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- Title
Neurotransmitter actions on transient amacrine and ganglion cells of the turtle retina.
- Authors
Jozsef Vigh; Paul Witkovsky
- Abstract
We obtained intracellular recordings from transient, OnOff amacrine and ganglion cells of the turtle retina. We tested the ability of neurotransmitter agonists and antagonists to modify the responses to light stimuli. The metabotropic glutamate agonist, 2-amino-phosphonobutyric acid (APB), selectively blocked On responses, whereas the amino-3-hydroxy-5-methylisoxazole-4-proprionic acid (AMPA) receptor antagonist, GYKI, blocked both On and Off responses. Although GYKI appeared to block excitation completely, suggesting an absence of N-methyl-d-aspartate (NMDA)-mediated responses, it was found that in the presence of ionotropic gamma-aminobutyric acid (GABA) blockers, the excitatory postsynaptic potential (EPSP) was prolonged. The late component of the EPSP was blocked by the NMDA antagonist, D-2-amino-5-phosphopentanoic acid (D-AP5). Picrotoxin (PTX) and bicuculline (BCC) induced a mean hyperpolarization of -6.4 mV, suggesting a direct effect of GABA on transient amacrine and ganglion cells, since antagonism of a GABA-mediated inhibition of release of glutamate by bipolars would depolarize third-order neurons. The acetylcholine agonist, carbachol, or the nicotinic agonist, epibatidine, depolarized all OnOff neurons. This action was blocked by d-tubocurarine. Cholinergic inputs to OnOff neurons increase their excitability without altering the pattern of light responsiveness.
- Subjects
RETINAL ganglion cells; RETINA cytology; TURTLES; NEUROTRANSMITTERS; NEURONS
- Publication
Visual Neuroscience, 2004, Vol 21, Issue 1, p1
- ISSN
0952-5238
- Publication type
Article
- DOI
10.1017/s095252380404101x