2011-03-24 06:40:06
Mice Serotonin controls a male mouse's choice of partner
A chemical in the brain controls sexual preference in mice, according to
scientists in China.
Male mice bred without serotonin lose their preference for females, a report in
Nature says.
The researchers say it is the first time that a neurotransmitter has been shown
to play a role in sexual preference in mammals.
Experts have warned about the dangers of drawing conclusions about human
sexuality.
The research team 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 shown by unmodified males.
When presented with a choice of partners, they showed no overall preference for
either males or females.
Start Quote
Any potential links between serotonin and human sexual preferences must be
considered somewhat tenuous
End Quote Professor Keith Kendrick Neuroscientist
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.
The report concludes: "Serotonergic signalling is crucial for male sexual
preference in mice. This is the first time, to our knowledge, that a
neurotransmitter in the brain has been demonstrated to be important in
mammalian sexual preference."
Humans
Sexual behaviour in mice is thought to be driven by their sense of smell.
Professor Keith Kendrick, a neuroscientist at the Babraham Institute in
Cambridge, said: "In terms of having potential relevance to understanding human
sexual preference/orientation, we are of course far less influenced by odour
cues in this context than mice are.
"There is some very limited evidence for altered responses to selective
serotonin uptake inhibitors (SSRIs) in the brains of homosexuals, but we have
been using psychoactive drugs which either increase or decrease serotonin
function for quite some time now, and while effects on sexual arousal,
impulsivity and aggression have often been reported, no effects on sexual
preference/orientation have.
"At this time therefore any potential links between serotonin and human sexual
preferences must be considered somewhat tenuous."