Epigallocatechin-3-Gallate (EGCG) Reduces Rotenone Effect on Stallion Sperm-Zona Pellucida Heterologous Binding.

This research study investigated the effects of rotenone on stallion sperm function and determined how the natural polyphenol component of green tea, known as Epigallocatechin-3-Gallate (EGCG), could help counteract these effects. The study found that EGCG could effectively counteract the negative effects of rotenone on the ability of stallion sperm to bind to the zona pellucida (ZP), an essential process for successful fertilization.

Research Objectives

• The researchers aimed to analyze how equine sperm responds to the inhibition of mitochondrial complex I, an important element in energy production, by a compound called rotenone which is known to inhibit mitochondrial complex I.
• They also wanted to determine if EGCG could counteract the negative impact of rotenone on equine sperm.

Methods

• The sperm was incubated in a modified Tyrode’s medium for two hours and then exposed to various concentrations of rotenone and EGCG, individually and in combination.
• Several factors such as the viability of cells, active mitochondria in live sperm, and intactness of the acrosome (a structure in sperm that contains enzymes necessary for penetrating the egg) were assessed.

Findings

• The study revealed that neither rotenone nor EGCG, alone or in combination, had any significant impact on the percentage of viable cells, live sperm with active mitochondria, and sperm with an intact acrosome.
• Nevertheless, the inhibition of mitochondrial complex I by rotenone had a negative impact on the capability of stallion sperm to bind to the zona pellucida (ZP), a critical step for successful fertilization.
• Interestingly, EGCG was found to significantly increase the number of sperm that could bind to the ZP, effectively counteracting rotenone’s impact.
• This effect, however, was not observed at the highest tested EGCG concentration (60 μm), suggesting that an optimal concentration of EGCG is needed for this protective effect.

Implications

• The findings suggest that EGCG, a natural component of green tea, could play a useful role in enhancing the fertility of stallion sperm, particularly under conditions where its energy production machinery is compromised due to exposure to toxins such as rotenone.
• This research extends our understanding of the protective effects of natural polyphenols against oxidative stress in the context of male fertility, hinting at potential applications in animal husbandry and reproductive medicine.