Scientists from the Scripps Research Institute (USA) have identified a brain pathway that regulates how vulnerable an individual is to the addictive properties of nicotine . The finding, published online by the journal Nature , could lead to new treatments for smoking cessation .
Specifically, researchers have found that nicotine stimulates the alpha-5 subunit of receptors present in large quantities in the brain in the habenulo-interpeduncular tract , a bundle of nerve fibers known to suppress reward signals. When activated, it induces the urge to consume nicotine .
Working with rodents, the scientists, led by Paul Kenny, have shown that altering receptor levels in the habenulo-interpeduncular tract changes the amount of nicotine that animals consume. Specifically, rodents that had this altered mechanism could consume much higher concentrations of nicotine, which normal animals find unpleasant and avoid.
The study could offer an explanation of why a genetic variation in the gene that encodes the alpha-5 subunit in humans increases vulnerability to tobacco addiction , making us more prone to developing lung cancer and chronic obstructive pulmonary disease, two associated pathologies to the habit of smoking.
