AUSTIN, Texas—Brain cells and corresponding brain circuits critical to the development and treatment of addiction have been identified by two members of the Institute for Neuroscience at The University of Texas at Austin.
The team of Dr. Adriana A. Alcantara, professor of psychology and neuroscience, and Monica L. Berlanga, Ph.D. candidate in the Institute for Neuroscience, investigated the nucleus accumbens; an area of the brain associated with pleasure and addiction, and took their research a step further by investigating addiction at the level of a single neuron.
A self-administered cocaine study conducted in rats, performed in collaboration with Dr. Christine Duvauchelle’s laboratory in the College of Pharmacy, allowed the researchers to examine acute, chronic and withdrawal scenarios. By labeling specific proteins in the brain, the team discovered that the cells of the brain called cholinergic interneurons were activated following the first exposure to cocaine. Furthermore, the more cocaine that rats self-administered, the more the neurons were activated, linking these specific cells to addiction.
“These neurons have previously been demonstrated to be involved in learning, which may be an important and possibly essential component of addiction,” Alcantara said. “Learning causes synaptic rewiring both in developing brains and in adult brains. Similarly, rewiring may also be occurring within these neuronal brain circuits during addiction. Once the connections associated with impulsivity or drug- seeking behavior or with the pleasure associated with the drug have been established, these connections, much like long-term memories, may never go away.
“These neurons serve as an interface between the nucleus accumbens, which is involved in reward and pleasure, and the prefrontal cortex, which is the area of the brain involved in higher order decision-making processes,” Alcantara added. “It is possible that during the development of addiction, the rewiring of these neurons may reinforce high-risk impulsive behavior or interfere with the vital decision-making processes involved in the inhibition of these behaviors. Remarkably, however, these neurons may also have the capacity to play a key role in the attenuation or prevention of drug addiction.”
These findings may provide insight into the brain circuits that should be targeted by pharmaceutical and behavioral prevention programs designed for the treatment of drug abuse and addiction. Their work also provides insight into other types of addiction and related brain disorders such as obsessive-compulsive disorder and schizophrenia.
The next stage of research will be to examine the neuroadaptive and long-term changes that accompany chronic abuse of cocaine and withdrawal from cocaine. Emphasis will be on receptor expression and synaptic structural changes that occur within these cholinergic neuronal microcircuits, which ultimately may shed light on such phenomena as craving and relapse.
Alcantara and Berlanga will present their research findings Nov. 2-7 at the Society for Neuroscience’s 2002 annual meeting in Orlando, Fla.
For more information contact: Michelle Bryant, College of Liberal Arts, 512-232-4730.