Endocrine Abstracts

Context: Polycystic ovary syndrome (PCOS) is associated with insulin resistance (IR) and obesity, both predisposing factors to type 2 diabetes. A very recently described adipokine, retinol-binding protein 4 (RBP-4), has been shown to modulate insulin signalling and possibly lead to IR. At present, there is no data that depict the relative expression of RBP-4 in either serum or adipose tissue of PCOS women.

Objectives: In women with PCOS compared to matched control women, we studied the mRNA expression of RBP-4 from subcutaneous (sc) and omental (om) adipose tissue and sc adipocytes. Furthermore, RBP4 protein levels were assessed in adipose tissue; serum RBP4 was also determined.

Methods: Real-time RT-PCR and western blotting were used to assess the relative mRNA and protein expression of RBP4. Biochemical measurements were also conducted. The Local Research Ethics Committee approved the study and all patients involved gave their informed consent, in accordance with the guidelines in The Declaration of Helsinki 2000.

Results: There was significant upregulation of RBP4 mRNA in both sc (P<0.05) and om (P<0.01) adipose tissue of PCOS women, when compared to normal controls; these findings were also reflected in isolated sc adipocytes (PCOS > controls; P <0.01). In addition to elevated serum RBP4 levels in women with PCOS (P<0.05), when compared to normal controls, RBP4 protein levels were significantly greater in both sc and om adipose tissue of PCOS women (P<0.05 and P<0.05, respectively).

Conclusions: RBP4, a new adipokine, is elevated in PCOS women. Our findings potentially introduce a novel concept into the aetiopathogenesis of insulin resistance in these women.