Friday, March 25, 2011

Gay or straight? Brain chemical decides sexual preference

LONDON: Chinese researchers have identified a chemical in the brain that controls sexual preference in mice. They found that male mice lose their normal preference for females if they have low levels of serotonin. Instead, they try to mate with either males or females. 

It is the first time that a neurotransmitter has been shown to play a role in sexual preference in mammals, according to the researchers. They first bred male mice whose brains were not receptive to serotonin. 
A series of experiments demonstrated that these mice had lost the preference for females. When presented with a choice of partners, they showed no overall preference for either males or females. 

When just a male was introduced into the cage, the modified males were far more likely to mount the male and emit a 'mating call' normally given off when encountering females than unmodified males were. Similar results were achieved when a different set of mice were bred. These lacked the tryptonphan hydroxylase 2 gene, which is needed to produce serotonin. 

However, a preference for females could be 'restored' by injecting serotonin into the brain.


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