Impaired Lipolysis, Diminished Fat Oxidation and Metabolic Inflexibility in Obese Girls with Polycystic Ovary Syndrome.

Impaired Lipolysis, Diminished Fat Oxidation and Metabolic Inflexibility in Obese Girls with Polycystic Ovary Syndrome.

J Clin Endocrinol Metab. 2017 Dec 06;:

Authors: Kim JY, Tfayli H, Michaliszyn SF, Arslanian S

Abstract
CONTEXT: Metabolic flexibility reflects the ability to switch from lipid to carbohydrate oxidation during insulin stimulation manifested in increased respiratory quotient (RQ). Despite insulin resistance in glucose metabolism in PCOS women and adolescents, little is known about adipose tissue metabolism and metabolic flexibility.
OBJECTIVE: To investigate whole-body lipolysis, substrate oxidation and metabolic flexibility in obese PCOS vs. non-PCOS girls.
PATIENTS/DESIGN: Twenty-one obese (BMI 32.7 ± 1.0 kg/m2) PCOS and 21 obese (33.3 ± 1.2 kg/m2) non-PCOS adolescent girls were pair-matched for age and race. Body composition (DEXA), abdominal visceral adipose tissue [VAT] (CT), sex hormones, lipid profile and adiponectin were measured. Whole-body lipolysis ([2H5]glycerol turnover), RQ, substrate oxidation (indirect calorimetry) were evaluated during fasting and during a 3-hr hyperinsulinemic (80 mu/m2/min)-euglycemic clamp together with assessment of insulin sensitivity (IS).
RESULTS: Despite similar BMI and percent body fat, PCOS vs. non-PCOS girls had significantly lower fasting lipolysis, lower fasting fat oxidation and less increase in RQ during hyperinsulinemia with impaired suppression in lipolysis and lipid oxidation, and diminished increase in glucose oxidation and lower IS. In multiple regression models the best predictors of metabolic flexibility were [using clinical parameters: adiponectin, fasting triglycerides and fasting insulin (R2=0.618, P<0.0001); using research parameters: IS, VAT, and baseline RQ (R2=0.756, P<0.0001)].
CONCLUSIONS: Obese PCOS vs. non-PCOS girls have decreased lipid mobilization, diminished fat oxidation and metabolic inflexibility. Whether or not this metabolic phenotype of adipose tissue dysfunction, conducive to fat accretion, plays a role in induction/maintenance of obesity in PCOS adolescents remains to be determined.

PMID: 29220530 [PubMed - as supplied by publisher]

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