The Impact Of Ilexonin A On Expression Of Bfgf, GAP-43 And Neurogenesis After Cerebral Ischemia-reperfusion In Rats

OBJECTIVE To explore the effect of IlexoninA on expression of bFGF, GAP-43 and neurogenesis and its possible mechanism after cerebral ischemia- reperfusion in Rats.METHODS The model of Middle cerebral artery occlusion(MCAO) was established to transient focal ischemia by placement of an intraluminal filament at the origin of right middle cerebral artery. The rats were divided randomly into: control, sham operation, model and IlexoninA (IA20, 40mg/kg) treatment groups. Neuronogical behavior was evaluated by Longa's scoring method. Morphological changes were investigated by HE staining. TTC staining was applied to observe cerebral ischemia in MCAO model group and IlexoninA treatment groups. Immunohistochemistry and western bloting were used to observe the expression of GAP-43 and bFGF protein in the ischemic brain tissue at different time of ischemia and reperfusion. Brdu was used to identify new proliferated cells, and Brdu/NeuN double-labeled cells was defined as anagenetic neurons. The effects of IA intervention (20, 40mg/kg) on neurological deficit score and the expression of GAP-43, bFGF and newborn neurons in ischemia surrounding areas were mainly quantified.RESULTS Neurological deficits of model were peaked at 3d(P<0.05 compared to 14d and 28d).In control and sham groups, there were scattered GAP-43 positive cells (mainly in the cortex), and the number of GAP-43 positive cells were peaked at 7d in model group. With the prolongation of reperfusion, the expression of GAP-43 decreased to 14d compared to the control and sham groups(P<0.01). GAP-43 protein in the control group and sham group, was much less.In model group, there was a certain amount at 3d after reperfusion, reached to peak at 7d, then reduced gradually, to 28d was still expression. Similarly, bFGF protein reached its peak at 7d after reperfusion, and then decrcased gradually, compared to other model times (P<0.05). Fluorescent double-labeled showed that there were some scattered newborn neurons in sham operation group; the model after reperfusion, there was a small amount of Brdu and Brdu/NeuN expression at 3d, peaked at 7d, then gradually reduced to 28d, still slightly higher than 3d. Control group without Brdu and Brdu/NeuN expression. After the intervention of IA20mg/kg,40mg/kg, fluorescence double-labeled newborn neurons were increased at different degrees, the neurological deficit score decreased significantly, and the expression of GAP-43 and bFGF protein in ischemia surrounding areas were increased,compare to model group at corresponding time points (P<0.05), with pronounced effct at dose of 40mg/kg.CONCLUSION1.Cerebral ischemia reperfusion injury induced the expression of GAP-43 and endogenous neurotrophic factor bFGF in the early and late recovery time. It is speculated that the early expression of GAP-43 and bFGF were involved to promote the survival of peripheral neurons and promote the new axon regeneration and synapse remodeling, thus promoting the recovery of neurological function.2. IlexoninA can promote the increased of neurogenesis in the cortex surrounding ischemic, which may be passed through upregulation of GAP-43, bFGF to promote axon regeneration and synapse formation, and promote the repair and regeneration of neurons to play its role of neuroprotective. Therefore, IlexoninA may offer potential applications in the treatment of ischemic cerebrovascular disease.