Intrinsic blue-light responses in avian Müller glial cells involve non-visual opsin activation and calcium release from internal stores

MARCHESE, N.A.; RIOS, M.N.; GUIDO, M.E.

Carlos Paz

Congreso; XXXIV Reunión Anual SAN 2019; 2019

Sociedad Argentina de Investigación en Neurociencias

The retina of birds contains different types of photoreceptors cells: the visualphotoreceptor cells (cones and rods), the Opn4-expressing cells (ganglion andhorizontal cells), and the Müller glial cells (MCs) that express the nonvisual opsinsOpn3 and Opn5 (blue and UV-light sensitive). MCs are the main glial cell type invertebrates? retina located all along the inner retina and controlling its physiologyby debris phagocytosis, K+ uptake, and trophic factors and neurotransmittersrelease. The present work aims to further characterize the intrinsic photoreceptorcapacity of the inner retina focusing on MCs. Therefore, Ca+2 responses to bluelight (BL) were evaluated by fluorescence Ca+2 microscopy in enriched MCsprimary cultures. A MCs subpopulation (45%) responded to a BL pulse (20 sec) byincreasing intracellular Ca2+ levels up to 20%. This response was not observed inpresence of the retinal bleacher hydroxylamine nor with red light stimulation.Further testing was performed with the Ca+2 chelator EGTA and the inhibitors forSERCA (thapsigargin), IP3 receptors (2-APB), and G protein-coupled receptors(Suramin). In this conditions, BL responses were absent except for EGTAtreatment. Our results show a direct and specific photic response of MCs to BLstimulation involving opsin and G protein activation that promote Ca+2 releasefrom internal stores; thus suggesting new roles for MCs in retinal physiology,possibly in visual and nonvisual processes regulated by light.