Ox-LDL影响Leydig细胞睾酮合成的机制研究

It is well-known that lipid metabolic disorders can lead to the damage of Leydig cells, causing male hypogonadism, but its molecular mechanism is not clear. Our previous study found that high fat diet decreased serum level of testosterone while the level of Ox-LDL in serum and Leydig cells were increased in male mice, indicating that there is a connection between Ox-LDL and testosterone in Leydig cells,but their interaction mechanism is unknown. This research will Clear high levels of Ox-LDL affect cellular structure and function of testosterone synthesis in leydig cells, the testicular local Ox-LDL and structure changes of testicular Leydig cell organelles in HFD mice model will be determinated;This study will reveal Ox-LDL impact the mechanism of testosterone synthesis in Leydig cells by detecting cAMP/PKA pathways , the enzyme activity of testosterone synthesis, mitochondrial function and fatty acid oxidation. To explore the mechanism of Ox-LDL influencing testosterone synthesis and mitochondrial function of Leydig cells ,the MAPK and NF-κB signal pathway will be determinated.This research would like to find a new mechanism of Ox-LDL leading to the disorder of androgen synthesis and then provide theoretical basis for the male hypogonadism and male infertility.

脂质代谢紊乱可导致睾丸Leydig细胞损伤，进而引发男性性腺功减退，但其分子机制尚不明确。我们前期研究发现，高脂饮食（HFD）小鼠的血清睾酮水平显著下降，血清Ox-LDL水平及睾丸Leydig细胞中Ox-LDL表达明显升高，提示Ox-LDL对Leydig细胞睾酮合成功能存在影响，但相关机制不明。为此本研究利用HFD模型小鼠，检测睾丸组织局部Ox-LDL以及睾酮水平，观察睾丸Leydig细胞中亚细胞器的结构变化，明确睾丸局部高水平Ox-LDL对Leydig细胞结构以及睾酮合成功能的影响；将Ox-LDL分别作用于原代Leydig细胞和TM3细胞系，检测cAMP/PKA通路、睾酮合成相关酶的活性、线粒体功能以及脂肪酸氧化关键蛋白，并通过细胞内MAPK和NF-κB信号通路分子的测定，阐明Ox-LDL影响Leydig细胞睾酮合成的分子机制。以期为揭示脂质代谢紊乱导致男性性腺功减退及不育症提供新思路。

肥胖引起的异常脂质/脂蛋白代谢可能通过抑制睾丸间质细胞的睾酮合成而影响精子的发生。确定脂蛋白的哪些成分抑制睾酮合成是至关重要的。循环氧化低密度脂蛋白(oxLDL)是LDL的氧化形式，已被报道为血清睾酮水平下降的独立危险因素。然而，oxLDL是否对Leydig细胞功能有损害作用及其具体机制的研究却很少。本研究首次揭示了高脂饲料喂养小鼠睾丸间质细胞中oxLDL的特异性定位和线粒体结构损伤。我们还发现oxLDL通过破坏电子传递链和抑制睾酮合成相关蛋白和酶(StAR、P450scc和3β- HSD)降低线粒体膜电位(MMP)，最终导致间质细胞线粒体功能障碍和睾酮合成降低。进一步实验表明oxLDL通过诱导CD36转录促进脂质摄取和线粒体功能障碍。同时oxLDL通过p38 MAPK信号通路促进间质细胞中COX2的表达。COX-2阻断可减轻oxldl诱导的StAR和P450scc的下降。我们的临床结果澄清了血清oxLDL水平的升高与循环睾酮水平的下降有关。我们的研究结果扩大了oxLDL的破坏性作用，并首次证明oxLDL是由异常脂质代谢引起的男性获得性性腺功能低下的一种新的代谢生物标志物。