Substantial neuroprotection against K⁺ deprivation-induced apoptosis in primary cerebellar granule neurons by novel dimer bis(propyl)-cognitin via the activation of VEGFR-2 signaling pathway

Summary: Background: Neuronal loss via apoptosis in CNS is the fundamental mechanism underlying various neurodegenerative diseases. Compounds with antiapoptotic property might have therapeutic effects for these diseases. In this study, bis(propyl)-cognitin (B3C), a novel dimer that possesses anti-AChE and anti-N-methyl-d-aspartate receptor activities, was investigated for its neuroprotective effect on K⁺ deprivation-induced apoptosis in cerebellar granule neurons (CGNs). Methods: Cerebellar granule neurons were switched to K⁺ deprived medium with or without B3C. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium assay, fluorescein diacetate (FDA)/propidium iodide (PI) staining, Hoechst staining, and DNA laddering assays were applied to detect cytotoxicity and apoptosis. Additionally, the expression of p-VEGFR-2, p-Akt, p-glycogen synthase kinase 3β (GSK3β), and p-extracellular signal-regulated kinase (ERK) was examined in CGNs. Results: Switching CGNs to K⁺ deprived medium resulted in remarkable apoptosis, which could be substantially blocked by B3C treatment (IC₅₀, 0.37 μM). Moreover, a rapid decrease in p-Tyr1054-VEGFR-2 was observed after the switch. B3C significantly reversed the inhibition of p-Tyr1054-VEGFR-2 as well as Akt and ERK pathways. VEGFR-2 inhibitor PTK787/ZK222584, as well as PI3-K inhibitor LY294002 and MEK inhibitor PD98059, each abolished the neuroprotective effect of B3C. Conclusions: Our results demonstrate that B3C blocks K⁺ deprivation-induced apoptosis in CGNs through regulating VEGFR-2/Akt/GSK3β and VEGFR-2/ERK signaling pathways, providing a molecular insight into the therapeutic potential of B3C for the treatment of neurodegenerative diseases.