A disrupted gut microbiome in male mice is bad for their reproductive health, and means a greater chance of health problems in their offspring.
Reducing the diversity and abundance of gut bacteria in male mice increases the risk of low birth weight, stunted growth and premature death in their offspring. This was discovered by geneticist Jamie Hackett of the European Laboratory for Molecular Biology in Rome and his colleagues. They published their results in the scientific journal Nature.
Antibiotics
Previous research has already shown that there is a link between the intestinal bacteria of mothers and their babies. However, little is known about the influence of the father’s intestinal bacteria. To learn more about this, Hackett and his team treated 28 male mice with antibiotics. This caused the amount of intestinal bacteria to decrease by a factor of ten, and the balance between bacterial species in their intestines shifted.
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12 other male mice had completed the same treatment two months earlier, and another 26 male mice received no treatment at all. After mating with female mice, the females gave birth to more than four hundred offspring.
Boys born to fathers with a disturbed intestinal microbiome were found to have various health problems. They had a significantly lower birth weight and were 2.5 times more likely to have severe growth retardation. In addition, about 17 percent of the mouse pups were found to die within three months.
The offspring of fathers who did not use antibiotics, or fathers who stopped taking antibiotics weeks before conception, had far fewer health problems. Of those, only 5 percent of the young died in their first three months.
Testicles
How the gut microbiome causes these effects is unclear. But further experiments revealed some clues. For example, mice given antibiotics had smaller testicles and lower sperm counts than mice that never took antibiotics.
They also had different amounts of certain sex hormones in their bodies, such as leptin and testosterone. These affect fertility. In addition, the antibiotic treatment appeared to be associated with changes in small molecules that regulate gene expression in sperm.
The disturbed intestinal microbiome of the males also appeared to influence the females. Female mice that mated with these males had changes in their placentas. As a result, it could not provide the fetus with sufficient nutrients.
Reproductive health
“This study is an important step forward in our understanding of the complex relationship between the gut and reproductive health,” said microbiologist Maria Gloria Dominguez-Bello of Rutgers University in New Jersey, who was not involved in the study. It’s the first time research shows that disruptions in a father’s microbiome can affect his own reproductive health, the quality of his sperm and the health of his offspring, she says.
The research also indicates that paternal health could be important for human pregnancies. Changes in the placenta are linked to pregnancy complications such as preeclampsia, or pre-eclampsia, says Hackett.
