Male Sex Hormones Essential For Female Fertility

Male sex hormones, such as testosterone in the ovaries helps regulate female fertility, likely by controlling follicle growth and development and preventing deterioration of follicles that contain growing eggs, reports the journal Molecular Endocrinology.

“The need for certain levels of male hormones in the female body and the strong influence these hormones have is often underappreciated,” said professors Stephen Hammes, and Louis S. Wolk at the University of Rochester Medical Center.

“Our findings open up a new line of research into how we can regulate male sex hormones, specifically in the ovaries, to improve fertility” they said.

Their research found that irregular androgen or male sex hormone levels in the ovaries of female mice is  a major cause of infertility .

Understanding how male hormones influence ovulation in mice may provide clues as to how to better regulate androgens and combat infertility in humans.

For example, women with polycystic ovarian syndrome (PCOS), have an overproduction of male hormones prohibiting regular ovulation.

Hammes, chief of the Division of Endocrinology and Metabolism at the University of Rochester, believes that better understanding the overall effects of androgen levels on infertility caused by PCOS, the No. 1 cause of infertility in women.

Polycystic ovarian syndrome effects  more than 6.1 million women in the United States ages 15 to 44  or  5 percent to 10 percent of women of childbearing age. It is s nearly as common as Type 2 diabetes which it is sometimes associated.

Previous research by Chawnshang Chang, at the University of Rochester found that completely eliminating androgen receptors in female mice leads to abnormal ovarian function and reduced fertility.

To determine which reproductive tissues regulate fertility only the androgen receptors from only ovarian cells, known as granulosa cells were removed in female mice.  All other androgen receptors in  reproductive tissues were left intact.

Female mice without androgen receptors in the ovarian granulosa cells had premature ovarian failure, and stopped ovulating too early, were sub-fertile and  had abnormal ovulation cycles. They had fewer and smaller eggs than the controlled mice.

These mice had fewer follicles their follicles and did not progress beyond pre-development stages and died before ovulation could occur.
This suggests male hormones is critical for ovarian granulosa cells development and fertility.

When androgen receptor signaling is blocked or eliminated in ovarian granulosa cells, ovarian follicles cannot progress to later stages of development, ultimately resulting in reduced fertility.

“We found that fertility problems are most likely present because androgen signaling in the ovary is abnormal,” said professor Aritro Sen, from the division of Endocrinology and Metabolism at the University of Rochester Medical Center .

“Previously, we assumed that androgen signaling in the brain – the hypothalamus and the pituitary – was at the root of the problem, but we found that is not the case.”