Puberty triggered by a KiSS

Puberty starts when a key gene called KiSS-1 switches on, US researchers say. The team, based at the University of Pittsburgh, say that the gene makes a protein that switches on another gene, which then triggers the production of reproductive hormones. The research, published in the journal Proceedings of the National Academy of Sciences, helps explain how reproductive hormones remain 'dormant' until a child's teenage years.

Puberty beings when an area of the brain begins to release a hormone called GnRH (gonadotropin-releasing hormone), which in turn triggers the release of other hormones that affect the ovaries and testes. In 2003, two groups of researchers discovered that a gene called GPR54 is defective in people who never start puberty - a rare condition called idiopathic hypogonadotrophic hypogonadism (IHH). In the latest study, the scientists have shown that puberty begins when the proteins produced by the GPR54 and KiSS-1 genes work together to switch on GnRH.

The researchers carried out their work in non-human primates, the only animals that have a reproductive system similar to humans. They discovered that by giving the animals kisspeptin, the protein produced by KiSS-1, they could 'wake up' the reproductive hormones from their childhood hibernation. The level of one of these hormones, called LH, increased twenty-five fold just 30 minutes after giving kisspeptin to male monkeys.

Team leader Tony Plant stressed that the KiSS and GPR54 genes are unlikely to be the whole story behind the onset of puberty. 'Other signalling systems, some of which have probably yet to be identified in humans, help control GnRH release in primates', he said. The scientists hope that by understanding what triggers puberty, they will be able to develop ways of preventing very early or delayed puberty from occurring in some children.