大气颗粒物暴露对小鼠妊娠和胚胎发育的影响

摘要

目的 探讨大气颗粒物(PM)亚急性暴露对小鼠妊娠和胚胎发育的影响.方法选择雌、雄小鼠各40只按1∶1合笼,将妊娠的雌鼠随机分为对照(A组)、小剂量PM暴露(B组)、中剂量PM暴露(C组)、大剂量PM暴露(D组)、超大剂量PM暴露(E组),每组8～11只.从妊娠0～19 d分别向A组小鼠咽后壁接种磷酸盐缓冲液,向B、C、D、E组小鼠咽后壁接种PM标准品SRM1649a混悬液(浓度分别为0.09、0.52、1.85、69.2μg/μl).于自动分娩发生时剖宫取胎,观察孕鼠体质量、妊娠天数、仔鼠宫内存活及生长情况和肝、肺组织的病理改变,计算仔鼠肺及肝脏体系数,检测仔鼠肺CYP1A1、肝CYP1A2蛋白及mRNA的表达.结果 (1)各组孕鼠均未出现自然死亡.各组孕鼠妊娠1、7 d时体质量比较,差异均无统计学意义(P＞0.05);妊娠至14、18 d时,E组孕鼠体质量[分别为(41.8±5.8)及(48.9±8.9)g]明显低于A组[分别为(45.9±1.8)及(56.2±4.9)g],差异均有统计学意义(P＜0.05).E组孕鼠妊娠天数[(19.3±1.3)d]也明显低于A组[(20.5±0.7)d],差异有统计学意义(P＜0.05);A、B、C、D组孕鼠间妊娠天数分别比较,差异均无统计学意义(P＞0.05).各组仔鼠肺体系数及肝体系数比较,E组孕鼠[(1.21±0.18)及(4.68±0.21)%]高于A、B、C及D组,且差异均有统计学意义(P＜0.05).(2)E组仔鼠的死亡率(23.0%)高于A(0.8%)、B(0.9%)、C(1.7%)及D组(3.7%),差异均有统计学意义(P＜0.05);A、B、C、D组仔鼠的死亡率依次升高,但差异无统计学意义(P＞0.05).(3)E组仔鼠肝、肺病理改变显著,肝脏特征性病理改变包括肝组织结构紊乱、肝细胞浊肿、胞质淡染;多数肝细胞胞质内出现脂肪变性,部分肝细胞固缩,胞质深染;肝组织内见炎细胞浸润和点灶状坏死.肺特征性病理改变包括肺细支气管管腔变窄、黏膜下层小血管充血;间质、肺泡水肿,肺泡间隔增厚,泡内、细支气管周中性粒细胞及淋巴细胞浸润.C、D组上述病变程度次之,A、B组正常或变化轻微.(4)E组仔鼠肺CYP1A1和肝CYP1A2蛋白表达水平(分别为1.20±0.40及2.55±0.89)高于A组(0.77±0.36及2.08±0.31),两组比较,差异有统计学意义(P＜0.05).肺CYP1A1 mRNA表达,C(0.36±0.12)、D(0.41±0.08)、E组(0.43±0.11)高于A组(0.21±0.10),D、E组高于B组(0.28±0.10),分别比较,差异均有统计学意义(P＜0.05).肝CYP1A2 mRNA表达,C(0.37±0.13)、D(0.36±0.14)、E组(0.43±0.16)高于A组(0.21±0.03),E组高于B组(0.24±0.11),分别比较,差异均有统计学意义(P＜0.05).结论 PM具有胚胎毒性作用.超大剂量PM亚急性暴露可导致小鼠的不良妊娠结局;中、高剂量PM暴露可导致癌相关基因CYP1 A1和CYP1 A2表达的上调,可能对个体的后期发育有潜在的不良效应.%Objective To investigate subacute exposure of airborne particulate matter (PM) on pregnancy and fetal development in female mice. Methods Forty female and forty male ICR adult mice group (A), small (B) , middle (C) , large (D) or overdose (E) PM challenge groups (n = 8 - 11), and were administered with 30 μl of phosphate buffered solution (A) or resuspended standard PM SRM 1649a at 0.09 (B), 0.52 (C), 1.85 (D) or 69.2 (E) μg/μl, once per trid from d 0 till d 19 of pregnancy via instillation onto the base of the tongue. Fetal mice were harvested by cesarean section at the time when spontaneous delivery occurred. Body weight of the pregnant mice, gestational days, intrauterine survival and growth, hepatic and pneumonic histopathological changes of the fetal mice were investigated. Lung/body and liver/body weight ratios were calculated. Expressions of mRNA and protein of CYP1A1 in the fetal lung and CYP1 A2 in the fetal liver were assayed. Results (1) All of the pregnant mice survived pregnancy throughout the entire experiment. Body weight of the pregnant mice was not significantly different among all the groups at gestational d 1 and 7 (P ＞ 0.05), but significantly lower in group E [(41.8 ± 5.8) and (48.9 ± 8.9) g] than in group A [(45.9 ± 1.8) and (56.2 ± 4.9) g] at