摘要
最近，住各种动物精子低温冷冻的实验中，提取于鸡蛋蛋黄中的低密度脂蛋白被视为优于全蛋黄溶液。与此同时，有研究认为蛋黄中的高密度脂蛋白可能对解冻后精子的生存产生负面影响。关于低密度脂蛋白和高密度脂蛋白在猕猴精子低温冷冻作用的研究还未有过报道。本研究在加和不加渗透型抗冻剂（甘油）两种情况下，通过与全蛋黄溶液对比的手段评价了两种脂蛋白在猕猴精子低温冷冻中的作用。此外，本研究也尝试多种能够改造精于膜与低密度脂蛋白结合体成分的添加剂对保存解冻精子活力的作用。我们的实验结果表明，低密度脂蛋白是伞蛋黄溶液在猕猴精子低温冷冻中发挥保护作用的主要成分。不管有无添加甘油，低密度脂蛋白与令蛋黄溶液在保存解冻精子活性方面作用相近，并未显现出任何优越性。通过加入胆同醇、胆固醇环糊精复合物或卵磷脂来改变精子膜与低密度脂蛋白结合体成分的方法并未改善解冻精子的存活状况；但加入甲基-β-环糊精则明显降低解冻精于的活力。高密度脂蛋白对猕猴精子低温冷冻保存不存在负面影响。对猕猴精子低温冷冻保存而言，本研究表明全蛋黄溶液相比较于稀释液中的有效成分低密度脂蛋白仍然具有优越性。
Low-density lipoprotein （LDL） extracted from hen egg yolk has recently been considered to be superior to whole egg yolk in sperm cryopreservation of various animal species. Meanwhile, there was a notion that high-density lipoprotein （HDL） in egg yolk may have a negative effect on post-thaw survival. The role of LDL and HDL in sperm cryopreservation of rhesus monkeys has not been explored. The present study evaluates their effect in comparison with egg yolk with or without the addition of permeable cryoprotectant （glycerol） on sperm cryopreservation of rhesus macaques. In addition, various additives intended to change the lipid composition of LDL-sperm membrane complex have also been tested for their effectiveness in preserving post-thaw viability. Our findings indicated that LDL is the main component in egg yolk that is responsible for its protective role for sperm cryopreservation in rhesus monkeys. Regardless of the presence or absence of glycerol, the protective role of LDL is similar to that of egg yolk and we did not observe any superiority in post-thaw survival with LDL when compared to egg yolk. Modifying the lipid composition of LDL-sperm membrane complex with the addition of cholesterol, cholesterol loaded cyclodextrin and phosphatidylcholine also did not yield any improvements in pest-thaw survival; while addition of methyl-β-cyclodextrin reduced post-thaw motility. HDL plays a neutral role in sperm cryopreservation of rhesus monkeys. The present study suggests that egg yolk may still hold advantages when compared with LDL as effective components in extenders for sperm cryopreservation in rhesus monkeys.
基金
This work was supported in part by funding from the National Natural Science Foundation of China （No. 30800845）, the Natural Science Fund for Distinguished Young Scholars of Zhejiang Province （No. R3100105）, and the NIH grants RR00169 and RR13439. We thank Dr. M. Anton for providing the detailed protocols of LDL and HDL extraction.
