Selective dopaminergic lesions of the ventral tegmental area impair preference for sucrose but not for male sexual pheromones in female mice

Abstract

The role of the meso-accumbens dopaminergic pathway in reward-related behaviours is the subject of intense investigation. In this regard, here we analyse the effects of specific lesions of dopaminergic cells of the ventral tegmental area (VTA) of female mice on two goal-directed behaviours, namely sucrose preference (intake of sucrose solution vs. water) and preference for male sexual pheromones (exploration of male-soiled vs. clean bedding). The results indicate that partial lesions of the VTA that impair neither locomotion nor general exploratory behaviour reduce the preference for sucrose (over a 48-h period) but do not alter the innate attraction that females display for male sexual pheromones (in 5-min tests). This differential effect of the lesions can be interpreted as demonstrating the existence of separate neural mechanisms and circuits for signalling the reward of different natural reinforcers (e.g. sweet taste of sucrose and sexual pheromones). Alternatively, VTA lesions may result in an impaired attribution of incentive salience (which depends on the dopaminergic tegmento-striatal system) of sucrose-predicting cues, thus leading to a long-term decrease in sucrose consumption. By contrast, the same lesions do not affect the unconditioned attraction to male-derived pheromones, which may depend on amygdalo-striatal pathways.