title: Effect of endurance training on retinol-binding protein 4 gene expression and its protein level in adipose tissue and the liver in diabetic rats induced by a high-fat diet and streptozotocin.
abstract: OBJECTIVE
  The present study was designed to investigate from which tissues the decrease in retinol-binding protein 4 (RBP4) expression could contribute to the improvement of serum RBP4 and insulin resistance (IR) after endurance training.
  
  
  METHODS
  Male 7-week-old Wistar rats were randomly assigned into four groups including control (C), trained (T), diabetic control (DC) and trained diabetic (TD). At 8 weeks-of-age, diabetes was induced by a high-fat diet and intraperitoneal injection of low-dose streptozotocin (STZ; 35 mg/kg). Rats in the T and TD groups carried out a 7-week exercise program on a motorized treadmill (15-20 m/min for 20 min/day for 5 weeks), whereas the C and DC remained sedentary in their cages. Tissues gene expression and protein levels of RBP4 were assessed by using real-time polymerase chain reaction and western blot, respectively, while serum RBP4 was measured using an enzyme-linked immunosorbent assay kit.
  
  
  RESULTS
  Exercise significantly improved IR and reduced serum concentration of RBP4 in the TD group. This reduction of serum RBP4 was accompanied by decreased RBP4 protein expression in visceral fat tissue. In contrast, exercise had no significant effect on RBP4 expression in liver and subcutaneous fat tissue in the TD group. Exercise also significantly decreased RBP4 gene expression in visceral fat tissue and muscle, whereas the effect of exercise on liver RBP4 messenger ribonucleic acid expression was not significant.
  
  
  CONCLUSIONS
  The present study showed that the mechanism for RBP4 reducing the effect of endurance training could involve decreased RBP4 messenger ribonucleic acid expression and its protein level in adipose tissue in STZ-induced diabetic rats.
authors.affiliation: Obesity and Eating Habits Research Center Endocrinology and Metabolism Molecular-Cellular Sciences Institute Tehran Iran ; Endocrinology and Metabolism Research Center Endocrinology and Metabolism Research Institute Tehran University of Medical Sciences Tehran Iran.
authors.forename: Masoume
authors.initials: M
authors.lastname: Mansouri
authors.affiliation: Department of Exercise Physiology Faculty of Physical Education and Sport Science Shahid Bahonar University Kerman Iran.
authors.forename: Rohollah
authors.initials: R
authors.lastname: Nikooie
authors.affiliation: Osteoprosis Research Center Endocrinology and Metabolism Research Institute Tehran University of Medical Sciences Tehran Iran.
authors.forename: Abasali
authors.initials: A
authors.lastname: Keshtkar
authors.affiliation: Endocrinology and Metabolism Research Center Endocrinology and Metabolism Research Institute Tehran University of Medical Sciences Tehran Iran.
authors.forename: Bagher
authors.initials: B
authors.lastname: Larijani
authors.affiliation: Biosensor Research Center Endocrinology and Metabolism Molecular-Cellular Sciences Institute Tehran Iran.
authors.forename: Kobra
authors.initials: K
authors.lastname: Omidfar
keywords: Endurance training; Insulin resistance; Retinol‐binding protein 4 gene and protein expression