By Merritt McKinney
NEW YORK, Sep 15 (Reuters Health) -- A protein that accumulates in the brain when mice repeatedly use cocaine may help explain the biological causes of addiction, according to US researchers. Learning how to block the buildup of the protein may lead to the development of new ways to treat addiction to cocaine and other drugs, the team suggests.
When mice are given cocaine occasionally, their brains produce high levels of certain proteins called Fos transcription factors, according to Dr. Eric J. Nestler, of Yale University School of Medicine in New Haven, Connecticut. However, when mice are repeatedly exposed to cocaine, their brains do not produce these proteins, according to the report by Nestler and colleagues published in the September 16th issue of the journal Nature. Instead, the brain accumulates another protein called delta-FosB.
"What we found is that chronic exposure to cocaine... can cause one particular protein in the brain to accumulate," Nestler told Reuters Health in an interview. "Once it's induced, it stays around for a long time," he said.
In the study, animals who accumulated high levels of delta-FosB were more likely to perform tasks for which they would be rewarded cocaine. In addition, the animals tended to have a greater response to the effects of cocaine, the researchers note.
The results indicate that the accumulation of the protein may trigger changes in the brain that "increase sensitivity to cocaine and thereby contribute to the development of cocaine addiction," Nestler and his colleagues conclude. "We see delta-FosB as part of the molecular switch" for addiction to cocaine and other drugs, Nestler said in the interview.
The research shows that "addicts are battling very powerful biological forces," Nestler said. "We all know that treatments for addiction are very inadequate," he said.
A medication that prevents the protein from accumulating or somehow blocks its consequences may be an effective treatment for addiction, he explained. Such an anti-addiction drug, when used in combination with psychological treatment, might help some addicts stop using cocaine and other drugs, he explained.
"We do want to figure out a way to block delta-FosB" to prevent addiction, he said. However, Nestler pointed out that developing treatments based on his team's findings may take years.
