[Research on the influence of diammonium glycyrrhizinate on the expression of NF-kappaB and neuron apoptosis after spinal cord ischemia-reperfusion injury in rats].

OBJECTIVE: To investigate the influence of diammonium glycyrrhizinate (DG) on the expression of NF-kappaB and neuron apoptosis after spinal cord ischemia-reperfusion injury in rats.

METHODS: Fourty-eight healthy SD male rats, weighing 220-270 g, were randomly divided into the experimental group and the control group, with 24 rats in each group. A model of spinal cord ischemia-reperfusion injury was completed by intercepting the rats' abdominal aorta between right and left renal arteries for 30 minunts. In the experimental group, each rat was injected 20 mg/kg DG via sublingual vein 10 minutes before ischemia occurred. Equal qualities of physiological saline were injected into the rats in the control group. The two groups were observed at 3, 24, 72 and 168 hours after ischemia-reperfusion, respectively. Lumbar myeloid tissues were prepared at the different times, respectively. The expression of NF-kappaB p65 in lumbar myeloid tissues was analyzed by immunohistochemistry and the apoptosis of neurons was examined by TUNEL reaction. Meanwhile, histological changes of spinal cord were observed by HE staining. Then the correlation between NF-kappaB and neuron apoptosis was analyzed.

RESULTS: HE staining showed obvious histological changes of spinal cord of the two groups. In the control group, myeloid tissue edema and normal neurons were observed at 3 hours; there were more histological changes at 24 hours and 72 hours; vacuoles in gray matters and some survived neurons were seen at 168 hours. The histological changes at each time in the experimental group were fewer than those in the control group. The immunohistochemical staining showed that the expression of NF-kappaB p65 was observed. After ischemia-reperfusion, the expression strengthened at 3 hours, reached the peak at 24 hours and then weakened slowly. At 3, 24, 72 and 168 hours after ischemia-reperfusion, the absorbency (A) value of NF-kappaB p65 in the experimental group was 0.306 0 +/- 0.024 4, 0.396 4 +/- 0.022 7, 0.296 6 +/- 0.021 1 and 0.267 9 +/- 0.015 3, respectively, and that in the control group was 0.361 1 +/- 0.017 7, 0.496 6 +/- 0.020 1, 0.356 3 +/- 0.0210 and 0.3014 +/- 0.018 1, respectively. There were significant differences between the two groups (P < 0.05). The inhabitation ratio of NF-kappaB p65 expression by DG was 15.40%, 20.17%, 19.28% and 11.11% at 3, 24, 72 and 168 hours after ischemia-reperfusion, respectively. Neuron apoptosis was observed, which strengthened at 3 hours and was the most serious at 24 and 168 hours after ischemia-reperfusion. At 3, 24, 72 and 168 hours after ischemia-reperfusion, the A value of neuron apoptosis in the experimental group was 0.1710 +/- 0.029 1, 0.175 5 +/- 0.0311, 0.175 1 +/- 0.027 9 and 0.183 2 +/- 0.023 7, respectively, and that in the control group was 0.236 8 +/- 0.063 6, 0.241 2 +/- 0.042 6, 0.201 5 +/- 0.049 8 and 0.250 1 +/- 0.048 4, respectively. There were significant differences between the two groups (P < 0.05). The inhabitation ratio of neuron apoptosis by DG was 27.79%, 27.23%, 13.08% and 26.74% at 3, 24, 72 and 168 hours after ischemia-reperfusion, respectively. The expression of NF-kappaB in myeloid tissues was positively correlated with neurons apoptosis in the two groups (r = 0.838, P < 0.01).

CONCLUSION: Spinal cord ischemia-reperfusion injury may cause a marked expression of NF-kappaB and notable evidence of neurons apoptosis. DG can reduce neurons apoptosis by inhibiting the expression of NF-kappaB.