Session: SUN 690-701-Obesity Pathophysiology
Poster Board SUN-694
OBJECTIVES:We assessed mitochondrial function and IMCL in obese adolescent girls with and without IR to determine (i) whether girls with IR have impaired mitochondrial function, and (ii) whether impaired mitochondrial function in girls with higher IR is related to higher IMCL.
METHODS: We examined 22 obese girls (mean BMI 38.5±7.53 kg/m2) 13-21 years old (mean age 16.6±2.4; mean bone age 16.9±1.3) for IR (defined as HOMA-IR>4). We compared mitochondrial function, IMCL in the tibialis anterior and soleus muscles, and MRI measures of visceral, subcutaneous and total adipose tissue (VAT, SAT and TAT) in girls with HOMA-IR>4 (IR group) vs. HOMA-IR<4 [insulin sensitive (IS) group]. Serum lipids and waist to hip ratio (W/H) were also measured.
RESULTS: Girls with IR (N=8) did not differ from the IS group (N=14) for age, bone age, weight, VAT or IMCL. However, the IR group had higher W/H (p=0.002), SAT (p=0.04) and TAT (p=0.047). In addition, the IR group had lower log ViPCr (1.9±1.0 vs. 2.7±0.6 mmol/min; p=0.04) and higher log TAU (3.8±0.6 vs. 3.5±0.2 secs; p=0.05), indicative of impaired mitochondrial function. We found similar results for log ViPCr (2.0±0.8 vs. 2.9±0.6 mmol/min; p=0.02) when IR and IS groups were dichotomized by HOMA-IR above or below the median (3.35). Using this categorization, the IR group had lower HDL (40.6±5.6 vs. 47.8±10.0 mg/dL; p=0.049), and higher VLDL (23.3±7.5 vs.15.5±7.9 mg/dL; p=0.03) and triglycerides (116.4±37.4 vs. 77.2±39.7 mg/dL; p=0.03) than the IS group. There were no differences between groups for total cholesterol or LDL.
CONCLUSION: Obese girls with increased IR have impaired mitochondrial function. This association is not mediated by IMCL alterations. Further studies are necessary to determine whether there is a causal relation between impaired mitochondrial function and IR in obesity and mediators of this relationship.
Nothing to Disclose: MS, MB, MT, HT, MM
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