gestational d 14 and 18 (P ＜0.05). The gestational days were significantly decreased in group E [(19.3 ± 1.3) d] when compared with group A [(20.5 ± 0.7) d; P ＜ 0.05] and were not significantly different among groups A, B, C and D (P ＞ 0.05). Lung/body and liver/body weight ratios of the fetal mice were significantly increased in group E [(1.21 ±0.18) and (4.68 ±0.21)%] as compared with groups A, B, C and D (P＜0.05). (2)Mortality rates of the fetuses were significantly higher in group E (23.0%) than in groups A (0.8%), B (0.9%), C (1.7%) and D (3.7%) (P ＜ 0.05), but were not significantly different among groups A,B, C and D (P ＞ 0.05) despite of an increasing tendency. (3) Pathological changes in the liver and lung of the fetuses were conspicuous in group E. The fetal liver injury was histopathologically evidenced by deranged tissue structure, degenerated parenchyma of hepatic cells, and mildly stained cytoplasm. Adipose degeneration was represented by clear-boundary intracytoplasmic vacuoles in most of the liver cells, and cell pyknosis with heavily stained cytoplasm was observed in some of the liver cells. Inflammatory cell infiltration and focal necrosis were occasionally found in the hepatic tissue. The fetal lung exhibited bronchiole with narrow lumina, vascular engorgement in the submucosal layer, interstitial and alveolar edema, thickened alveolar septum, granulocyte and lymphocyte infiltrations within the pulmonary alveoli and around the bronchioles. The above pathological changes were lesser in groups C and D, and were not or least found in groups A and B. (4) Protein expressions of CYP1A1 in the fetal lung and CYP1A2 in the fetal liver were significantly increased in group E (1.20 ± 0.40 and 2.55 ± 0.89) when compared with group A (0.77 ±0.36 and 2.08 ±0.31) (P ＜ 0.05). mRNA expressions of CYP1A1 in the fetal lung were significantly increased in groups C (0.36 ±0.12), D (0.41 ±0.08) and E (0.43 ±0.11) compared with group A (0.21 ±0.10), and significantly increased in groups D and E compared with group B (0.28 ±0.10,P＜0.05). mRNA expressions of CYP1 A2 in the fetal liver were significantly increased in groups C (0.37 ±0.13), D (0.36 ±0.14) and E (0.43 ±0.16) compared with group A (0.21 ±0.03), and significantly increased in group E compared with group B (0.24± 0.11, P ＜ 0.05). Conclusions PM elicited embryotoxigenicity and resulted in adverse pregnancy outcomes in mice by intrauterine exposure of overdose PM. The expressions of cancer-related genes CYP1A1 and CYP1A2 were up-regulated in organs after the middle- and large-dose subacute exposure of PM, which may have a potential role on the future development.