LACTATE: a valuable energy substrate in maintaining survival and function in the inner retina

Purpose To evaluate the effect of lactate on Müller cell and retinal ganglion cell (RGC) survival and function. Methods The human Müller cell line MIO‐M1 was incubated in media with the presence and absence of 6 mM glucose and furthermore with the presence and absence of respectively 10 mM and 20 mM l‐lactate for 2 and 24 h. Same conditions were used in primary mice Müller cells and RGC. Cell survival was assessed through MTT. Müller cell function was evaluated through the Müller cells’ ability to take up glutamate. Results Both 10 mM and 20 mM l‐Lactate increased cell survival after 2 and 24 h with and without the presence of glucose. After 24 h only 20 mM increased cell survival in Müller cells incubated in media containing glucose. Glutamate uptake increased in glucose restricted Müller cells compared to cells with glucose availability. The addition of lactate to the incubation media decreased the uptake in both glucose supplemented and restricted cells. After 24 h this effect was altered resulting in increased glutamate uptake in response to 10 mM l‐Lactate. Conclusions We hereby verify lactate as being an important energy substrate for the survival of Müller cells both in the presence and absence of glucose. Furthermore, our study indicates that Müller cells prefer lactate as an energy substrate compared to glutamate after 2 h, however after 24 h the energy substrate requirement enhances resulting in a compensatory increase in glutamate uptake.