Study Of Molecular Mechanism For PNPLA5 Gene Affecting Male Rats Reproductive Ability

Patatin-like Phospholipase Domain Containing Protein(PNPLA5)is a member of the PNPLA family,which has a lipase hydrolase activity.Over-expression of PNPLA5 gene decreases triglycerides storage in cells.PNPLA5 is mainly expressed in skin,testis and epididymis.PNPLA5 knockout can cause disorder of blood lipid metabolism,such as increased levels of blood total cholesterol,triglycerides,and high-density lipoprotein cholesterol in male rats.Lipid metabolism disorder can make low synthesis of male testosterone,the significant increase of spermatogenic epithelial cells apoptosis and abnormal sperm rate.Our preliminary study found that PNPLA5 knockout affected the pregnancy rate in male rats,but the molecular mechanism was still unclear.The study of PNPLA5 gene affecting male reproduvtive ability may provide an important theoretical basis.In this study,we used male PNPLA5 knockout rats as the experimental group and wild type rats as the control group.We expanded the number of PNPLA5 knockout male rats,testing pregnancy rate,average litter size,sperm morphology,sperm motility and testis histological structure.The results showed that the pregnancy rate from PNPLA5 knockout rats exhibted a significantly decreased(P<0.001)but average litter size had no change(P>0.05)when compared with the wild type rats.PNPLA5 knockout rat sperm tails were abnormal.PNPLA5 knockout significantly decreased the curvilinear velocity and progressive of sperm(P<0.01 and P<0.05,seperately)and down-regulated α-tubulin protein expression level.HE pathological analysis showed that the histological structure of testis was loose and arranged in disorder and the epithelial cells fell to the lumen.Tunel staining results suggested that the number of apoptotic cells of testicular tissue was significantly increased in the knockout group(p<0.001).Western blot results indicated that the Bax expression was significantly up-regulated,the Bcl-2 expression was down-regulated and the Caspase-9 expression was up-regulated in the testis of PNPLA5 knockout rat.In conclusion,PNPLA5 knockout could affect male rat sperm morphology,sperm motility and testis histological structure,which might reduced male rats reproductive ability.