The scientists compared gene and protein expression patterns in specific brain areas—the ventral tegmental area (VTA) and the substantia nigra—in 10 cocaine overdose victims and 11 age-matched, drug-free control subjects.
They found significant increases in glutamate receptor subunits in the VTA of the cocaine abusers. Glutamate is a neurotransmitter, a class of compounds involved in regulating cell–cell communication. It is involved in neuronal excitability and is associated with learning, memory, and synaptic plasticity.
In addition, the scientists found significant increases in CREB (cyclic AMP responsive element binding protein), a molecule that regulates gene expression and is associated with addiction and memory, in the abusers’ brains.
The scientists say this study marks the first attempt to identify molecular neuropathological markers that may be associated with cocaine addiction.
These results show that cocaine abuse can lead to significant alterations in the expression of specific genes in defined brain areas associated with addictive behavior. Identifying such molecular markers in human drug abusers broadens our understanding of the neuropathology associated with drug abuse and may help identify new biological targets for developing medications to treat addictive disorders.
The study, published by Dr. Scott Hemby and colleagues and supported by the National Institute on Drug Abuse, appeared in the May 2003 issue of the Journal of Neurochemistry.
