| OBJECTIVE Free radical theory for radiation damage believes that, a great deal of free radicals can be induced that result in peroxidation of the whole body. Grape Seed Procyanidins (GSP), a kind of nature plant polyhydroxybenene compound extracted from grape seeds, are well known for their antioxidant activity and the ability of scavenging free radicals. However, these compounds have also been reported to have a series of biopharmacological activities, such as cardiovascular protection, anticarcinogenic, and antibacterial actions. Peroxidative reaction is one of the important mechanisms for irradiation damage, but related researches about its protective role in radiation damage were less reported. This study was designed to investigate the protective role of single GSP, as well as GSP combined with casein, in radiation-induced damage and intend to explain the mechanisms. METHODS Rats in normal control group and irradiation group were raised with routine feed specially composed by the experimental animal center, and rats in GSP group and combining group were freely fed and supplemented with 1% GSP and 1% GSP+5% casein respectively. Ten days later, all rats except those of normal control group were exposed to whole-body 60Co-gamma-radiation at a dose of 7 Gy for 7'40'', with distance from the radiation source of 1.52 m. Seven days later, 6 survival rats randomly selected from each group were killed. The spleen index, WBC and the level of serum MDA, SOD, endotoxin were determined with TBA method and colorimetry et al. The apoptosis rate and bcl-2 proteins expression of spleen cells and the jejunum mucosal morphometrics were also detected by flow cytometry and scanning electron microscope. Mice in normal control group and irradiation group were raised with routine feed, and mice in GSP group and combining group were freely fed and supplemented with 0.5% GSP and 0.5% GSP+3% casein respectively. Ten days later, all mice except those of normal control group were exposed to whole-body 60Co-gamma-radiation at a dose of 6 Gy, the survival rate of the irradiated mice in 30 days was observed. RESULTS 1. Percentage of vitality: 1.1 the percentage of vitality of the mice irradiated with γ-rays of 6 Gy in 30 days: irradiation group was 35%, GSP group was 45%, combining group was 55%. Compared with irradiation group, the survival rate in GSP group and combining group were improved by 28.6% and 57.1% respectively. 1.2 the percentage of vitality of the rats irradiated with γ-rays of 7 Gy in 7 days: irradiation group was 55%, GSP group was 65%, combining group was 90%. Compared with irradiation group, the survival rate in GSP group and combining group were improved by 18.2% and 63.6% respectively. 2. Effect on peroxidative impairments: 2.1 the level of serum MDA(nmol/ml): normal control group was 6.20±0.84, irradiation group was 11.43±1.27, GSP group and combining group were significantly lower than irradiation group, were 9.05±0.95 and 8.57±0.95 respectively(P<0.05,P<0.01). 2.2 the level of serum SOD(U/ml): normal control group was 241.7±12.3, irradiation group was 172.1±9.3, GSP group and combining group were significantly higher than irradiation group, were 196.6±10.5 and 210.7±11.7 respectively(P<0.01). 3. Effect on jejunum mucosa barrier impairments: 3.1 the jejunum mucosal morphometrics: In irradiation group intestinal mucosa was thin and mucosa atrophy occurred, villus was short, in mucosa lamina propria plenty of lymphocytes were seen. SEM showed the top of villus had obvious ulcerations. In GSP group and combining group, the pathomorphologic injury degree was obviously slighter than irradiation group. 3.2 the level of serum endotoxin(Eu/ml): normal control group was 75.7±8.7, irradiation group was 343.5±35.0, GSP group and combining group were significantly lower than irradiation group, were 293.0±22.0 and 261.5±24.7 respectively(P<0.05, P<0.01). 4. Effect on immune system 4.1 WBC(×109/L): normal control group was 9.2±0.83, irradiation group was 0.35±0.10, GSP group and combining group were significantly higher than irradiation group, were 0.65±0.18 and 0.85±0.37 respectively(P<0.05).4.2 the spleen index(g/Kg): normal control group was 2.48±0.22, irradiation group was 1.41±0.13, GSP group and combining group were significantly higher than irradiation group, were 1.61±0.14 and 1.63±0.14 respectively(P<0.05). 4.3 the apoptosis rate of spleen cells(%): normal control group was 6.5±1.7, irradiation group was 46.8±5.8, GSP group and combining group were significantly lower than irradiation group, were 35.3±2.4 and 27.9±1.8 respectively(P<0.01). 4.4 bcl-2 proteins expression of spleen cells: The results showed that bcl-2 proteins expression of spleen cells were obviously up-regulated in GSP group and combining group compared with in irradiation group. 5. Effect on protein nutritional status and the function of liver: 5.1 the level of serum TP and Alb(g/L): normal control group were 72.3±7.3 and 28.7±3.1, irradiation group was 52.8±4.2 and 13.2±1.8, GSP group and combining group were significantly higher than irradiation group, were 61.3±4.7,16.0±2.0 and 63.8±5.2,19.7±2.2 respectively(P<0.05, P<0.01). 5.2 the level of serum GPT and GOT(IU/L): normal control group were 35.3±3.8 and 91.8±8.2, irradiation group was 55.3±4.8 and 135.8±12.5, GSP group and combining group were significantly lower than irradiation group, were 46.8±3.2,116.8±10.6 and 43.5±4.2,113.2±11.8 respectively(P<0.05, P<0.01). CONCLUSION Our experiment results showed that GSP or alternatively GSP combined with casein, could effectively improve the survival rate in irradiated mice and rates, obviously relieve peroxidative impairments and jejunum mucosa barrier impairments from acute radiation injury, significantly attenuate the sharp decreasing of spleen index, WBC, serum proteins and the liver function impairments following irradiation, and also could inhibit spleen cells apoptosis induced by irradiation, markedly up-regulate bcl-2 protein expression in spleen cells in radiation-injuried rates, however effects of combining group were better.
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