Determinants of intramyocellular lipid accumulation after dietary fat loading in non-obese men.
Aims/Introduction:  Accumulation of intramyocellular lipid (IMCL) is associated with insulin resistance. However, the factors affecting the change in IMCL remain to be elucidated. The aim of the present study was to determine the factors that influence the change in IMCL level after high-fat loading.


METHODS
The study subjects were 37 non-obese men. Each subject consumed a high-fat diet for 3 days after a normal-fat diet for 3 days. After each diet program, IMCL levels in the tibialis anterior (TA-IMCL) and soleus (SOL-IMCL) were measured by proton magnetic resonance spectroscopy. Glucose infusion rate (GIR) was evaluated by euglycemic hyperinsulinemic clamp as an index of peripheral insulin sensitivity.


RESULTS
The high-fat diet significantly increased TA-IMCL and SOL-IMCL by ∼30 and ∼20%, respectively (P < 0.05), whereas it did not significantly alter GIR. The increase in SOL-IMCL, but not in TA-IMCL, negatively correlated with serum high molecular weight (HMW)-adiponectin (r = -0.36, P < 0.05) and HMW-/total-adiponectin ratio (r = -0.46, P < 0.05). Although high-fat diet-related changes in SOL-IMCL showed high inter-individual variations, in subjects doing exercise, changes in SOL-IMCL (r = 0.55, P < 0.05) and TA-IMCL (r = 0.61, P < 0.05) positively correlated with daily physical activity level. In contrast, in sedentary subjects, changes in SOL-IMCL (r = -0.50, P < 0.01) and TA-IMCL (r = -0.48, P < 0.05) negatively correlated with daily physical activity.


CONCLUSIONS
HMW-adiponectin and daily physical activity are determinants of IMCL accumulation by a high-fat diet. Intriguingly, the effect of daily physical activity on the change in IMCL depends on the level of regular exercise. (J Diabetes Invest,doi: 10.1111/j.2040-1124.2010.00091.x, 2011).
Department of Medicine, Metabolism and Endocrinology.
Yuko
Y
Sakurai
Department of Medicine, Metabolism and Endocrinology ; Sportology Center, Graduate School of Medicine, Juntendo University, Tokyo.
Yoshifumi
Y
Tamura
Department of Medicine, Metabolism and Endocrinology.
Kageumi
K
Takeno
Department of Medicine, Metabolism and Endocrinology.
Naoki
N
Kumashiro
Department of Medicine, Metabolism and Endocrinology.
Fumihiko
F
Sato
Department of Medicine, Metabolism and Endocrinology ; Sportology Center, Graduate School of Medicine, Juntendo University, Tokyo.
Saori
S
Kakehi
Department of Medicine, Metabolism and Endocrinology ; Sportology Center, Graduate School of Medicine, Juntendo University, Tokyo.
Shinichi
S
Ikeda
Institute of Health and Sports Science and Medicine ; Department of Exercise Physiology, Graduate School of Health and Sports Science, Juntendo University, Chiba.
Yuji
Y
Ogura
Institute of Health and Sports Science and Medicine ; Department of Exercise Physiology, Graduate School of Health and Sports Science, Juntendo University, Chiba.
Norio
N
Saga
Institute of Health and Sports Science and Medicine ; Department of Exercise Physiology, Graduate School of Health and Sports Science, Juntendo University, Chiba.
Hisashi
H
Naito
Institute of Health and Sports Science and Medicine ; Department of Exercise Physiology, Graduate School of Health and Sports Science, Juntendo University, Chiba.
Shizuo
S
Katamoto
Department of Medicine, Metabolism and Endocrinology.
Yoshio
Y
Fujitani
Department of Medicine, Metabolism and Endocrinology.
Takahisa
T
Hirose
Department of Medicine, Metabolism and Endocrinology ; Sportology Center, Graduate School of Medicine, Juntendo University, Tokyo ; Center for Therapeutic Innovations in Diabetes ; Center for Beta Cell Biology and Regeneration, Graduate School of Medicine, Juntendo University, Tokyo, Japan.
Ryuzo
R
Kawamori
Department of Medicine, Metabolism and Endocrinology ; Sportology Center, Graduate School of Medicine, Juntendo University, Tokyo.
Hirotaka
H
Watada
Adiponectin; Intramyocellular lipid; Physical activity