Scientists have been trying to understand addiction for many years.
What causes a person to repeatedly use substances that are detrimental to health, friends/family, and overall well-being? This question and more is being asked by Matt Palmatier of the ETSU Psychology Department, along with graduate student Curtis Bradley and other students at ETSU.
“With substance abuse, it is multi-faceted,” Palmatier said. “You have to have genetic predisposition, your brain has to make certain changes in response to the drug, but you also have to be in an environment where the drug is both available and easily accessible.”
Unlike drugs like heroin, cocaine and methamphetamine, nicotine does not induce intoxication, but is still one of the world’s leading addictive substances.
“Part of the reason for that is because the way nicotine primes the reward system. It makes the predictors of other rewards in your environment more salient,” Palmatier said.
This increases the driving force that environmental incentives have on behavior. Palmatier and his team are working to uncover how these incentive-promoting effects of nicotine lead to dependence.
One example of these environmental factors that has a draw on a person’s behavior may be flavors used in tobacco products.
“Menthol, or that minty taste you get in many stimuli before you ever smoke, mint chocolate chip ice cream, toothpaste, gum etc. At some point that minty flavor is going to become a conditioned reinforcer and increases your appeal and behavior for menthol,” Palmatier said.
If the prospect of mint is appealing, and nicotine is interacting and amplifying the appealing effect of menthol in the brain that may make people more likely to smoke.
To test this hypothesis, Palmatier and his team give rats the equivalent of mint candy — a solution of water, menthol and sucrose. A control group receives just mint and water. When the rats associate the mint and sucrose, the mint takes on new properties, which Palmatier describes as ‘conditioned reinforcers.’
“Conditioned reinforcers are like the smells of delicious foods, you can’t eat them, but they predict the availability of yummy foods and make it more likely that you will eat those foods,” Palmatier said.
The rats are then placed in testing boxes with sipper tubes; one contains water and the other contains unsweetened mint flavor.
“When they drink a little bit of mint, [no sugar] they also get an IV infusion of nicotine. At really low doses of nicotine, [the group that has had nicotine paired with sucrose in the past] will self-administer the nicotine, they’ll take a lot of it. If we do the same thing with the rats that have had mint not paired with sugar, then those rats will not self-administer [nicotine] at all,” Palmatier said.
Palmatier and his team are getting strong results that are helping to identify further the processes of substance abuse, what is fast becoming an epidemic.
If you are interested in this field of study, contact Palmatier at firstname.lastname@example.org. Palmatier will also be a panel judge at the Great Weed Debate at the D.P. Culp Center on April 21.