Voluntary exercise improves performance of a discrimination task through effects on the striatal dopamine system

Abstract

We have previously demonstrated that voluntary exercise facilitates discrimination learning in a modified T-maze. There is evidence implicating the dorsolateral striatum (DLS) as the substrate for this task. The present experiments examined whether changes in DLS dopamine receptors might underlie the exercise-associated facilitation. Infusing a D1R antagonist into the DLS prior to discrimination learning facilitated the performance of nonexercising rats but not exercising rats. Infusing a D2R antagonist impaired the performance of exercising rats but not nonexercising rats. Exercise-associated facilitation of this task may rely on an exercise-induced decrease in D1R and increase in D2R activation in the DLS.

© 2014 Eddy et al.; Published by Cold Spring Harbor Laboratory Press.

Figures

Figure 1.

Cannulae placements for Experiments 1 and 2. Numbers on the right go from anterior to bregma (top) to posterior to bregma (bottom). Note that the number of dots does not necessarily represent the total number of cannulae, as there was overlap in several of the placements. (Adapted from Paxinos and Watson [2007] with permission from Elsevier © 2007.)

Figure 2.

Trials to a criterion of eight consecutive correct arm choices in rats receiving intra-DLS D1R antagonist or vehicle infusions (A) or D2R antagonist or vehicle infusions (B) immediately prior to testing. In the saline-infused groups, exercisers reached criterion in fewer trials than nonexercisers. In the D1R antagonist-infused groups, exercisers showed no effect of infusion, while nonexercising rats receiving antagonist showed improved performance. In the D2R antagonist-infused groups, nonexercisers showed no effect of infusion, while exercising rats receiving antagonist showed impaired performance.

Figure 3.

Time per trial in rats receiving intradorsolateral striatum D1R antagonist or vehicle infusions (A) or D2R antagonist or vehicle infusions (B) immediately prior to testing. Dorsolateral striatum D1R antagonist infusion slowed performance in exercise and nonexercise groups. Dorsolateral striatum D2R antagonist infusion did not result in any apparent motor effects.