Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Disrupting cocaine-memories to battle addiction

15.09.2005


Addicts crave drugs and suffer relapse not just because of the alluring high of drugs, but also because they are compelled by the powerful, haunting memory associations with the environment surrounding their drug taking. Thus, treatments that could eliminate those memory associations could prove effective in treating addiction, researchers believe.



In two papers in the September 15, 2005, issue of Neuron, two groups of researchers report important progress toward such treatments, showing that they can selectively knock out memory associations connected with receiving cocaine.

In one paper, Jonathan Lee and his colleagues at the University of Cambridge create an animal model of such cocaine memory formation by first teaching rats to associate the poking of their noses into a food bin with an infusion of cocaine into the brain and with the activation of a signal light. They infused cocaine into the amygdala, a brain region involved in forming and processing emotional memories.


The researchers then extinguished the drug-related memory by giving the animals only saline solution when they poked their nose into the bin, activating the light.

In their procedure, the researchers then added a new drug-associated response by requiring the animals to press a lever to obtain cocaine, with the lever also activating the same signal light.

Their purpose was to test the effects of treatment on a memory process called "reconsolidation." The theory underlying reconsolidation is that when memories are recalled they become malleable, subject to disruption.

To discover whether they could disrupt reconsolidation of the drug-related memory, before the animals were exposed to the new lever-pressing task, the researchers injected into the amygdalas of the trained animals a molecule that would effectively shut down the gene that produces a protein called Zif268. This protein is known to be active when cocaine-conditioned memories are created. The injected molecule was "anti-sense" DNA that would attach to the gene, blocking its activation.

The researchers found that such anti-sense DNA treatment disrupted the rats’ ability to learn to associate the new lever-pressing behavior with the signal light to obtain cocaine, despite the fact that the animals showed no other differences from a control group in lever-pressing activity or nosepoke response and thus no difference in general motivation or activity.

The researcher wrote that "Drug-associated stimuli are critically important in the acquisition of prolonged periods of drug-seeking behavior, maintenance of this behavior in the absence of reward, and precipitation of relapse to drug seeking in the absence of reward. Therefore, the ability to disrupt retroactively the conditioned reinforcing properties of a drug cue provides a potentially powerful and novel approach to the treatment of drug addiction by diminishing the behavioral impact of drug cues and thereby relapse."

Lee and his colleagues point out that the basic processes of such drug-associated memory reconsolidation are distinct enough from normal memory that "it is possible to manipulate preexisting maladaptive memories in a highly specific manner, without affecting either the reconsolidation of other established memories or the consolidation of new memories."

In a second Neuron paper, Courtney Miller and John Marshall of the University of California, Irvine, explored how another brain region, the nucleus accumbens, operated in cocaine-associated memories. The nucleus accumbens receives neural input from the amygdala and is involved in motivating such reward-related behavior as drug seeking.

In their experiments, the researchers taught rats to associate one of two connected chambers with receiving cocaine and measured how well the rats remembered that association and chose to move to that chamber.

The researchers’ analysis of molecular regulatory pathways in the animals’ nucleus accumbens revealed that a master neural regulatory pathway, triggered by a molecular switch called ERK, was activated when the trained animals showed a preference for the "cocaine chamber."

What’s more, the researchers discovered that drugs that blocked the ERK pathway prevented the trained animals’ memory retrieval of their preference for that chamber.

And to their surprise the researchers found that the drugs also blocked memory reconsolidation--significantly reducing the rats’ preference for the cocaine chamber even two weeks after being given.

"To our knowledge, the current study is the first to identify a molecular mechanism that blocks both retrieval and reconsolidation of any type of memory," wrote Miller and Marshall.

"While much remains to be understood concerning the cellular processes underlying the effects of ERK in drug-stimulus associations and other types of learning and memory, the present findings offer hope for treating cue-elicited relapse in addicts," concluded Miller and Marshall.

"It is widely accepted that memories for drug-associates stimuli, which are strong and resistant to extinction, are responsible for much of the relapse seen in addicts. The present findings suggest that these highly resistant memories may again be made labile and thus susceptible to disruption by pharmacological or other neurobiological interventions, providing opportunities for new therapies," they concluded.

Heidi Hardman | EurekAlert!
Further information:
http://www.neuron.org.
http://www.cell.com

More articles from Health and Medicine:

nachricht Researchers release the brakes on the immune system
18.10.2017 | Rheinische Friedrich-Wilhelms-Universität Bonn

nachricht Norovirus evades immune system by hiding out in rare gut cells
12.10.2017 | University of Pennsylvania School of Medicine

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

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

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Terahertz spectroscopy goes nano

20.10.2017 | Information Technology

Strange but true: Turning a material upside down can sometimes make it softer

20.10.2017 | Materials Sciences

NRL clarifies valley polarization for electronic and optoelectronic technologies

20.10.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>