Featured Research

from universities, journals, and other organizations

Strength Of Cocaine Cravings Linked To Brain Response

Date:
March 19, 2006
Source:
UT Southwestern Medical Center
Summary:
Rats that have a strong craving for cocaine have a different biochemical response to the drug than their less-addicted counterparts, researchers at UT Southwestern Medical Center have found.

Dr. David Self (right), associate professor of psychiatry, and graduate student Scott Edwards have found that rats that are more highly addicted to cocaine develop a different biochemical reaction to the drug than less-addicted ones. The research may help explain why addicts find it so difficult to give up the drug.
Credit: Image courtesy of UT Southwestern Medical Center

Rats that have a strong craving for cocaine have a different biochemical response to the drug than their less-addicted counterparts, researchers at UT Southwestern Medical Center have found.

The difference lies in the pleasure-seeking area of the brain, according to a study available online and appearing in a future issue of the journal Neuropsychopharmacology.

"This work shows that there are profound alterations in the brain mechanisms that regulate motivated behavior with addiction," said Dr. David Self, associate professor of psychiatry at UT Southwestern and senior author of the paper.

"It really shows that the addicted person is ill-equipped to cope because the brain is now wired to make them crave drugs more and get less satisfaction out of the drug or other life events that may be rewarding, and this study found biological changes that would explain these behavioral changes," said Dr. Self.

The researchers looked at dopamine receptors — molecules on cell surfaces that are activated when dopamine or other molecules bind to them. They focused on two types of receptors called D1 and D2.

Molecules that activate D1 are believed to decrease the craving response, while D2 activators are believed to increase it. Both of the receptors bind to the neurotransmitter dopamine in a part of the brain called the mesolimbic dopamine system.

In the study, rats had tubes surgically implanted that fed into their bloodstream, through which they could give themselves cocaine injections by pressing a lever. Some rats voluntarily gave themselves higher doses of cocaine than others did, an indication that they were more addicted to the cocaine.

The rats then went through three weeks of cocaine withdrawal, during which time they ceased to press the lever. At the late stages of withdrawal, a drug that specifically activated the D2 receptor was given to see if it would prompt the rats to press the lever again in search of cocaine. In another experiment, the rats were given a small dose of cocaine and a drug that activated the D1 receptor to see if the drug would block them from seeking more cocaine.

The strongly addicted rats responded more aggressively to the craving-enhancing D2 activator than the less-addicted rats did, and were not as strongly deterred by the D1 activator.

"It's as if the cocaine-addicted animal is less easily satisfied and more easily induced to seek drugs due to alterations in these receptors," Dr. Self said.

Before the researchers administered cocaine, the rats were tested to see how much they moved around when given D1 or D2 activator drugs. Before getting the cocaine, their responses to each drug were the same. After being trained to take the cocaine, the strongly addicted rats were much more sensitive to the D2 activator but less sensitive to the D1 activator. These tests showed that the difference in sensitivity developed during the addiction process, rather than being already present in the animals from the beginning.

The researchers don't know, however, whether the responses in the rats they studied were due to changes in the numbers of the receptors or to the biochemical actions of the receptors already present. Future research may help clarify those different scenarios, Dr. Self said.

Understanding how receptors control cravings may be applicable to humans, although addiction is a complicated mix of brain biochemistry and learned responses to environmental cues, as well as stress, Dr. Self said.

"If people do become addicted and say they want to quit, their brain system for inhibiting craving is weaker. We want to try to strengthen those systems that help them inhibit their craving," he said.

The lead author in the study was Scott Edwards, a neuroscience graduate student at UT Southwestern. Other UT Southwestern researchers involved in the study were Kimberly Whisler, a research associate in psychiatry, Dwain Fuller, faculty associate in psychiatry, and Dr. Paul Orsulak, professor of psychiatry and pathology.

The work was supported in part by the National Institute on Drug Abuse.


Story Source:

The above story is based on materials provided by UT Southwestern Medical Center. Note: Materials may be edited for content and length.


Cite This Page:

UT Southwestern Medical Center. "Strength Of Cocaine Cravings Linked To Brain Response." ScienceDaily. ScienceDaily, 19 March 2006. <www.sciencedaily.com/releases/2006/03/060319184332.htm>.
UT Southwestern Medical Center. (2006, March 19). Strength Of Cocaine Cravings Linked To Brain Response. ScienceDaily. Retrieved October 22, 2014 from www.sciencedaily.com/releases/2006/03/060319184332.htm
UT Southwestern Medical Center. "Strength Of Cocaine Cravings Linked To Brain Response." ScienceDaily. www.sciencedaily.com/releases/2006/03/060319184332.htm (accessed October 22, 2014).

Share This



More Mind & Brain News

Wednesday, October 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

First-Of-Its-Kind Treatment Gives Man Ability To Walk Again

First-Of-Its-Kind Treatment Gives Man Ability To Walk Again

Newsy (Oct. 21, 2014) A medical team has for the first time given a man the ability to walk again after transplanting cells from his brain onto his severed spinal cord. Video provided by Newsy
Powered by NewsLook.com
Portable Breathalyzer Gets You Home Safely

Portable Breathalyzer Gets You Home Safely

Buzz60 (Oct. 21, 2014) Breeze, a portable breathalyzer, gets you home safely by instantly showing your blood alcohol content, and with one tap, lets you call an Uber, a cab or a friend from your contact list to pick you up. Sean Dowling (@SeanDowlingTV) has the details. Video provided by Buzz60
Powered by NewsLook.com
Your Birth Season Might Determine Your Temperament

Your Birth Season Might Determine Your Temperament

Newsy (Oct. 20, 2014) A new study says the season you're born in can determine your temperament — and one season has a surprising outcome. Video provided by Newsy
Powered by NewsLook.com
Movies Might Desensitize Violence For Parents, Not Just Kids

Movies Might Desensitize Violence For Parents, Not Just Kids

Newsy (Oct. 20, 2014) A study suggests that parents become desensitized to violent movies as well as children, which leads them to allow their kids to view violent films. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins