牛磺酸对精子发生和成熟的调控作用研究

We have previously found that taurine was widely distributed in testis, epididymis and sperm. Taurine could be synthesized in both testis and epididymis and could promote the growth of testis, stimulate the secretion of LH and testosterone, increase sperm quality, suggesting that taurine may play a vital role in the spermatogenesis and sperm maturation, but the mechanisms are still unknown. The present research aims to approach the correlation between taurine and cells in the testis and epididymis especially spermatogenic cells during different stages of development by detecting the expression level and cell types in which cysteine sulfinate decarboxylase (CSD),taurine synthesis key enzyme, and taurine transporter (TAUT) were expressed as well as the distribution of taurine in the testis and epididymis using the method of Real-time PCR, Western-blot, in situ hybridization and immunohistochemistry. Meanwhile, the role of taurine on spermatogenesis and sperm maturation was approached by detecting the effect of taurine on spermatogenesis, mature correlated hormones, spermatogenic function and the ability of epididymis on sperm maturation by animal experiment and cell culture. Finally, the regulative mechanisms of taurine on sperm spermatogenesis and sperm maturation would be elucidated in order to provide a theoretical foundation for taurine's utilization in the reproduction of male animals as well as human beings.

课题组前期研究发现：牛磺酸广泛分布于睾丸、附睾和精液中；睾丸和附睾均可合成牛磺酸；牛磺酸可促进睾丸发育，刺激LH和睾酮分泌，提高附睾精子质量，提示牛磺酸可能对精子发生和成熟具有重要影响，但其确切作用及机制尚不清楚。项目拟通过定量RT-PCR、Western blot、原位杂交和免疫组化等方法检测牛磺酸合成关键酶-半胱亚磺酸脱羧酶（CSD）和牛磺酸转运体（TAUT）在不同发育阶段大鼠睾丸和附睾中的时空表达特征，检测不同发育阶段睾丸和附睾中牛磺酸的含量及分布的细胞类型，探讨牛磺酸与睾丸和附睾组织内各类型细胞尤其是各阶段生精细胞发育的相关性；通过动物试验结合体外细胞培养，检测牛磺酸对精子发生和成熟相关激素分泌、睾丸生精功能和附睾促精子成熟功能的影响，探讨牛磺酸对精子发生和成熟的作用，最终阐明牛磺酸对精子发生发育和成熟的调控机制，为牛磺酸在种公畜/禽和人类男性生殖中的应用奠定理论基础。

前期研究结果提示，牛磺酸可能对精子发生和成熟具有重要影响，但其确切作用及机制尚不清楚。项目通过定量RT-PCR和原位杂交等方法检测了：CSD、TAUT和牛磺酸在大鼠睾丸和附睾组织中的时空表达特征，牛磺酸对正常大鼠、生精障碍模型及弱精子症模型大鼠精子发生和精子成熟的影响。结果证明：①随着年龄的增长，睾丸及附睾三个区域CSD、TAUT mRNA和蛋白的表达量均呈下降趋势；睾丸间质细胞和附睾上皮细胞是CSD和TAUT表达的主要位点；在不同发育阶段血清、睾丸和附睾中均存在高浓度的牛磺酸，且呈现随年龄增长而下降的趋势；在睾丸组织中牛磺酸主要分布在间质细胞和各级生精细胞中，附睾组织中主要分布在间质细胞和上皮细胞中。结果表明，睾丸和附睾组织均可生物合成牛磺酸，且需要从血液中转运以满足自身需求；牛磺酸对睾丸和附睾组织的发育和功能（睾丸雄激素合成和精子发生功能，附睾精子成熟功能） 密切相关，且牛磺酸含量下降可能是老龄动物精子质量低下的原因之一。②牛磺酸能明显提高雄性大鼠血清中T3、GnRH、LH、T、DHT、PRL和INH B的含量，显著增加睾丸组织中T、DHT和cAMP的含量。结果表明，牛磺酸可能首先通过作用于下丘脑-垂体来影响甲状腺腺和睾丸的分泌功能，刺激T3和T/DHT的分泌，继而影响精子的发生和成熟。③牛磺酸可促进大鼠精子发生，其机制可能是：牛磺酸能够刺激雄激素合成，维持生精上皮结构完整，改善睾丸内细胞的能量代谢，为生精细胞提供适宜的环境，提高生精细胞的稳定性，促进生精细胞分化发育，加快精子细胞形态和功能的成熟，阻止生殖细胞损伤变性。④牛磺酸对附睾精子成熟有促进作用，其机制可能是：牛磺酸可稳定精子形态；通过调节精子线粒体代谢促进精子运动；稳定附睾管腔形态，维持附睾微环境的稳态，刺激精子成熟相关因子的分泌，促进精子在附睾中的成熟。项目研究结果为牛磺酸在种公畜/禽和人类男性生殖中的应用奠定了理论基础。