Hormones drive emotions in young males

The emotions of adolescent males, at least among sheep, are influenced by the changing patterns of reproductive hormones that occur as individuals become more sexually mature, according to researchers from the University of Glasgow and Oslo University Hospital in Norway.

The researchers say the findings are significant because a variety of medical conditions, such as growth deficiency, early onset gender identity disorder and cancers in reproductive tissues, are treated using drugs that temporarily ‘turn off’ the reproductive system.

The long-term effects or side effects of these treatments when they are used on adolescents are not known.

The researchers conducted studies on 92 sheep to investigate what would happen if puberty did not occur, by blocking changes in hormones using common human drugs. The Glasgow team worked with colleagues from the Oslo hospital’s Norwegian School of Veterinary Science and AgroParisTech.

“We used sheep because the time course of pubertal development is more similar to humans than laboratory rodents,” said Professor Neil Evans of the University of Glasgow.

“As sheep are flock animals, and like to see other sheep, an easy way to test their emotional response is to place them in social isolation for a two-minute period. This was done at three times, before, during and after puberty.

“The results showed that females had a greater emotional response than males, both before and after puberty. Interestingly, the results also showed that the emotional response of males, but not females, was significantly altered when puberty was blocked.”

Evans said the results suggested that changes in hormones during adolescence drive changes in the brains of males that alter emotional reactivity. The findings could have implications for the treatment of medical conditions occurring at the time of puberty.

But he said the link between reproductive hormones and how the brain works raised the possibility that other medical conditions affecting how humans think and behave, such as Alzheimer’s disease, could be affected by, or could be treated with, drugs that changed activity within the reproductive system.

The precise hormonal changes that bring about these alterations in behaviour, exactly how they act within the brain and whether such changes are permanent, will be the subject of further studies planned by the research team.

A report of the research is available from Science Direct.