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An in vitro investigation into the effects of Ritalin and Dopamine on human sperm and the functionality of the Dopamine Transporter (DAT) protein on human sperm membranes
Ferguson, L. M. 2025. An in vitro investigation into the effects of Ritalin and Dopamine on human sperm and the functionality of the Dopamine Transporter (DAT) protein on human sperm membranes. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scho...
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| Format: | Thesis |
| Language: | English |
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Stellenbosch : Stellenbosch University
2025
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| _version_ | 1867613902417690624 |
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| access_status_str | Open Access |
| author | Ferguson, Lisa Marie |
| author2 | Skosana, Bongekile |
| author_browse | Ferguson, Lisa Marie Skosana, Bongekile |
| author_facet | Skosana, Bongekile Ferguson, Lisa Marie |
| author_sort | Ferguson, Lisa Marie |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Ferguson, L. M. 2025. An in vitro investigation into the effects of Ritalin and Dopamine on human sperm and the functionality of the Dopamine Transporter (DAT) protein on human sperm membranes. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/6325a03f-81f7-4693-8dd3-8d53428199be |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/132174 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:43:31.605Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2025 |
| publishDateRange | 2025 |
| publishDateSort | 2025 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/132174 An in vitro investigation into the effects of Ritalin and Dopamine on human sperm and the functionality of the Dopamine Transporter (DAT) protein on human sperm membranes Ferguson, Lisa Marie Skosana, Bongekile Du Plessis, Stefan Qulu-Appiah, Lihle Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Biomedical Sciences. Division of Medical Physiology. Methylphenidate -- Side effects Human reproduction Dopamine -- Agonists Spermatozoa -- Physiology UCTD Ferguson, L. M. 2025. An in vitro investigation into the effects of Ritalin and Dopamine on human sperm and the functionality of the Dopamine Transporter (DAT) protein on human sperm membranes. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/6325a03f-81f7-4693-8dd3-8d53428199be Thesis (PhD)--Stellenbosch University, 2025. ENGLISH ABSTRACT: Background: Methylphenidate (MPH), commonly known as Ritalin, is widely prescribed for attention deficit hyperactivity disorder (ADHD). Due to its cognitive-enhancing effects, it is abused as a recreational drug, particularly among males. Psychotropic drugs such as Ritalin influence dopaminergic signalling by increasing the bioavailability of dopamine. Catecholamines such as dopamine are present in the mammalian reproductive system. They are believed to play a role in fertilization where dopamine regulates functions such as motility via dopamine D2 receptor (DRD2) activation. Research indicates that both dopamine and Ritalin may influence sperm functions, but findings are conflicting regarding their effects. Further investigation into the roles of the dopamine transporter (DAT) and DRD2 in human sperm is essential. Objectives: To identify and localize DAT and DRD2 on human sperm membranes and determine DAT functionality on human sperm. To investigate the in vitro effects of Ritalin and dopamine on human sperm functional parameters. Methods: Utilizing an immunofluorescence (IF) assay, spermatozoa were stained with anti-DAT and anti-DRD2 primary antibodies to visualize DAT and DRD2 on human sperm membranes. DAT functionality, kinetic characteristics, and sensitivity to inhibition were assessed with fluorescent probe ASP+, and fluorescence was quantified using a spectrophotometer. Furthermore, sperm functional parameters such as sperm motility and kinematics, viability, acrosome reaction (AR), DNA fragmentation, reactive oxygen species (ROS), and mitochondrial membrane potential (MMP) were assessed after treatment with varying concentrations of MPH, ritalinic acid (RA), dopamine and L-741,626 (a DRD2 antagonist) after 1, 2 and 3 hours. In addition, combination effects of the treatments were analysed after 2 hours of treatment. Results: The IF assay indicated that DAT localized with strong immunoreactivity to the sperm mid-piece region, with weaker signals in the acrosomal and flagella regions. The uptake assay revealed a linear accumulation of ASP+ in human sperm, proving DAT to be functional. Quantitatively, DAT on human sperm has an apparent Km of 20.34 μM, similar to DAT in other tissues and cell types. In this study, we demonstrated that the exposure of sperm to MPH impairs sperm function by increasing the rate of premature ARs and decreasing sperm viability. Likewise, RA has a deleterious effect on sperm progressive motility, viability, and AR. Finally, MPH significantly decreased DRD2 protein expression in sperm. To our knowledge, this is the first study investigating the in vitro effects of MPH on sperm parameters. We are also the first study to demonstrate the effects of these compounds on sperm AR, DNA fragmentation, ROS, and MMP. At higher dopamine concentrations, sperm motility, viability, and AR were affected negatively. Additionally, at lower concentrations, the DRD2 antagonist L-741,626 negatively affected sperm motility, viability, and AR. Dopamine significantly decreased DRD2 expression in sperm while L-741,626 treatment significantly increased DAT protein levels. Conclusion: This study reveals that human spermatozoa express the DRD2 and DAT, which indicates a functional dopaminergic system in human sperm. Ritalin (MPH), via a dopamine mechanism, negatively affects sperm motility, viability, and AR. Caution needs to be exercised by males of reproductive age who utilize this drug. AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar. Doctoral 2025-05-28T13:39:52Z 2025-05-28T13:39:52Z 2025-03 Thesis https://scholar.sun.ac.za/handle/10019.1/132174 en Stellenbosch University xxiv, 267 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Methylphenidate -- Side effects Human reproduction Dopamine -- Agonists Spermatozoa -- Physiology UCTD Ferguson, Lisa Marie An in vitro investigation into the effects of Ritalin and Dopamine on human sperm and the functionality of the Dopamine Transporter (DAT) protein on human sperm membranes |
| title | An in vitro investigation into the effects of Ritalin and Dopamine on human sperm and the functionality of the Dopamine Transporter (DAT) protein on human sperm membranes |
| title_full | An in vitro investigation into the effects of Ritalin and Dopamine on human sperm and the functionality of the Dopamine Transporter (DAT) protein on human sperm membranes |
| title_fullStr | An in vitro investigation into the effects of Ritalin and Dopamine on human sperm and the functionality of the Dopamine Transporter (DAT) protein on human sperm membranes |
| title_full_unstemmed | An in vitro investigation into the effects of Ritalin and Dopamine on human sperm and the functionality of the Dopamine Transporter (DAT) protein on human sperm membranes |
| title_short | An in vitro investigation into the effects of Ritalin and Dopamine on human sperm and the functionality of the Dopamine Transporter (DAT) protein on human sperm membranes |
| title_sort | in vitro investigation into the effects of ritalin and dopamine on human sperm and the functionality of the dopamine transporter dat protein on human sperm membranes |
| topic | Methylphenidate -- Side effects Human reproduction Dopamine -- Agonists Spermatozoa -- Physiology UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/132174 |
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