The association between infertility in men and women, and obesity is long known. Researchers at the Johns Hopkins Children’s Center study believe that they have understood the causes of infertility in women with obesity along with the mechanism of working.
The results of their study done on experimental mice were published in the September 2010 issue of the journal Cell Metabolism. The National Institutes of Health funded the study. This article tries to understand the knowledge gained from this study.
What Research Learnt About the Causes of Infertility in Women ?
- The researchers wanted to study the effect of high insulin levels on the pituitary gland and how such a condition leads to infertility in obese women.
- The pituitary gland is an organ which produces hormones (signalling molecules) and is closely associated with child birth in women.
- The study found that high insulin levels for long initiate certain changes in the hormones of this organ.
- Such development lead to disruption in the functioning of the female reproductive organ ovaries affecting fertility.
- Earlier, insulin resistance a hallmark of obesity was believed to be the culprit of infertility.
- It is a risk factor for a condition known as polycystic ovary syndrome (PCOS) which is the most common cause of infertility, affecting up to one in 10 women.
- The present research reveals that it is the increased sensitivity of insulin’s effects on this organ which leads to infertility.
- It was learnt that tissues in the body respond differently to obesity disorder.
- If liver cells and muscles become insulin resistant, the pituitary gland becomes sensitive to this hormone (insulin).
- This knowledge calls for a new treatment for infertility involving reduction of insulin sensitivity of the gland.
- As of now, physicians tried to lower insulin levels in the body for addressing infertility owing to their belief in insulin resistance being the culprit.
Details of the Research:
The researchers tried to learn more about a type of pituitary organ cells known as gonadotrophs which produce luteinizing hormone (LH). This LH signalling molecule is closely related to initiation and ending of many critical chemical reactions of ovulation and fertility. The scientists guessed that with increased insulin levels, gonadotroph cells start over-producing LH disrupting the process of ovulation.
To test their guess, the research team produced experimental obese mice which did not have insulin receptors in their pituitary glands. Changes in these mice were to compared with the changes in obese mice possessing insulin receptors, as part of the study.
After three months, the obese mice with insulin receptors which also consumed high fat diet, developed all the PCDS symptoms suggesting infertility.The mice without insulin receptors in them though obese had normal levels of LH hormones, regular reproductive cycles and normal ovulation or egg formation for fertility.
Conclusion: The study confirms the role of pituitary gland under high insulin levels as one of the causes of infertility in women with obesity. It suggests that the ovaries too get affected because of their partial role in the processes of ovulation and fertility along with the pituitary gland.
