[Home]   [Full version]  

Research Links Change in Brain with Addiction

Feb 01 ,Medicine & Health


A researcher at the University at Buffalo's Research Institute on Addictions (RIA) has found a change in the brain that occurs after drug use and that may contribute to drug addiction.

The finding, reported in the January 2007 issue of the journal Biological Psychiatry, demonstrates that repeated exposure to different types of drugs of abuse such as cocaine, nicotine, amphetamine, and alcohol lead to a persistent or long-term reduction in the electrical activity of dopamine neurons in the brain.

Dopamine neurons are the origin of the reward pathway responsible for the "feel good" experience that is such a strong component of drug use and abuse.

"A persistent reduction in dopamine neuron electrical activity after repeated exposure to different types of drugs appears to be the result of excessive excitation of dopamine neurons," according to Roh-Yu Shen, Ph.D., a neuroscientist and the lead investigator on the study. "This represents a new and potentially critical neural mechanism for addiction and provides a working model that suggests how the reward pathway function is altered and how these changes can be responsible for triggering intense craving and compulsive drug-seeking."

Initial exposure to drugs of abuse causes dopamine neurons to release dopamine in target areas of the brain that provide the reward effect of using drugs. Repeated abuse of drugs results in long-lasting changes in the function of the reward pathway that leads to craving for drugs and the compulsion for more drugs.

Shen is a senior research scientist at RIA and holds adjunct appointments in the Department of Pathology and Anatomical Sciences in the UB School of Medicine and Biomedical Sciences and Department of Psychology in the UB College of Arts and Sciences. Her colleagues on this study include Kar-Chan Choong, RIA research assistant, who performed the experiments, and Alexis C. Thompson, Ph.D., RIA research scientist and research associate professor in UB's Department of Psychology.

Shen said the persistent or long-lasting nature (3-6 weeks in animal models equivalent to approximately two years in humans) of this effect helps to explain why it is so difficult to abstain from

using cocaine, nicotine, amphetamine and alcohol. In addition, she added, it is a time-dependent effect that is not seen immediately after drug use, but rather manifests over a period of time following drug use and intensifies over time.

Shen and colleagues have concluded that the persistent reduction in dopamine activity parallels the long-lasting nature of addictive behaviors, including intensified craving and compulsive drug-seeking behavior. A next step is for treatment researchers to develop treatment protocols that build on this biological finding.

Source: University at Buffalo

Related stories:

Learning how not to be afraid
Why do some people have the ability to remain calm and relaxed even in the most stressful situations? New experiments in mice by Howard Hughes Medical Institute (HHMI) researchers are providing insight into how the brain changes when the animals learn to feel safe and secure in situations that would normally make them anxious.
Singing to females makes male birds' brains happy
The melodious singing of birds has been long appreciated by humans, and has often been thought to reflect a particularly positive emotional state of the singer. In a new study published in the online, open-access journal PLoS ONE on October 1, researchers at the RIKEN Brain Science Institute in Japan have demonstrated that this can be true. When male birds sang to attract females, specific "reward" areas of their brain were strongly activated. Such strong brain activation resulted in a similar change in brain reward function to that which is caused by addictive drugs.
Beginning to see the light
(PhysOrg.com) -- Scientists have detailed the active form of a protein which they hope will enhance our understanding of the molecular mechanisms of vision, and advance drug design.
Abuse of painkillers can predispose adolescents to lifelong addiction
No child aspires to a lifetime of addiction. But their brains might. In new research to appear online in the journal Neuropsychopharmacology this week, Rockefeller University researchers reveal that adolescent brains exposed to the painkiller Oxycontin can sustain lifelong and permanent changes in their reward system – changes that increase the drug's euphoric properties and make such adolescents more vulnerable to the drug's effects later in adulthood.
Looking beyond the drug receptor for clues to drug effectiveness
Antipsychotic drugs that are widely used to treat schizophrenia and other problems may not work as scientists have assumed, according to findings from Duke University Medical Center researchers that could lead to changes in how these drugs are developed and prescribed.
Cocaine: How addiction develops
Permanent drug seeking and relapse after renewed drug administration are typical behavioral patterns of addiction. Molecular changes at the connection points in the brain's reward center are directly responsible for this. This finding was published by a research team from the Institute of Mental Health (ZI) in Mannheim, the German Cancer Research Center (DKFZ) in Heidelberg and the University of Geneva, Switzerland, in the latest issue of Neuron. The results provide researchers with new approaches in the medical treatment of drug addiction.
1 sleepless night increases dopamine in the human brain
Just one night without sleep can increase the amount of the chemical dopamine in the human brain, according to new imaging research in the August 20 issue of The Journal of Neuroscience. Because drugs that increase dopamine, like amphetamines, promote wakefulness, the findings offer a potential mechanism explaining how the brain helps people stay awake despite the urge to sleep. However, the study also shows that the increase in dopamine cannot compensate for the cognitive deficits caused by sleep deprivation.
Cocaine-induced synaptic plasticity linked to persistent addictive behaviors
The persistent nature of addiction is its most devastating feature. Understanding the mechanism underlying this phenomenon is the key for designing efficient therapy. Two separate studies published by Cell Press is the August 14 issue of the journal Neuron identify specific cocaine-induced changes in dopamine (DA) neurons that play a pivotal role in behaviors associated with drug addiction.

News discussion:

Research in Medicine & Health news

[Home]   [Full version]