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

ARANDA, MARCOS L.; GONZALEZ FLEITAS M FLORENCIA; CONCHA, LUIS; ALTSCHULER, FLORENCIA; CALANNI, JUAN S.; DORFMAN, DAMIÁN; NARVAEZ, OMAR; SANDE, PABLO H.; ROSENSTEIN, RUTH E

Carlos Paz, Provincia de Córdoba

Congreso; XXXIV Reunión Anual de la SAN; 2019

Sociedad Argentina de Investigación en Neurociencias

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