Adolescent, Adult Rats Respond Differently to Nicotine and Nicotine Related Environments

One critical aspect of drug addiction is the effect of conditioned cues on drug-seeking behavior. Scientists at the University of Wisconsin-Madison have reported that adolescent and adult rats exhibit different behaviors in response to nicotine and nicotine-related environments, suggesting there are molecular differences in adolescent and adult rat brains.


The researchers examined how injections of nicotine stimulated movement in rats. Over 10 days, the scientists injected nicotine or saline into 16 adolescent and 16 young adult male rats. Immediately following the injections, they placed the rats in plastic chambers and observed their movements for 90 minutes.


The stimulant properties of nicotine caused rats in both groups to walk or run more, but the drug had a greater overall effect on adults. It also significantly increased rearing (standing on hind legs), a sign of curiosity and exploring,


in adults. But the scientists' key finding was that adolescent rats, when re-exposed to the plastic chamber following a saline injection, failed to show any enhanced motor activity in the absence of nicotine. The adult rats, on the other hand, did exhibit drug-induced cue conditioning as evidenced by increased movement in the drug-paired environment following a saline injection. The scientists speculate that the drug-associated conditioning seen in adult rats is associated with specific brain regions and circuitry that may not be mature in adolescent rats.


WHAT IT MEANS: These findings are an important step toward understanding the biological effects of nicotine on the adolescent brain, and suggest that plasticity-the ability of the brain to form new connections between nerve cells, a process that occurs predominantly during youth-may be partly responsible for differences between adolescents and adults regarding drug-seeking behaviors. This study implies that the development of brain systems involved in drug abuse may begin in adolescence.


Lead author Terri Schochet and her colleagues published this NIDA-supported study in the online version of the April 2004 issue of Psychopharmacology.


This article comes from this PDF file


National Institute of Drug Abuse Addiction Research News


For more information contact:


Reporters, call Michelle Person at 301-443-6245.


Congressional staffers, call Mary Mayhew at 301-443-6071.


The National Institute on Drug Abuse (NIDA) is a component of the National Institutes of Health, U.S. Department of Health and Human Services. NIDA supports more than 85 percent of the world's research on the health aspects of drug abuse and addiction. The Institute carries out a large variety of programs to ensure the rapid dissemination of research information and its implementation in policy and practice. Fact sheets on the health effects of drugs of abuse and other topics are available in English and Spanish. These fact sheets and further information on NIDA research and other activities can be found on the NIDA home page at drugabuse.