EFFECT OF EXPERIMENTAL GLAUCOMA ON THE NON-IMAGE FORMING VISUAL SYSTEM

DE ZAVALIA N; PLANO SA; FERNANDEZ DC; LANZANI MF; SALIDO E; BELFORTE N; KELLER SARMIENTO MI; GOLOMBEK DA; ROSENSTEIN RE

Congreso; 3rd World Congress of Cronobiology; 2011

Purpose: Glaucoma is a leading cause of blindness worldwide, characterized by specific visual field defects due to the loss of retinal ganglion cells and damage to the optic nerve head. Medications and surgery can help to slow the progression of some forms of the disease, but at present, there is no cure. Recent evidences indicate that a population of retinal ganglion cells is intrinsically photosensitive (through the expression of a specific photopigment, melanopsin), and transmits light information to the suprachiasmatic nuclei (SCN), where the principal pacemaker center for circadian rhythm is located, regulating several non-visual processes, like synchronization of the biological clock, photic suppression of pineal melatonin synthesis, and pupillary light responses. The aim of this work was to study the effect of glaucoma induced by weekly injections of chondroitin sulphate (CS) on the levels of rhodopsin and melanopsin, pupillary light reflex, photic suppression of pineal melatonin synthesis, expression of cfos in the suprachiasmatic nuclei (SCN) and locomotor activity rhythms. Methods: CS was injected in one eye and vehicle in the contralateral eye, once a week, during 10 weeks. In a group of animals, the injections of CS or vehicle were performed bilaterally. For the assessment of pupillary light reflex, animals were weekly injected in one eye with vehicle or CS, while the contralateral eye remained intact. The levels of rhodopsin and melanopsin were measured by western blot and immunohistochemistry, the melatonin content was determinated by RIA, after a light pulse of 20 min (white or blue light) and the expression of cfos induced by a light pulse of 10 min was analyzed by immunohistochemistry. Locomotor activity rhythms were determinated with infrared detectors of motion. Results: Melanopsin levels and pupil contraction was significantly lower in eyes injected with CS with respect to controls (p