Brain-derived neurotrophic factor reduces blood glucose level in obese diabetic mice but not in normal mice

Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family. However, it is not yet known if BDNF works on the endocrine system itself. Here we report that BDNF improves hyperglycemia in obese diabetic animals. BDNF reduced the blood glucose level in obese db/db diabetic mice in which the effect of BDNF was age-dependent and high under the condition of hyperinsulinemia, while BDNF showed no effect on non-diabetic db/m mice. These results suggest that BDNF ameliorates insulin resistance by enhancing insulin action in peripheral tissues. Furthermore, BDNF was found to reduce the plasma insulin level in db/db mice. Among the neurotrophin family, NT-3 also reduced the blood glucose level in db/db mice. These results provide a novel insight that neurotrophin functions on the endocrine system as well as the nervous system.