Synaptic Chemistry of Identified Cells in the Vertebrate Retina

Although the structure, synaptic connections and physiological responses of the different cell types in the vertebrate retina are fairly well understood (for review, see Cajal 1972; Rodieck 1973), the synaptic chemistry, in particular the neurotransmitters used by retinal neurons, is much less well known. Many investigators have shown that certain neurotransmitter candidates, such as γ-aminobutyric acid (GABA), acetylcholine (ACh) and dopamine (DOPA), or their related enzymes, are present in the vertebrate retina (Francis 1953; Kuriyama et al. 1968; Ehinger et al. 1969; Nichols and Koelle 1969; Graham et al. 1970; Lam 1972a,b, 1975). In addition, Ames and Pollen (1969) have studied the pharmacological effects of transmitter candidates and antagonists on the responses of retinal ganglion cells.