Researchers have unveiled new insights about the preovulatory follicular fluid (PFF) of donkeys, highlighting its species-specific characteristics and its significant role in sperm function modulation. The study reveals how the redox profiling of this fluid can protect donkey sperm from oxidative stress, which is pivotal for enhancing fertility outcomes.
Conducted by scientists at the Autonomous University of Barcelona, this groundbreaking research explores how various antioxidant and oxidative stress indicators present within donkey PFF can improve the motility and viability of sperm during the fertilization process. The findings suggest substantial benefits for reproductive technologies aimed at donkeys and potentially other equine species.
The follicular fluid serves as the nurturing environment for developing oocytes and plays multiple roles within the female reproductive system, including the preservation of sperm functionality. It is known to shield both oocytes and sperm from oxidative stress—an imbalance between reactive oxygen species (ROS) and antioxidants—that can adversely affect reproductive health.
For this study, the researchers analyzed ten PFF samples collected from Catalan jennies and nine ejaculates from Catalan donkeys. They focused on various redox biomarkers, including enzymatic antioxidants like superoxide dismutase (SOD) and catalase (CAT), and oxidative biomarkers such as total oxidant status (TOS) and advanced oxidation protein products (AOPP).
Key findings reveal significant differences between the PFF of donkeys and those from other species. For example, the activity levels of certain antioxidants observed were lower than those reported for cattle and pigs. The researchers noted lower values of SOD (0.49 IU/mL) and CAT (0.30 IU/mL), indicating the unique composition of donkey PFF.
Further experimentation demonstrated the protective role of PFF on sperm. When sperm were incubated with PFF, intracellular ROS levels were significantly reduced, maintaining both motility and viability over time. After two hours of incubation at 38 °C, the sperm showed increased total motile and progressively motile counts, clearly establishing the efficacy of PFF as beneficial for sperm health.
Interestingly, the PFF did not adversely affect mitochondrial activity, contradicting some previous studies which suggested oxidative stress could impair mitochondrial function. Instead, the antioxidants present within the donkey PFF provided adequate protection, indicating its potential for use in assisted reproductive technologies.
These findings have important implications for the development of media for oocyte maturation and fertilization processes, especially concerning assisted reproductive techniques (ART) used with donkeys. Improving the formulation of these media with identified antioxidants from donkey PFF could lead to enhanced fertility outcomes.
This research marks the first comprehensive redox profiling of donkey PFF, providing pivotal insights for both veterinary reproductive health and broader applications within the field of reproductive biology. By thoroughly mapping the unique biochemical makeup of donkey PFF and its protective properties, the study paves the way for future advancements and optimized protocols in equine reproductive management.