Modulation of the release of [ 3H]-dopamine elicited by electrical stimulation in the turtle retina

Abstract

1. We have studied the action of dopaminergic agents on the release of [ 3H]-dopamine, evoked by electrical stimulation in the superfused preparation of the retina of the swamp turtle Pseudemys scripta elegans. 2. The release of radioactivity was not reduced by D2 agonists per se, but it was decreased by the mixed D1/D2 agonist, apomorphine, and by simultaneous application of a D1 and a D2 agonist. It was increased by a D2 antagonist, by a D1 antagonist or by a mixed D1/D2 antagonist. 3. These findings suggest that a negative feedback control of dopamine release could exist in turtle retina and, in contrast to the rabbit retina where it involves D2 receptors alone, it would require the coactivation of both D2 and D1 receptors.