This article is only available in the PDF format. Download the PDF to view the article, as well as its associated figures and tables.
Neurons containing dopamine were first demonstrated in the retina more than 25 years ago, and since then a vast amount of research has been carried out on the role of dopamine and dopaminergic neurons in the visual system. Of 15 to 20 neuroactive substances thought to be released from synaptic sites in the retina, dopamine is now one of the best characterized.
Over the years, our view of the role of dopamine in the retina has changed substantially. Originally it was thought that dopamine, like L-glutamate, acetylcholine, γ-aminobutyric acid, and glycine (other, well-characterized, neuroactive substances found in the retina) served as a retinal neurotransmitter, acting directly on retinal cell membranes to alter membrane potential or resistance. More than a decade ago, evidence was provided that a number of neuroactive substances released from synaptic sites in the brain interact with membrance receptors linked to intracellular enzyme systems. These enzyme systems usually
Dowling J. Neurology and Neurobiology. Arch Ophthalmol. 1990;108(8):1080. doi:10.1001/archopht.1990.01070100036025