Effect of the flavonoid, oroxylin A, on transient cerebral hypoperfusion-induced memory impairment in mice.

Oroxylin A is a flavonoid compound that is found in the root of Scutellaria baicalensis Georgi. The aim of this study was to determine the effects of oroxylin A on memory impairment induced by transient bilateral common carotid artery occlusion (2VO) in mice. The ameliorating effect of oroxylin A on memory impairment was investigated using a passive avoidance task, the Y-maze task, and the Morris water maze task in mice. Oroxylin A was found to significantly reverse 2VO-induced cognitive impairments in the passive avoidance and Y-maze tasks in a dose dependant manner (P<0.05). Moreover, oroxylin A (5 mg/kg, p.o.) shortened the escape-latency and prolonged swimming times in the target quadrant during the probe trial in the Morris water maze task (P<0.05). Histochemical and immunohistochemical studies showed that the number of Nissl bodies and OX-42 positive cells in the hippocampal CA1 and dentate gyrus regions were attenuated by oroxylin A. Moreover, phosphorylated cAMP response element-binding protein (CREB) and brain derived neurotrophic factor (BDNF) positive cell numbers were markedly increased in animals treated with oroxylin A than in untreated 2VO controls. These results suggest that oroxylin A dramatically attenuates the memory impairment induced by 2VO, and that this effect may be mediated by the neuroprotective effects of oroxylin A as supported oroxylin A induced reductions in activated microglia and increases in BDNF expression and CREB phosphorylation.