A study has found that the negative effects of drinking alcohol take longer to disappear from a man's sperm than previously thought. Given the link between alcohol and birth defects, the findings are important for potential fathers to take into account when considering starting a family.
Preconception maternal health has long been a critical factor influencing pregnancy and child developmental outcomes. Drinking before and during pregnancy has been a focus of concern because of its association with fetal alcohol syndrome (FAS), which can cause abnormal fetal facial features, low birth weight and/or height, attention and hyperactivity disorders, and poor coordination. Women have historically been responsible for abstaining from alcohol to avoid developing FAS; only recently has the focus shifted to the father's drinking as a trigger.
Research shows that sperm contains a wealth of epigenetic information, which can be altered by exposure to a range of different stressors, including alcohol. Now, a new study by researchers at Texas A&M University examines the effects of alcohol consumption on sperm, the epigenetic changes produced by drinking alcohol, and how long these changes last.
Michael Golding, corresponding author of the study, said: "For many years, the problem of male drinking has been ignored. In the past five to eight years, we began to notice that in some cases, the father's impact on alcohol exposure and fetal development was very large. In this project, we wanted to see how long it took for the effects of alcohol on sperm to disappear. We thought that the return to normal would be relatively quick, but this was not the case. The abstinence process lasted more than a month."
In the United States, as in many countries around the world, most men drink alcohol. Previous studies have produced conflicting results regarding the effects of alcohol intake on male fertility; some studies have shown modest reductions, while others have reported no observed effects. In the current study, the researchers used mouse models to revisit the effects of alcohol exposure on the sperm epigenome.
They exposed male mice to 6% or 10% alcohol for 10 weeks and then abstained for four weeks, and used RNA sequencing to examine gene expression patterns in the epididymis, the long coiled tube structure at the tip of each testicle that stores sperm. The control group was exposed only to water. The researchers observed that long-term alcohol exposure resulted in changes in gene pathways in the epididymis related to mitochondrial function, oxidative stress, and systemic stress responses that persisted one month after cessation of drinking.
"During alcohol withdrawal, the liver experiences chronic oxidative stress and sends a signal to the entire male body," Goldin said. "The reproductive system interprets this signal and says, 'Oh, we live in an environment where there's a lot of oxidative stress. I need to program my offspring to be able to adapt to this environment.'"
The researchers suspect that these alcohol-induced changes may contribute to problems such as FAS, noting that a person does not need to drink excessively to experience withdrawal symptoms. "In the model we used, even having three or four beers after get off work a few days a week can cause withdrawal when the behavior stops. You may not feel intoxicated, but your body is experiencing chemical changes," Goldin said. The researchers hope their findings will change the narrative about who is responsible for alcohol-related birth defects and relieve some of the stress for women.
"The question 'Did you drink while you were pregnant?' can be psychologically traumatic for women." Golding said. "It's also difficult for doctors to have this conversation. But if they don't, then FAS isn't diagnosed right away and the child may not get the support they need until later in life."
It's crucial that couples planning to start a family know how far in advance they need to stop drinking to prevent birth defects. Based on the findings, researchers recommend that men abstain from alcohol for three months before trying to conceive, just to be sure.
"There's still a lot of work to be done to get a firm answer, but we know that sperm is formed within 60 days, and the abstinence process takes at least a month. So, I would estimate a wait of at least three months," Goldin said.
The study was published in the journal Andrology.