Regulation of puberty and growth by the brain

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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