Using Cocaine Once Alters Your Brain's Reward Circuit Forever, Study on Mice Reveals

Researchers have investigated the effects of cocaine use on gene expressions. Getty Images

Using cocaine, even once, has been shown to change the brain's reward circuitry in a new study on mice.

The researchers examined how six parts of the brain in control of the response to reward react when the rodents used cocaine. And while the response of mice isn't entirely comparable to humans, the researchers believe their findings could form the basis of further research into cocaine use, addiction and treatment.

In order to replicate human addiction, the mice in the study were allowed to take and become addicted to cocaine. The team then analyzed the brain wiring of the animals to see if it had changed.

The scientists investigated the gene expressions of mice when they first ingested the drug, after they were addicted and after withdrawal periods of 24 hours and 30 days. The mice were then reintroduced to the drug and tested once again.

Using cocaine once, as well as experiencing a withdrawal for the drug and using it again after a long period of time, changed the gene expressions in their brains associated with addiction and corresponding behaviors, the study suggested.

"The experimental design thus allowed us to study how gene expression across brain reward regions changes over time as a result of volitional cocaine intake," said lead author Dr. Eric Nestler, of Icahn School of Medicine at Mount Sinai, New York.

John Krystal, the editor of the journal Biological Psychiatry where the study was published, said in a statement: "This study elegantly highlights the complexity of the brain's molecular response to self-administered cocaine, pointing to mechanisms that might be targeted by treatments."

Unlike other studies that honed in one specific gene, parts of the brain or factor of addiction, this paper tried to tie these factors together.

A previous study by Mount Sinai researchers published in the journal Nature Communications earlier this year found a protein the immune system produces when cocaine enters the body could play a role in the development of cocaine addiction.

The protein, called granulocyte-colony stimulating factor, was found to change how much a mouse wanted cocaine, without interrupting their desire for other substances.

Such studies are important. The latest figures on cocaine use in the U.S. by the State Department show that more people were using the drug in 2017 than ever before and it was easier to buy.