Characterization of Green Fluorescent Protein Expression in the Retina of the GAD67–GFP Knock–in Mouse

Abstract

Abstract: : Purpose: To study the morphology and distribution of green fluorescence protein (GFP) in the retina of the newly established GAD67–GFP knock–in mouse, a model to study GABA–ergic neurons. Methods: The eyes of adult GAD67–GFP knock–in mice were investigated by light– and electron microscopy. Whole mounts of the retina were prepared and the distribution of GFP–positive neurons quantified. Results: Most animals showed a well developed retina. Mild focal changes were located in the photo receptor layers. GFP was expressed in neurons that distributed evenly throughout the retina. Displaced amacrine cells in the GCL showed a density of 1006 ±170 cells/mm². In the INL, the density of amacrine cells in the central region was 8821 ±448 cells/mm², in the peripheral region 6825 ±408 cells/mm². Two laminae in the IPL showed intense GFP fluorescence. GFP fluorescence was also detected in some bipolar cells and in the photoreceptor cells and inner segments. Conclusions: The distribution and cytoarchitecture of GABA–ergic amacrine and displaced amacrine cells in the mouse retina shows similarities to other species. The presence of GAD67 in special regions of the photoreceptors is new. The potential role of GABA in connection with the photo receptors has to be further studied.

Keywords: amacrine cells • retina: neurochemistry • microscopy: light/fluorescence/immunohistochemistry