Melatonin prevents apoptosis of photoreceptors during development in vitro

MONACO, S; GERMAN, OLGA; ROTSTEIN, NORA; ROSENSTEIN, RUTH; POLITI, LUIS E.

Huerta Grande, Córdoba

Congreso; 1er Congreso Conjunto de la Sociedad Argentina de Neuroquímica y el Taller de Neurociencias; 2009

MELATONIN PREVENTS APOPTOSIS OF PHOTORECEPTORS DURING DEVELOPMENT IN VITRO     Monaco, S*; German, OL*; Rotstein, NP*, Rosenstein, R× and Politi, LE* *Instituto de Investigaciones Bioquímicas de Bahía Blanca, Conicet. Universidad Nacional del Sur. ×Laboratorio de Neuroquímica Retiniana y Oftalmología Experimental, Conicet. Facultad de Medicina, Universidad de Buenos Aires. smonaco@criba.edu.ar   Abstract Apoptosis a key process in the nervous system development, is required for establishing the final number of neurons and removing neural precursors that form inappropriate synapses. Abnormal apoptosis has been also involved in several neurodegenerative diseases, including those occurring in the retina, like retinitis pigmentosa and age related macular degeneration. In these diseases, apoptotic photoreceptor (PR) death leads to vision loss. Hence, finding exogenous factors that prevent PR apoptosis is relevant for treating these pathologies. Considering tha toxidative stress is involved in inducing photoreceptor death and that melatonin (Mel), is a potent antioxidant, we investigated the effect of Mel on PR apoptosis. For this purpose, pure retinal cultures from newborn rats were incubated for six days with or without 40nM Mel, and finally fixed. Cell viability was determinated by propidium iodide assay; apoptotic cell death was evaluated by TUNEL assay and DAPI staining; and mitochondrial integrity was analyzed using MitoTracker Red. Incontrol conditions, in the absence of trophic factors, PRs initiate an apoptotic process after 4 days in vitro. Mel improved cell viability and reduced the number of apoptotic PRs after 6 days in vitro, with a parallel increase in the amount of PRs preserving mitochondrial membrane integrity. Moreover, Mel decreased about 75 the production of lipid peroxidation products (thiobarbituric acid reactive species, TBARS) and by 50 that of reactive oxygen species (ROS). These results suggest that Mel prevents PR apoptosis in vitro, probably by acting as an antioxidant, decreasing ROS accumulation.