Therapeutic effect of melatonin in experimental uveitis.

SANDE, P; FERNANDEZ, D; ALDANA MARCOS, H; CHIANELLI, M.; AISEMBERG, J.; SILBERMAN, D.M.; SAENZ, D.; ROSENSTEIN, R.

AMERICAN JOURNAL OF PATHOLOGY

AMER SOC INVESTIGATIVE PATHOLOGY, INC

Lugar: Rockville Pike, Bethesda, MD (USA); Año: 2008 vol. 173 p. 1702 - 1713

0002-9440

Am J Pathol. 2008 Dec;173(6):1702-13. Epub 2008 Nov 13. Therapeutic effect of melatonin in experimental uveitis. Sande PH, Fernandez DC, Aldana Marcos HJ, Chianelli MS, Aisemberg J, Silberman DM, Sáenz DA, Rosenstein RE. Laboratorio de Neuroquímica Retiniana y Oftalmología Experimental, Universidad de Buenos Aires, Centro de Estudios Farmacológicos y Botánicos Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina. Abstract Uveitis is a common ophthalmic disorder that can be induced in hamsters by a single intravitreal injection of bacterial lipopolysaccharide (LPS). To examine the therapeutic effects of melatonin on uveitis, a pellet of melatonin was implanted subcutaneously 2 hours before the intravitreal injection of either vehicle or LPS. Both 24 hours and 8 days after the injection, inflammatory responses were evaluated in terms of i) the integrity of the blood-ocular barrier, ii) clinical signs, iii) histopathological studies, and iv) retinal function. Melatonin reduced the leakage of proteins and cells in the anterior segment of LPS-injected eyes, decreased clinical signs such as dilation of the iris and conjunctival vessels, and flare in the anterior chamber, and protected the ultrastructure of the blood-ocular barrier. A remarkable disorganization of rod outer segment membranous disks was observed in animals injected with LPS, whereas no morphological changes in photoreceptor outer segments were observed in animals treated with melatonin. Furthermore, melatonin prevented a decrease in LPS-induced electroretinographic activity. In addition, melatonin significantly abrogated the LPS-induced increase in retinal nitric-oxide synthase activity, tumor necrosis factor-alpha, and nuclear factor kappaB p50 and p65 subunit levels. These results indicate that melatonin prevents the clinical, biochemical, histological, ultrastructural, and functional consequences of experimental uveitis, likely through a nuclear factor kappaB-dependent mechanism, and support the use of melatonin as a new therapeutic strategy for the treatment of uveitis.