Adipose tissue plasticity during catch-up fat driven by thrifty metabolism: relevance for muscle-adipose glucose redistribution during catch-up growth.
OBJECTIVE
Catch-up growth, a risk factor for later type 2 diabetes, is characterized by hyperinsulinemia, accelerated body-fat recovery (catch-up fat), and enhanced glucose utilization in adipose tissue. Our objective was to characterize the determinants of enhanced glucose utilization in adipose tissue during catch-up fat.


METHODS
White adipose tissue morphometry, lipogenic capacity, fatty acid composition, insulin signaling, in vivo glucose homeostasis, and insulinemic response to glucose were assessed in a rat model of semistarvation-refeeding. This model is characterized by glucose redistribution from skeletal muscle to adipose tissue during catch-up fat that results solely from suppressed thermogenesis (i.e., without hyperphagia).


RESULTS
Adipose tissue recovery during the dynamic phase of catch-up fat is accompanied by increased adipocyte number with smaller diameter, increased expression of genes for adipogenesis and de novo lipogenesis, increased fatty acid synthase activity, increased proportion of saturated fatty acids in triglyceride (storage) fraction but not in phospholipid (membrane) fraction, and no impairment in insulin signaling. Furthermore, it is shown that hyperinsulinemia and enhanced adipose tissue de novo lipogenesis occur concomitantly and are very early events in catch-up fat.


CONCLUSIONS
These findings suggest that increased adipose tissue insulin stimulation and consequential increase in intracellular glucose flux play an important role in initiating catch-up fat. Once activated, the machinery for lipogenesis and adipogenesis contribute to sustain an increased insulin-stimulated glucose flux toward fat storage. Such adipose tissue plasticity could play an active role in the thrifty metabolism that underlies glucose redistribution from skeletal muscle to adipose tissue.
Summermatter
Serge
S
Department of Medicine/Physiology, University of Fribourg, Fribourg, Switzerland.
Marcelino
Helena
H
Arsenijevic
Denis
D
Buchala
Antony
A
Aprikian
Olivier
O
Assimacopoulos-Jeannet
Françoise
F
Seydoux
Josiane
J
Montani
Jean-Pierre
JP
Solinas
Giovanni
G
Dulloo
Abdul G
AG
D017667:Adipocytes / Q000378:metabolism / Q000473:pathology; D000273:Adipose Tissue / Q000254:growth & development* / Q000378:metabolism*; D000818:Animals; D001823:Body Composition; D003924:Diabetes Mellitus, Type 2 / Q000453:epidemiology; D004041:Dietary Fats / Q000378:metabolism*; D004734:Energy Metabolism; D005947:Glucose / Q000378:metabolism*; D005951:Glucose Tolerance Test; D006130:Growth Disorders / Q000150:complications / Q000378:metabolism*; D006801:Humans; D006946:Hyperinsulinism / Q000378:metabolism; D008055:Lipids / Q000502:physiology*; D008297:Male; D018482:Muscle, Skeletal / Q000254:growth & development* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D022722:Thermogenesis
D004041:Dietary Fats; D008055:Lipids; D005947:Glucose