Dopaminergic control of food choice preference and tVTA influence on learned helplessness

This thesis investigated a rodent model of Parkinson’s disease, with a bilateral lesion of the substantia nigra, for the presence of motor and non-motor symptoms, with the latter covering aspects related to food intake, pain, and depression. We showed that a co-lesion of the tail of the ventral tegmental area (tVTA) is sufficient to reverse these parkinsonian-like symptoms. We next studied the influence of the dopaminergic system on food choice by selectively destroying dopamine neurons and their terminals and testing the animals with a free-choice high-fat high-sugar diet. We reported an increase in fat intake with the loss of dopaminergic transmission, or the blockade of D₁ receptors, in the rostral part of the lateral nucleus accumbens. Finally, we showed an increased excitatory synaptic transmission in the tVTA associated with the development of learned helplessness in rats. Overall, this work has thus contributed to the progress of our knowledge of central dopaminergic systems’ influence on behavior, affecting motor skills, pain, food intake, and mood.