Location: Livestock Bio-Systems
Title: Gonadotropin-releasing hormone II and its receptor regulate motility, morphology, and kinematics of porcine spermatozoa in vitroAuthor
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DESAULNIERS, AMY - University Of Nebraska |
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ROSS, CAITLIN - University Of Nebraska |
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CEDERBERG, REBECCA - University Of Nebraska |
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LOVERCAMP, K - University Of Central Missouri |
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Lents, Clay |
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WHITE, BRETT - University Of Nebraska |
Submitted to: General and Comparative Endocrinology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 12/5/2024 Publication Date: 12/18/2024 Citation: Desaulniers, A.T., Ross, C.E., Cederberg, R.A., Lovercamp, K.W., Lents, C.A., White, B.R. 2024. Gonadotropin-releasing hormone II and its receptor regulate motility, morphology, and kinematics of porcine spermatozoa in vitro. General and Comparative Endocrinology. 361. Article 114653. https://doi.org/10.1016/j.ygcen.2024.114653. DOI: https://doi.org/10.1016/j.ygcen.2024.114653 Interpretive Summary: Approximately 80% of swine producers in the United States utilize artificial insemination, requiring an estimated 30 million doses of semen every year. Many boars, however, have poor fertility, which results in a critical need to understand testicular function to develop methods to improve semen production and quality. ARS scientists, in collaboration with researchers from the University of Nebraska, discovered that sperm from boars have a hormone receptor called gonadotropin-releasing hormone receptor 2 (GnRHR2). The pig is one of just a few species that has a functional GnRHR2. Researchers found that GnRHR2 in sperm is localized to a very special region that connects the tail of the sperm to its head. They found that GnRH2, which actives GnRHR2, is present in the seminal plasma of ejaculated semen and that treating boar sperm with GnRH2 enhanced motility of sperm that is necessary for the fertilization process. This research is expected to lead to improvements in production and quality of boar semen for increased fertility of swine herds. Technical Abstract: The second form of gonadotropin-releasing hormone (GnRH-II) and its receptor (GnRHR-II) are abundantly produced within the porcine testis and immunolocalize within the seminiferous tubules, suggesting a role in spermatogenesis and/or sperm function. The objective of this study was to quantify GnRH-II and GnRHR-II abundance within boar reproductive tract tissues and examine their role in porcine sperm function. Immunoblotting revealed GnRHR-II abundance was 12-fold greater (P < 0.0001) within the testis compared with other reproductive organs. Within seminiferous tubules, GnRHR-II prominently immunolocalized to elongating spermatids. In ejaculated spermatozoa, GnRHR-II immunolocalized to the connecting piece. GnRH-II was also detected in seminal plasma, likely originating from the testis as GnRH-II concentrations were greatest in testicular homogenates (P < 0.0001) compared with other reproductive tissues. To assess the effects of GnRH-II/GnRHR-II on sperm function, extended semen samples were treated with GnRHR-II analogues and evaluated via computer-assisted sperm analysis (CASA). In Experiment 1, semen treatment with increasing concentrations of GnRHR-II agonist (D-ala6 GnRH-II) revealed that two concentrations (0.1 and 100 µM) tended to decrease the percentage of bent sperm tails versus vehicle-treated semen (P < 0.10). In Experiment 2, semen treatment with increasing concentrations of GnRHR antagonist (SB-75/Cetrorelix) indicated that only 10 µM SB-75 impaired CASA metrics compared with vehicle-treated samples (P < 0.05). In Experiment 3, semen treatment with both 100 µM D-ala6 GnRH-II and 10 µM SB-75 partially rescued sperm motility and morphology measures. These data suggest that GnRH-II and its receptor regulate porcine sperm function in an autocrine/paracrine manner. |