The therapeutic effect of epigallocatechin gallate on the neurological recovery after spinal cord injury in rat

English Keywords:Spinal cord injury  Epigallocatechin gallate  Neurotrophic factor  Apoptosis  Rat

English Abstract:

  【Abstract】 Objectives: To investigate the therapeutic effects and underlying mechanism of epigallocatechin gallate(EGCG) administered by subarachnoid injection in spinal cord injury(SCI) in rats. Methods: 40 adult Sprague-Dawley rats were randomly divided into four groups with 10 in each group as follows: sham group(group A), laminectomy only; control group(group B), after SCI, subarachnoid injection of same volume of control solution; 10mg/kg EGCG-treated group(group C), after SCI, 10mg/kg EGCG was given by subarachnoid injection; 20mg/kg EGCG-treated group(group D), after SCI, 20mg/kg EGCG was given by subarachnoid injection. SCI was induced by using the modified weight-drop method(10g×4cm) at T10 level. EGCG(10 or 20mg/kg) was administered by subarachnoid injection at lumbar level 4 immediately after SCI. At 1d, 3d, 1w, 2w, 3w and 4w of post-operation, the locomotor functional recovery was assessed by using open-field locomotor tests and inclined-plane tests. At 4 weeks of post-operation, the segments of spinal cord encompassing the injury site were removed for histopathological analysis. Immunohistochemical and Western blot analyses were performed to observe the expressions of: the brain-derived neurotrophic factor(BDNF), glial cell line-derived neurotrophic factor(GDNF), B cell CLL/lymphoma-2(Bcl-2) and Bcl-2-associated X protein(Bax). Results: In group A, the BBB score and inclined plate test angle did not change much after operation. While at 1d, 3d, 1w, 2w, 3w and 4w after operation, the BBB scores and inclined pate test angles of group B, C and D were significantly lower than those in group A(P＜0.05). At 1d and 3d after operation, the BBB scores and inclined-plated angles of group B, C and D did not show significantly difference(P＜0.05). At 1w, 2w, 3w and 4w after operation, the BBB scores and inclined plated test angles in group C and D were significantly higher than those in group B(P＜0.05). There were no differences between group C and D in the BBB scores and inclined plated test angles(P＞0.05). At 4w of post-operation, the LFB staining in group B, C and D shows less myelin distribution compared with group A(P＜0.05). Group C and D have more myelin distribution compared with group B(P＜0.05). Further, in the center of the injured cord, there was more myelin in group D than group C(P＜0.05). Immunohistochemistry result showed that the positive expressions of BDNF, GDNF, Bcl-2 and Bax in group A were weaker than those in group B, C and D. The positive expression of BDNF, GDNF and Bcl-2 in group C and D were higher than those in the group B, while, the expression of Bax was weaker. Western blot results showed that expressions of BDNF, GDNF, Bcl-2 and Bax in group B, C and D were much higher than those in the group A(P＜0.05). The expressions of BDNF and GDNF in group C and D were higher than group B(P＜0.05). There was no difference between group C and D. The expression of Bcl-2 in group C and group D was higher than group B(P＜0.05). The expressions of Bax in group C and D was lower than that in group B(P＜0.05). Moreover, the expression of Bax in group D was lower than that in group C(P＜0.05). Conclusions: EGCG administered by subarachnoid injection can significantly improve locomotor recovery, and this neuroprotective effect may be related to the up-regulation of BDNF and GDNF, and the inhibition of apoptosis-related proteins.