BACKGROUND: The mobilization of endogenous stem cells is an effective way to promote repair following ischemic brain damage. Buyang Huanwu decoction (BHD) can effectively improve cerebral blood flow and protect against cerebral ischemia/reperfusion damage.OBJECTIVE: To study the effects of BHD on cell proliferation and differentiation in the hippocampal dentate gyrus of rats following cerebral infarction, to investigate the protective effects of BHD against cerebral infarction, and to analyze the dose-effect relationship.DESIGN, TIME AND SETTING: This randomized, controlled, animal study was performed at the Laboratory of Department of Physiology, Henan College of Traditional Chinese Medicine, China from June 2007 to February 2008.MATERIALS: A total of 36 male, Sprague Dawley rats, aged 20-21 months, were equally and randomly assigned to the following groups: sham operation, model control, and nimodipine, as well as high-dose, moderate-dose, and low-dose BHD. BHD was composed of milkvetch root, Chinese angelica, red peony root, earthworm, peach seed, safflower, and Szechwan Iovage rhizome, which were provided by the Outpatient Department, Henan College of Traditional Chinese Medicine, China.METHODS: The Chinese medicinal ingredients described above were decocted. The extal carotid artery was ligated in rats from the sham operation group. Rat models of focal cerebral infarction were established by middle cerebral artery occlusion in the model control and nimodipine groups, as well as the high-dose, moderate-dose, and low-dose BHD groups. The drugs were administered by gavage 5 days, as well as 2 hours, prior to model induction. Rats in the nimodipine group were daily administered a 6 mg/kg nimodipine suspension by gavage. Rats in the high-dose, moderate-dose, and low-dose BHD groups were administered daily 26, 13, and 6.5 g/kg BHD, respectively. Rats in the sham operation and model control groups were treated with an equal volume of saline.MAIN OUTCOME MEASURES: The effects of BHD on neurological dysfunction score, brain water content, cell proliferation and differentiation in the hippocampal dentate gyrus, and pathological changes in the ischemic brain hemisphere were measured in cerebral infarction rats.RESULTS: Compared with the sham operation group, the neurological dysfunction score, brain water content, number of BrdU-positive cells, BrdU/NeuN-positive cells, and BrdU/GFAP-positive cells in the hippocampal dentate gyrus significantly increased in the model control group (P < 0.01). Compared with the model control group, neurological dysfunction score and brain water content were significantly decreased (P<0.01 or 0.05), as were the number of BrdU-positive and BrdU/NeuN-positive cells (P < 0.01 or 0.05). The number of BrdU/GFAP-positive cells was significantly reduced (P<0.05) in the nimodipine group, high-dose, moderate-dose, and low-dose BHD groups. Compared with the nimodipine group, the neurological dysfunction score was significantly reduced in the moderate-dose BHD group (P < 0.05). However, the number of BrdU-positive cells was significantly increased in the rat hippocampal dentate gyrus in the high-dose and moderate-dose BHD groups (P<0.01 or 0.05). The following was determined by microscopy: slightly disarranged neural cells, mild vascular dilatation, inflammatory cell infiltration, and light tissue edema were observed in the nimodipine group; inflammatory cell infiltration was reduced in the low-dose BHD group; cerebral edema and inflammatory cell infiltration were significantly reduced in the high-dose and in the moderate-dose BHD group. Electron microscopy revealed lipofuscin, slightly swollen mitochondria, and normal rough endoplasmic reticulum in the high-dose and moderate-dose BHD groups. Improvement was best in the moderate-dose BHD group.CONCLUSION: Cerebral ischemia activated proliferation of neural stem cells in the rat hippocampal dentate gyrus. The actions of BHD against cerebral ischemiaJrepeffusion damage correlated with proliferation and differentiation of neural stem cells in the hippocampal dentate gyrus. A moderate-dose of BHD resulted in the most effective outcome.