Eucommia Leaf Extract Induces BDNF Production in Rat Hypothalamus and Enhances Lipid Metabolism and Aerobic Glycolysis in Rat Liver

Background: Mutations in the brain-derived neurotrophic factor (BDNF) gene and its receptor, tyrosine receptor kinase B (TrkB), have been reported to cause severe obesity in rodents. Our previous study demonstrated that the oral administration of 5% Eucommia leaf extract (ELE) or ELE aroma treatment (ELE aroma) produced anti-obesity effects. Objective: In this study, we investigated the effects of ELE on glycolysis and lipid metabolism in male Sprague–Dawley rats, as well as the effects of ELE on BDNF in rat hypothalamus. Methods and Results: A significant reduction and a reduction tendency in the respiratory quotient were observed in association with 5% ELE and ELE aroma treatment, respectively. Furthermore, RT-qPCR results showed significant increases in Cpt2, Acad, Complex II, and Complex V mRNA levels in the liver with both treatments. In addition, in rat hypothalamus, significant elevations in BDNF, Akt, PLCγ proteins and CREB phosphorylation were observed in the 5% ELE group and the ELE aroma group. Furthermore, the Ras protein was significantly increased in the ELE aroma group. On the other hand, significant dephosphorylation of ERK1/2 was observed by the western blotting in the 5% ELE group and the ELE aroma group. Conclusion: These findings suggest that the ELE treatment enhances the lipid metabolism and increases the aerobic glycolytic pathway, while ELE-induced BDNF may affect such energy regulation. Therefore, ELE has the possibility to control metabolic syndrome.