Dopaminergic regulation of cone retinomotor movement in isolated teleost retinas. 1. Induction of cone contraction is mediated by D2 receptors

In the retinas of lower vertebrates, retinal photoreceptors and melanin pigment granules of the retinal pigment epithelium (RPE) undergo characteristic movements in response to changes in light intensity and to signals from an endogenous circadian clock. To identify agents responsible for mediating light and/or circadian regulation of these retinomotor movement, the authors investigated the effects of hormones and neurotransmitters on cone, rod, and RPE movements in the green sunfish, Lepomis cyanellus . Its reported that 3,4-dihydroxyphenylethylamine (dopamine) mimics the effect of light by inducing light-adaptive retinomotor movements in all three cell types. Together the results inducate that dopamine indices light-adaptive retinomotor movements in cones, rods, and RPE cells by activating D2 receptors.