Stressed mole rats hold clues to human infertility

LONDON (Reuters) - A bizarre hairless rodent living underground in Africa may offer clues about the links between stress and human infertility, scientists said on Monday.

Stressed-out mole-rats become infertile after constant bullying by the colony's "queen", the only female to reproduce. But this infertility is reversible and when the queen dies, a previously non-breeding female quickly takes her place.

Chris Faulkes, a biologist at the University of London, believes the animals' behaviour patterns translate into suppression of certain fertility hormones and understanding the process could help explain stress-related infertility in humans.

"Similar things might be happening in humans," he said in a telephone interview. "It's likely that it is all acting on similar pathways in the brain."

Stress has long been known to be an important factor in infertility in both women and men -- but working out why is a challenge.

Faulkes, who is presenting his mole-rat research at the annual meeting of the European Society of Human Reproduction and Embryology in Lyon, France, is convinced animals can provide part of the answer.

The example of the subterranean rodent, which lives in colonies of between 100 and 300 animals, is extreme and the ability of the mole-rat queen to dominate other individuals by shoving them around is unusual.

But the blind creatures are far from alone in managing fertility within a social group. Other creatures exhibiting socially-induced reproductive suppression include primates like marmosets and tamarins, mongooses, and members of the dog family, such as wolves and jackals.

In the case of the mole-rats, it appears that ovulatory cycles in females are suppressed by reduction of luteinising and follicle stimulating hormones, while testosterone and sperm count levels fall in non-breeding males.

Faulkes and his colleagues are also researching the role that genes may play in different forms of social bonding and mating patterns.

"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," he said.

Mon Jul 2, 2007 8:55 AM IST

By Ben Hirschler