012 Feb 28.
This study was designed to evaluate the effect of acute (2 h daily) and repeated (2 h daily for 2 or 10 consecutive days) immobilization stress (IMO) on: 1) the steroidogenic machinery homeostasis; 2) cAMP signaling; and the expression of receptors for main markers of 3) adrenergic and 4) glucocorticoid signaling in Leydig cells of adult rats. The results showed that acute IMO inhibited steroidogenic machinery in Leydig cells by downregulation of Scarb1 (scavenger receptor class B), Cyp11a1 (cholesterol side-chain cleavage enzyme), Cyp17a1 (17α-hydroxylase/17,20 lyase), and Hsd17b3 (17β-hydroxysteroid dehydrogenase) expression. In addition to acute IMO effects, repeated IMO increased transcription of Star (steroidogenic acute regulatory protein) and Arr19 (androgen receptor corepressor 19 kDa) in Leydig cells. In the same cells, the transcription of adenylyl cyclases (Adcy7, Adcy9, Adcy10) and cAMP-specific phosphodiesterases (Pde4a, Pde4b, Pde4d, Pde7a, Pde8a) was stimulated, whereas the expression of the genes encoding protein kinase A subunits were unaffected. Ten times repeated IMO increased the levels of all adrenergic receptors and β-adrenergic receptor kinase (Adrbk1) in Leydig cells. The transcription analysis was supported by cAMP/testosterone production. In this signaling scenario, partial recovery of testosterone production in medium/content was detected. The physiological significance of the present results was proven by ex vivo application of epinephrine, which increased cAMP/testosterone production by Leydig cells from control rats in greater fashion than from stressed. IMO did not affect the expression of transcripts for Crhr1/Crhr2 (corticotropin releasing hormone receptors), Acthr (adrenocorticotropin releasing hormone receptor), Gr (glucocorticoid receptor), and Hsd11b1 [hydroxysteroid (11-β) dehydrogenase 1], while all types of IMO stimulated the expression of Hsd11b2, the unidirectional oxidase with high affinity to inactivate glucocorticoids. Thus, presented data provide new molecular/transcriptional base for "fight/adaptation" of Leydig cells and new insights into the role of cAMP, epinephrine, and glucocorticoid signaling in recovery of stress-impaired Leydig cell steroidogenesis.
这项研究旨在评估急性（每天 2 小时）和重复（连续 2 或 10 天每天 2 小时）固定应激（IMO）对以下方面的影响：1）甾体生成机制的稳态；2）cAMP 信号转导；3）肾上腺素能和 4）糖皮质激素信号的主要标志物的受体在成年大鼠的睾丸间质细胞中的表达。结果表明，急性 IMO 通过下调 Scarb1（清道夫受体 B 类）、Cyp11a1（胆固醇侧链裂解酶）、Cyp17a1（17α-羟化酶/17,20 裂解酶）和 Hsd17b3（17β-羟甾体脱氢酶）的表达，抑制了睾丸间质细胞的甾体生成机制。除了急性 IMO 作用外，重复 IMO 还增加了睾丸间质细胞中 Star（甾体生成急性调节蛋白）和 Arr19（雄激素受体共阻遏子 19kDa）的转录。在相同的细胞中，腺苷酸环化酶（Adcy7、Adcy9、Adcy10）和 cAMP 特异性磷酸二酯酶（Pde4a、Pde4b、Pde4d、Pde7a、Pde8a）的转录被刺激，而蛋白激酶 A 亚基的基因表达不受影响。10 次重复 IMO 增加了睾丸间质细胞中所有肾上腺素能受体和β-肾上腺素能受体激酶（Adrbk1）的水平。cAMP/睾酮产生的分析得到了支持。在这种信号情景下，检测到中/内容物中睾酮产生的部分恢复。肾上腺素的离体应用证明了本研究结果的生理意义，它增加了来自对照大鼠的间质细胞中的 cAMP/睾酮产生，比来自应激大鼠的增加更多。IMO 不影响 Crhr1/Crhr2（促肾上腺皮质激素释放激素受体）、Acthr（促肾上腺皮质激素释放激素受体）、Gr（糖皮质激素受体）和 Hsd11b1[羟甾（11-β）脱氢酶 1]的转录本的表达，而所有类型的 IMO 都刺激 Hsd11b2 的表达，这种单向氧化酶对失活糖皮质激素具有高亲和力。因此，所提供的数据为睾丸间质细胞的“战斗/适应”提供了新的分子/转录基础，并深入了解 cAMP、肾上腺素和糖皮质激素信号在恢复应激损伤的睾丸间质细胞甾体生成中的作用。
