苯并[a]芘染毒小鼠神经组织的形态学改变及细胞凋亡

Study on the morphological damage and cell appoptosis of nerve tissue in mice exposed to benzopyrene

目的 研究苯并 [a]芘 (BaP)染毒小鼠神经组织的损伤状况。方法 将 5 0只昆明种小鼠随机分为 5组 ,每组 10只 ,染毒组分为高、中、低 3个剂量组 ,并设溶剂对照及空白对照组。染毒组用含BaP的植物油溶剂进行腹腔注射 ,每组分别注射 7.8、3.2和 1.3mg/kg ,每周 4次 ,连续染毒 10周。溶剂对照组用植物油溶剂作平行处理 ,空白对照组不做处理。 10周后取各组小鼠脑组织大脑皮质、海马、小脑和脑干部分以及脊髓、坐骨神经制作普通石蜡切片及电镜切片 ,光镜及电镜观察组织损伤的形态学指标 ,并用DNA断点末端核糖核酸转移酶地高辛标记 (TUNEL)法进行细胞原位凋亡检测。结果 BaP染毒组在光镜及电镜下可见到组织损伤的形态学改变 ,高剂量组各组织在光镜及电镜下可见较为集中的坏死区 ,未做原位凋亡检测 ;中剂量组原位细胞凋亡阳性率为 90 .0 2 %～94 .2 2 % ;低剂量组原位细胞凋亡阳性率为 6 2 .4 5 %～ 77.5 4 % ;而溶剂对照及空白对照组各组织未见组织损伤 ,原位细胞凋亡阳性率很低 (4.6 0 %～ 5 .5 7% )。结论 BaP具有神经毒性 ,可损伤神经组织并使神经细胞胞核内DNA断裂 。

Objective To stduy the toxicological effects of benzopyrene(BaP) on mammalian animal's nerve tissue. Methods 50 Kunming mice were divided into 5 groups at random,the exposed groups(3 dose level groups),the vehicle control group and standard control group.Every group got 10 mice.The exposed groups were treated by intraperitoneal injection with BaP dissolved in vegetable oil at 7.8,3.2 and 1.3 mg/kg respectively,4 times/week,for 10 weeks,the vehicle control group were given vegetable oil and the standard control group were not given any treatment.All the mice were anesthetized with 0.02 mol/L pentobarbital and infused with 1.33 mol/L paraformaldehyde dissolved in PBS through heart after 10 weeks.Then the brain,spinal cord and sciatic nerve were removed.Slices of these tissues were made and morphological changes were observed by optical microscope and electron microscope.Cell appoptosis was examined by TUNEL(TdT mediated x dUTP nick end labeling) method. Results Morphological observations showed tissue injury in BaP exposed groups.There were focal necrosis areas found in the high dose group.The cell apoptosis rates in 3.2 and 1.3 mg/kg groups were 90.02%～ 94.22% and 62.45%～77.54% respectively,significantly higher than those of vehicle control group and standard control group(4.60%～5.57%). Conclusion BaP is neurotoxic.It could damage the nerve tissue as well as induce DNA breaks and cell apoptosis.