Raised serum, adipocyte, and adipose tissue retinol-binding protein 4 in overweight women with polycystic ovary syndrome: effects of gonadal and adrenal steroids

J Clin Endocrinol Metab. 2007 Jul;92(7):2764-72. doi: 10.1210/jc.2007-0091. Epub 2007 Apr 24.


Context: Polycystic ovary syndrome (PCOS) is associated with insulin resistance and obesity. Recent studies have shown that serum retinol-binding protein 4 (RBP4) levels increase with obesity. Currently, no data exist on the relative expression of RBP4 in either serum or adipose tissue of PCOS women.

Objectives: mRNA expression of RBP4 from sc and omental (om) adipose tissue and sc adipocytes in overweight PCOS women were compared with matched controls; RBP4 protein in adipose tissue and serum RBP4 levels were also assessed. Additionally, we studied the effects of testosterone, 17beta-estradiol, androstenedione, and dehydroepiandrosterone sulfate on RBP4 expression in adipose tissue explants.

Design: Real-time RT-PCR and Western blotting were used to assess the relative mRNA and protein expression of RBP4. Biochemical measurements were also performed.

Results: Compared with controls, there was significant up-regulation of RBP4 mRNA in sc (P < 0.05) and om (P < 0.01) adipose tissue as well as isolated sc adipocytes (P < 0.01) of PCOS women. In addition to elevated serum RBP4 levels in PCOS women (P < 0.05), RBP4 protein levels were significantly greater in sc and om adipose tissue of PCOS women (P < 0.05 and P < 0.05, respectively). Furthermore, in human sc and om adipose tissue explants, 17beta-estradiol significantly increased RBP4 mRNA expression, protein levels, and secretion into the culture media (P < 0.05).

Conclusions: The precise reason for elevated levels of RBP4 in overweight PCOS women is unknown, but it appears that 17beta-estradiol may play a role in their regulation in adipose tissue.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adipocytes / cytology
  • Adipocytes / drug effects*
  • Adipocytes / physiology*
  • Adult
  • Androgens / pharmacology
  • Androstenedione / pharmacology
  • Cells, Cultured
  • Dehydroepiandrosterone Sulfate / pharmacology
  • Estradiol / pharmacology
  • Female
  • Gene Expression / drug effects
  • Gene Expression / physiology
  • Glucose Transporter Type 4 / genetics
  • Glucose Transporter Type 4 / metabolism
  • Humans
  • Hypoglycemic Agents / pharmacology
  • Insulin / pharmacology
  • Omentum / physiology
  • Overweight / physiology*
  • Polycystic Ovary Syndrome / physiopathology*
  • RNA, Messenger / metabolism
  • Retinol-Binding Proteins / genetics*
  • Retinol-Binding Proteins / metabolism
  • Retinol-Binding Proteins, Plasma
  • Steroids / pharmacology*
  • Subcutaneous Fat / physiology
  • Testosterone / pharmacology


  • Androgens
  • Glucose Transporter Type 4
  • Hypoglycemic Agents
  • Insulin
  • RBP4 protein, human
  • RNA, Messenger
  • Retinol-Binding Proteins
  • Retinol-Binding Proteins, Plasma
  • SLC2A4 protein, human
  • Steroids
  • Testosterone
  • Androstenedione
  • Estradiol
  • Dehydroepiandrosterone Sulfate