The teenage hormone that triggers puberty and prevents cancer

The appropriately named kisspeptin was discovered by accident, and has some surprising effects.

Whatever your parents told you, it’s not about the birds and the bees. Ultimately, reproduction seems to be about a protein molecule called kisspeptin. The name has nothing to do with foreplay, however. Kisspeptin was discovered in Hershey, Pennsylvania, and its name comes from the town’s other great research success: Hershey’s Kisses chocolates.

At some point, most people’s brain starts to secrete kisspeptin; when it does, the hypothalamus begins to produce a chemical called gonadotropin-releasing hormone, or GnRH. Written down, it looks like a teenage grunt and that’s what it leads to. GnRH release is a crucial moment at the beginning of puberty. It brings about the secretion of hormones that start egg or sperm production and create the characteristic signs of sexual maturity.

On 12 September, the King’s College London professor Kevin O’Byrne discussed the “enigma” of GnRH at a conference at the University of Bristol. The central enigma is the unanswered question of what kicks off puberty – we still don’t know what activates kisspeptin to release GnRH.

It seems to have something to do with the brain’s monitoring of stress and nutrition. Without good fat reserves and a relaxed demeanour, the chemical sages won’t let you enter the trials of reproduction. That’s why girls suffering from anorexia can experience disrupted menstruation.

Kisspeptin’s role in puberty was discovered by accident when researchers were looking at its anti-cancer properties. Controlling the teenage brain is not the only thing it can do. GnRH is now used as a part of some cancer treatment routines because it stops the production of oestrogen, a hormone that seems to play a role in stimulating tumour growth.

Here’s another clue: some of the ugliest rodents on the planet, known as “naked mole rats”, are awash with kisspeptin – and they don’t get cancer.

Most animals have levels of kisspeptin neurons that vary according to sex as well as reproductive state. New research shows that naked mole rats have high kisspeptin and GnRH levels no matter what their readiness for reproduction.

That is particularly odd because, despite these high levels of kisspeptin, most naked mole rats don’t develop the ability to breed. Like some species of bee, naked mole rats live in colonies in which only a queen and a few consorts develop the ability to reproduce. The rest are workers that remain sterile all their lives. And those are long lives.

Their extraordinary resistance to developing cancers makes naked mole rats the longestliving rodents. Mice and rats typically live for two or three years; naked mole rats often live for two decades or more. Understanding what kisspeptin does for the naked mole rat could assist our fight against the ravages of ageing.

However, our slowly increasing grasp of kisspeptin and GnRH is causing a dilemma. The age at which human beings hit puberty is falling – on average, it has fallen by five years since 1920. It’s less of a problem for boys than for girls, for whom “precocious puberty” is linked with an increased risk of breast cancer, mental disorders and, in later life, polycystic ovary syndrome.

That raises the question of whether we should intervene. There’s still a lot we don’t know but research has shown that an injection of kisspeptin kicks off puberty artificially. More usefully, drugs that block kisspeptin prevent puberty from starting and doctors are starting to intervene in the most extreme cases of precocious puberty. Some see this as a risky thing to do when we have no long-term data on the outcome.

This new branch of science might not yet have hit puberty but it is already starting to give us trouble.

Teenage kicks: Kisspeptin not only triggers puberty but also helps fight cancer

Michael Brooks holds a PhD in quantum physics. He writes a weekly science column for the New Statesman, and his most recent book is At the Edge of Uncertainty: 11 Discoveries Taking Science by Surprise.

This article first appeared in the 23 September 2013 issue of the New Statesman, Can Miliband speak for England?

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Why have men become so lonely – and how does it affect their health?

New findings show the consequences of having a lonely heart.

Go out and get some friends. No, seriously. Hop on the Tube and act faux-interested in the crap-looking book your fellow commuter is reading, even if it's on their Kindle. Chances are it's better than the one in your bag, and they're probably a decent human being and just as lonely, like you and me.

A new slate of facts and figures are showing just how widespread loneliness, is while simultaneously being amazingly terrible for your health.

Research led by Steven Cole from the medicine department at University of California, Los Angeles is showing the cellular mechanisms behind the long known pitfalls of loneliness. Perceived social isolation (PSI) – the scientific term for loneliness –increases the exposure to chronic diseases and even mortality for individuals across the world.

The authors examined the effects of loneliness on leukocytes, also known as white blood cells, which are produced from stem cells in the bone marrow and are critical to the immune system and defending the body against bacteria and viruses. The results showed loneliness increases signalling in the sympathetic nervous system, which is responsible for controlling our fight-or-flight responses, and also affects the production of white blood cells.

Recently, the Movember Foundation, which focuses on men's health and wellbeing, carried out a survey with the help of YouGov investigating friendship and loneliness amongst men. The results are alarming, with only 11 per cent of single men across the spectrum in their early 20s to late-middle age saying they had a friend to turn to in a time of crisis, the number rising to 15 per cent for married men.

Friendship has shown not only to be important to a person's overall wellbeing, but can even add to a person's earnings. A previous study involving 10,000 US citizens over 35 years showed people earned 2 per cent more for each friend they had.

The Movember Foundation survey comes soon after the Office for National Statistics (ONS) showed that men in Britain make up 58 per cent of the 2.47m people living alone between the ages of 45 and 64. The reasons behind this figure include marrying later in life and failed marriages, which usually result in children living with the mother. Women still make up the majority of the 7.7m single-occupant households across all ages in the country, at approximately 54 per cent.

Chronic loneliness seems to have slowly become a persistent problem for the country despite our hyper-connected world. It's an issue that has made even Jeremy Hunt say sensible things, such as "the busy, atomised lives we increasingly lead mean that too often we have become so distant from blood relatives" about this hidden crisis. He's previously called for British families to adopt the approach of many Asian families of having grandparents live under the same roof as children and grandchildren, and view care homes as a last, not first, option.

The number of single-person households has continued to increase over the years. While studies such as this add to the list of reasons why being alone is terrible for you, researchers are stumped as to how we can tackle this major social issue. Here's my suggestion: turn off whatever screen you're reading this from and strike up a conversation with someone who looks approachable. They could end up becoming your new best friend.