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Effect of glutamate analogues and inhibitory neurotransmitters on the electroretinograms elicited by random sequence stimuli in rabbits.

1998; National Institutes of Health; Volume: 39; Issue: 11 Linguagem: Inglês

Masayuki Horiguchi, Shiro Suzuki, Miyuki Kondo, Atsuhiro Tanikawa, Yozo Miyake,

Neuroscience and Neuropharmacology Research

To study the origin of the different components of the electroretinogram (ERG) elicited by a random binary m-sequence stimulus.Electroretinograms were recorded from pigmented rabbits before and after the injection of glutamate analogues (2-amino-4-phosphono-butyric acid [APB; DL form] and cis-2,3-piperidine-dicarboxylic acid [PDA]) and inhibitory neurotransmitters (glycine and gamma-aminobutyric acid [GABA]) to abolish the contribution of different cell types to the ERG. Two types of stimuli were used: conventional full-field stimulation with short- and long-duration flashes and a random binary m-sequence of flashes designed to mimic the pseudorandom binary m-sequence stimulation used in the multifocal ERG technique.The effects of APB and PDA on the first-order kernel of the random ERGs were similar to those on the photopic short-flash ERG. Glycine and GABA minimized the oscillatory potentials (OPs) of the photopic ERGs, and also reduced the amplitude of the positive wave of the first-order kernel slightly but caused a large reduction in the amplitude of the second-order kernel.The data suggest that the ON and OFF bipolar cells contribute significantly to the photopic short-flash ERG, as previously shown, and to the first-order kernel of the responses elicited by the pseudorandom binary sequence stimuli. The second-order kernel and the OPs receive a strong contribution from the cells of the inner retinal layers.