Effects of apomorphine on the rabbit electroretinogram.

Experiments were conducted in both albino and pigmented rabbits to determine the effects of apomorphine on the electroretinogram (ERG). Injection of apomorphine (0.1 to 1.5 mg/kg) into the left carotid artery produced dose-related decreases in the b-wave, predominantly in the b2-wave amplitude, and also increases in the c-wave amplitude. No significant changes were observed in the a-wave amplitude or in the attendant latencies. The ERG changes apparently were not related to systemic drug effects. The effects of the drug were similar for both albino and pigmented rabbits. Apomorphine, a dopamine agonist, has the opposite effect on the b2-wave of the ERG when compared with the effect of chlorpromazine, a dopamine antagonist. Involvement of dopamine receptors is not unexpected, since the retina is rich in dopamine, especially in the inner plexiform layer.