Androcoll-E large selects a subset of live stallion spermatozoa capable of producing ROS.

This research aimed to investigate if Single Layer Centrifugation (SLC) using Androcoll-E Large could isolate a specific subset of stallion sperm capable of producing Reactive Oxygen Species (ROS) even after undergoing osmotic stress. The results suggest that Androcoll-E Large potentially selects a higher proportion of spermatozoa that are capable of producing superoxide anion (a ROS) physiologically.

Methodology

• The study tested a hypothesis that, after 24 hours of semen storage, Single Layer Centrifugation (SLC) selects a specific group of spermatozoa that can better withstand osmotic shocks.
• SLC was performed using a silane-coated silica-based colloid formulation known as Androcoll-E Large, which is optimized for equine spermatozoa. The rest of the samples served as controls and were left un-centrifuged (UC). They both underwent different osmotic challenges at 75 and 900 mOsm, and eventually returned to an isosmolarity (equal distribution of solute inside and outside of the cell) level of 300 mOsm. This was achieved by using Biggers-Whitten-Whittingham (BWW) medium.
• Three properties – viability, mitochondrial membrane potential (MMP), and superoxide anion (O2·-) production of both UC and SLC selected spermatozoa were analyzed.

Results

• The research showed that the viability and MMP decreased in both UC and SLC spermatozoa after they were subjected to changing osmotic stress levels, and a subsequent return to isosmolarity did not reverse these effects.
• The production of O2·- was found to be increased in SLC samples across all osmotic conditions compared to UC samples. Furthermore, after undergoing stress at 900 mOsm, there was a higher percentage of living sperm showing O2·- production in both UC and SLC spermatozoa, being more evident in SLC sperm.
• When returning the spermatozoa to isosmolarity (300 mOsm), the proportion of living UC spermatozoa producing O2·- increased, while in SLC spermatozoa, this percentage did not change.
• As there was no significant difference in viability, MMP, and cell volume between SLC and UC spermatozoa after undergoing osmotic stress, it was concluded that Androcoll-E Large likely selected a higher percentage of spermatozoa that are able to produce O2·- even under stress conditions.

Implications

• This research can have relevant implications in animal reproductive biology. The method using Androcoll-E Large in SLC can be used to select higher yield of stallion spermatozoa that are more likely to survive and function under different osmotic conditions, probably enhancing their overall fertility potentials.
• These findings can also provide more insights towards the contribution of ROS in sperm functionality.