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SM Lima, VR C Nunes, LC L Silveira, DS F Ventura; Identification of Retinal Bipolar Cells by Protein Kinase C-Like Immunoreactivity in a Tropical Fish (Hoplias malabaricus) . Invest. Ophthalmol. Vis. Sci. 2002;43(13):743.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: In fish retina, bipolar cells have multiple morphological subtypes that receive mixed inputs from both rods and cones or cone bipolar cells that receive input only from cone(Sherry, DM & Yazulla S, J Comp Neurol 329:188-200, 1990). In mammals, monoclonal antibody against protein kinase C (PKC) has been used as a marker for rod-dominant on-bipolar cells. The goal of our study is to examine which bipolar cells could be identified by PKC-like immunoreactivity, estimate their density and synaptic target at inner plexiform layer. Methods: Experiments were performed on adult thrairas, Hoplias malabaricus, fixed with 4% paraformaldehyde in 0.1M phosphate buffer. Retinal vertical sections and wholemounts were labeled by anti-PKC immunocytochemistry and revealed with avidin-biotin peroxidase method. Bipolar cells were identified, and the morphology and size of their cell bodies and axon terminals were evaluated. Results: Two bipolar cell classes were identified both in wholemounts and vertical sections. One class was heavily stained, had somas in the upper portion of the inner nuclear layer (INL), large bulbous axon terminals in the "b" sublayer of the INL (17,3 2,1µm in diameter), and its morphology corresponds to rod-dominated on-bipolar cells of other fishes. Another class was weakly stained, had somas located slightly vitread to the former class, smaller axon terminals in the "b" sublayer of the INL (12,7 1,7 µm in diameter) and its morphology corresponds to cone-dominated on-bipolar cells. The estimated PKC immunoreactive cell density was 1921 cell/mm2 and few appendages were attached to both types of axon terminals. No immunoreactivity was found in the IPL sublamina "a". Conclusion: Anti-PKC immunoreactivity could be an useful bipolar cell marker in fishes. We are planning to use this technique to quantify the effects of mercury contamination in the Amazon basin on the visual system.
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