Berberine inhibits gluconeogenesis in spontaneous diabetic rats by regulating the AKT/MAPK/NO/cGMP/PKG signaling pathway

This work was aimed to investigate the action mechanism of berberine (BBR) on gluconeogenesis. The effects of BBR were examined in rat primary hepatocytes and confirmed in vivo in spontaneous diabetic rats. Protein levels were assessed by Western blot. Immunofluorescence staining was utilized for visualizing protein expression, while qRT-PCR helped for the determination of gene expression at the mRNA level. Besides, cGMP concentration was measured using ELISA, whereas NO level was assessed by spectrophotometry. BBR inhibited gluconeogenesis by downregulating G6Pase and PEPCK via inhibition of CREB phosphorylation. Moreover, BBR enhanced NO and cGMP concentrations, leading to the activation of the NO/cGMP/PKG signaling via activating AKT1/MAPK axis. The in vivo experiments were consistent with the findings obtained in vitro. Hence, BBR represents a drug candidate for diabetic patients and its mechanism of action may be driven via the AKT/MAPK/NO/cGMP/PKG pathway.