Seminal plasma MicroRNA dynamics in stallion semen due to progressive motility and conception success

This study aims to investigate the expression patterns of miR-34b, miR-122, let-7a in seminal plasma of stallions in relation to progressive motility and conception success, and to evaluate their potential as biomarkers. Fifteen adult stallions were enrolled in study. One ml of seminal plasma was kept at -80 °C, 2 ml of fresh semen was sampled from each stallion for sperm analysis, and the rest were used for artificial insemination only for one mare. Two groups were formed as high progressive motility (HPM; n:8) and low progressive motility (LPM; n:7), based on progressive motility. Besides, two groups were formed as positive (n:8) and negative (n:7) pregnancy groups according to 14th day pregnancy results. Motility and progressive motility values determined by computer-assisted semen analyzer. Flow cytometry was used to evaluate the viability, HMMP, PMAI, non-capacitated sperm rate and LPO parameters. MicroRNAs were evaluated with qPCR. Prediction of targets, protein-protein interactions and functional enrichment analyses were also performed. Total (82.13 ± 3.04; p < 0.01) and progressive (45.88 ± 6.03; p < 0.001) motilities, and non-capacitated sperm rates (45.76 ± 3.92; p < 0.05) were greater in HPM. Compared to LPM, miR-34b (p < 0.05) and miR-122 (p < 0.05) were upregulated in HPM approximately 11- and 6-fold, respectively. miR-34b and total motility were positively correlated (0.674; p < 0.01). Target gene analysis revealed a network of 102 genes and 421 edges. Moreover, significant interaction networks involving 19 proteins were determined. Performed enrichment analysis showed selected miRNAs significantly regulate crucial pathways. Regulatory differences of miR-34b and miR-122 in seminal plasma might serve to determine the characteristics of stallion semen.