锰接触对大鼠生长发育的毒性影响

A Study on the Toxicologic Effect of Manganese on Rats

目的评价锰对机体生长发育造成的毒性影响。方法24只SD大鼠随机分为2组,分别口服高、低剂量氯化锰(MnCl2·4H2O)。另选12只SD大鼠为对照组。检测大鼠作锰接触后对食物利用率、血清、脑匀浆的单胺氧化酶(MAO)和超氧化物岐化酶(SOD)活性的影响,以及对中脑黑质TH免疫反应阳性神经元的影响。结果锰接触60d后高、低剂量组大鼠的食物利用率无明显改变;大鼠血清和脑匀浆的MAO比对照组明显升高,而SOD活性则明显降低;中脑黑质、酪氨酸羟化酶(TH)免疫反应阳性神经元的反应强度、神经元数密度(NV)和反应阳性产物的相对光密度(OD),高、低剂量组大鼠均比对照组显著降低。结论短期的锰接触对大鼠的一般情况影响不大;随着锰接触剂量的增加,血清和脑匀浆的MAO则明显升高,而SOD活性明显降低;且锰接触会导致中脑黑质TH阳性反应神经元的损害。

Objective To evaluate the toxicity of manganese on the growth and development of rats. Method 36 male SD rats were randomly divided into 3 groups： high dose Mn-exposed group （MnCl2·4H2O, 5 g/L）, low dose Mn-exposed group （0.5 g/L） and control group （distilled water only）. Manganese containing water was given ad libitum. Food consumption rate, levels of monoamine oxidase （MAO） and the activities of superoxide dismutase （SOD） in blood and brain were determined. Immuno-reactivity of tyrosine hydroxylase （TH） in substantia nigra （SN） of midbrain was analyzed. Result Changes of food consumption rate were not found in these 3 groups of rat. Compared with the control group, activities of MAO were increased, while the SOD activity was decreased in the high dose and low dose Mn-exposed group, and the difference was significant. In SN, NV and OD of the TH-positive neurons were decreased in both high dose and low dose Mn-exposed groups than in the rats in control group. Conclusion The increase in MAO activities was correlated with the dosage of manganese.The increase in MAO activity was accompanied with a decreased in SOD aeitivity. Mn-exposure resulted in the damage of TH-positive neurons in SN of midbrain in rats.