Smoking is a well-known risk factor for subsequent alcohol abuse, but the mechanisms underlying this link are unknown.
The study conducted in rats showed that even a single exposure to nicotine temporarily changes how the brain's reward system responds to alcohol and increases the reinforcing properties of alcohol via stress hormones.
"Our findings indicate the mechanisms by which nicotine influences the neural systems associated with alcohol abuse, providing a foundation for conceptualizing strategies aimed at diminishing the link between smoking and later alcohol abuse," senior author Dr. John Dani, of the Baylor College of Medicine, said.
Dr. Dani and his team found that rats exposed to nicotine subsequently sought to drink alcohol more often than other rats.
Also, signaling in the brain's reward system was dampened when the nicotine-exposed animals consumed alcohol.
This decreased reward response to alcohol arose via two mechanisms: an initial activation of stress hormone receptors and a subsequent increase in inhibitory signaling in the brain.
These processes were responsible for causing the rats to self-administer more alcohol after nicotine exposure.
The study is published in the Cell Press journal Neuron.
--ANI (Posted on 20-07-2013)