Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Strength of cocaine cravings linked to brain response

15.03.2006


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, who holds the Wesley Gilliland Professorship in Biomedical Research.

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.

Aline McKenzie | EurekAlert!
Further information:
http://www.utsouthwestern.edu

More articles from Life Sciences:

nachricht Microscope measures muscle weakness
16.11.2018 | Friedrich-Alexander-Universität Erlangen-Nürnberg

nachricht Good preparation is half the digestion
16.11.2018 | Max-Planck-Institut für Stoffwechselforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: UNH scientists help provide first-ever views of elusive energy explosion

Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.

Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...

Im Focus: A Chip with Blood Vessels

Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.

Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

Im Focus: Penn engineers develop ultrathin, ultralight 'nanocardboard'

When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure

Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

European Space Talks: Weltraumschrott – eine Gefahr für die Gesellschaft?

23.10.2018 | Event News

 
Latest News

Purdue cancer identity technology makes it easier to find a tumor's 'address'

16.11.2018 | Health and Medicine

Good preparation is half the digestion

16.11.2018 | Life Sciences

Microscope measures muscle weakness

16.11.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>