The coexistence of three neuroactive substances in amacrine cells of the chicken retina.

For the first time in the vertebrate retina, we have demonstrated that 3 neuroactive substances coexist in a single neuron. Using immunofluorescence, immunoperoxidase, and autoradiographic techniques, we found a subpopulation of amacrine cells in the chicken retina exhibited enkephalin- and neurotensin-like immunoreactivity and high-affinity uptake of glycine. Biochemical evidence showed that glycine release in this retina is inhibited by enkephalin and enhanced by neurotensin1.14. It is therefore possible that the two peptides form a push-pull system in self-regulating the glycine release from retinal amacrine cells.