Activation of autophagy in photoreceptor necroptosis after experimental retinal detachment.

AIM To investigate whether photoreceptor necroptosis induced by z-VAD-FMK (pan caspase inhibitor) was involved the activation of autophagy and whether Necrostatin-1, a specific necroptosis inhibitor, could inhibit this induction of autophagy after experimental retinal detachment. METHODS Experimental retinal detachment models were created in Sprague-Dawley rats by subretinal injection of sodium hyaluronate and subretinal injections of z-VAD-FMK, vehicle or z-VAD-FMK plus Necrostatin-1. Three days after retinal detachment, morphologic changes were observed by transmission electron microscopy. In other animals, retinas were subjected to immunoprecipitation and Western Blotting, then probed with anti-RIP1, phosphoserine, LC-3II or caspase 8 antibody. RESULTS It was proved by immunoprecipitation and western blotting, that photoreceptor necroptosis was mediated by caspase-8 inhibition and receptor interacting protein kinase (RIP1) phosphorylation activation. Transmission electron microscope and western blotting results indicated that photoreceptor necroptosis was involved the LC-3II and autophagosomes induction. We also discovered Necrostatin-1 could inhibit RIP1 phosphorylation and LC-3II induction. CONCLUSION These data firstly indicate photoreceptor necroptosis is associated with the activation of autophagy. Necrostatin-1 protects photoreceptors from necroptosis and autophagy by down-regulation of RIP1 phosphorylation and LC-3II.