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Influence of Prolactin Secretion Changes on Sperm Head Size and Freezability in Ibex and Mouflon
Paula Bóveda Gómez1, Rosario Velázquez1, Lucía Martínez-Fresneda1
1Department of Animal Reproduction, INIA-CSIC, Madrid, Spain.
Abstract:
This work examined the influence of induced changes in prolactin (PRL) secretion on sperm cryoresistance of ibex and the mouflon. PRL secretion was modified in a first experiment by the use of bromocriptine (BCR, dopamine agonist) during the non-breeding season, and in a second experiment by the use of sulpiride (SLP, dopamine D2-receptor antagonist) during the rutting season. Slow and ultra-rapid freezing protocols were used to cryopreserve sperm samples. BCR decreased blood plasma PRL concentrations, whereas SLP increased them. Cryoresistance ratios (CRs) for curvilinear velocity (VCL), straight-line velocity (VSL), and average path velocity (VAP) in BCR-treated mouflons were lower than in controls using slow-freezing (p < 0.05), while CRs of motility and morphologically normal sperm of BCR-treated mouflons were greater than controls with ultra-rapid freezing (p < 0.05). BCR increased the head sperm dimensions in ibexes (p < 0.001); conversely, BCR decreased the head dimensions in mouflons (p < 0.001). CR-motility, CR-amplitude of lateral head displacement (ALH), CR-viability, and CR-acrosome integrity in SLP-treated mouflons were lower than in controls with slow-freezing (p < 0.01); CR-viability and CR-acrosome were lower than controls with ultra-rapid freezing (p < 0.05). In ibexes, CR-ALH was lower for SLP-treated (p < 0.05). SLP treatment increased head dimensions in ibexes (p < 0.001) but did not affect the sperm head of mouflons. Our findings show that high levels of blood plasma PRL negatively affect the cryoresistance of ibex and mouflon sperm.
Insights
Induced changes in prolactin (PRL) secretion impact sperm cryoresistance in ibex and mouflon. High PRL levels negatively affect sperm cryoresistance, influencing motility and morphology after freezing.
Area of Science:
- Reproductive Biology
- Animal Science
- Endocrinology
Background:
- Prolactin (PRL) plays a role in reproduction, but its specific impact on sperm cryoresistance in wild ungulates is not fully understood.
- Understanding factors affecting sperm cryoresistance is crucial for effective conservation and artificial reproduction strategies.
Purpose of the Study:
- To investigate the influence of experimentally altered prolactin secretion on the cryoresistance of ibex and mouflon sperm.
- To assess the effects of dopamine agonists and antagonists on PRL levels and subsequent sperm cryopreservation outcomes.
Main Methods:
- Prolactin secretion was manipulated using bromocriptine (BCR) during the non-breeding season and sulpiride (SLP) during the rutting season in ibex and mouflon.
- Sperm samples were cryopreserved using both slow and ultra-rapid freezing protocols.
- Cryoresistance ratios (CRs) for various sperm parameters (motility, velocity, morphology, viability, acrosome integrity) were analyzed.
Main Results:
- Bromocriptine (BCR) decreased PRL levels and negatively impacted sperm cryoresistance in mouflon with slow-freezing, but improved it with ultra-rapid freezing.
- Sulpiride (SLP) increased PRL levels, leading to reduced cryoresistance in mouflon sperm across both freezing methods.
- Hormonal treatments differentially affected sperm head dimensions in ibex and mouflon, with SLP increasing dimensions in ibex.
Conclusions:
- Elevated prolactin levels are detrimental to the cryoresistance of ibex and mouflon sperm.
- PRL secretion modulation has differential effects on sperm cryoresistance depending on the freezing protocol and species.
- These findings highlight the importance of hormonal balance for successful sperm cryopreservation in these species.
