Browsing by Author "Goss, Dale Mark"

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    Short abstinence: Impact on the seminal plasma proteome and accessory sex gland secretions
    (Stellenbosch : Stellenbosch University, 2018-03) Goss, Dale Mark; Du Plessis, Stefan S.; Van der Horst, Gerhard; Stellenbosch University. Faculty of Health Sciences. Dept. of Biomedical Sciences : Medical Physiology.
    ENGLISH ABSTRACT: Various studies have sought to determine the typical versus optimal abstinence period after which semen samples should be collected, and many have been found to be contradictory. Several factors influence the semen microenvironment and subsequent sperm basic and functional parameters. In this study we focused on important biomarkers of prostate, seminal vesicle and epididymal secretion. Furthermore, extensive proteomic analysis of seminal plasma was performed for a more comprehensive understanding of the observations. Semen samples were obtained from normozoospermic donors (n = 16) after 4 days and 4 hours of ejaculatory abstinence (EA) and standard semen analysis was performed with the assistance of computer aided sperm analysis (CASA), while the seminal plasma citric acid, neutral alpha-glucosidase and fructose concentrations were measured photometrically with commercially available assay kits. Protein identification was performed using advanced mass spectrometric techniques and pathways were analysed on both Reactome and String databases. Results of this study displayed significant decreases in semen volume, sperm concentration, total sperm count, and pH after 4 hours of ejaculatory abstinence when compared to 4 days. Furthermore, increases in total sperm motility and progressive motility after short EA periods were observed, accompanied by significant reductions in all epididymal and accessory sex gland biomarker concentrations. However, due to the decreased sperm number, these concentrations translated to a significant increase in citric acid and a decrease in fructose available per spermatozoon, which, along with the effects on semen pH, could more than likely be responsible for increased metabolic function and subsequent increase in the available energy for sperm motility. Proteomic analysis identified 22 differentially expressed seminal plasma proteins, with 18 proteins upregulated after 4 days of EA and 3 upregulated after 4 hours of EA. Of the proteins differentially expressed, 5 proteins from 4 days of EA and 2 proteins from 4 hours of EA, were identified to be related to sperm function and thus selected for pathway analysis. proteins were found to be prominent components of cellular processes including metabolism, apoptosis and cell process regulation, which can be linked directly and indirectly to sperm motility parameters. To conclude, the mechanisms by which very short EA improves sperm motility depends on seminal plasma composition thereby affecting metabolic function and protein interactions.