NADPH Oxidase 5 and Melatonin: Involvement in Ram Sperm Capacitation.

Area of Science:

• Reproductive biology
• Cellular physiology
• Biochemistry

Background:

• Reactive oxygen species (ROS) are crucial for mammalian sperm capacitation.
• NADPH oxidase 5 (NOX5) is a primary ROS source in human and equine sperm.
• Melatonin is known to reduce ROS and regulate NOX activity in somatic cells.

Purpose of the Study:

• Identify NOX5 in ram spermatozoa and its changes during in vitro capacitation.
• Investigate melatonin's effect on NOX5 expression, localization, and superoxide levels in capacitated ram sperm.

Main Methods:

• Western blot analysis to detect NOX5 protein.
• Indirect immunofluorescence (IIF) to analyze NOX5 localization.
• DHE/Yo-Pro-1 assay to quantify superoxide levels.
• Calcium ionophore A23187 and NOX inhibitor GKT136901 treatments.

Main Results:

• NOX5 was detected in ram spermatozoa with varying immunotypes during capacitation.
• Superoxide levels increased post-capacitation and with A23187, but decreased with GKT136901.
• GKT136901 inhibited sperm capacitation and acrosome reaction.
• Melatonin (micromolar) prevented increased superoxide and NOX5 immunotype changes during capacitation.

Conclusions:

• NOX5 is present in ram spermatozoa, with its distribution changing during capacitation.
• Melatonin prevents these NOX5 distribution changes and reduces superoxide levels.
• Melatonin may exert its antioxidant effect during ram sperm capacitation by modulating NOX5 activity.