By targeting specific cells of the central nervous system, the effects of amphetamines can be reduced and more targeted treatment of drug addicts can be developed.
Dopamine (DA) is a neurotransmitter, a biochemical molecule that enables communication within the nervous system, and one of the molecules that directly influence behavior. Dopamine is one of the most important reward molecules in the brain and is linked to addiction-related disorders. Here, researchers have looked at the role of amphetamines, which have been classified as narcotics since 1967. According to their study published in the journal Neuron on 15th January, which focuses on the calcium signaling of astrocytes the glial cells of the central nervous system, the behavioral effects of amphetamines can be reduced. Ultimately, this discovery could make it possible to develop more targeted treatments for drug addiction.
Michelle Corkrum from the University of Minnesota (USA) and her colleagues, working with mice, discovered that amphetamines, which are known to increase dopamine, have effects on astrocytes. Traditionally regarded as brain support cells and ignored in terms of their active contribution to brain function, they can indeed play an important role in information processing.
Specifically, astrocytes respond to dopamine, and thus amphetamine, by increasing the calcium in the nucleus accumbens, one of the brain’s most important reward centers. By reducing their activity, the behavioral effect of amphetamines in mice decreased, the researchers found.
“These findings suggest that astrocytes contribute to amphetamine signaling, dopamine signaling and overall reward signaling in the brain,” said Michelle Corkrum. As a result, astrocytes are a potentially new type of cell that can be specifically targeted to develop effective therapies for diseases with deregulated dopamine, she continued.
Based on these findings, she plans to continue this research by studying what happens with repeated exposure, withdrawal and reintegration of amphetamine. She is also interested in understanding how the stage of addiction or disease can affect the need to increase or decrease astrocyte activity.
The importance of conditioning
Scientists are often interested in the role of dopamine to better understand addiction symptoms. Some users cannot stop using the drug because of this neurotransmitter. Psychoactive substances release dopamine, which activates various interconnected brain regions (the reward cycle). This release of dopamine creates an influx of pleasure, and in return for this pleasure, the substance will prompt the brain to continue using it. In the dependent person, this system is deregulated so the absence of the stimulating substance leads to craving.
In drug addicts stimuli regularly associated with use, such as a ritual time or place, can activate the release of dopamine even before the substance is taken which often leads to the development of psychological dependence.
12.3 million Americans, or about 5% of the adult population, have used amphetamines at least one time in their lives and about 600.000 are habitual users. 42% of those admitted to emergency rooms for amphetamine related issues are women.