Neonatal thermal lesions of the mesolimbocortical dopaminergic projection decrease food-hoarding behavior.

In order to examine the effect of neonatal depletion of the dopaminergic mesocortical projection on the development of prefrontal cortex-mediated behaviors, male and female adult rats with neonatally applied thermal lesions of the dopaminergic A10 cell group in the ventral tegmental area were studied in a food-hoarding situation. Control male animals hoarded significantly more pellets than females. Neonatal depletion of dopamine in the prefrontal cortex strongly decreased food-hoarding activity in contrast with previous studies by others which have shown that neonatal lesions of the prefrontal cortex allow sparing of food-hoarding activity. Biochemical analysis demonstrated an approximately 50% depletion of both dopamine and serotonin in the prefrontal cortex of males, whereas noradrenaline levels were unchanged. The brains of the female rats were used to visualize the decreased dopaminergic and serotonergic innervation of the forebrain. Hoarding scores showed a significant positive correlation with the measured dopamine content of the medial prefrontal cortex, and not with the serotonin content. These results imply that the integrity of the dopaminergic projection to the prefrontal cortex is essential for food-hoarding behavior to occur and that food-hoarding activity is not spared after neonatal depletion of dopamine.