Heterologous Seminal Plasma Reduces the Intracellular Calcium and Sperm Viability of Cryopreserved Stallion Spermatozoa.

The research study explores the effect of adding heterologous seminal plasma (SP) from high-quality sperm producing stallions to cryopreserved sperm from poor quality semen producing stallions and finds that it did not repair damages but rather caused further deterioration in the semen quality.

Research Objective

• The primary goal of this research was to assess whether the supplementation of heterologous SP from a stallion with high sperm quality could improve the function parameters of sperm from genetically superior stallions that produce poor quality semen.

Research Methodology

• The researchers separated the sperm from poor quality semen producing stallions into three parts. Two of them had SP from good quality semen producing stallions added at rates of 20% and 30%, while the third didn’t have any SP added and served as a control.
• They were then incubated at 37°C for 30 minutes to conduct analysis.
• Different sperm parameters like membrane integrity, mitochondrial membrane potential (MMP), mitochondrial superoxide (mtROS) generation, and intracellular calcium status were evaluated using flow cytometry at various time intervals during the incubation.

Key Findings

• Results showed that the percentage of dead sperm increased in the groups that had 20% and 30% SP added during the incubation period.
• No significant changes in MMP were observed in the control and treatment groups at any of the time intervals.
• Interestingly, an increase in sperm mtROS production was observed in the SP-supplemented group compared to the control group during the incubation period.
• Furthermore, the populations of live sperm with high intracellular calcium reduced during incubation in the SP-associated groups.

Conclusion

• The addition of heterologous SP to poor quality sperm did not repair cryopreservation-related damage, but instead led to even worse semen quality.
• The damage was evidenced by the reduction in viability and the increase in reactive oxygen species (ROS) production, which could be attributed to the high amount of dead cells or unidentified factors that induce oxidative stress in stallion spermatozoa.