OBJECTIVE: To examine the effects of Yokukansan(YKS) extract on two endogenous modulators of anxiety, brain-derived neurotrophic factor(BDNF)and serotonin (5-HT)_(2A) receptors pharmacologically, in the ischemic rat model of dementia.METHODS: The cerebral ischemia(CI) was induced by bilateral occlusion of the vertebral and common carotid arteries(4-vessel occlusion ischemia). The CI was combined with the amyloid-β42 peptide(A42) injected intracerebroventricularly, and referreβdto as CI+Aβ. Anxiety-like behaviors were assessed by elevated plus maze(enclosed arm), light/dark transition test(dark chamber), and open-field test.Wet-dog shakes were induced by the 5-HT_(2A) receptor agonist 2, 5-dimethoxy-4-iodoamphetamine(DOI). The concentration of BDNF in serum was determined by enzyme-linked immuno sorbent assay.RESULTS: CI + Aβ increased anxiety, as demonstrated by the increase of time spent in the enclosed arms and dark chambers, and locomotion in the outer zone of the open field(thigmotaxis). CI + Adecreased the serum concentration of BDNF. YKS reβ-duced the anxiety-like behaviors, suppressed the DOI-induced wet-dog shakes and increased serum BDNF concentrations.CONCLUSION: Our findings suggest that YKS extract improves CI + Aβ-induced anxiety by antagonizing 5-HT_(2A) receptors and increasing BDNF.