In 2013 a man with obesity underwent an ordinary bariatric surgery to reduce his stomach in Hvidovre Hospital in Denmark. It couldn’t be the aim of this report, but because of one exception. He provided his sperm sample three times - a week before, a week after and a year after the operation.
The aim of the researchers was to investigate a captivating but arguable assumption that a man’s background can change his sperm and the possibility to cause a change of his children. The act of thought is based on principal thinking about Mendelianism. Children inherit the genes from their parents or not and is this the main reason of excessive body weight, stress, malignant neoplastic diseases.
But according to last scientific reports that something more is at work. Dr. Romain Barres of the University of Copenhagen and his colleagues in 2010 comment upon feeding male rats a high-fat diet and then mated them with females. In comparison with male rats fed a regular diet, those on the high-fat diet fathered offspring that tended to gain more weight, develop more fat and demonstrated problems with regulating insulin levels.
Eating junk food is just one of several experiences a father can have that can change his progeny. Stress is another. Male rats exposed to stressful experiences — like smelling the odor of a fox — will father pups that have a dampened response to stress.
Scientists have focused on sperm to find a nexus between a father’s experiences and his progeny’s biology. A male’s germ cell presents DNA to an egg but a the same time those genes are regulated by special molecules or epigenetic factors. Epigenetic factors can react to different external acts by silencing some genes and activating others as needed. Some studies suggest the changes in epigenetic factors can be handed down to offspring via sperm.
This was proven by Dr. Tracy L. Bale, a neuroscientist at the University of Pennsylvania, and her colleagues, when they looked at the sperm of stressed male rats, for example, they found unusual levels of epigenetic molecules called microRNAs. They created a cocktail of microRNAs and injected them into embryos from unhurried fathers. As Dr. Bale and her colleagues reported recently, the embryos developed into rats with modified stress responses.
It is possible that external acts can determinate human health in similar ways has huge implications. But researchers have only started to investigate the epigenetics of fatherhood. As is often the case when scientists turn from animal experiments to humans, the results have been provocative but hardly clear-cut.
In 2013, Adelheid Soubry and her colleagues (KU Leuven University in Belgium) reported about epigenetic differences between children with obese fathers and those with lean ones. The main question is about the reason of these changes and is it only the excessive body weight. Dr. Barres et al. investigated sperm samples collected from
10 obese men and 13 samples collected from thin ones. They found more than 9,000 genes in which the methylation pattern differed between lean and obese men.
After that they investigated the changing of methylation process after bariatric surgery and weight loss. According to the report published in Thursday in the journal Cell Metabolism, Dr. Barres et al. recognized more than 3,900 differently methylated genes a year after surgery. All in all its hard to say if these changes have the influence on descendants. It requests more studying involving hundreds of people to prove it.