TALLAHASSEE, Fla., Jan. 29 (UPI) -- Florida State University researchers said nicotine exposure early in life can have long-term neurobiological consequences evidenced in mood disorders.
The researchers injected adolescent rats twice daily with either nicotine or saline for 15 days and later subjected the rats to several experiments involving stressful situations and pleasurable ones.
Study leader Carlos Bolanos said that behavioral changes symptomatic of depression can emerge after one week of nicotine cessation and -- most surprising -- that even a single day of nicotine exposure during adolescence can have long-lasting effects.
"Some of the animals in our study were exposed to nicotine once and never saw the drug again," Bolanos said in a statement. "It was surprising to us to discover that a single day of nicotine exposure could potentially have such long-term negative consequences."
The study, published online in the journal Neuropsychopharmacology, found the rats exposed to nicotine engaged in behaviors symptomatic of depression and anxiety such as repetitive grooming, decreased consumption of rewards and becoming immobile in stressful situations instead of engaging in typical escape-like behaviors. The researchers were able to alleviate the rats' symptoms with antidepressant drugs, or more nicotine.
However, adult rodents exposed to the same nicotine regimen as the adolescents did not display depression-like traits.
The researchers suggest the findings may also be true for humans.