ABSTRACT
Conjugated linoleic acid (CLA) has been shown to cause a reduction in obesity in several species. CLA-induced body fat loss is enhanced when mice are fed coconut oil (CO) and involves increased lipolysis. The objective of this paper was to determine if the CLA-induced lipolysis in mice fed with different oil sources was time-dependent. Mice were fed 7 % soybean oil (SO) or CO diets for 6 week and then supplemented with 0 or 0.5 % CLA for 3, 7, 10 or 14 days. Body fat and ex-vivo lipolysis was determined. Body fat was reduced by CO on day 7 (P < 0.01) and in both CO and SO-fed mice (P < 0.05) in response to CLA on d14. Lipolysis was increased by CLA in CO-fed mice (P < 0.01) but not in SO-fed mice on day 7 and 10, but on day 14 CLA increased lipolysis in both CO- and SO-fed mice (P < 0.001). Expression and activation level of proteins involved in lipolysis and lipogenesis was determined by western blotting and real-time PCR, respectively. No significant differences were detected in protein expression. CO-fed mice had greater fatty acid synthase and stearyl CoA desaturase 1 mRNA expression and less acetyl CoA carboxylase mRNA expression (P < 0.01). Sterol regulatory binding protein 1c was decreased by CLA in CO-fed mice and increased in SO-fed mice (P < 0.05). Malic enzyme expression was increased by CLA (P < 0.001) and CO (P < 0.01). Therefore, CLA-induced lipolysis occurs more rapidly in CO vs SO-fed mice and lipogenesis is decreased in CO-fed mice with CLA supplementation.