纳米二氧化钛染毒对大鼠脑皮层细胞内钙离子浓度和钙蛋白酶1表达的影响

Effects of nano-TiO_2 on cerebral cortex intracellular calcium concentration and calpain 1 expression in rats

目的研究纳米二氧化钛染毒对大鼠脑皮层细胞内钙离子浓度([Ca2+]i)和钙蛋白酶1(calpain 1)表达的影响。方法将50只健康SPF级雄性Wistar大鼠随机分为5组,分别为对照(蒸馏水)组和低(62.5 mg/kg)、中(125 mg/kg)和高(250mg/kg)剂量纳米二氧化钛染毒组及微米二氧化钛(250 mg/kg)染毒组,每组10只。采用灌胃方式进行染毒,每天1次,连续染毒60d,测定大鼠脑皮层细胞内[Ca2+]i和calpain 1的表达水平。结果与对照组比较,仅高剂量纳米二氧化钛染毒组大鼠脑皮层细胞内[Ca2+]i升高,差异有统计学意义(P<0.05);而低、中剂量纳米二氧化钛及微米二氧化钛染毒组大鼠脑皮层细胞内[Ca2+]i略有升高趋势,但差异均无统计学意义(P>0.05)。且随着纳米二氧化钛染毒剂量的升高,大鼠脑皮层细胞内[Ca2+]i呈上升趋势。与对照组比较,纳米二氧化钛及微米二氧化钛染毒组大鼠脑皮层组织calpain 1表达水平略有升高趋势,但差异均无统计学意义(P>0.05)。结论在本实验剂量下,纳米二氧化钛染毒可导致大鼠脑皮层细胞内[Ca2+]i升高,但并未影响calpain 1的表达。

Objective To study the effects of nano-titanium dioxide on intracellular free calcium concentration（[Ca^2＋]i） and the expression of calpain 1 in the cerebral cortex of rats. Methods A total of 50 SPF Wistar rats were randomly divided into five groups：control group（distilled water）,three nano-titanium dioxide groups（62.5,125 and 250 mg/kg body weight） and microsize group（250 mg/kg body weight）. Titanium dioxide was given to the rats through gavage,once a day for 60 consecutive days. The intracellular [Ca2 ＋]iand the expression of calpain 1 in cortex were detected. Results Compared with the control group, the intracellular [Ca^2＋]iincreased significantly in 250 mg/kg nano-titanium dioxide groups（P〈0.05）;The intracellular[Ca^2＋]iraised a little in 62.5 mg/kg and 125 mg/kg nano-titanium dioxide groups and micro-size group,the differences were not statistically significant. With the increase of nano-titanium dioxide infected dose, the intracellular [Ca^2＋]iincreased in the cerebral cortex of rats. Compared with the control group,the expression of calpain 1 in cortex raised a little in the nano-titanium dioxide groups and micro-size group,but there was no statistically significant difference. Conclusion Nano-titanium dioxide exposure may cause increase of [Ca^2＋]ilevel in rats,but not significantly effect on the expression of calpain 1.