Exploring Addiction

Cocaine, heroin activate same genes as salt
October 1, 2011
Exploring Addiction

A new study shows that certain drugs may have gained some of their addictive power by hijacking the same nerve cells and connections in the brain that serve a powerful, ancient instinct: the appetite for salt.

The study, conducted by researchers at Duke Medical Center and colleagues in Australia, shows how certain genes are regulated in the hypothalamus, a part of the brain that controls the equilibrium of salt, water, energy, reproduction, and other rhythms. The scientists found—at least in rats—that the gene patterns activated by stimulating an instinctive behavior, salt appetite, were the same groups of genes regulated by addiction to cocaine or opiates such as heroin.

The findings, say Wolfgang Liedtke, an assistant professor of medicine and neurobiology at Duke and co-lead author of the study, published in Proceedings of the National Academy of Sciences, “could lead to a new understanding of addictions and the detrimental consequences when obesitygenerating foods are overloaded with sodium”—and could lead to new treatments.

“Though instincts like salt appetite are basically genetic neural programs, they may be substantially changed by learning and cognition,” says co-lead author Derek Denton, a professor at the University of Melbourne and the Florey Neuroscience Institute. “Once the genetic program is operating, experiences that are part of the execution of the program become embodied in the overall patterns of an individual’s behavior, and some scientists have theorized that drug addiction may use nerve pathways of instinct.”

Deeply embedded pathways of an ancient instinct may explain why addiction treatment with the chief objective of abstinence is so difficult, Denton says. Liedtke suggests that this might be relevant given the appreciable success of approaches that don’t involve abstinence, like replacing heroin with methadone and cigarettes with nicotine gum or patches.