The effect of chronic sucrose consumption during adolescence on dopamine D2 receptor function in a rodent model

Sugar consumption has been suggested to alter the dopaminergic motivation-reward systems of the brain. Adolescence is a major period of development in the dopaminergic motivation-reward systems, making this system particularly vulnerable during this period, yet the consequences of chronic excess sugar consumption on dopamine receptor function during adolescence have not been thoroughly examined. This study investigated the effects of unrestricted access to sucrose solution throughout adolescence (PND35-60) on dopamine D2 receptors in the striatum, using a male rodent model. Positron emission tomography imaging using [11C]raclopride was conducted on one cohort of animals (N=12) on the final day of treatment and following a 6 week washout. Data were analysed using partial saturation analysis to give measures of functional D2 receptor density and apparent D2 receptor affinity. Mixed ANOVA found a range of significant main effects and interactions between treatment group and time in functional D2 receptor density in three rostro-caudal levels of striatum. There were no significant treatment group or time effects on apparent D2 receptor affinity. Autoradiography imaging using [3H]raclopride was conducted on a second cohort of animals (N=12), following a 10 day washout. There was no significant difference in total D2 receptor density between treatment groups in any region of interest in the striatal area. These results suggest that chronic excess sugar consumption during adolescence impacts functional, but not total, D2 receptor density in the striatum and these effects may last into adulthood.