If naked mole-rats are stressed the sperm count of males goes down, while ovulation is commonly halted in females, say researchers from the University of London. They believe this phenomenon could give us useful insight into how stress may affect fertility in humans. Studies have indicated in the past that women under stress have a higher risk of irregular ovulation.
The team, lead by Dr. Chris Faulkes, suggest that rats may help us understand what is going on when humans are stressed – the mechanisms involved and why fertility is affected.
In naked-mole rat colonies, only one female reproduces – the queen. A colony can have up to 300 animals. The queen ‘bullies’ males and females into infertility. The naked-mole rat lives in semi-arid parts of Africa where conditions are harsh. Dr. Faulkes said “The queen exerts her dominance over the colony by, literally, pushing the other members of the colony around.”
The infertile animals get on with the business of gathering food for the common good; no time is wasted on mating rituals.
Dr Faulkes said “Social suppression of reproduction in marmoset monkeys is very similar to that in naked mole-rats, and as these are primates the applications to understanding human stress-related infertility aren’t so far fetched. In humans, we know that various kinds of stress – physical and psychological – can affect fertility. She shoves them to show who’s boss. We believe that the stress induced in the lower-ranking animals by this behaviour affects their fertility. There appears to be a total block to puberty in almost all the non-breeding mole-rats so that their hormones are kept down and their reproductive tracts are underdeveloped”
Faulkes added “Humans vary widely in the way in which they form social bonds with their partners, offspring and kin. By making careful comparisons with model species like mole-rats, we may be able to tease apart the relative contribution of genes, environment, upbringing and culture to complex social behaviour in our own species.”
Faulkes is presenting his work today at the European Society of Human Reproduction and Embryology conference, Lyons, France.
The scientists noticed that in non-breeding females, vital fertility hormones seem to be suppressed as a result of their subordinate position. Testosterone levels are lowered in males, as is sperm production. However, when the queen is about to mate with the males those levels rise.
Written by: Christian Nordqvist
Editor: Medical News Today