Researchers from University of California, Berkeley and the Canadian Institute for Advanced Research have discovered that the effects of a stress-activated hormone lingers long after the stress ends, promoting infertility in women. In a study, it is shown that blocking the hormone can reinstate ideal reproductive conditions, normalizing fertility.
Stress is a major contributor to cases of infertility, causing three-quarters of couples under 30 years old to have difficulty conceiving within three months of their first attempt and 15 percent still unable to get pregnant after a year of trying. It causes the release of gonadotropin inhibitory hormone (GnIH), which researchers say can easily be knocked out to restore balance in the reproductive system.
First discovered 15 years ago in quail, GnIH was found to be a strong fertility suppressant. Its mammalian equivalent RFamide-related peptide (RFRP) was isolated in 2009 in humans.
Researchers observed that exposing male rats to stressors increased levels of RFRP in their brains. Similar negative fertility effects were seen in female rats, although levels of RFRP remained high in them long after stressors were removed.
"GnIH seems to be the main player because it is elevated in the brain's hypothalamus for a full estrus cycle after the stress ends. When we knocked down levels of GnIH, we restored all reproductive behavior back to normal," said Daniela Kaufer, integrative biology associate professor from UC Berkeley and one of the authors for the study.
George Bentley, also an integrative biology professor from UC Berkeley and co-author for the study, added that since it is known that human GnIH is found in the gonads and brain and that the hormone disrupts steroid production in the ovaries, manipulating it has the potential to address infertility in humans.
On the other hand, manipulating GnIH may also be a solution toward addressing overpopulation concerns in feral animals. Boosting the hormone in cats and dogs, for instance, may induce infertility permanently, taking away the need for capture and neutering and spaying.
Anna Geraghty, a graduate student from UC Berkeley and the study's lead investigator, noted that the study showed that even though chronic stress is not extreme enough to stop a woman's period, it would still hamper reproductive function.
The study received funding support from the Nateional Institute of Child Halth and Human Development and the National Institute of Mental Health through a BRAINS grant. Other authors for the study include Lance Kriegsfeld, Sheng Zhao and Sandra Muroy.
