Forskning
October 30, 2014
Effects of adolescence caffeine consumption on cocaine sensitivity
C E O’Neill et al, 2014, Effects of adolescence caffeine consumption on cocaine sensitivity, Neuropsychopharmacology, published online ahead of print.
Abstract: Caffeine is the most commonly used psychoactive substance, and consumption by adolescents has risen dramatically in recent years. We identified the effects of adolescent caffeine consumption on cocaine sensitivity and determine neurobiological changes within the nucleus accumbens (NAc) that may underlie caffeine-induced hypersensitivity to cocaine. Male Sprague-Dawley rats consumed caffeine (0.3 g/L) or water for 28 days during adolescence (postnatal day 28-55; P28-P55) or adulthood (P67-P94). Testing occurred in the absence of caffeine during adulthood (P62-82 or P101-121). Cocaine-induced and quinpirole (D2 receptor agonist)-induced locomotion was enhanced in rats that consumed caffeine during adolescence. Adolescent consumption of caffeine also enhanced the development of a conditioned place preference at a sub-threshold dose of cocaine (7.5 mg/kg, i.p.). These behavioral changes were not observed in adults consuming caffeine for an equivalent period of time. Sucrose preferences were not altered in rats that consumed caffeine during adolescence suggesting there are not differences in natural reward. Caffeine consumption during adolescence reduced basal dopamine levels and augmented dopamine release in the NAc in response to cocaine (5 mg/kg, i.p.). Caffeine consumption during adolescence also increased the expression of the dopamine D2 receptor, dopamine transporter, adenosine A1 receptor, and decreased adenosine A2 A receptor expression in the NAc. Consumption of caffeine during adulthood increased adenosine A1 receptor expression in the NAc, but no other protein expression changes were observed. Together these findings suggest that caffeine consumption during adolescence produced changes in the NAc that are evident in adulthood and may contribute to increases in cocaine-mediated behaviors.
