STIMULATION OF CITRATE SYNTHASE ACTIVITY IN GASTROCNEMIUS MUSCLE OF B6 AND B6.A MICE FED WITH HIGH FAT DIET FOR 12 WEEKS

Citrate synthase (CS) is a key mitochondrial enzyme (Nes Nusi et al.2013). The aim was to investigate effects of 12 weeks of high fat diet (HFD, 45% kcal fat) on C57BL/6J (B6) mice and Congenic (rs3676616-D10Utsw1)/KjnB6 (B6.A) mice. CS activity in gastrocnemius and heart muscles of mice fed with HFD for 12 weeks were examined by spectrophotometer. CS activity was higher in gastrocnemius muscle of B6 compared to B6.A mice (659.1 ± 121.7 vs 398.1± 129.4 U/g protein, respectively, p<0.0001) than when mice were fed control high carbohydrate diet (HCD). CS activity was also higher in the heart of B6 compared to B6.A mice (2172.2 ± 312.8 versus 1182.53 ± 379.9 U/g protein, respectively, p < 0.0001). Twelve weeks of HFD led to an increase (P < 0.05) in CS activity of gastrocnemius and decrease (P < 0.05) in CS activity of heart for both mice strains. Western blot was employed to investigate AMPK, GLUT4, P38 and ERK1/2 proteins. There was no difference in these proteins activation between mice strains and their diets. These results suggest that HFD can stimulate CS activity in tissues with low oxidative potential and inhibits it in tissues with high oxidative potential