Melatonin Prevents Biochemical, Histological, Clinical, And Functional Alterations Provoked By Endotoxin-Induced Uveitis In The Golden Hamster

RUTH E. ROSENSTEIN; PABLO SANDE; DIEGO FERNANDEZ; MóNICA CHIANELLI; DAFNE SILBERMAN; HERNáN ALDANA MARCOS; DANIEL SáENZ

Fort Lauderdale, Florida, USA

Congreso; The Association for Research in Vision and Ophthalmology; 2007

The Association for Research in Vision and Ophthalmology

Purpose: The aim of this study was to investigate the effect of melatonin on endotoxin-induced uveitis in the golden hamster.Methods: For this purpose, a pellet of 20 mg melatonin was implanted subcutaneously two hours before the intravitreal injection of 1ìg lipopolysaccharide from the outer membrane of gram-negative bacteria (LPS). The inflammatory response was evaluated in terms of: (i) integrity of the blood aqueous barrier (protein and cell content in samples of aqueous humor), (ii) histopathological changes, (iii) clinical evaluation (with a score index based on clinical symptoms), and (iv) functional changes assessed by scotopic electroretinographic activity.Results:Melatonin reduced the leakage of proteins and cells in the anterior segment of eyes injected with LPS (p<0.01) and decreased anterior and posterior clinical signs (conjunctival hyperemia, alterations of episcleral vessels, corneal edema, synechiae, cataracts and posterior segment alterations) provoked by LPS (p<0.05). Retinal layer thickness in animals treated with LPS plus melatonin was significantly lower (p <0.01) than in eyes injected with LPS in the absence of melatonin. Inflammatory cellular infiltration induced by LPS was significantly lower (p <0.01) in animals treated with melatonin. A remarkable disorganization of rod outer segment membranous disks and the presence of dense bodies and membranous debris between these segments was observed in animals injected with LPS, whereas not obvious morphological changes in photoreceptor outer segments were observed in animals treated with LPS plus melatonin. Furthermore, melatonin prevented the decrease in scotopic electroretinographic a- and b-wave amplitude induced by LPS (p< 0.01). Conclusions: The present results show that melatonin prevents clinical, biochemical, histological, and functional consequences of experimental uveitis. :