Neuroprotective Effect of Hwangryunhaedok-tang on the Brain Ischemia Induced by Four-Vessel Occlusion in Rats

황련해독탕(黃連解毒湯)의 4-VO로 유발한 흰쥐뇌허혈에 대한 신경보호효과

Objectives: Hwangryunhaedok-tang (Huang-lian-jie-du-tang, HRHDT, 黃連解毒湯) is a traditional Korean herbal medicine that is formulated with Coptidis Rhizoma, Phellodendri Cortex, Scutellariae Radix and Gardeniae Fructus. HRHDT is cold (寒) and bitter (苦) in nature and has general properties of clearing heat and detoxifying (淸熱解毒), strengthening the stomach and settling the liver (健胃平肝), and reducing inflammation, fever and swelling. This formula can prevent and treat artherosclerosis, hyperplasia of the endothelium, cerebral fluid circulation, cerebral vascular deterioration through aging, impairment of neurotransmitters, or disruption of the functioning of the cerebral cortex following infection or trauma. The purpose of the study reported here was to determine the neuroprotective effect of HRHDT on global ischemia induced by 4-vessel occlusion in Wistar rats. Methods: HRHDT extract was lyophilized after extraction with 85% methanol and 100% water. Rats were induced to 10 minutes of forebrain ischemia by 4-vessel occlusion (4-VO) and reperfused again. HRHDT was administered with a dose of 100 mg/kg, and 500 mg/kg of 85% methanol extracts and 100 mg/kg of 100% water extracts, respectively, at 0 min and 90 min after 4-VO. Rats were killed at 7 days after ischemia and the number of CA1 pyramidal neurons was counted in hippocampal sections stained with cresyl violet. Results: Body temperature of animals showed no significant difference between saline-treated groups and HRHDT extracts-treated groups until 5 hours of reperfusion. This result indicated that neuroprotective effects of HRHDT extracts were not due to hypothermic effects. The administration of HRHDT showed a significant neuroprotective effect on hippocampal CA1 neurons at 7 days after ischemia compared to the saline-treated group (P<0.001). HRHDT methanol extracts of 100 mg/kg, 500 mg/kg and HRHDT water extracts of 100 mg/kg showed 88.5%, 98.3% and 95.1 % neuroprotection, respectively. Conclusions: The results of this study demonstrate that administration of HRHDT is highly effective in reducing neuronal damage in response to transient global cerebral ischemia. HRHDT may involve many mechanisms that might account for its high degree of efficacy. A number of factors including free radicals, glutamate, calcium overload, NO, and various cytokines have been proposed to have an important role in causing neuronal death after short periods of global ischemia. Further studies are needed to know the neuroprotective mechanisms of HRHDT.