Effects of leucine and creatine supplementation on insulin sensitivity of rats treated with dexamethasone

We aimed to evaluate the effects of leucine (Leu) and creatine (Cr) supplementation on dexamethasone (DEXA) treated animals on insulin sensitivity (IS). Adult male Wistar rats were randomly divided into DEXA, DEXA + Leu (DEXA-Leu), DEXA + Cr (DEXA-CR) and Control par-fed group. DEXA-treated groups received 5 mg/kg/d for 7 days; DEXA-LEU group received 0.135 g/kg/d of Leu; DEXA-CR group received 5 mg/kg/d of Cr. Blood samples were collected for measuring plasma glucose and insulin levels. Plantaris muscle was removed for protein expression. Fasting glycemia was significantly increased in DEX group when compared with CON-PF group (5.2±0.2mmol/L in DEX group vs. 7.9±0.3 mmol/L in CON-PF group; p<0.05) and both Leu and Cr supplementation aggravated such effect (16.1±0.9mmol/L in DEX-LEU group and 15.1±1.0mmol/L in DEX-CR group; p<0.001 vs. DEX and CON-PF groups). Plasma insulin showed the same result pattern observed in fasting glucose (37.1±1.5μU/ml in DEX group vs. 15.2±0.9μU/ml in CON-PF group; p<0.05; 65.7±10.0μU/ml in DEX-LEU group and 53.5±1.7μU/ml in DEX-CR group; p<0.05 vs. DEX and CON-PF groups). HOMA-IR demonstrated decreased IS in DEX group when compared with CON-PF group (12.7±3.0 DEX group vs. 1.9±0.13 CON-PF group; p<0.01) and Leu and Cr supplementation aggravated this response (47.7±4.9 DEX-LEU group and 39.6±1.3 DEX-CR group; p<0.05 vs. DEX and CON-PF groups).