Nerve cells near the base of the brain play a key role in linking stress and fertility, according to new research.
The nerve cells - known as RFRP neurons - become active in stressful situations and then suppress the activity of the reproductive system. In the study, the team at Otago University used transgenic techniques to artificially increase the activity of RFRP neurons in mice. This replicates what happens in stressful situations and when levels of the stress hormone cortisol are high.
Study lead author Professor Greg Anderson at the Centre of Neuroendocrinology at Otago University, New Zealand, said, 'Although it is known that stress steroids like cortisol [known as the 'fight or flight' hormone are probably part of the mechanism involved, it is also known that the brain cells that control reproduction are unable to respond to cortisol, so there seemed to be a missing link in the circuit somewhere.'
The researchers found that when RFRP neuron activity was high, reproductive hormones were suppressed and the reproductive cycles of female mice were disrupted. Most interestingly, they also discovered that the reproductive system continued to function normally when cortisol levels were high but RFFP neurons had been artificially 'switched off'. This told the researchers that RFRP neurons are a critical link between stress and fertility. They found that the effect was more pronounced in female mice.
'We have now shown that the RFRP neurons are indeed the missing link between stress and infertility. They become active in stressful situations, perhaps by sensing the increasing levels of cortisol, and they then suppress the reproductive system,' Professor Anderson added.
The research is the culmination of more than a decade of work from Professor Anderson's New Zealand-based research group who focus on understanding the link between stress and infertility.
Next the researchers plan to investigate whether drugs could be used to specifically block the RFFP neurons and overcome stress-induced infertility. Although this could be a promising treatment in the future Professor Anderson adds, 'There are such drugs available, but they're not approved for human use and they would likely need refining.'
The research was published in The Journal of Neuroscience.