Berberine is known to improve glucose and lipid metabolism disorders,
but the mechanism is still under investigation. In this paper, we explored the effects of berberine
on the weight, glucose levels, lipid metabolism, and serum insulin of KKAy mice and investigated
its possible glucose and lipid-regulating mechanism. We randomly divided KKAy mice into two groups: berberine
group (treated with 250 mg/kg/d berberine) and control group. Fasting blood glucose (FBG), weight,
total cholesterol (TC), triglyceride (TG), high-density lipoprotein-cholesterol (HDL-c), low-density
lipoprotein-cholesterol (LDL-c), and fasting serum insulin were measured in both groups. The oral glucose
tolerance test (OGTT) was performed. RT2 PCR array gene expression analysis was performed using skeletal
muscle of KKAy mice. Our data demonstrated that berberine significantly decreased FBG, area under the
curve (AUC), fasting serum insulin (FINS), homeostasis model assessment insulin resistance (HOMA-IR) index,
TC, and TG, compared with those of control group. RT2 profiler PCR array analysis showed that berberine
upregulated the expression of glucose transporter 4 (GLUT4), mitogen-activated protein kinase 14 (MAPK14),
MAPK8(c-jun N-terminal kinase, JNK), peroxisome proliferator-activated receptor α (PPARα), uncoupling
protein 2 (UCP2), and hepatic nuclear factor 4α(HNF4α), whereas it downregulated the expression of PPARγ,
CCAAT/enhancer-binding protein (CEBP), PPARγ coactivator 1α(PGC 1α), and resistin. These results suggest
that berberine moderates glucose and lipid metabolism through a multipathway mechanism that includes
AMP-activated protein kinase-(AMPK-) p38 MAPK-GLUT4, JNK pathway, and PPARα pathway.