Abstract
Abstract: :
Purpose: We have produced transgenic mice expressing human aldose reductase (HAR) under control of the smooth muscle alpha actin (SMAA) promoter to study the effects of polyol accumulation on vessels. Unexpectedly, in addition to vascular cells, HAR is highly expressed in a subset of neuronal cells in inner nuclear layer (INL) of SMAA-HAR retinas. In this study, we have investigated the identity of these neurons. Methods: Transgenic mice expressing HAR under control of the smooth muscle alpha actin (SMAA) promoter were produced by pro-nuclear microinjection. Two of three transgenic lines exhibited high levels of HAR expression in the retina, as determined by western blotting. The cellular localization of HAR was determined by immunostaining flat mounted and vibratome-sectioned retina preparations with a series of cell-type specific antibodies. Antibodies to HAR, SMAA, GFAP (glial fibrillary acid protein expressed by glial cells), CRALBP (cellular retinaldehyde binding protein expressed by RPE and Muller cells), calbindin (expressed by horizontal cells), PKC-α (the MC5 clone labeling rod bipolar cells and cone outer segments) and recoverin (expressed by photoreceptors and a sub-population of cone bipolar cells ) were used to determine the identity of HAR-expressing cells in the INL. Results: The retinas of SMAA-HAR transgenic mice contained two separate populations of HAR-expressing cells; perivascular cells associated with retinal vessels and neurons with cell bodies located in the middle of the INL. The HAR-positive neurons possess synaptic terminals that are clearly visible in the inner plexiform layer (IPL). These HAR-positive neurons were not labeled by antibodies to PKC-α, GFAP, calbindin or CRALBP in double labeling studies. The expression of recoverin is being examined. Conclusion: We have identified a population of HAR-positive neurons in SMAA-HAR transgenic mice whose general morphology, pattern of synaptic arborization and immunolabeling characteristics are consistant with cone bipolar cells. Although the physiological implications of HAR expression in these cone bipolar cells has not been established, this transgenic line may present a unique model for selectively disrupting cone bipolar cell function.
Keywords: 330 bipolar cells • 606 transgenics/knock-outs • 434 immunohistochemistry