Mitochondrial inhibition of retinal Müller cells alter glutamate homeostasis and their ability to sustain retinal ganglion cells

Purpose Glia‐neuron partnership is important for inner retinal homeostasis and any disturbances may result in retinal ganglion cell (RGC) death. Müller cells support RGCs with essential functions such as removing excess glutamate and providing neurons with energy sources. In this study, we evaluated consequences of mitochondrial inhibition on retinal Müller cells and their ability to sustain RGCs. Methods The human Müller glial cell line, MIO‐M1, as well as mono‐ and co‐cultures of primary C56Bl/6 mouse Müller cells and RGCs, was used as cellular models. Cells were treated with 10 uM antimycin A to inhibit mitochondrial function. Changes in glutamate uptake in Müller cells were examined by kinetic assays with 3H‐ l ‐glutamate. Cell viability was evaluated by LDH assays. Regulations in gene and protein expression were evaluated by qPCR and western blotting. Results Mitochondrial inhibition significantly reduced protein‐ and mRNA expression of the major glutamate transporter, EAAT1, in Müller cells. Moreover, mitochondrial inhibition significantly decreased Müller cell glutamate uptake. Mitochondrial inhibition solely did not effect cell viability neither in Müller cells nor in RGC. However, simultaneous mitochondrial inhibition and starvation significantly decreased survival of both cell types. The protective effect of Müller cells in co‐cultures of primary RGCs and MCs were attenuated during mitochondrial inhibition. Conclusions Inhibition of mitochondrial function alter the neuroprotective characteristics of Müller cells by decreasing the expression of glutamate transporter and functional reduction of glutamate uptake. Furthermore, the impaired mitochondrial activity may affect the ability of Müller cells to maintain a cellular homeostasis in such way that their ability to protect RGCs may to suffer.