trans-10,cis-12 Conjugated linoleic acid prevents adiposity but not insulin resistance induced by an atherogenic diet in hamsters

While conjugated linoleic acid (CLA) has received a great deal of attention as a supplement that can favourably modify body composition, its potential impact on insulin sensitivity has not received equal attention. The aim of the present work was to analyse the effects of trans-10,cis-12 CLA isomer on insulin sensitivity in hamsters fed an atherogenic diet. Hamsters were divided into three groups: one group was fed a chow diet (control) and the other two a semipurified atherogenic diet supplemented with 0.5% linoleic acid (LA) or trans-10,cis-12 CLA, respectively. Serum glucose, FFAs, insulin, leptin and adiponectin were measured using commercial kits. HOMA-IR was calculated using the formula of Matthews et al. PPARγ mRNA was assessed in epididymal adipose tissue by reverse transcription-polymerase chain reaction (RT-PCR). After 6 weeks, atherogenic feeding produced an increase in body fat accumulation as compared with control feeding. The addition of trans-10,cis-12 CLA to the atherogenic diet avoided this feature. Atherogenic feeding also led to significantly higher serum concentrations of glucose, insulin, FFAs, as well as greater HOMA-IR values. trans-10,cis-12 CLA did not prevent these effects. No significant differences were found among experimental groups in serum leptin and adiponectin concentrations, nor in PPARγ expression. In summary, although the addition of trans-10,cis-12 CLA to an atherogenic diet reduces fat accumulation, it does not improve the impairment of insulin action associated with this feeding. The maintenance of insulin resistance in hamsters fed the atherogenic CLA-enriched diet is probably due to the high serum FFA concentration observed in these animals.