January 31, 2011

Possible Genetic Nicotine Addiction Trigger Isolated

Experts at the Scripps Research Institute campus in Florida have found a genetic mechanism that controls nicotine addiction in the brain--a discovery which could open the door for more effective smoking cessation aids.

Lead researcher Paul Kenny, an associate professor with Scripps Research, and colleagues analyzed protein molecules known as nicotinic acetylcholine receptors, or nAChRs. Specifically, they were looking at nAChRs that contained a specific subunit, ÃŽ±5, in order to determine what role it played in the regulation of nicotine consumption, the organization said in a Sunday press release.

They discovered first that mice that were genetically altered to lack the subunit were more likely to consume higher quantities of nicotine than regular mice. When those mice were re-altered back to normal status, their nicotine consumption habits returned to a normal range, and those with decreased ÃŽ±5* nAChRs were reported to be "more aggressive in seeking higher doses of nicotine" than their unaltered, more restrained counterparts.

"The scientists then worked out the biochemical mechanisms through which ÃŽ±5* nAChRs operate in the medial habenula to control the addictive properties of nicotine," the Scripps Research press release said. "They found that ÃŽ±5* nAChRs regulate just how responsive the habenula is to nicotine, and that the habenula is involved in some of the negative responses to nicotine consumption. So when ÃŽ±5* nAChRs do not function properly, the habenula is less responsive to nicotine and much more of the drug can be consumed without negative feedback from the brain."

The study was published Sunday in the online edition of the journal Nature.

"We believe that these new data establish a new framework for understanding the motivational drives in nicotine consumption and also the brain pathways that regulate vulnerability to tobacco addiction," Kenny said in a statement. "These findings also point to a promising target for the development of potential anti-smoking therapies."


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