Effect of ginkgo biloba L. extract on apoptosis and NF-κB signaling pathways in the spleen tissue of mice with radiation damage

Abstract

Objective To investigate the influence of Ginkgo biloba L. extract (EGB) on the expression of apoptosis-related protein and NF-κB signaling pathway in the spleen tissue of mice with radiation damage. Methods The mice were divided randomly into normal control group (NC), irradiation control group (IC), low dose EGB group (IC+EGBL), medium dose EGB group (IC+EGBM) and high dose EGB group (IC+EGBH) according to the random number table, with 12 rats in each group. The mice in the low, middle and high dose EGB groups were given EGB respectively by 5, 10, 20 mg/kg, and the normal and irradiation control group were given saline by intraperitoneal injection once daily for 14 days. On the 15th day, the mice in all groups were uniformly irradiated with 4.0 Gy γ-rays for one time except normal control group. After 24 hours, Bcl-2, Bax and caspase-3 protein expression were measured by immunohistochemical method. The IKKβ expression was detected by qRT-PCR method, and the content of NF-κB p65 and IKKα in serum was detected by Elisa method in spleen tissue. Results Comparing with IC group, the expression of Bax (54.31 ± 1.59, 42.04 ± 1.56, 32.08 ± 2.43 vs. 68.68 ± 3.12) and caspase-3 protein (55.73 ± 2.61, 45.81 ± 2.59, 36.78 ± 2.23 vs. 72.18 ± 1.84) in IC+EGBL, IC+EGBM and IC+EGBH group were significantly decreased (P<0.05), the expression of Bcl-2 protein (30.33 ± 1.28, 39.80 ± 2.86, 44.42 ± 3.64 vs. 22.80 ± 2.01) in IC+EGBL, IC+EGBM and IC+EGBH group significantly increased (P<0.05), the expression of IKKβ mRNA (1.43 ± 0.06, 1.31 ± 0.06, 1.17 ± 0.09 vs. 1.64 ± 0.10) and the level of NF-κB p65 (129.38 ± 8.41 pg/ml, 111.28 ± 9.09 pg/ml, 95.41 ± 6.88 pg/ml vs. 145.64 ± 6.29 pg/ml) and IKKα (160.10 ± 8.94 pg/ml, 144.00 ± 8.36 pg/ml, 108.84 ± 13.74 pg/ml vs. 176.38 ± 8.54 pg/ml) in IC+EGBL, IC+EGBM and IC+EGBH group significantly decreased (P<0.05). Conclusions The EGB can reduce the expression of apoptotic protein Bax and caspase-3 in spleen cells induced by radiation, elevate the expression level of apoptotic protein Bcl-2, and inhibit the damage caused by radiation by regulating NF-κB signaling pathway. Key words: Ginkgo folium; Extracts; Radiation protection; Apoptosis; NF-kappa B; Mice