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

August 1, 2016, Wake Forest University Baptist Medical Center
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

Finding unravels nature of cognitive inflexibility in fragile X syndrome

January 22, 2018
Mice with the genetic defect that causes fragile X syndrome (FXS) learn and remember normally, but show an inability to learn new information that contradicts what they initially learned, shows a new study by a team of neuroscientists. ...

Epilepsy linked to brain volume and thickness differences

January 22, 2018
Epilepsy is associated with thickness and volume differences in the grey matter of several brain regions, according to new research led by UCL and the Keck School of Medicine of USC.

Research reveals atomic-level changes in ALS-linked protein

January 18, 2018
For the first time, researchers have described atom-by-atom changes in a family of proteins linked to amyotrophic lateral sclerosis (ALS), a group of brain disorders known as frontotemporal dementia and degenerative diseases ...

Fragile X finding shows normal neurons that interact poorly

January 18, 2018
Neurons in mice afflicted with the genetic defect that causes Fragile X syndrome (FXS) appear similar to those in healthy mice, but these neurons fail to interact normally, resulting in the long-known cognitive impairments, ...

How your brain remembers what you had for dinner last night

January 17, 2018
Confirming earlier computational models, researchers at University of California San Diego and UC San Diego School of Medicine, with colleagues in Arizona and Louisiana, report that episodic memories are encoded in the hippocampus ...

Recording a thought's fleeting trip through the brain

January 17, 2018
University of California, Berkeley neuroscientists have tracked the progress of a thought through the brain, showing clearly how the prefrontal cortex at the front of the brain coordinates activity to help us act in response ...

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.