Although Silymarin (SMN) has powerful antioxidant properties, little is known about its effects on the quality of frozen-thawed boar sperm. The present study aimed to evaluate the influences of SMN added to the thawing extender on boar sperm parameters essential for fertilization. The frozen-thawed semen was diluted in a Modena thawing extender supplemented with different concentrations of SMN (0, 5, 10, 20 and 50 μM respectively), and then the changes in quality parameters, antioxidant capacity, mitochondrial function and in vitro fertilization (IVF) capability of frozen-thawed sperm were assessed. Here we demonstrated that the motility, plasma membrane integrity and acrosomal integrity of frozen-thawed sperm improved efficiently by SMN (p < .05). In antioxidant parameters evaluation, the tROS level and MDA content of frozen-thawed spermatozoa were reduced in the 20 μM SMN group, while the T-AOC activity significantly increased (p < .05), indicating that the supplementation with SMN can promote the antioxidant capacity of frozen-thawed boar sperm. Besides, we also discovered that the addition of SMN significantly upregulated ATP content and enhanced the mitochondrial activity of sperm. More interestingly, SMN promoted the activities of mitochondrial respiratory chain complexes (MRCC) I, II, III and IV in frozen-thawed sperm significantly. Functionally, the higher penetration rate and increased total efficiency of fertilization were observed in the 20 μM SMN group. In summary, supplementation with SMN in the thawing medium ameliorates the quality of frozen-thawed boar sperm by enhancing mitochondrial respiratory capacity, producing large amounts of ATP and regulating ROS formation.
Keywords: antioxidants; boar semen; cryopreservation; silymarin.
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