The effect of kainate on protein kinase C,GABA, and the uptake of serotonin in the rabbit retina in vivo |
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Authors: | N. N. Osborne R. J. McCord J. Wood |
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Affiliation: | (1) Nuffield Laboratory of Ophthalmology, Oxford University, OX2 6AW Oxford, UK |
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Abstract: | The purpose of this study was to investigate the effect of kainate on protein kinase C (PKC), -aminobutyrate (GABA) and serotonin uptake in the rabbit retina. Kainate when injected into the vitreous humour produces a change in the GABA immunoreactivity within 6 hours. After 3 days, remnants of the normal GABA immunoreactivity still persist and additionally astrocyte and microglia-like elements stain positively for GABA. After 7 days exposure to kainate none of the normal GABA immunoreactivity is apparent, instead a number of round-shaped elements which may be reactive astrocytes and/or microglia stain positively for GABA. During these stages kainate does not affect the PKC immunoreactivity associated with the on-bipolar cells. Six hours following kainate treatment the ability of certain GABA amacrine cells to take up exogenous serotonin is unaffected. After three days only a few of these cells can still take up exogenous serotonin and then not avidly. After seven days the GABA/serotonin amacrine cells cannot take up exogenous serotonin suggesting that all of these neurons are irreversibly damaged. One hour after treatment with kainate both calcium-dependent and-independent PKC species are translocated from the cytosolic to membrane compartments. After 5 hours and 7 days there was also evidence from the enzyme assay experiments that kainate caused the calcium-dependent and-independent PKC enzymes to be translocated but because the total enzyme activity was reduced due perhaps to down-regulation of the enzyme this was difficult to assess precisely. However, the electrophoresis/blotting experiments of tissues exposed for 5 hours (but not one hour) to kainate established clearly that , , and PKC are translocated from cytosolic and membrane compartments. |
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Keywords: | Kainate retina GABA protein kinase C |
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