Circulatory changes of the novel adipokine adipolin/CTRP12 in response to metformin treatment and an oral glucose challenge in humans.

OBJECTIVE: Adipolin/CTRP12 is a novel adipokine with anti-inflammatory and glucose-lowering properties in rodents. We sought to investigate the effects of metformin treatment (850 mg twice daily for 6 months) and a 2 h 75 g oral glucose tolerance test (OGTT) on serum adipolin concentrations in humans. DESIGN: Cross-sectional study [PCOS (n = 83) and control (n = 39) subjects]. Serum adipolin was measured by ELISA. Metformin treatment (850 mg twice daily for 6 months) was offered to all women with PCOS, 34 women participated but 21 women completed 6 months of metformin therapy. Reasons for subjects not completing the study were nausea and gastrointestinal side effects (n = 4), pregnancies (n = 5), noncompliance (n = 2) and loss of contact (n = 2). RESULTS: Metformin treatment (850 mg twice daily for 6 months) substantially increased serum adipolin concentrations (P < 0·05) in women with polycystic ovary syndrome (PCOS), a pro-inflammatory state associated with obesity, diabetes, dyslipidaemia and atherosclerosis. Furthermore, changes in waist-hip ratio, glucose, triglycerides, CRP and carotid intima media thickness showed significant negative associations with changes in adipolin levels (P < 0·05, P < 0·01); in multiple regression analyses, only changes in glucose were predictive of changes in adipolin levels (ß = -0·570, P = 0·009). Serum adipolin decreased significantly in response to the OGTT in PCOS and control subjects at 90 min (P < 0·05) and 120 min (P < 0·01). CONCLUSIONS: Adipolin and/or novel pharmacologic agents that increase adipolin's circulating concentrations might constitute a novel approach in the treatment of insulin resistant states.

Metformin increases the novel adipokine cartonectin/CTRP3 in women with polycystic ovary syndrome.

CONTEXT: Recently cartonectin was reported as a novel adipokine, with lower levels in diet-induced obese mice, glucose-lowering effects, and antiinflammatory and cardioprotective properties. Polycystic ovary syndrome (PCOS) is a proinflammatory state associated with obesity, diabetes, dyslipidemia, and cardiovascular complications. OBJECTIVES: The objective of the study was to investigate cartonectin levels and regulation in sera and adipose tissue (AT) as well as the effects of metformin of women with PCOS and control subjects. DESIGN: This was a cross-sectional study [PCOS (n = 83) and control (n = 39) subjects]. Real-time PCR and Western blotting were used to assess mRNA and protein expression of cartonectin. Serum cartonectin was measured by an ELISA. RESULTS: Serum and omental adipose tissue cartonectin were significantly lower in women with PCOS compared with control subjects (P < .05 and P < .01, respectively). Furthermore, cartonectin showed a significant negative association with body mass index, waist to hip ratio, glucose, insulin, total cholesterol, low-density lipoprotein-cholesterol, triglycerides, High sensitivity C-reactive protein (hs-CRP) and intima-media thickness (P < .05 and P < .01, respectively); in multiple regression analyses, triglycerides (P =.040) and hs-CRP (P = .031) were predictive of cartonectin levels (P < .05). After 6 months of metformin treatment, there was an associated increase in serum cartonectin (P < .05). Importantly, changes in hs-CRP were significantly negatively correlated with changes in serum cartonectin (P = .033). Finally, cartonectin protein production and secretion into conditioned media were significantly increased by metformin in control human omental AT explants (P < .05). CONCLUSIONS: Serum and omental AT cartonectin are lower in women with PCOS. Metformin treatment increases serum cartonectin levels in these women and in omental AT explants.