From New Scientist – one of the better science email newsletters, incidentally:
“Clubbers who take the “love drug” ecstasy really might be “loved up”. Studies in rats suggest the drug causes a brain surge of oxytocin – the hormone that helps bond couples, as well as mothers to their babies.
Earlier research found increased oxytocin in the blood of people who had taken ecstasy. However, many drugs increase blood oxytocin without raising it in the brain – something thought necessary for any “pro-social” effects.
Iain McGregor at the University of Sydney in Australia, and his colleagues studied the effects of ecstasy in rats, which, like people, become more sociable on the drug. “It’s very characteristic behaviour. They lie next to each other and chill out,” McGregor says.
The team gave the rats the equivalent of two to three ecstasy tablets in an adult human and found that the drug activated oxytocin-containing neurons in an area of their brains called the hypothalamus. When they gave the rats a drug that blocked brain receptors for oxytocin, the increased sociability almost disappeared.
Why it didn’t disappear entirely isn’t clear. It could be that the dose of the receptor blocker was too low, or that other brain chemicals, such as dopamine, are also involved in triggering the sociable behaviour, McGregor says.”