Effect of apigenin on microglia in penumbra after acute transient focal cerebral ischemia-reperfusion injury in rats / 中草药

ABSTRACT

Objective: To study the effect of apigenin on the expression of microglia in penumbra and cerebral water content after acute transient focal cerebral ischemia-reperfution injury in rats. Methods: The acute transient focal cerebral ischemia-reperfusion models in rats were established with the modified suture method. Male Sprague-Dawley rats were randomly divided into Sham group, model group, and apigenin groups (there were 6, 24, 48, 72 h, and 7 d reperfusion treatments in the model and apigenin groups, n = 12). All of them are 11 groups. The neurological behavior scores were valued. By FITC labeled isolectin B4 (FITC-ILB4) histochemistry staining, the infiltration of monocytes and the changes of cell morphology and number of brain-derived microglia in penumbra of six rats in every group were observed under laser scanning confocal microscope (LSCM). Water content was measured in isolated brain tissue of other six rats. Results: The positive cells of ILB4 (ILB4+) including microglia cells (Rhod 6G-) and infiltration of monocytes (Rhod 6G+) were found in cerebral ischemic area around penumbra of rats after 6 h ischemia-reperfusion in model group; The morphology changed to Amoeba-like; Microglia increased significantly after 48 h and reached to peak in 72 h, which mainly belonged to the proliferation of brain-derived microglia in Amoeba-like morphology. Microglia cell decreased in 7 d, and microglia in apigenin group obviously decreased more than that in model group (P<.05, 0.01) with the similar morphological change in corresponding time points. In 48 and 72 h of cerebral ischimia, the water content in brain tissue of rats in apigenin group was markedly lower than that in model (P<0.01). There was negative line correlation between the neurological behavior score and the number of ILB4 + cells in penumbra of model group (r=-0.415, P<.05). Apigenin could reduce the degree of neurological deficiency in model group and mitigate the brain injury effectively. Conclusion: A part of microglia cells inpenumbra are associated with brain injury; Apigenin shows the protection on acute transient focal cerebral ischemia-reperfution injury in rats, which maybe relates with down-regulating the microglia cell number and inhibiting the excessive activation of microglia cell.