Treatment with melatonin after onset of experimental uveitis attenuates ocular inflammation

SANDE, P; DORFMAN, D.; FERNANDEZ, D; CHIANELLI, M.; DOMINGUEZ RUBIO, A.P.; FRANCHI, A.; SILBERMAN, D.M.; ROSENSTEIN, R.; SAENZ, D.

BRITISH JOURNAL OF PHARMACOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2014 vol. 171 p. 5696 - 5707

0007-1188

BACKGROUND AND PURPOSEUveitis is a prevalent intraocular inflammatory disease and one of the most damaging ocular conditions. Pre-treatment withmelatonin prevented ocular inflammation induced by an intravitreal injection of bacterial LPS in the Syrian hamster. Here, wehave assessed the anti-inflammatory effects of melatonin administered after the onset of ocular inflammation.EXPERIMENTAL APPROACHThe eyes of male Syrian hamsters were intravitreally injected with vehicle or LPS. Melatonin was injected i.p. every 24 h,starting 12 or 24 h after the LPS injection. A clinical evaluation (with a score index based on clinical symptoms), the numberof infiltrating cells, protein concentration and PGE2 and PGF2α levels in the aqueous humour, as well as retinal NOS activity,lipid peroxidation and TNF-α levels were assessed. Retinal function was assessed by scotopic electroretinography, and lightmicroscopy and immunohistochemistry were used to evaluate the state of the retinal structure.KEY RESULTSBoth treatment regimens with melatonin decreased clinical symptoms, reduced the leakage of cells and proteins, anddecreased PG levels in aqueous humour from eyes injected with LPS. In addition, melatonin treatment blocked the decrease inscotopic electroretinogram a- and b-wave amplitude, protected the retinal structure and reduced the increase in NOS activity,lipid peroxidation and TNF-α levels, induced by LPS.CONCLUSIONS AND IMPLICATIONSThese results indicate that treatment with melatonin, starting after the onset of uveitis, attenuated ocular inflammationinduced by LPS in the Syrian hamster and support the use of melatonin as a therapeutic resource for uveitis treatment.