Müller glial cells’ photosensitivity effects over glutamate-glutamine cycle components

MARCHESE, NATALIA A.; MÓNACO, PAULA; RIOS, MAXIMILIANO N.; GUIDO, MARIO E.

Buenos AIres

Congreso; ENCUENTRO SAN 2022; 2022

Sociedad Argentina de Investigación en Neurociencias

Müller cells (MC), the main glial cell type in the retina, are novel photic elements given the expression of blue- and UV-light sensitive opsins (Opn3, RGR and Opn5) and their intrinsic calcium responses elicited by blue light (BL). Each MC constitutes the core of retinal functional units, where its anatomical location allows the interaction with all of its cell types and accounts for their multiple functions, including glutamate recycling. Within the glutamate-glutamine cycle, MC are responsible for the reuptake of glutamate, through membrane transporters (GLAST), and its conversion to glutamine by glutamine synthase (GS) activity, to be transported back to neurons. We explored BL-induced modifications in glutamate metabolism by evaluating its main components in basal conditions and in neuron-conditioned medium. BL stimulation (1h) to primary cultures of avian MC does not modify GS nor GLAST levels. However, immunocytochemichal analysis of GLAST expression in MC reveals a light-evoked effect over cellular vesicles containing GLAST which marked increase in area and intensity after BL, which are restored upon returned to dark. Notably, the light-evoked cellular re-arrangement is blunted when neuronal-conditioned media is added. More experiments could untangle the physiological implication of photic induced changes in MC over glutamate metabolism.