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GABA as a potential transmitter in lizard photoreceptors: Immunocytochemical and biochemical evidence
Author(s) -
Engbretson Gustav A.,
Anderson Kathy J.,
Wu JangYen
Publication year - 1988
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.902780314
Subject(s) - biology , lizard , glutamate decarboxylase , glutamate receptor , immunocytochemistry , retina , population , neurotransmitter , retinal , gamma aminobutyric acid , anatomy , receptor , microbiology and biotechnology , neuroscience , endocrinology , biochemistry , zoology , enzyme , demography , sociology
The retina of the desert night lizard, Xantusia vigilis , was examined for immunoreactivity to antibodies against γ‐aminobutyric acid and L‐glutamate decarboxylase. At the electron microscopic level it was found that a distinct population of the photoreceptor cells was immunoreactive to both antibodies. Computer‐assisted reconstruction of serial sections positively identified the immunoreactive receptors as cones. These cones constituted 15% of the photoreceptors in the retinal sections, and they were morphologically distinct. The mean diameter of the labeled cone synaptic pedicles was 5.8 μm whereas that of the unlabeled pedicles was 7.9 μm, a statistically significant difference. L‐glutamate decarboxylase was extracted from the lizard brain, positively identified radiometrically, and shown by immuno‐diffusion to crossreact with the antibody used for localization. The authors suggest that the immunoreactive cones synthesize and accumulate γ‐aminobutyric acid. Whether or not it is used by those cones as a neurotransmitter should be tested directly.