PRIMORDIAL instincts that drive animals to seek out salt may be governed by the same mechanism that drives drug addicts to hunt down their fix.

Researchers deprived mice and rats of salt, then offered them salty water to drink. After killing the animals they examined gene activity in the hypothalamus, the brain’s “reward” centre. They found that gratification genes had been activated – the same genes that are active in cocaine and heroin addicts when their craving has been satisfied.

If the team used a drug to block the effects of dopamine, the neurotransmitter associated with feelings of enjoyment, the animals did not drink the salty water. This suggests that the urge to seek out salt is indeed linked to the reward mechanism (Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.1109199108).

The discovery might open up new ways to treat addiction. “We’re not saying the new data tells us how to cure addiction, but it does point to new avenues of investigation,” says team member Derek Denton of the University of Melbourne, Australia.