Fig. 3

PPARα is essential for utilization of lipid for oxidative phosphorylation. a, b Measurement of (a) retinal oxygen consumption with a Seahorse XFe analyzer revealed that (b) baseline and maximal retinal oxygen consumption rate (OCR) were significantly increased in wild-type (WT) retinas when long-chain fatty acid palmitate (Palm) was provided, suggesting that Palm is used as an oxidizable substrate in normal conditions (BSA, n = 12; Palm, n = 11). c, d Retinal OCR was unaffected by Palm in Pparα ^-/- retinas, suggesting that retinal use of lipid as an oxidizable substrate is impaired in the absence of PPARα (BSA, n = 9; Palm, n = 12). e, f Oral administration of PPARα agonist fenofibrate (Feno) for 1 month prior to tissue harvest increased oxygen consumption in isolated rat retinal mitochondria (mitos) provided with lipid palmitoylcarnitine (PC) as an oxidizable substrate (n = 4). g RNA levels of lipid transporters and fatty acid oxidation (FAO) enzymes were decreased in Pparα ^-/- retinas (n = 5/genotype). *P ≤ 0.05; **P ≤ 0.01; ***P ≤ 0.001, unpaired two-tailed Student’s t test