IT MIGHT be possible to develop a pill that turns aggressive louts into mild-mannered gentlemen.
鈥淧eacenik鈥� mice modified to have a missing brain receptor fail to pick the usual fights when 鈥渋ntruder鈥� males are introduced into their cages. That suggests that drugs that block the receptor should reduce aggression, says Scott Young of the US National Institute of Mental Health in Bethesda, Maryland. A French company, Sanofi-Synthelabo, has already developed such a drug, though it has yet to be tested on people.
If suitable drugs do turn out to have a calming effect without substantial side effects, Young foresees them being given to people who become aggressive after brain damage or because of illnesses such as Alzheimer鈥檚. But authorities would no doubt be tempted to dish them out more widely, to problem inmates in jails, for example.
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鈥淲e hope that for certain patients, attacking this receptor will be useful, but what that spectrum of patients will be I can鈥檛 predict at this point,鈥� says Young. 鈥淚 don鈥檛 know if it would be as widely used and abused as something like Valium.鈥�
Young and his team wanted to see what would happen if mice couldn鈥檛 make a receptor for vasopressin, a hormone mainly known for regulating absorption of water from the kidneys. However, vasopressin also influences behaviour through separate brain receptors. The team genetically engineered male mice so that they couldn鈥檛 make the vasopressin 1b receptor, one of two known brain receptors for the hormone.
When the peacenik mice were placed in different situations, the team discovered that they avoided fights. 鈥淭heir social aggression was markedly reduced, and most of the peacenik mice didn鈥檛 attack intruder animals,鈥� says Young. 鈥淓ven those that did showed much reduced attacking behaviour.鈥�
The only side effect appeared to be a slight problem with recognising other mice. 鈥淭here was a modest deficit in social recognition,鈥� says Young, whose team included researchers at the University of Bristol.
Apart from that, the mice were completely normal. They had sex when females were placed in the cage. They sought food when hungry, proving that they still had motivation to hunt if not the will to fight. And their movement and senses all appeared normal.
Reporting their results in Molecular Psychiatry (vol 7, p 975), the team speculates that the lack of receptor could affect how the animal perceives the threat of an intruder. The big question is whether drugs which block V1bR will dampen aggression in people as well.