Journal of Neuroscience, Vol 4, 1271-1280, Copyright © 1984 by Society for Neuroscience
Regulatory effect of dopamine on spatial properties of horizontal cells in carp retina
T Teranishi, K Negishi and S Kato
Three types of light-induced response (L-, RG-, and YRB -type S-
potentials) recorded from isolated retinas of the carp (Cyprinus carpio)
were identified by their spectral response and later by morphological
localization of the recording sites marked with an intracellular Lucifer
Yellow (LY). Horizontal cells in a given layer, generating one of the above
response types, are electrically coupled via gap junctions, so that the
injected LY normally diffused to several neighboring cells. The spatial
property of the three types of responses was examined by enlarging the
diameter of a light spot (0.25 to 4.0 mm) and displacing the spot (0.5 mm
diameter) along a straight 4-mm line which passed over the recording point
at the middle. In normal retinas, the half-decay distance of response
amplitude with spot displacement was shorter in the order of L-, RG-, and
YRB -type responses, and correspondingly the dye diffusion area was
narrower in the same order of cells. Dopamine (DA; 10 to 20 microM),
applied to the vitreous fluid beneath the isolated retina, altered the
spatial property of all types of responses by increasing the amplitude of
responses to central spots and decreasing that of those to distant spots,
and it restricted the intracellular LY to single injected cells. In
contrast, in retinas from which DA interplexiform cells had been deprived
by prior destruction with a neurotoxin, 6-hydroxydopamine, the amplitude of
responses became smaller while the half-decay distance was longer by 1.1-
to 1.6-fold, depending upon the cell type, and the dye diffusion area in
all types of cells became wider by 2-fold as compared to those in normal
retinas.(ABSTRACT TRUNCATED AT 250 WORDS)
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