Effect of cryopreservation on nitric oxide production by stallion spermatozoa.

This study investigates how the freezing and thawing process (cryopreservation) affects the ability of stallion sperm cells to produce nitric oxide (NO). It found that cryopreserved stallion sperm cells increase their production of NO, particularly when egg yolk is absent from the extender used in the preservation process. The presence of NO correlates positively with the sperm cells’ motility and velocity after thawing, implying a role for NO in the functionality of cryopreserved sperm, although this is not the case when egg yolk extenders are used.

Investigation Method

• The researchers utilized flow cytometry to evaluate nitric oxide (NO) production by stallion sperm cells before and after freezing and thawing. To do this, they loaded the sperm suspension with the probe, 4,5-diaminofluorescein diacetate.
• They further investigated the presence of nitric oxide synthase (NOS), the enzyme responsible for producing NO, using a technique called Western blotting. They used three different antibodies: anti-NOS1, anti-NOS3, and anti-universal NOS.

Findings

• NO was detectable in both fresh (not frozen) and freeze-thawed sperm. However, they noted an increase in NO production after freezing and thawing, but only when the extender (a solution used to preserve sperm) did not contain egg yolk.
• The anti-NOS1 antibody labeled a band with an approximate molecular mass of 83 kDa, while the antibody against NOS3 revealed a band of roughly 96 kDa in both fresh and frozen-thawed sperm samples. These findings confirm the presence of NOS in stallion sperm.
• NO production exhibited a positive correlation with sperm motility and velocity after thawing. The suggests that NO plays a crucial role in the functioning of cryopreserved stallion sperm cells. However, the production of NO is compromised when an egg yolk-containing extender is used.

Implications

• The findings of this research have important implications for processes involving the cryopreservation of stallion sperm. It suggests that the choice of extender could affect the functionality of the sperm after thawing due to its impact on NO production.
• This research contributes to the understanding of how cryopreservation affects stallion sperm at a molecular level. Future studies can extend these findings to improve the outcomes of cryopreservation and promote the fertility of thawed sperm.