Stress enhances sperm performance

A recent study reveals the hidden effects of stress on sperm motility. The researchers found that stress-induced events give the male reproductive system a big boost once the event has passed.

The research, led by experts at the University of Colorado Anschutz Medical Campus, provides valuable insights into the influence of stress on reproductive processes.

The findings indicate that stress-induced changes in sperm motility occur after a stressful event rather than during it. Once the stressor is no longer present, sperm performance is enhanced.

These insights shed light on how stress impacts reproduction and could potentially improve birth rates, especially following challenging times like the COVID pandemic.

Significance of the study

The researchers noted that semen quality and fertility has declined over the last 50 years in correspondence with the rise of environmental stressors.

However, they noted, the cellular mechanisms involved and their impact on sperm functions have been unclear.

“In a repeated sampling human cohort study, we identify a significant effect of prior perceived stress to increase sperm motility 2-3 months following stress,” wrote the study authors.

The results expand upon previous studies which revealed significant stress-associated changes in sperm RNA.

“Together, these studies identify a time-dependent, translational signaling pathway that communicates stress experience to sperm, ultimately affecting reproductive functions.”

Stress and sperm motility

The researchers observed notable changes in extracellular vesicles (EVs) – tiny particles released from the male reproductive tract that aid sperm development and maturation. The changes occurred after the stressful event had passed, which was unexpected.

“Our findings show a significant, time-dependent increase in sperm motility following perceived stress, which aligns with previous studies on changes in the microRNA in human sperm,” explained lead study author Dr. Tracy Bale.

“This timing, where sperm function improves after stress, might be evolutionarily beneficial to increasing birth rates, particularly following challenging times like those experienced during the COVID pandemic.”

Enhanced sperm performance

The study showed that stress-induced EVs enhanced both sperm motility and mitochondrial respiration, the process that generates energy for cell function.

“Imagine you have a car that’s struggling to get up a steep hill. When the engine is stressed, the car becomes less efficient. However, with a little more gas, you can boost the overall performance for a smoother drive,” said study first author Nickole Moon.

“Just as your car becomes more efficient under stress, cells improve their energy production and movement when stress-induced factors are present.”

This effect was observed in both human and animal studies, suggesting that the stress-response mechanism could be universal across species.

Impact of stress on fertility

While the study focuses on the male reproductive system, the research team emphasizes the importance of understanding how stress affects both partners in the fertility process.

“The impact of stress on germ cells, fertility, and the mechanisms underlying the transmission of parental stress experiences across generations are not well understood,” noted lead researcher Dr. Neill Epperson.

The team is conducting additional research to understand how stress information is transmitted into EVs and how this influences fertilization and brain development.

“As stress is a common part of daily life, understanding its effects on reproduction and development will be essential for improving fertility and addressing broader ecological impacts on endangered species,” noted Dr. Bale.

The researchers will also be launching a trial to further explore the relationship between EVs and sperm in seminal fluid, providing deeper insights into how stress affects future offspring.

Sperm adaptation to stress

The findings from this study open up new questions about the evolutionary role of stress in sperm adaptation.

By enhancing sperm motility and energy production after stress, this response may have developed as a survival mechanism.

The researchers speculate that during periods of environmental or social hardship, such as during famines or pandemics, the ability of sperm to perform better may have provided an evolutionary advantage by increasing reproductive success in challenging conditions.

Understanding this adaptive response could not only shed light on human fertility but also offer insights into other species’ reproductive strategies.

The study is published in the journal Nature Communications.

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