Animal study finds surprising clues to obesity-induced infertility

Infertility is common among obese women, but the reasons remain poorly understood and few treatments exist. Now a team of Johns Hopkins Children’s Center scientists, conducting experiments in mice, has uncovered what it considers surprising evidence that insulin resistance, long considered a prime suspect, has little to do with infertility in women with type 2 diabetes, polycystic ovary syndrome or metabolic syndrome, all obesity-related conditions in which the body becomes desensitized to insulin and loses the ability to regulate blood sugar.

In a report published online Nov.10 in the journal Diabetes, the Johns Hopkins scientists say that the real culprit appears to be insulin sensitivity in the ovaries and the pituitary.
The Johns Hopkins team said that its findings show that these organs escape insulin resistance and, awash with high levels of circulating insulin common in obesity, develop abnormal cell signaling that disrupts ovulation and eventually leads to infertility.

“Our findings suggest that the focus should shift from treating insulin resistance in peripheral tissue to taming insulin sensitivity in the pituitary and ovaries,” said lead investigator Sheng Wu, of the Johns Hopkins Children’s Center. Scientists traditionally have treated obesity-induced infertility by lowering blood insulin to counter the effects of insulin resistance...