A new molecule was recently discovered that is critical for
puberty to occur in all animals including humans.
This molecule, rather incredibly named kisspeptin after the
Hershey Kiss chocolate, acts in the brain to stimulate
gonadotropin-releasing hormone (GnRH) neurons.
The GnRH neurons control when puberty occurs and, henceforth,
fertility in adulthood.
At the time of puberty there is also a well-known growth
spurt.
Like the onset of puberty, this growth spurt is also
controlled by the brain but involves a different group of
cells called growth hormone-releasing hormone (GHRH) neurons.
These GHRH neurons regulate the release of growth hormone
into the blood, which then controls the growth spurt.
Recent studies in the laboratory of Prof.
Allan Herbison, in the Otago School of Medical Sciences in
Dunedin, have shown that synthesis of the kisspeptin molecule
in the brain increases from birth and peaks at the time of
puberty.
Subsequent studies have shown that this kisspeptin activates
the GnRH neurons.
Interestingly, the release of growth hormone into the blood
also peaks at the time of puberty.
These observations have raised the possibility that the
kisspeptin cells and GHRH neurons may act in synergy to
initiate pubertal development and growth.
This is backed up by the fact that both pubertal onset and
growth is disrupted in transgenic mouse models characterised
by a loss of either kisspetin or growth hormone action.
Experiments, funded by both the University of Queensland and
the Otago School of Medical Sciences, will address the
possibility that kisspeptin cells in the brain may activate
GHRH neurons to regulate growth hormone release and pubertal
development.
Studies will take advantage of unique transgenic mouse models
in which the molecule kisspeptin or its receptor have been
deleted, as well as dwarf mouse models that do not respond to
growth hormone.
The ability to perform these studies follows from the
development of a method in the laboratory of Prof.
Chen Chen, at the University of Queensland, that accurately
determines the secretion of growth hormone in the mouse.
The results of these studies will greatly increase our
understanding of the mechanisms within the brain that control
puberty and growth in adolescence.
They have the potential to provide the foundations for new
treatments aimed at treating adolescents with abnormally
advanced or delayed puberty and growth.
- Prof Allan Herbison
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