家蚕氟中毒后中肠NADPH-细胞色素P450还原酶和NADPH-细胞色素C还原酶活性的变化

为了探究家蚕对NaF的代谢机制,以家蚕耐氟品种T6和氟化物敏感品种734为材料,从5龄起蚕开始分别添食50、100、200、400 mg/kg NaF溶液处理后的桑叶,检测蚕体中肠微粒体酶液中的黄素蛋白NADPH-细胞色素P450还原酶(CPR)和NADPH-细胞色素C还原酶(CR)的活性变化。氟物化敏感品种734的4个NaF处理组第3天的中肠CPR活性低于对照组,其余时间几乎都高于对照组,400 mg/kg NaF处理组在第4天的CPR活性最高,且各NaF处理组的CPR活性差异显著(P<0.05);耐氟品种T6 NaF处理组和对照组的中肠CPR活性整体上呈先升后降的趋势,几乎都在第2天达到最高值,各组之间的差异不显著(P>0.05)。氟化物敏感品种734的4个NaF处理组的中肠CR活性呈现先升后降的趋势,而对照组呈下降趋势;耐氟品种T6的50、100、400 mg/kg NaF处理组在第1～2天的中肠CR活性呈明显下降趋势,之后的变化相对较小,对照组的CR活性仅在第3～4天略高于NaF处理组,而其余时间NaF处理组的CR活性较高。2个家蚕品种添食不同浓度NaF后的中肠CR活性差异均不显著(P>0.05)。试验结果显示,耐氟品种T6在NaF作用下中肠的CPR和CR活性变化范围(分别为对照组的0.4～2.0倍和0.3～2.9倍)远小于氟化物敏感品种734这2种酶的活性变化范围(分别为对照组的0.6～9.3倍和0.4～4.6倍)。初步推测CPR和CR与家蚕对氟化物代谢具有一定的关联。

Activity Variations of NADPH Cytochrome P450 Reductase and NADPH Cytochrome C Reductase in Midgut of Fluoride Poisoned Bombyx mori

In order to explore the metabolic mechanism of silkworm(Bombyx mori) to NaF,the fluoride resistant silkworm variety T6 and the sensitive variety 734 were used as materials.Their 5th instar newly exuviated larvae were fed with mulberry leaves which had been soaked in 50,100,200 and 400 mg/kg NaF solutions respectively and were examined for activity variations of NADPH cytochrome P450 reductase(CPR) and NADPH cytochrome C reductase(CR) of microsomal flavoproteins in midgut of silkworm.CPR activity in midgut of the sensitive variety 734 in 4 NaF-treated groups was lower than the control group on day 3 after feeding with NaF-treated mulberry leaves,and was higher than the control group in almost all the other time.CPR activity in 400 mg/kg NaF-treated group was the highest on day 4,and CPR activity in different NaF-treated groups had significant differences(P<0.05).CPR activity in midgut of the fluoride resistant silkworm variety T6 in both the NaF-treated group and the control group increased first and then declined,and almost reached their highest values on day 2,while there were no significant differences between different groups(P>0.05).CR activity in midgut of the sensitive silkworm variety 734 in 4 NaF-treated groups increased first and then declined,while that of the control group merely declined.CR activity in midgut of the fluoride resistant silkworm variety T6 in 50,100,400 mg/kg NaF-treated groups showed a clear downward trend on day 1 to day 2,and changed slightly afterwards.CR activity in the control group was only slightly higher than those of NaF-treated groups on day 3 to day 4,and was lower than those of the NaF-treated groups in all the other time.There was no significant difference on CR activity in midgut of the two silkworm varieties between various NaF concentration treatment groups(P>0.05).The experimental results showed that the variation range of CPR and CR activity in midgut of the fluoride resistant silkworm variety T6(0.4~2.0 folds and 0.3~2.9 folds respectively compared to the control group) was far less than that of the sensitive silkworm variety 734(0.6~9.3 folds and 0.4~4.6 folds respectively compared to the control group),suggesting certain relationship of CPR and CR with fluoride metabolism in silkworm.