June 16, 2009
WASHINGTON – Researchers from University of California, Berkeley claim to have found a missing piece of puzzle about how stress causes sexual dysfunction and infertility.
The study showed that stress delivers a double whammy on reproductive system and fertility.
It is already known that stress boosts levels of stress hormones – glucocorticoids such as cortisol – that inhibit the body’s main sex hormone, gonadotropin releasing hormone (GnRH), and subsequently suppresses sperm count, ovulation and sexual activity.
However, the new study showed that stress also increases brain levels of a reproductive hormone named gonadotropin-inhibitory hormone, or GnIH, discovered nine years ago in birds and known to be present in humans and other mammals.
This small protein hormone, a so-called RFamide-related peptide (RFRP), impedes reproduction by directly inhibiting GnRH.
The study conducted using animal models showed that the stress hormones not only suppress GnRH but also boost the suppressor GnIH – a double whammy for the reproductive system.
“We know stress affects the top-tier reproductive hormone, GnRH, but we show, in fact, that stress also affects another high-level hormone, GnIH, to cause reproductive dysfunction,” said lead author Elizabeth Kirby, a graduate student at UC Berkeley’s Helen Wills Neuroscience Institute.
“This work provides a new target for researchers, a new way to think about infertility and dysfunction. The more we know, the more we can look for ways to treat it,” she added.
The results will be published the week of June 15 in the Online Early Edition of the journal Proceedings of the National Academy of Sciences (PNAS). (ANI)