Accumulation of membranes and photoreceptor degeneration in mouse retina

Ultrastructural response of photoreceptors to 10 days of treatment with reserpine and bromocryptine, and to 10 days of illumination, was studied. Treatment with isoproterenol was also applied in some experiments with continuous illumination. Treatment with bromocryptine and reserpine induced elongation of rod outer segments and accumulation of membranes in the subretinal space. Increased incidence of apoptosis but not of autophagocytosis was observed in both cases. Continuous illumination with or without treatment with isoproterenol was found to induce intracellular accumulation of membranes, autophagocytosis and apoptosis. Incidence of apoptosis was slightly decreased in the case of isoproterenol application. We conclude that intracellular or extracellular accumulation of membranes can function as the apoptotic trigger in photoreceptors. Triggering of apoptosis was not dependent on autophagocytosis. Possible role of membrane peroxidation in photoreceptor cell death is discussed.