A diet enriched with citrulline (CIT) reduces white adipose tissue (WAT) mass. We recently showed that CIT stimulated β-oxidation in rat WAT explants from young (2-4 months) but not old (25 months) rats. Here we show that both in old rats and high-fat-diet-fed young rats, uncoupling protein one (UCP1) mRNA and protein expressions were weaker than those in young control rats. Selectively in WAT from young rats, a 24h CIT treatment up-regulated expressions of UCP1, peroxisome proliferator-activated receptor-α (PPARα), PPARγ-coactivator-1-α and mitochondrial-transcription-factor-A whereas it down-regulated PPARγ2 gene expression, whatever the diet. These results suggest that CIT induces a new metabolic status in WAT, with increased β-oxidation and uncoupling of respiratory chain, resulting in energy expenditure that favors fat mass reduction.
Keywords: ARG, arginine; ASL, argininosuccinate lyase; ASS, argininosuccinate synthase; BSA, bovine serum albumin; CD, control diet; CIT, citrulline; CPT1-b, carnitine palmitoyl transferase 1-b; EPI, epididymal; HFD, high-fat-diet; KREBS, Krebs Ringer Buffer Saline; NEFA, non-esterified fatty acids; NO, nitric oxide; NOS, nitric oxide synthase; PEPCK-C, cytosolic phosphoenolpyruvate carboxykinase; PGC-1α, peroxisome proliferator-activated receptor gamma co-activator 1α; PKA, protein kinase A; PPAR, peroxisome proliferator-activated receptor; RET, retroperitoneal; TFAM, mitochondrial transcription factor A; UCP1; VLCAD, very long chain acyl-CoA dehydrogenase; WAT, white adipose tissue; adipose tissue; browning; citrulline; fatty acids; obesity.