The Journal of Neuroscience, April 1, 2003, 23(7):2872
Demonstration of Cholinergic Ganglion Cells in Rat Retina:
Expression of an Alternative Splice Variant of Choline
Acetyltransferase
Osamu
Yasuhara,
Ikuo
Tooyama,
Yoshinari
Aimi,
Jean-Pierre
Bellier,
Tadashi
Hisano,
Akinori
Matsuo,
Masami
Park, and
Hiroshi
Kimura
Molecular Neuroscience Research Center, Shiga University of Medical
Science, Otsu 520-2192, Japan
Acetylcholine acts as a neurotransmitter in the retina. Although
previous physiological studies have indicated that some retinal ganglion cells may be cholinergic, several immunohistochemical studies
using antibodies to choline acetyltransferase (ChAT) have stained only
amacrine cells but not ganglion cells. Recently, we identified a splice
variant of ChAT mRNA, lacking exons 6-9, in rat peripheral nervous
system. The encoded protein was designated as ChAT of a peripheral type
(pChAT), against which an antiserum was raised. In the present study,
we examined expression of pChAT in rat retina, both at the protein
level by immunohistochemistry using the antiserum and at the mRNA level
by RT-PCR. Immunohistochemistry revealed that although no
positive neurons were found in untreated intact retinas, many neurons
became immunoreactive for pChAT after intravitreal injection of
colchicine. Damage of the optic nerve was also effective in disclosing
positive cells. Such positive neurons were shown to be ganglion cells
by double labeling with a retrograde tracer that had been injected into
the contralateral superior colliculus. Western blot analysis and RT-PCR
revealed a corresponding band to the pChAT protein and to the amplified pChAT gene fragment, respectively, in retinal samples. In addition, ChAT activity was definitely detected in retinofugal fibers of the
optic nerve. These results indicate the presence of cholinergic ganglion cells in rat retina.
Key words:
retinal ganglion cells; immunohistochemistry; RT-PCR; neurotransmitter; alternative splicing; cholinergic
transmission
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