Medical Physiology

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Browsing Medical Physiology by browse.metadata.advisor "Bongekile, Skosana"

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    A mechanistic study on the mu-opioid receptor in human spermatozoa
    (Stellenbosch : Stellenbosch University, 2021-12) Van Niekerk, Nadia; Du Plessis, Stefan; Marais, Erna; Bongekile, Skosana; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Biomedical Sciences: Medical Physiology.
    Background: Infertility remains a complex and often unexplained phenomenon. The effect of opioids on male reproductive parameters is best understood by the suppression of the hypothalamic- pituitary-gonadal (HPG) axis. However, since the discovery of all three opioid receptor types on human spermatozoa, it has been hypothesized that the opioid system plays a regulatory role on sperm functional parameters. Literature regarding the possible mechanisms involved in these regulatory processes remain contradictory and scarce. Therefore, this study aimed to clarify the role of the mu- opioid receptor in human spermatozoa. Methods: 30 semen samples were collected from healthy, human donors of reproductive age. Each sample was divided into 4 equal groups and treated accordingly. The study consisted of a control group, a codeine (opioid agonist) treated group, a naloxone (opioid antagonist) treated group, and a combination (codeine and naloxone) treated group. After a 3 hour incubation period, sperm functional parameters were assessed: Total motility, progressive motility and sperm kinematics were assessed using the Computer-Aided Sperm Analysis (CASA) system. Furthermore, viability, acrosome reaction and DNA fragmentation were investigated. By performing western blot analyses the total expression of A-kinase anchoring protein 3 (AKAP3) and protein kinase C𝛼 (PKC𝛼) were evaluated. Results: No differences in sperm functional parameters were detected. It was observed that codeine influenced the acrosome reaction and DNA fragmentation negatively, and that naloxone seemed to alleviate these effects, but the results were not significant. Interestingly, the study found that naloxone significantly decreased the total protein expression of AKAP3 (1 ± 0.016 vs. 0.766 ± 0.025). Conclusion: In order to clarify the role of opioid receptors on spermatozoa membranes, more research is necessary. The study results suggest that opioids may utilize sperm-specific signalling mechanisms downstream of the opioid receptors located on human spermatozoa. Understanding these mechanisms could prove to be invaluable in enhancing our understanding of infertility.