Study using animal model provides clues to why cocaine is so addictive

August 1, 2016
A pile of cocaine hydrochloride. Credit: DEA Drug Enforcement Agency, public domain

Scientists at Wake Forest Baptist Medical Center are one step closer to understanding what causes cocaine to be so addictive. The research findings are published in the current issue of the Journal of Neuroscience.

Cocaine addiction is a debilitating neurological disorder that affects more than 700,000 people in the United States alone, according to the Substance Abuse and Mental Health Services Administration. With repeated use, tolerance may develop, meaning more of the drug is required to achieve the same euphoric effect. Cocaine addiction can be characterized by repeated attempts at abstinence that often end in relapse.

"Scientists have known for years that cocaine affects the and , so we designed our study to gain a better understanding of how tolerance to cocaine develops via the dopamine transporters," said Sara R. Jones, Ph.D., professor of physiology and pharmacology at Wake Forest Baptist and lead author of the study.

"Currently there isn't any effective treatment available for cocaine addiction so understanding the underlying mechanism is essential for targeting potential new treatments."

Using an animal model, the research team replicated cocaine addiction by allowing rats to self-administer as much cocaine as they wanted (up to 40 doses) during a six-hour period. Six-hour-a-day access is long enough to cause escalation of intake and tip over from having controlled intake to more uncontrolled, binge-like behavior, Jones said.

Following the five-day experiment, the animals were not allowed cocaine for 14 or 60 days. After the periods of abstinence, the researchers looked at the animals' dopamine transporters and they appeared normal, just like those in the control animals that had only received saline.

However, a single self-administered infusion of cocaine at the end of abstinence, even after 60 days, fully reinstated tolerance to cocaine's effects in the animals that had binged. In the control animals that had never received cocaine, a single dose did not have the same effect.

These data demonstrate that cocaine leaves a long-lasting imprint on the dopamine system that is activated by re-exposure to cocaine, Jones said. This 'priming effect,' which may be permanent, may contribute to the severity of relapse episodes in .

"Even after 60 days of abstinence, which is roughly equivalent to four years in humans, it only took a single dose of cocaine to put the rats back to square one with regard to its' dopamine system and tolerance levels, and increased the likelihood of binging again," Jones said. "It's that terrible cycle of addiction."

Jones added that hope is on the horizon through preclinical trials that are testing several amphetamine-like drugs for effectiveness in treating addiction.

Explore further: Novel compound halts cocaine addiction and relapse behaviors

Related Stories

Novel compound halts cocaine addiction and relapse behaviors

April 23, 2014
A novel compound that targets an important brain receptor has a dramatic effect against a host of cocaine addiction behaviors, including relapse behavior, a University at Buffalo animal study has found.

Long-term cocaine addiction therapy developed

December 30, 2015
(MedicalXpress)—A team of researchers with the University of Kentucky has developed a long-term chemical treatment option for cocaine addiction. In their paper published in Proceedings of the National Academy of Sciences, ...

New insights on how cocaine changes the brain

November 25, 2015
The burst of energy and hyperactivity that comes with a cocaine high is a rather accurate reflection of what's going on in the brain of its users, finds a study published November 25 in Cell Reports. Through experiments conducted ...

Genes for two molecules in rats found to be involved in response to cocaine and other stimulants

April 26, 2016
(Medical Xpress)—A team of researchers affiliated with the University of Michigan and the University of Alabama has found two molecules expressed in rats that are involved in their response to cocaine and other stimulants. ...

Carrots and sticks fail to change behaviour in cocaine addiction

June 16, 2016
People who are addicted to cocaine are particularly prone to developing habits that render their behaviour resistant to change, regardless of the potentially devastating consequences, suggests new research from the University ...

Recommended for you

'Residual echo' of ancient humans in scans may hold clues to mental disorders

July 26, 2017
Researchers at the National Institute of Mental Health (NIMH) have produced the first direct evidence that parts of our brains implicated in mental disorders may be shaped by a "residual echo" from our ancient past. The more ...

Cellular roots of anxiety identified

July 26, 2017
From students stressing over exams to workers facing possible layoffs, worrying about the future is a normal and universal experience. But when people's anticipation of bad things to come starts interfering with daily life, ...

Laser used to reawaken lost memories in mice with Alzheimer's disease

July 26, 2017
(Medical Xpress)—A team of researchers at Columbia University has found that applying a laser to the part of a mouse brain used for memory storage caused the mice to recall memories lost due to a mouse version of Alzheimer's ...

Brain disease seen in most football players in large report

July 25, 2017
Research on 202 former football players found evidence of a brain disease linked to repeated head blows in nearly all of them, from athletes in the National Football League, college and even high school.

Zebrafish study reveals clues to healing spinal cord injuries

July 25, 2017
Fresh insights into how zebrafish repair their nerve connections could hold clues to new therapies for people with spinal cord injuries.

Lutein may counter cognitive aging, study finds

July 25, 2017
Spinach and kale are favorites of those looking to stay physically fit, but they also could keep consumers cognitively fit, according to a new study from University of Illinois researchers.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.