As if kids weren’t enough to worry about in the wake of the COVID-19 pandemic, apparently children-to-be can see adverse affects, as well, according to researchers looking into biological mechanisms by which stress alters sperm and impacts brain development in generations to come.
 
Prolonged fear or anxiety can have a lasting impact on sperm composition, according to a study published by researchers at the University of Maryland School of Medicine in the journal Nature Communications.
 
When a father experiences stress, it creates changes in the extracellular vesicles that interact with maturing sperm, researchers said. Extracellular vesicles are small, membrane-bound particles that transport proteins, lipids, and nucleic acids between cells, and are abundant in the reproductive tract, where they play a role in sperm maturation.
 
“There are so many reasons that reducing stress is beneficial especially now when our stress levels are chronically elevated and will remain so for the next few months,” Tracy Bale, PhD, the corresponding author of the study, said in reference to the COVID-19 pandemic. “Properly managing stress can not only improve mental health and other stress related ailments, but it can also help reduce the potential lasting impact on the reproductive system that could impact future generations.”
 
The research was conducted on extracellular vesicles in mice, and found that following a treatment with the stress hormone corticosterone, there were dramatic changes in the overall size of the extracellular vesicles, as well as changes in their protein and small RNA content.
 
When sperm were incubated with these previously stressed-altered extracellular vesicles prior to fertilizing an egg, the resulting mouse pups showed significant changes in patterns of early brain development, and as adults these mice were also significantly different than controls for how they responded to stress themselves.
 
Following these results, researchers recruited students from the University of Pennsylvania, who donated sperm each month for six months, and completed quetionnaires about their perceived stress state in the preceding month. They found that students who had experienced elevated stress in the months prior showed significant changes in the small RNA content of their sperm, while those with stagnant stress levels experienced little or no sperm change. The human data confirms a very similar pattern found in the mouse study.
 
“Our study shows that the baby’s brain develops differently if the father experienced a chronic period of stress before conception, but we still do not know the implications of these differences,” Bale said. “Could this prolonged higher level of stress raise the risk for mental health issues in future offspring, or could experiencing stress and managing it well help to promote stress resilience? We really don’t know at this point, but our data highlight why further studies are necessary.”
 
Stress-induced changes in the male reproductive system take place at least a month after the stress is attenuated and life has resumed its normal patterns, researchers said.
 
“This research represents a critical step in understanding important mechanisms that underlie the field of intergenerational epigenetics,” UMSOM Dean E. Albert Reece, MD, PhD, MBA, said. “Such knowledge is crucial to identify early interventions to improve reproduction and early childhood development down the road.”
 
While the study did not evaluate stress management interventions and their impact on changes in sperm composition, Bale contends that any lifestyle habits that are good for the brain are likely good for the reproductive system.
 
“It is important to realize that social distancing does not have to mean social isolation, especially with modern technologies available to many of us,” Joshua Gordon, the Director of the National Institute of Mental Health said. “Connecting with our friends and loved ones, whether by high tech means or through simple phone calls, can help us maintain ties during stressful days ahead and will give us strength to weather this difficult passage.”