Journal of Neuroscience, Vol 7, 319-329, Copyright © 1987 by Society for Neuroscience
An indoleamine system in photoreceptor cell terminals of the Long-Evans rat retina
DA Redburn and L Churchill
Uptake of 3H-serotonin is localized to the outer plexiform layer in
Long-Evans rat retinas. Autoradiographic accumulation is seen only after in
vitro incubation in the light, with retinas isolated from the underlying
sclera. Potassium stimulates the release of 3H-serotonin. In this species,
amacrine cells do not accumulate these compounds; thus the outer plexiform
layer appears to be the only site of uptake and release of this
indoleamine. The age-related loss of 3H-serotonin accumulation in the outer
plexiform layer of retinal dystrophic rats coincides temporally with the
spontaneous degeneration of photoreceptor cells that occurs in this
species. Electron-microscopic autoradiography of 3H-serotonin accumulation
further confirms that uptake is localized to rod and cone terminals in the
outer plexiform layer. The specific accumulation of indoleamines into rod
and cone terminals that is observed in the light but is absent in darkness
suggests that indoles have an important physiological role in
photoreceptors.