Effects of pyridoxine on a high-fat diet-induced reduction of cell proliferation and neuroblast differentiation depend on cyclic adenosine monophosphate response element binding protein in the mouse dentate gyrus.

In this study, we challenged pyridoxine to mice fed a high-fat diet (HFD) and investigated the effects of pyridoxine on HFD-induced phenotypes such as blood glucose, reduction of cell proliferation and neuroblast differentiation in the dentate gyrus using Ki67 and doublecortin (DCX), respectively. Mice were fed a commercially available low-fat diet (LFD) as control diet or HFD (60% fat) for 8 weeks. After 5 weeks of LFD or HFD treatment, 350 mg/kg pyridoxine was administered for 3 weeks. The administration of pyridoxine significantly decreased body weight in the HFD-treated group. In addition, there were no significant differences in hepatic histology and pancreatic insulin-immunoreactive (-ir) and glucagon-ir cells of the HFD-treated group after pyridoxine treatment. In the HFD-fed group, Ki67-positive nuclei and DCX-ir neuroblasts were significantly decreased in the dentate gyrus compared with those in the LFD-fed mice. However, the administration of pyridoxine significantly increased Ki67-positive nuclei and DCX-ir neuroblasts in the dentate gyrus in both LFD- and HFD-fed mice. In addition, the administration of pyridoxine significantly increased the protein levels of glutamic acid decarboxylase 67 (GAD67) and brain-derived neurotrophic factor (BDNF) and the immunoreactivity of phosphorylated cyclic AMP response element binding protein (pCREB) compared with the vehicle-treated LFD- and HFD-fed mice. In contrast, the administration of pyridoxine significantly decreased HFD-induced malondialdehyde (MDA) levels in the hippocampus. These results showed that pyridoxine supplement reduced the HFD-induced reduction of cell proliferation and neuroblast differentiation in the dentate gyrus via controlling the levels of GAD67, pCREB, BDNF, and MDA.