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Rosie Mcdowell, Timothy Curtis, Graham McGeown; Downregulation of aldehyde detoxification enzymes in the diabetic retina. Invest. Ophthalmol. Vis. Sci. 2013;54(15):269.
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© ARVO (1962-2015); The Authors (2016-present)
Previous studies have demonstrated accumulation of the acrolein-derived advanced lipoxidation end-product, FDP-lysine, in retinal Müller cells during diabetes. The aim of the present study was to begin to elucidate the mechanisms by which this adduct accumulates within the diabetic retina, including examination of the expression of aldehyde detoxification enzymes and also enzymes involved in polyamine metabolism.
RNA from the retinas of Sprague Dawley rats was isolated to determine the expression of aldehyde detoxification genes by RT-PCR. For immunohistochemistry, eyes were subject to fixation in 4% PFA, cryo-sectioning and then labelling with anti-bodies against ALDH1a1, ALDH2, AKR1B1 and AKR7a2. In separate experiments, male Sprague-Dawley rats were rendered diabetic by a single injection of streptozotocin (65mg/kg) and eye tissue was harvested after 3 months disease duration. RNA was isolated from the retinas of six diabetic animals and six age matched sham controls and then processed for RT-PCR. All animal care and experimental procedures strictly conformed to the ARVO Statement for the use of Animals in Ophthalmic and Vision Research.
RT-PCR indicated ALDH1a1, 2, 3a1, 3a2, 9, 16, 18a1 AKR1b1 and 7a2 were expressed in the rat retina. Immunohistochemistry experiments revealed that ALDH1a1, 2, AKR1B1 and 7a2 are principally localised to retinal Müller cells. The comparison of mRNA transcripts between control and diabetic animals indicated that ALDH1a1 7a2 and 3a2 were significantly down-regulated in whole retinal extracts of diabetic animals, whilst polyamine metabolic enzyme levels were unchanged.
Down-regulation of detoxifying enzymes in retinal Müller cells may represent a major mechanism contributing to the selective accumulation of FDP-lysine adducts in these cells during diabetes.
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