Plasma levels and adipose tissue messenger ribonucleic acid expression of retinol-binding protein 4 are reduced during calorie restriction in obese subjects but are not related to diet-induced changes in insulin sensitivity.
BACKGROUND
Retinol-binding protein 4 (RBP4) may play a role in the development of insulin resistance.


OBJECTIVE
We investigated whether RBP4 adipose tissue mRNA expression and plasma level are related to insulin sensitivity during a diet-induced weight loss.


METHODS
Obese women followed a dietary intervention composed of a 4-wk very low-calorie diet (VLCD), a 2-month low-calorie diet, and 3-4 months of a weight maintenance (WM) phase.


METHODS
Clinical investigation was performed before and at the end of each phase. Insulin sensitivity was assessed with the euglycemic hyperinsulinemic clamp. Adipose tissue mRNA and plasma levels of RBP4 were determined using reverse transcription-quantitative PCR and ELISA, respectively.


RESULTS
Weight and fat mass decreased during VLCD and were stabilized during WM. Glucose disposal rate increased during VLCD and remained elevated thereafter. Plasma levels of RBP4 decreased after VLCD and, although increasing at subsequent phases, remained lower than prediet values. Adipose tissue mRNA levels were diminished after VLCD, and increased during low-calorie diet and WM to reach basal values. Basal RBP4 levels or diet-induced variations of RBP4 were not different in lean women and two groups of obese women with high- and low-insulin sensitivity.


CONCLUSIONS
Severe calorie restriction promotes a reduction in adipose tissue and plasma levels of RBP4. The study does not bring evidence for a role for RBP4 in the regulation of diet-induced changes in insulin sensitivity.
Vitkova
Michaela
M
Institut National de la Santé et de la Recherche Médicale Université Paul Sabatier U858, IFR31, BP 84225, 31432 Toulouse Cedex 4, France.
Klimcakova
Eva
E
Kovacikova
Michaela
M
Valle
Carine
C
Moro
Cédric
C
Polak
Jan
J
Hanacek
Jiri
J
Capel
Frédéric
F
Viguerie
Nathalie
N
Richterova
Blanka
B
Bajzova
Magda
M
Hejnova
Jindra
J
Stich
Vladimir
V
Langin
Dominique
D
D000273:Adipose Tissue / Q000502:physiology*; D000328:Adult; D031204:Caloric Restriction; D004038:Diet, Reducing; D005260:Female; D015870:Gene Expression / Q000502:physiology; D015309:Glucose Clamp Technique; D051275:Glucose Transporter Type 4 / Q000235:genetics; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D008875:Middle Aged; D009765:Obesity / Q000178:diet therapy* / Q000503:physiopathology*; D012333:RNA, Messenger / Q000378:metabolism; D012177:Retinol-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D054839:Retinol-Binding Proteins, Plasma; D015431:Weight Loss / Q000502:physiology
D051275:Glucose Transporter Type 4; D007328:Insulin; C101326:RBP4 protein, human; D012333:RNA, Messenger; D012177:Retinol-Binding Proteins; D054839:Retinol-Binding Proteins, Plasma; C495692:SLC2A4 protein, human