Cocaine poisons reward cells in brain
By Dipali Pathak
Fewer dopamine-producing cells in the brains of cocaine users demonstrates that the drug has a toxic effect on these so-called reward cells, said experts at Baylor College of Medicine in Houston in a recent in the journal Psychiatry Research.
"Although we have always known that cocaine is a dangerous drug, for the first time we can now physically see that dopamine cells are lost in the brains of cocaine users," said Karley Little, M.D., associate professor in the Menninger Department of Psychiatry and Behavioral Sciences at BCM.
Brain tissue studies
He and his colleagues studied brain tissue taken from people who had died. They examined the tissue microscopically, comparing the number of dopamine cells in the brains of 10 cocaine users to those in the brains of nine people matched for age who did not use the drug.
They found 16 percent fewer dopamine cells in the brains of cocaine users. Their studies indicated that the loss was recent, and they also determined that the people were not born with fewer such cells.
Dopamine and pleasure
"Dopamine plays a big role in the awareness of pleasurable things in the environment, including food and sex," said Little, also a staff psychiatrist at the Michael E. DeBakey Veterans Affairs Medical Center in Houston. "The lack of dopamine cells may make a person less responsive to natural rewards, whether it’s in the workplace or in a relationship."
Dopamine is a neurotransmitter produced in several areas of the brain. Like all neurotransmitters, it aids in the transmission of messages from one cell to another.
Lack of cells
The lack of dopamine cells could also lead to withdrawal or depression symptoms, said Little.
He said that the effects of cocaine use vary among users. However, his study indicates the dangers associated with the drug’s use.
Creating models of understanding
"This is just the beginning of the story. We can now create a model to understand the biochemistry involved, such as how cocaine is toxic and why it is more toxic in some than others," said Little.
Previous work by Little indicated that dopamine uptake is increased by cocaine exposure in the same individuals, which might have contributed to the toxic effects.
Others who participated in the study include Eric Ramssen, Ryan Welchko, Vitaly Volberg, Courtney J. Roland and Bader Cassin of the University of Michigan.
Funding for this work came from the National Institute of Drug Abuse.
