Protective effects of the antioxidant Ginkgo biloba extract and the protease inhibitor aprotinin against Leiurus quinquestriatus venom-induced tissue damage in rats
J. Fatani, A.A. Al-Zuhair, H.I. Yaquob, H.A. Abdel-Fattah, A.I. El-Sayed, M.A. El-Sayed, F.
Oxidative stress and proteases have been implicated in several diseases and extensive evidence indicates that antioxidants and protease inhibitors help prevent organ functional damage. Leiurus quinquestriatus (LQQ) scorpion venom causes cellular injuries that may lead to multiple organ failure. Thus, the capability of the antioxidant "natural standardized extract of Gingko biloba leaves (Gin, EGb 761)" and the non-selective protease inhibitor, aprotinin, in ameliorating venom-induced biochemical alterations indicative of cellular injury and oxidative stress was studied to determine their effectiveness in protecting rats from venom-evoked cellular damages. Thus, in this study, rats were treated with LQQ venom (0.3mg.kg-1, subcutaneously) alone or after Gin (150mg.kg-1, orally, daily for 2 weeks before venom) and/or aprotinin (Apr, 46000 KIU.kg-1, intraperitoneally, 30 min before venom). Control groups were injected with saline or treatment modalities. Lungs and hearts were excised after decapitating rats (n=8/group) 60 min after venom injection and the following activities were measured: reduced glutathione (GSH), malondialdehyde (MDA) - an index of lipid peroxidation, glutathione peroxidase (GPx), glucose-6-phosphate dehydrogenase (G6PD), and lactate dehydrogenase (LDH). Our findings demonstrate that LQQ venomsignificantly elevated GSH (p 0.05 vs. control), MDA (p 0.05), G6PD (p 0.05), and LDH activities (p 0.001) in hearts of envenomed rats. The venom also elevated MDA (p 0.05 vs. control) and reduced GSH and GPx (p 0.05) in the lungs of envenomed rats. In general, pretreatment with EGb761 attenuated LQQ venom-evoked increases in GSH (p 0.05 vs. venom), MDA in rat hearts and lungs (p 0.05 vs. venom), plus LDH in the heart (p 0.01). Aprotinin alone significantly reduced the venom-elicited increase in G6PD and LDH activities and the decrease in GPx levels (p 0.05). In general, these protective effects of EGb761 on GSH, MDA (p 0.01 vs. venom) and LDH (p 0.001) in the heart and/or lung were potentiated when combined with aprotinin. We concluded that the effectiveness of EGb761 and Apr in ameliorating venom-evoked biochemical changes indicative of necrosis and free radical generation point out the involvement of oxidative stress and proteases in venom-evoked cellular damages seen in this study in isolated rat hearts and lungs.
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