PurposePoint and null mutations in interphotoreceptor retinoid-binding protein (IRBP) cause retinal dystrophy in affected patients and IRBP-deficient mice with unknown mechanism. This study investigated whether IRBP protects cells from damages induced by all-trans-retinal (atRAL), which was increased in the Irbp−/− retina.MethodsWild-type and Irbp−/− mice retinal explants in buffer with or without purified IBRP were exposed to 800 lux light for different times and subjected to retinoid analysis by high-performance liquid chromatography. Purity of IRBP was determined by Coomassie Brilliant Blue staining and immunoblot analysis. Cellular damages induced by atRAL in the presence or absence of IRBP were evaluated in the mouse photoreceptor-derived 661W cells. Cell viability and death were measured by 3-(4,5-dimethyl-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) and TUNEL assays. Expression and modification levels of retinal proteins were determined by immunoblot analysis. Intracellular reactive oxygen species (ROS) and nitric oxide (NO) were detected with fluorogenic dyes and confocal microscopy. Mitochondrial membrane potential was analyzed by using JC-1 fluorescent probe and a flow cytometer.ResultsContent of atRAL in Irbp−/− retinal explants exposed to light for 40 minutes was significantly higher than that in wild-type retinas under the same light conditions. All-trans-retinal caused increase in cell death, tumor necrosis factor activation, and Adam17 upregulation in 661W cells. NADPH oxidase-1 (NOX1) upregulation, ROS generation, NO-mediated protein S-nitrosylation, and mitochondrial dysfunction were also observed in 661W cells treated with atRAL. These cytotoxic effects were significantly attenuated in the presence of IRBP.ConclusionsInterphotoreceptor retinoid-binding protein is required for preventing accumulation of retinal atRAL, which causes inflammation, oxidative stress, and mitochondrial dysfunction of the cells.

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ObjectiveThe purpose of this study is to investigate the retinal effects of methamphetamine.IntroductionMETH, a highly addictive stimulant of neurotransmitters is associated with cardiovascular and neurological diseases. METH‐induced ophthalmic complications are also present but have been insufficiently investigated.Materials and methodsC57BL/6J mice were administrated progressively increasing doses of METH (0 to 6 mg/kg) by repetitive intraperitoneal injections for 5 days (4 times per day). Norepinephrine levels in plasma were measured by ELISA. Cross‐sections of the central retinal artery (CRA) and retina were stained with hematoxylin and eosin. Expression of various proteins was determined by immunostain and immunoblot in the CRA and retina.ResultsElevated norepinephrine levels in plasma were induced by METH (6.49±1.72 ng/mL, n=5), compared with saline treatment (1.38±0.48, P<0.001, n=5). After treatment of METH, the ocular pupil was dilated and retinal thicknesses of the outer nuclear layer, outer plexiform layer, inner nuclear layer, and inner plexiform layer were decreased. Platelet endothelial cell adhesion molecule‐1 (PECAM‐1) protein expression level was decreased in the CRA and retina of METH‐treated mice, along with the endothelial proteoglycans glypican‐1 and syndecan‐1. Moreover, a regulator of the extracellular matrix, membrane type 1 matrix metalloproteinase (MMP‐14), but not MMP‐2 and MMP‐9, was increased in the retina by METH treatment.ConclusionThese results suggest that METH administration is involved in retinal degeneration with a vascular loss of PECAM‐1 and the glycocalyx, and an increase of MMP‐14 in the CRA and retina.Support or Funding InformationThis work was supported by funding from the National Institute of Health (NIH) EY025632.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.