Many cellular processes in spermatozoa, including apoptosis and motility, are regulated by miRNA. Different miRNAs and molecular pathways are involved in asthenozoospermia (AS) conditions, which are thought to be one of the causes of infertility with reduced sperm motility. Thirty-two semen samples from four Holstein bulls with normozoospermia (NS), total motility ≥ 70%, and progressive motility ≥ 60%, and 32 semen samples from four bulls with AS, total motility ≤ 40%, and progressive motility ≤ 32% were used to investigate the function of apoptosis-related miRNAs in the AS group. Samples were then aspirated into a 0.5 mL straw after dilution with a Tris-egg yolk extender and frozen at -196°C. After freezing, semen samples were thawed for 2 weeks at 37°C and sperm kinematic parameters, plasma membrane integrity, acrosome integrity, DNA fragmentation, apoptosis status, and expression of apoptosis-related miRNAs (miR-2114, miR-296-3p, miR-455-3p, and miR345-3p) were evaluated. Our results showed that the functional and flow cytometric parameters of the NS group were significantly better than those of the AS group. In the NS group, miR-455-3pp and miR-2412 were upregulated, while miR-345-3p was downregulated compared with the AS group. In the AS group, miR-296-39, miR-2412, and miR-345-3p levels were strongly correlated with membrane integrity, DNA fragmentation, and apoptosis status. The findings demonstrated that the selected miRNAs based on bioinformatic analysis in AS and NS samples had a substantial association with functional and flow cytometry indicators and may be involved in regulating apoptosis and motility in AS samples.
Keywords: apoptosis; asthenozoospermia; bulls; miRNA; normozoospermia.