Pharmacological study of the chicken's monocular optokinetic nystagmus: involvement of the ON retinal channel evidenced by the glutamatergic separation of ON and OFF pathways.
The chicken's monocular optokinetic nystagmus (OKN), recorded by the magnetic search coil technique, displays a directional asymmetry, the temporal-nasal (T-N) stimulation being more efficient than the nasal-temporal (N-T) one to evoke the reflex. The intravitreal administration of APB, a glutamate agonist which selectively blocks the ON retinal channel strongly reduced the eye monocular OKN; it also induced spontaneous eye movements in the T-N direction. The intravitreal injection of PDA another glutamate analog, which reduces the OFF channel, while increasing the activity of the ON channel, induced a large increase in OKN velocity gain, especially for a N-T stimulation at the lowest drum speeds. These results indicate the main involvement of the ON retinal channel in the OKN genesis and the inhibitory effect of the OFF channel upon this oculomotor reflex.
Bonaventure
N
N
Centre de Neurochimie du CNRS, Strasbourg, France.
Kim
M S
MS
Jardon
B
B
Yücel
H
H
D000613:Aminobutyrates / Q000494:pharmacology; D000818:Animals; D002645:Chickens; D004596:Electroretinography / Q000187:drug effects; D005133:Eye Movements / Q000187:drug effects; D017120:Nystagmus, Optokinetic / Q000187:drug effects*; D010875:Pipecolic Acids / Q000494:pharmacology; D017470:Receptors, Glutamate / Q000378:metabolism*; D012160:Retina / Q000187:drug effects*; D015349:Vision, Monocular; D014795:Visual Pathways / Q000502:physiology*
D000613:Aminobutyrates; D010875:Pipecolic Acids; D017470:Receptors, Glutamate; C029262:2,3-piperidinedicarboxylic acid; C012729:2-amino-4-phosphonobutyric acid