L-NBP, a multiple growth factor activator, attenuates ischemic neuronal impairments possibly through promoting neuritogenesis.

In China, L-3-n-butylphthalide (L-NBP) showed promising pharmacological actions in stroke treatment. Analyzing the characteristics of L-NBP might provide valuable hints for new drug design. The current study is aimed to determine the effects of L-NBP on neuritogenesis and further to elucidate the neuronal protection against stroke impairment in vitro. L-NBP was applied to rat pheochromocytoma PC12 cells and cultured rat cortical neurons under the normoxic condition and the oxygen-glucose deprivation/reoxygenation (OGD/R) insults, respectively. Immunofluorescence staining, western blot analysis, Sholl analysis, lactate dehydrogenase (LDH) release assay, 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium (MTT) reduction assay and enzyme-linked immunosorbent assay (ELISA) were performed. L-NBP could concentration-dependently stimulate the development of growth cones, enhance the neuritic branches and synapse formation. It indicated that L-NBP possibly promoted the neuritogenic activity in a stage-dependent manner. Further research proved that L-NBP could promptly activate epidermal growth factor (EGF) receptor, up-regulate the expressions of extracellular signal-regulated kinase1/2 (ERK1/2), cAMP response element-binding protein (CREB) and E-26-like protein 1 (ELK-1). In addition, L-NBP enhanced the sustained expressions of brain derived neurotrophic factor (BDNF) and nerve growth factor (NGF). The inhibition to the receptors of EGF, NGF,BDNF could attenuate L-NBP induced neuritogenic and neuronal survival after the OGD/R toxicity. Basing on these investigations, we concluded that L-NBP might reconstruct the impaired neuronal network and improved the neuronal complexity after the ischemic insults through multiple pathways which at least were via the activations of EGF receptor, BDNF and NGF related signals.