Purpose:
To analyze the therapeutic effect of melatonin on experimentally- induced uveitis in cats.
Methods:
Twenty intact young physically and ophthalmologically healthy male European Short Hair cats. Lipopolysaccharide (LPS) was injected intravitreally into one eye, while the contralateral eye was injected with vehicle. Melatonin was orally administered every 24 h to a group of 10 cats, from 24 h before until 45 days after intravitreal injections. During a period of 45 days, eyes from both groups (untreated and treated with melatonin) were evaluated by means of clinical scoring, assessment of the integrity of the blood-ocular barrier (determined via measurement of protein concentration and cell content in samples of aqueous humor), functional analysis, and following euthanasia, histological examination of the retinas
Results:
In LPS-treated eyes, several clinical signs were observed until day 45 post-injection. The treatment with melatonin significantly decreased the clinical score. In LPS-injected eyes, melatonin significantly preserved the integrity of the blood-ocular barrier, as shown by a decrease in the number of infiltrating cells and protein concentration in the aqueous humor. Mean amplitudes of scotopic electroretinographic a- and b-waves were significantly reduced in eyes injected with LPS, whereas melatonin significantly prevented the effect of LPS. At 45 days after injection, LPS induced alterations in photoreceptors and the inner portion of the retina, whereas melatonin protected the retinal structure.
Conclusions:
These results indicated that melatonin prevented clinical, biochemical, functional, and histological alterations induced by LPS injection. Thus, melatonin might constitute a useful tool for the treatment of feline uveitis.
Keywords: melatonin • uveitis-clinical/animal model • retina