Effect of exogenous sperm capacitation inducers on stallion sperm.

This research studied the impact of different inducers on sperm capacitation in stallions, in particular the effect on sperm quality and capacitation markers. The results showed positive effects on intracellular calcium levels, membrane fluidity, tyrosine phosphorylation levels, and acrosomal exocytosis. The research concluded that further studies are required to evaluate how these changes affect horse fertilization in vitro.

Initial Problem and Proposed Solution

• While sperm from various mammalian species can be capacitated in vitro in the right lab conditions, the best conditions for sperm capacitation in stallions remained unclear prior to this research.
• This study aimed to evaluate the effect of different capacitating inducers in two types of media, Whitten and Tyrode, and assess their impact on factors related to sperm capacitation.

Research Approach

• Stallion sperm was incubated with different combinations of capacitating inducers at 38.5°C in an air atmosphere.
• The sperm quality, including motility, mitochondrial membrane potential, and lipid peroxidation, was assessed.
• Early markers of capacitation, like membrane fluidity and intracellular calcium levels, were evaluated.
• Late capacitation markers, such as tyrosine phosphorylation events and the sperm’s ability to perform acrosomal exocytosis, were used.
• Finally, a heterologous zona pellucida binding assay was used to evaluate the sperm.

Key Findings

• The capacitating conditions examined led to an increase in intracellular calcium levels and membrane fluidity in both media.
• The addition of 2 or 3 inducers to both media increased levels of tyrosine phosphorylation and acrosomal exocytosis after exposure to progesterone.
• The results suggested that stallion sperm incubated in these conditions showed cellular and molecular changes consistent with sperm capacitation.
• The binding capacity of sperm incubated in capacitation conditions was confirmed by the zona pellucida binding assay, which is a critical step for successful in vitro fertilization in stallions.

Implications and Future Research

• These findings indicate the potential for, and importance of, further research on these conditions’ effects on in vitro fertilization in horses.
• This research is valuable and might contribute to a better understanding and improvement of horse reproduction practices.