Year of Publication


Competition Category

Biological Sciences


Arts and Sciences




Previous studies have shown that adolescents raised in impoverished conditions are more likely to develop drug abuse in adulthood. In addition, both stress-inducing living conditions (impoverishment/isolation) and drugs of abuse may lead to an increase in the c-fos transcription factor in the reward circuit of the brain, particularly in the nucleus accumbens. The aim of the current study was to quantify the number of c-fos positive cells in the nucleus accumbens of enriched and isolated rats exposed to the opioid remifentanil. Thirty-two male Sprague-Dawley rats were raised in either enriched or isolated conditions for one month, after which they received 10 i.v. infusions of 3 μg/kg remifentanil or saline through the jugular vein. Eighty-five minutes after the last infusion, rats underwent perfusions. After immunohistochemistry was performed on tissue containing the nucleus accumbens, the average number of c-fos positive cells per slice was obtained using ImageJ. Using a 2x2 between subjects ANOVA, with drug and environment as factors, this research demonstrated a main effect of environment on c-fos expression in the nucleus accumbens, with isolated rats expressing more c-fos positive cells than enriched rats. However, there was no significant effect of drug treatment, suggesting that remifentanil did not increase total c-fos as expected. This study demonstrated the cellular consequences of being raised in different living conditions, as it showed that individuals raised under high levels of stress may be at risk of altered cell signaling and gene expression in the reward system of the brain.


Usman Z. Hamid won the first place in the Biological Sciences category.