ABSTRACT Objectives : In this study, the anti-stress effects of ethanolic extract of Opuntiaficus-indica (OF70E) were investigated.Methods : To determine the effects of OF70E on physical stress, changes in whole-body cortisol level or behavior were monitored in zebrafish. After treatment with 0.9% saline or OF70E for 6 min, all fish underwent net handling stress (NHS), which induced physical stress. And t hen, we conducted open field test (OFT) or sacrificed fish for collecting body fluid from whole-body. We u sed the cortisol enzyme-linked immunoassay kit to measure the amount of cortisol in each zebrafish sample.Results : In result, compared with normal group which were not treated b y NHS, whole-body cortisol levels were significantly increased in stressed-control group. Compare d with control group, pretreatment with OF70E at concentrations of 25, 50 and 100 mg/L for 6min significantly inhibited the increase of whole-body cortisol levels induced by NHS(p<0.05). To anti-stress effects of OF70E on behavior, we conducted OFT after the induction of NHS following pretreatment of OF70E. As results of OFT, compared with unstressed-normal group, distance moved was significantly decreased by induction of NHS in stressed-control group ( p<0.05). OF70E-pretreatment blocked decreases of distance moved increased by NHS (p<0.05). And meandering movement, immobility and turn angle were significantly increase d by NHS in stressed-control group compared with unstressed-normal group (p<0.05). OF70E-pretreatment prevented the increases of meanderin g movement immobility and turn angle by NHS (p<0.05).Conclusions : In conclusion these results suggest that OF70E-pretreatment may prevent stress responses.Key words : Net handling stress, Zebrafish, Opuntiaficus-indica, Whole-body cortisol, Open field test
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