Low-intensity treadmill exercise and bright light upregulate brain-derived neurotrophic factor expression and intracellular signaling pathway in rat hippocampus and cerebral cortex

Abstract

Continuous exercise and bright light affect brain function, particularly in seasonal affective disorders. However, the underlying mechanism of action remains unclear. In this study, we examined whether low-intensity treadmill exercise and 4 weeks of bright light exposure change the expression of brain-derived neurotrophic factor (BDNF), phosphoinositide 3-kinase/AKT (PI3K/AKT) pathway, protein kinase C (PKC), extracellular signal-regulated kinases (ERK1/2), cyclic adenosine monophosphate (cAMP) response element-binding protein (CREB), vascular endothelial growth factor (VEGF), and glycogen synthase kinase-3β (GSK-3β) in the brain of 5-week old Sprague–Dawley male rats by performing western blot analysis. We demonstrated that BDNF expression significantly increased with exercise and light exposure compared to a control group. Moreover, we found that the expression levels of PI3K, PKC, p-ERK1/2, p-CREB, p-AKT, and VEGF increased significantly in the hippocampus and cortex with exercise and light exposure compared to the levels from a control group. However, phosphorylated GSK-3β level was unchanged, and even slightly decreased with exercise and light exposure. These results suggest that low-intensity treadmill exercise and bright light exposure induce BDNF expression and activate its downstream kinase signaling pathway, which in turn activate CREB-mediated transcription of neurotrophic factors and may stimulate neurogenesis and improve neuronal functions.