Sphingosine-1-phosphate (S1P) receptor agonism decreases ceramide accumulation in the skeletal muscle of aged and obese mice. Intramuscular accumulation of total ceramide (A), individual ceramide species (C; B), and other sphingolipids and ceramide metabolites (C) are shown. mRNA expression of the sphingosine-1-phosphate receptors (D) was measured by quantitative PCR. aP < 0.05 vs. lean (YNG), bP < 0.05 vs. FAT vehicle (VEH), cP < 0.05 vs. OLD VEH by 1-way ANOVA, n = 8/group. Cer, ceramide; dh-Cer, dihydroceramide; FTY720, S1P analog; Sph, sphingosine; Sph-1-Ph, sphingosine-1-phosphate; S1PR, S1P receptor.