Effect of cyclovirobuxine D on human growth-associated protein 43 and neurocan expression in ischemic brain tissue of stroke-prone renovascular hypertensive rats

BACKGROUND: Experimental data indicate that human growth-associated protein 43 mRNA expression coincides with axonal growth during nerve ganglion development; while neurocan, secreted from astrocytes, can inhibit sprouting and elongation of the axonal growth cone. OBJECTIVE: To verify regulatory effects of cyclovirobuxine D (CVB-D) extracted from Chinese box branchlet on human growth-associated protein 43 (GAP-43), and neurocan expression in brain tissue of stroke-prone renovascular hypertensive (RHRSP) rats, at different time points after cerebral ische-mia/reperfusion. DESIGN: Randomized grouping design and controlled animal study. SETTING: This study was performed at the Center of Guangdong Hospital of Traditional Chinese Medicine (a national key laboratory) from March 2003 to September 2006. MATERIALS: 100 healthy male Sprague-Dawley rats, aged 2-3 months and weighing 90-120 g, were se- lected for this study. CVB-D was provided by Nanjing Xiaoying Pharmaceutical Factory (Batch number: 307701). METHODS: The initial tip of renal arteries was clamped bilaterally for 10 weeks to establish the RHRSP model. 100 RHRSP rats were randomly divided into 4 groups: naive group (n = 10), sham surgery group (n = 10), CVB-D group (n = 40), and lesion group (n = 40). Rats in the naive group did not undergo any treatment, and cervical vessels of rats in the sham surgery group were exposed, but not blocked. The right middle cerebral artery of rats in the CVB-D group and lesion group were occluded to establish cerebral ischemia. Rats in the CVB-D group were intraperitoneally injected with CVB-D (6.48 mg/kg) every day and with saline (1.5 mL/injection) twice a day. Rats in the lesion group were intraperitoneally injected with saline (2 mL/injection). MAIN OUTCOME MEASURES: Immunohistochemistry was applied to detect GAP-43 and neurocan expression in the ischemic penumbra region of CVB-D and lesion brains at 2 hours post-cerebral ischemia and at 1, 7, 14, and 30 days post-perfusion (n = 10 at each time point). Similarly, GAP-43 and neurocan expres- sion was detected in the right hemisphere of na?ve and sham-operated animals. The results were expressed as positive cells. RESULTS: A total of 100 rats were included in the final analysis. The number of GAP-43 positive cells in- creased in the CVB-D group 1, 7, 14, and 30 days post-cerebral ischemia/perfusion compared to the lesion group, as indicated by a significant difference between the CVB-D and lesion group (P < 0.05-0.01). The number of neurocan-positive cells decreased in the CVB-D group on the first day compared to the model group; however, there was no significant difference between the two groups (P > 0.05). On post-ischemia days 7, 14, and 30, the number of neurocan-positive cells in the CVB-D group was significantly less than in the lesion group (P < 0.05). Both, GAP-43 and neurocan expression was not detectable in brains of na?ve and sham-operated animals. CONCLUSION: CVB-D treatment up-regulated GAP-43 expression and down-regulated neurocan expression in the ischemic region of RHRSP rats.