Effect and mechanism of berberine against polycystic ovary syndrome

What is the prevalence of insulin resistance (IR) and the contributions of intrinsic and extrinsic IR in women diagnosed with polycystic ovary syndrome (PCOS) according to the Rotterdam criteria? We report novel clamp data in Rotterdam diagnosed PCOS women, using World Health Organization criteria for IR showing that women with PCOS have a high prevalence of IR, strengthening the evidence for an aetiological role of IR in both National Institutes of Health (NIH) and Rotterdam diagnosed PCOS in lean and overweight women. PCOS is a complex endocrine condition with a significant increased risk of gestational diabetes and type 2 diabetes. Using a cross-sectional study design, 20 overweight and 20 lean PCOS (Rotterdam criteria), 14 overweight and 19 lean body mass index (BMI)-matched control non-PCOS women underwent clinical measures of IR after a 3-month withdrawal of insulin sensitizers and the oral contraceptive pill. In an academic clinic setting, glucose infusion rate (GIR) on euglycaemic-hyperinsulinaemic clamp was investigated as a marker of insulin sensitivity. PCOS women were more IR than BMI-matched controls (main effect for BMI and PCOS; P < 0.001). IR was present in 75% of lean PCOS, 62% of overweight controls and 95% of overweight PCOS. Lean controls (mean ± SD; GIR 339 ± 76 mg min⁻¹ m⁻²) were less IR than lean PCOS (270 ± 66 mg min⁻¹ m⁻²), overweight controls (264 ± 66 mg min⁻¹ m⁻²) and overweight PCOS (175 ± 96 mg min⁻¹ m⁻²). The negative relationship between BMI and IR reflected by GIR was more marked in PCOS (y = 445.1 - 7.7x, R² = 0.42 (P < 0.0001) than controls (y = 435.5 - 4.6x, R² = 0.04 (P < 0.01)). The study did not use glucose tracer techniques to completely characterize the IR, as well as the lack of matching for body composition and age. IR is exacerbated by increased BMI, supporting intrinsic IR in PCOS. BMI impact on IR is greater in PCOS, than in controls, irrespective of visceral fat, prioritizing lifestyle intervention and the need for effective therapeutic interventions to address intrinsic IR and prevent diabetes in this high-risk population. This investigator-initiated trial was supported by grants from the National Health & Medical Research Council (NHMRC) Grant number 606553 (H.J.T., N.K.S. and S.K.H.) as well as Monash University and The Jean Hailes Foundation. H.J.T. is an NHMRC Research Fellow. N.K.S. is supported through the Australian Government's Collaborative Research Networks (CRN) programme. A.E.J. is a Jean Hailes and NHMRC scholarship holder. The authors declare that there is no conflict of interest associated with this manuscript.

We identify berberine (BBR), a compound isolated from a Chinese herb, as a new cholesterol-lowering drug. Oral administration of BBR in 32 hypercholesterolemic patients for 3 months reduced serum cholesterol by 29%, triglycerides by 35% and LDL-cholesterol by 25%. Treatment of hyperlipidemic hamsters with BBR reduced serum cholesterol by 40% and LDL-cholesterol by 42%, with a 3.5-fold increase in hepatic LDLR mRNA and a 2.6-fold increase in hepatic LDLR protein. Using human hepatoma cells, we show that BBR upregulates LDLR expression independent of sterol regulatory element binding proteins, but dependent on ERK activation. BBR elevates LDLR expression through a post-transcriptional mechanism that stabilizes the mRNA. Using a heterologous system with luciferase as a reporter, we further identify the 5' proximal section of the LDLR mRNA 3' untranslated region responsible for the regulatory effect of BBR. These findings show BBR as a new hypolipidemic drug with a mechanism of action different from that of statin drugs.