AsianScientist (Nov. 21, 2014) – Researchers have discovered that neural circuitry previously shown to be vital to triggering ovulation and maintaining fertility also plays a key role in molding the male brain.
In new research appearing in the Journal of Neuroscience, a team led by University of Otago’s Professor Allan Herbison shows that male-specific signalling in the gonadotropin-releasing hormone (GnRH) neurons of new-born mice is crucial to generating a testosterone surge that occurs up to five hours after birth.
This brief but powerful increase in testosterone blood levels, which only takes place in males, is known to cause their brains to develop differently to females. Among other effects, these brain differences are implicated in the patterns of neurological disorders that men and women suffer.
Prof. Herbison says that sex differences in brain function are established during the later stages of fetal development and around birth, but the actual cellular mechanisms underlying these important actions remained unknown.
Through a series of investigations in mice, he and his colleagues have now shown that a small group of GnRH neurons in the brain’s hypothalamus become active only in new-born males and not females.
Additionally, they found that a small population of kisspeptin neurons also appear at this time, once again only in males. In their latest investigations, the researchers also show that male mice lacking kisspeptin receptors on their GnRH neurons do not experience the usual testosterone surge following birth. They also determined that, as adult males, such mice had female-like brain characteristics.
Prof. Herbison says the team’s new findings reveal that kisspeptin, which has only been discovered to play any role in fertility in the past decade or so, is a much more remarkable molecule than previously thought.
“Not only does kisspeptin signalling act as a master switch for puberty and ovulation, we now show how in the first hours of drawing breath it also triggers our brains to develop differently according to our sex.”
The article can be found at: Kumar et al. (2014) Murine Arcuate Nucleus Kisspeptin Neurons Communicate with GnRH Neurons In Utero.
Source: University of Otago.
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