Non image forming visual system alterations induced by experimental optic neuritis: therapeutic effect of melatonin

FLORENCIA ALTSCHULER; MARCOS LUIS ARANDA; OMAR NARVÁEZ; JUAN SALVADOR CALANNI; MARÍA FLORENCIA GONZÁLEZ FLEITAS; PABLO H SANDE; DAMIÁN DORFMAN; LUIS CONCHA; RUTH E. ROSENSTEIN

Congreso; XXXIV Reunión Anual de la SAN; 2019

Optic neuritis (ON) is an inflammatory condition of the optic nerve (OpN), which leads to retinal ganglion cell (RGC) loss. A subset of RGCs expressing the photopigment melanopsin regulates non-image-forming (NIF) visual system functions such as pupillary light reflex(PLR) and circadian rhythms. ON can be induced by a single microinjection of bacterial lipopolysaccharide (LPS) into the OpN. We analyzed the effect of ON on the NIF visualsystem, and the effect of melatonin on NIF visual system alterations induced by ON. OpNs from male Wistar rats received vehicle or LPS, and one group of animals received a subcutaneous pellet of melatonin. LPS significantly decreased blue light-evoked PLR, andinduced a misconnection between the retina and the suprachiasmatic nuclei (assessed by ex vivo magnetic resonance images). LPS induced a significant decrease in Brn3a(+) RGCs, but not in melanopsin(+) RGC number. A bilateral injection of LPS significantly increased the light (but not dark) phase locomotor activity, rhythm periodicity, and activity offset time. Melatonin prevented the decrease in blue light-evoked PLR, and locomotor activity rhythm alterations induced by ON. These results support that ON provoked alterations of thecircadian physiology, and that melatonin protected the NIF visual system function against ON.