L-Lactate Protects Skin Fibroblasts against Aging-Associated Mitochondrial Dysfunction via Mitohormesis

Figure 3

The response of fibroblasts intracellular signaling to L-lactate treatment. (a) Percentage of oxidized (GSSG)/total intracellular glutathione in fibroblasts before (CTRL) and 1 hour after addition of 5 mM L-lactate (PULSE), 24 hours after L-lactate withdrawal (POST), and 3 days after addition of 5 mM L-lactate (CONST). (b) Relative ratio of phosphorylated/total AMPK in fibroblasts before (CTRL) and 1 hour after addition of 5 mM L-lactate (PULSE), 1 hour after L-lactate withdrawal (POST), and 3 days after addition of 5 mM L-lactate (CONST). (c) Relative expression (normalized to GAPDH mRNA) of TFAM and POLG mRNAs as a measure of PGC1α activity in fibroblasts before (CTRL) and 4 hours after addition of 5 mM L-lactate (PULSE), 24 hours after L-lactate withdrawal (POST), and 3 days after addition of 5 mM L-lactate (CONST). (d) mtDNA copy number per cell as a measure of mitochondrial abundance in fibroblasts treated with 0–10 mM L-lactate for 3 days. (e) Basal and maximal (after uncoupling with FCCP) respiration of fibroblasts in complete media without treatment (CTRL) or 3 days after addition of 5 mM L-lactate (LAC). (f) Relative signal from MTT assay performed in fibroblasts treated with 0–10 mM L-lactate for 3 days. (g) Proliferation of fibroblasts treated with 0–10 mM L-lactate for 3 days measured by direct counting of cells negative for Trypan blue inclusion. (^∗significantly different from CTRL; ; ^#significantly different from PULSE; ).

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