Human Sperm Remain Motile After a Temporary Energy Restriction but do Not Undergo Capacitation-Related Events

Area of Science:

• Reproductive Biology
• Sperm Metabolism
• Cellular Physiology

Background:

• Sperm capacitation is crucial for fertilization, involving complex metabolic regulation.
• Energy restriction in mouse sperm enhances fertility, but human sperm responses to starvation are unknown.

Purpose of the Study:

• Investigate the effects of nutrient deprivation and recovery on human sperm function.
• Determine the metabolic and functional changes during human sperm starvation and subsequent recovery.

Main Methods:

• Human sperm incubated in nutrient-rich (NUTR) or nutrient-deprived (STRV) media.
• Assessed motility, kinematics, ATP, cAMP, intracellular Ca2+, and protein tyrosine phosphorylation.
• Evaluated effects of mitochondrial inhibitors and sperm energy recovery (SER) treatment.

Main Results:

• Starvation (STRV) reduced motility, kinematics, ATP, cAMP, and tyrosine phosphorylation, while increasing intracellular Ca2+.
• Starved sperm remained motile for over 27 hours, relying on mitochondrial oxidative phosphorylation.
• Sperm energy recovery (SER) rapidly restored motility, ATP, cAMP, and Ca2+ levels, but not tyrosine phosphorylation.

Conclusions:

• Human sperm utilize endogenous metabolites for motility during starvation.
• SER treatment effectively rescues human sperm function, suggesting potential for modulating in vitro fertilizing ability.