Endocannabinoid metabolism in rod outer segments depends on the illumination state of the retina

GIUSTO, N.M.; CHAMORRO AGUIRRE, E.; PASQUARÉ, S.J.; GAVEGLIO, V.L.

Córdoba

Congreso; LII Reunión Anual SAIB; 2016

The aim of the present research was to determine how the synthesis and hydrolysis of endocannabinoid 2arachidonoylglycerol (2-AG) are modulated by the illumination state of the retina. To this end, lysophosphatidate phosphohydrolase (LPAPase) and monoacylglycerol lipase (MAGL) activities were evaluated in purified rod outer segments (ROS) obtained from dark-adapted retinas or light-adapted retinas. Retinas were dissected from the eyes after dark or light adaptation. Dark-adapted bovine ROS (DROS) and bleached ROS (BLROS) were purified by a discontinuous gradient of sucrose from retinas whose optic cup was maintained under dim red light or exposed to light (288 candelas/m3, 3000 luxes) for 30 min. LPAPase and MAGL activities were evaluated using [3H]oleoyllysophosphatidic acid and [3H]Glycerol-MAG as substrates, respectively. When [3H]-LPA was used, [3H]-MAG and [3H]-oleoyl were produced and both were stimulated by 150 % in BLROS. However, MAGL activity determined by [3H]-Glycerol production was not modified in BLROS. These results suggest a distinct effect exerted by light on endocannabinoid 2-AG metabolism, thus indicating a potential role of this lipid in phototransduction. LI