Abstract: Objective To study the effects of flavonoids from scutellaria stem and leaf(SSF) on memory impairment and the expression of choline acetyltransferase(ChAT) and nitric oxide synthase(NOS) in chronic cerebral ischemia rats. Methods The model of chronic cerebral ischemia was established by bilateral carotid artery occlusion for 2 months with female SD rats. The functions of learning and memory were detected by Morris water maze, the expression of ChAT, neuronal nitric oxide synthase(nNOS), inducible nitric oxide synthase(iNOS) and endothelial nitric oxide synthase(eNOS) were examined by immunohistochemical method. Results Compared with the sham group, memory ability was significantly decreased, the expressions of ChAT and eNOS significantly decreased, as well as the expressions of nNOS and iNOS were dramatically increased in cerebral ischemia group rats. However, the treatment with 17.5, 35 and 70 mg·kg^-1 SSF for 38 d of the ischemic rats showed a significant improvement in impairment of memory ability and the abnormal changes of ChAT, eNOS nNOS and iNOS in the brain of ischemic rats. Conclusion SSF can improve the memory impairment induced by chronic cerebral ischemia in rats, which may be related to regulation of the abnormal changes of ChAT and NOS in the ischemic rats’ brain.

Key words: flavonoids from stem and leaf of scutellaria baicalensis georgi, chronic cerebral ischemia, Morris water maze, chloine acetyltransferase, nitric oxide synthase