Protracted motivational dopamine-related deficits following adolescence sugar overconsumption.
Neuropharmacology. 2018-02-01; 129: 16-25
DOI: 10.1016/j.neuropharm.2017.11.021
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Adolescence represents a critical period characterized by major neurobiological
changes. Chronic stimulation of the reward system during adolescence might
constitute an important factor of vulnerability to pathological development.
Increasing evidences suggest that adolescent overconsumption of sweet palatable
foods impact reward-based processes. However, the neurobiological bases of these
deficits remain poorly understood. Previous studies have demonstrated
motivational deficits for palatable foods after sweet diet exposure during
adolescence that might involve the dopamine (DA) system, a central actor in
incentive processes. In the present study, the impact of adolescent sugar
overconsumption on the sensitivity of the DA system was tested using
pharmacological (Experiment 1) and receptor expression approaches (Experiment 2).
Adolescent rats received free and continuous access to 5% sucrose solution from
post-natal day 30-46. At adulthood, the functionality of the DA system in
motivational processes was tested using systemic injections of specific DA
receptors D1R or D2R agonists and antagonists during a motivation-dependent
progressive ratio task (Experiment 1). Sucrose-exposed rats showed a lower
motivation for saccharin and a decreased sensitivity to the effects of both D1R
and D2R stimulation and blockade. In Experiment 2, Sucrose-exposed animals
presented a lower expression of both D1R and D2R in the nucleus accumbens, a
central brain region for incentive processes, but not in dorsal striatum or
prefrontal cortex. These findings highlight the impact of sucrose overconsumption
during adolescence on DA system that may support deficits in reward-related
disorders.