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1 The effects of paeoniflorin (PF), a compound isolated from Paeony radix, on neurological impairment and histologically measured infarction volume following transient and permanent focal ischemia were examined in Sprague-Dawley rats.2 In transient ischemia model, rats were subjected to a 1.5-h occlusion of the middle cerebral artery (MCA). The administration of PF (2.5 and 5 mg kg À1 , s.c.) produced a dose-dependent decrease in both neurological impairment and the histologically measured infarction volume. Similar results were also obtained when PF (2.5, 5, and 10 mg kg À1 , s.c.) was given in permanent ischemia model. 3 The neuroprotective effect of PF (10 mg kg À1 , s.c.) was abolished by pretreatment of DPCPX (0.25 mg kg À1, s.c.), a selective adenosine A 1 receptor (A 1 R) antagonist. 4 PF (10, 40, and 160 mg kg À1 , i.v.) had no effect on mean arterial pressure (MAP) and heart rates (HR) in the conscious rat. Additionally, PF (10 À3 mol l À1) had no effect on noradrenaline-(NA-) or high K þ concentration-induced contractions of isolated rabbit primary artery. 6 The results demonstrated that activation of A 1 R might be involved in PF-induced neuroprotection in cerebral ischemia in rat. However, PF had no 'well-known' cardiovascular side effects of classical A 1 R agonists. The results suggest that PF might have the potential therapeutic value as an anti-stroke drug.

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