Neuroprotective effect of ligustilide against ischaemia-reperfusion injury via up-regulation of erythropoietin and down-regulation of RTP801

BACKGROUND AND PURPOSE Ligustilide, the main lipophilic component of Danggui, has been reported to protect the brain against ischaemic injury. However, the mechanisms are unknown. Here, we investigated the roles of erythropoietin (EPO) and the stress-induced protein RTP801 in neuroprotection provided by ligustilide against ischaemia-reperfusion (I/R) damage to the brain. EXPERIMENTAL APPROACH The efficacy of ligustilide against I/R damage was assessed by neurological deficit, infarct volume and cell viability, using the middle cerebral artery occlusion model in rats in vivo and rat cultured neurons in vitro. EPO and RTP801 were analysed by Western blot. Over-expression of RTP801 was achieved by transfection of an expression plasmid. KEY RESULTS Ligustilide decreased the neurological deficit score, infarct volume and RTP801 expression and increased EPO transcription in I/R rats, and increased cell viability and EPO and decreased LDH release and RTP801 in I/R neurons. Also, ligustilide increased ERK phosphorylation (p-ERK). The positive effects of ligustilide on p-ERK, cell viability and EPO were blocked by PD98059, but not LY294002 and SB203580. In addition, transfection of SH-SY5Y cells with RTP801 plasmid increased RTP801 and LDH release, while ligustilide inhibited the effects of transfection on RTP801 expression and also increased cell viability. CONCLUSION AND IMPLICATIONS Ligustilide exerts neuroprotective effects against I/R injury by promoting EPO transcription via an ERK signalling pathway and inhibiting RTP801 expression, This compound could be developed into a therapeutic agent to prevent and treat ischaemic disorders.