Page URL:

Surprise new link between obesity and infertility

13 September 2010
Appeared in BioNews 575

Infertility in women is often linked to obesity. A new study published in Cell Metabolism suggests that insulin signalling in the pituitary gland could play a key role. 

Obese individuals can also sometimes be insulin resistant (IR), with tissues and organs such as the liver, fat and muscle being affected. Insulin resistance is closely linked to conditions such as type II diabetes, and is also thought to play an important part in infertility.

Previous work carried out by the group based at the Johns Hopkins Children's Centre found that the pituitary gland - a region of the brain involved in the regulation of hormones - contains many insulin receptors.

In their new study, the researchers set out to see if cells in the pituitary gland were IR and whether this contributed to infertility. They created mice that lacked these pituitary insulin receptors, and surmised that if IR was the link between obesity and infertility, the mice lacking the insulin receptors should be infertile. However, to their surprise, these mice had normal fertility.

The researchers then went on to assess the effect of insulin signalling in obesity, by feeding the mice an unhealthy, high-fat diet for three months. Whereas normal obese mice became infertile and had abnormal reproductive hormone levels, the mice without the receptors had normal reproductive function and near-normal hormone levels.

The authors concluded that these findings show that, firstly the pituitary gland remains sensitive to insulin, and secondly when there are high levels of insulin, as occurs in obesity, this sets off a hormonal chain reaction which leads to infertility.

Professor Andrew Wolfe, who led the study, said 'There was a sense that the reproductive dysfunction was due to insulin resistance', however, 'What we propose is a fundamentally new model showing that different tissues respond to obesity differently and that while cells in the liver and muscle become insulin resistant, cells in the pituitary remain sensitive to insulin'.

Doctors have traditionally focused on lowering insulin resistance as a way of treating infertility. But this new model suggests that decreasing the pituitary glands sensitivity to insulin could be an important new target for treatment instead.

A missing link from obesity to infertility found
EurekAlert |  7 September 2010
Johns Hopkins researchers unravel clues to infertility among obese women
EurekAlert |  7 September 2010
Rescue of Obesity-Induced Infertility in Female Mice due to a Pituitary-Specific Knockout of the Insulin Receptor
Cell Metabolism |  7 September 2010
28 June 2010 - by Dr Charlotte Maden 
Women using assisted reproductive technology (ART) to conceive have a higher rate of miscarriage if they are overweight, say a group of UK scientists....
22 March 2009 - by Dr Rebecca Robey 
British scientists have found that a common gene variant that predisposes carriers to obesity is also linked to polycystic ovary syndrome (PCOS). PCOS has long been known to be associated with obesity but the new study is the first to identify a genetic link between the two...
14 July 2008 - by Antony Starza-Allen 
Two studies presented at the annual European Society of Human Reproduction and Embryology conference in Barcelona have contributed new research findings into male infertility by examining the relationships between obesity and diabetes, and sperm quality. Studying the link between obesity and sperm quality, researchers from the University...
17 December 2007 - by Ailsa Stevens 
Overweight women are significantly more likely to experience fertility problems, according to a study published in the journal Human Reproduction last week. Obesity is defined in adults as having a body mass index (BMI) above 30. The study found that for every BMI unit above 29, the...
Log in to add a Comment.

By posting a comment you agree to abide by the BioNews terms and conditions

Syndicate this story - click here to enquire about using this story.