Dose-dependent effects of procyanidin on nerve growth factor expression following cerebral ischemia/ reperfusion injury in rats

Feng Li; Hai Xie; Ying Gao; Tongxia Zhan

摘要：BACKGROUND: Recently, grape seed procyanidin (GSP) has been shown to be exhibit antioxidant effects, effectively reducing ischemia/reperfusion injury and inhibiting brain cell apoptosis.OBJECTIVE: To study the effects of GSP on nerve growth factor (NGF) expression and neurological function following cerebral ischemia/reperfusion injury in rats.DESIGN: Randomized controlled study based on SD rats.SETTING: Weifang Municipal People's Hospital. MATERIALS: Forty-eight healthy adult SD rats weighing 280-330 g and irrespective of gender were provided by the Experimental Animal Center of Shandong University. GSP derived from grape seed was a new high-effective antioxidant provided by Tianjin Jianfeng Natural Product Researching Company (batch number: 20060107). Rabbit-anti-rat NGF monoclonal antibody was provided by Beijing Zhongshan Biotechnology Co., Ltd., and SABC immunohistochemical staining kit by Wuhan Boster Bioengineering Co., Ltd. METHODS: The present study was performed in the Functional Laboratory of Weifang Medical College from April 2006 to January 2007. Forty-eight SD rats were randomly divided into the sham operation group, ischemia/reperfusion group, high-dose GSP (40 mg/kg) group, or low-dose GSP (10 mg/kg) group (n = 12 per group). Ischemia/reperfusion injury was established using the threading embolism method of the middle cerebral artery. Rats in the ischemia/reperfusion model group were given saline injection (2 mL/kg i.p.) once daily for seven days pre-ischemia/reperfusion, and once more at 15 minutes before reperfusion. Rats in the high-dose and low-dose GSP groups were injected with GSP (20 or 5 mg/mL i.p., respectively, 2 mL/kg) with the same regime as the ischemia/reperfusion model group. The surgical procedures in the sham operation group were as the same as those in the ischemia/reperfusion model group, but the thread was approximately 10 mm long, thus, the middle cerebral artery was not blocked. MAIN OUTCOME MEASURES: NGF expression in the ischemic penumbra of the temporal cortex was detected by immunohistochemistry, and positive cells counted by light microscopy (×400). The positive cell rate was calculated by [(positive cells/total cells) × 100%]. Neurological function was scored after 2-hour ischemia/48-hour reperfusion. Higher scores reflected more severe neurofunctional defect. RESULTS: The positive rate of NGF expression in all groups receiving ischemia/reperfusion was significantly higher than that in the sham operation group (q=3.87, P < 0.05). The positive rate of NGF expression in the high-dose and low-dose GSP groups were significantly higher than that in the model group (q=4.12, P < 0.05), and were greater in the high-dose compared to low-dose GSP groups (q=4.22, P < 0.05). Neurological function scores in the high-dose and low-dose GSP groups were significantly lower than that in the ischemia/reperfusion model group (q=3.92, P < 0.05). Neurological function score in the high-dose GSP group was significantly less than that in the low-dose GSP group (q=4.02, P < 0.05). CONCLUSION: GSP may up-regulate brain-derived NGF expression in a dose-dependent manner following cerebral ischemia/reperfusion injury in order to improve neurological function and protect the brain.