Characterization of fertile and infertile dog seminal plasma proteins and their correlation with semen quality: Preliminary study

Significant deterioration in semen quality is associated with increased male infertility. Alterations in the sperm proteome resulting from infertility are not well understood. The aim of this study was to examine the connection between the proteome and the quality of spermatozoa in fertile and infertile dogs. The research was conducted on 11 male dogs, including 3 German shepherds, 3 Turkish Kangal, 2 Cane Corso, and 3 Golden Retrievers, aged 4 and 6 years (4.81 +/- 0.75). Four of the 11 dogs constituted the infertile study group because of conception failure observed in at least 3 (3-5) matings with different fertile females within 1 year, and seven dogs from different owners constituted the fertile control group. Semen was manually manipulated and collected from all dogs in the presence of a female dog in heat. Ejaculates were used for spermatological examination and protein analysis. Computer-assisted semen analysis (CASA) was used to evaluate semen samples. In spermatological parameters, motility, kinematic parameters, morphology and plasma membrane integrity were evaluated. Gel electrophoresis (SDS-PAGE) was used to analyze proteins in sperm. The semen quality of infertile dogs was significantly lower. Motility, progressive motility, viability and plasma membrane integrity were statistically significantly lower in the infertile group than in the fertile group (P < 0.05). In morphological parameters, acrosome, head, middle part, tail and total defects were found to be statistically significantly higher in sterile dogs than in fertile dogs (P < 0.05). In the study, a total of 8 protein bands with molecular weights (MW) ranging from 11.0 to 245.0 kDa were identified in the protein analysis of semen. Variations in the sperm proteome composition were shown to be dependent on fertility. These proteins were associated with important metabolite pathways. Additionally, correlations of these bands with various spermatological parameters were revealed. The result of the study suggests that seminal plasma proteins play a role in semen quality and may be potential fertility biomarkers.