Abstract
The effects on ganglion celllight responses and spontaneous activity of neuro-transmitter candidates, applied by nebulizer spray and iontophoresis, were studied in the isolated carp retina. ACh, GABA, and substance P had strong effects on the ganglion cells; dopamine and the amino acids aspartate, glutamate, and glycine had only weak effects. ACh and substance P exerted their actions even when synaptic transmission was blocked by cobalt chloride, suggesting postsynaptic receptors for those agents on the ganglion cell membrane. The 3 amino acids and dopamine do not appear to act directly on the ganglion cells. The pharmacological sensitivity of ganglion cells was correlated with their physiological response type. About three-quarters of ON/OFF and half of other transiently responding ganglion cells were excited by micromolar concentrations of cholinergic agonists; most ON-center sustained ganglion cells were insensitive. The light response of some of the ACh-sensitive cells could be suppressed by cholinergic antagonists. Substance P generally excited ganglion cells with an ON-component in their light response. GABA inhibited cells of all response types, but affected least the OFF-center tonic cells. In view of these observations, and of corroborating histological evidence, we propose that ACh, GABA, and substance P are neurotransmitters that are released by amacrine cells and affect receptors located on ganglion cells.
Original language | English (US) |
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Pages (from-to) | 81-99 |
Number of pages | 19 |
Journal | Brain Research |
Volume | 234 |
Issue number | 1 |
DOIs | |
State | Published - Feb 18 1982 |
Externally published | Yes |
Keywords
- GABA
- carp ganglion cells
- carp retina
- inner plexiform circuits
- substance P
ASJC Scopus subject areas
- Neuroscience(all)
- Molecular Biology
- Clinical Neurology
- Developmental Biology