子宫内B[a]P暴露与子代鼠BPDE-DNA加合物及胰腺功能损伤的关系

Association of intrauterine benzo[a]pyrene exposure with benzo[a]pyrene diolepoxide(BPDE)-DNA adduct levels and pancreatic functional impairment in offspring rats

目的了解子宫内苯并[a]芘(B[a]P)暴露子代鼠体内二氢二醇环氧苯并[a]芘(BPDE)-DNA加合物水平,以及对胰腺功能损伤和糖代谢的影响。方法40只母鼠随机分为空白对照组、标准剂量组[2μg/(kg·d)]、低剂量组[200μg/(kg·d)]、中剂量组[800μg/(kg·d)]和高剂量组[1600μg/(kg·d)],每组8只。孕1 d起各剂量组采用B[a]P玉米油混合物0.2 mL/100 g体重灌胃,空白对照组采用相同剂量玉米油灌胃,至产后21 d。分析各组子代鼠2 d、21 d、12周BPDE-DNA加合物水平和胰腺发育情况;采用Spearman秩相关分析子代鼠胰体比与B[a]P暴露剂量的相关性;采用葡萄糖耐量(GTT)和胰岛素耐量(ITT)试验分析各组12个月子代鼠糖代谢差异。结果各组母鼠和子代鼠外观均无异常,活动、饮食、饮水和精神状况无差异,无实验动物死亡、流产和早产。2 d子代鼠BPDEDNA加合物水平最高,M(Q_(R))为1089.60(586.10)~1405.49(346.47)pg/mL;12周子代鼠未检出BPDE-DNA加合物。2 d(r_(s)=-0.620,P=0.001)和21 d(r_(s)=-0.801,P=0.001)子代鼠胰体比与B[a]P暴露剂量呈负相关。2 d子代鼠胰腺发育不全,组织松散;12周子代鼠胰腺发育良好,外分泌部紧实。GTT试验结果显示,腹腔注射葡萄糖后,各组子代鼠GLU先上升,30 min后呈下降趋势(F=365.578,P<0.001);ITT试验结果显示,腹腔注射胰岛素后,各组子代鼠GLU均呈下降趋势(F=461.215,P<0.001)。结论子代鼠BPDE-DNA加合物水平均随B[a]P暴露剂量的增加而升高;12个月后出现胰岛素抵抗和糖耐量受损。子宫内B[a]P暴露会影响子代鼠胰腺发育,导致子代鼠成年后糖代谢异常。

Objective To investigate the benzo[a]pyrene(B[a]P)diolepoxide(BPDE)-DNA adduct levels in offspring rats with intrauterine exposure to B[a]P,and examine the effects of BPDE-DNA adduct levels on pancreatic functional impairment and glucose metabolism in offspring rats.Methods Forty pregnant rats were randomly divided into the blank control group,standard-dose group,low-dose group,medium-dose group and high-dose group(daily dose of 0,2,200,800,1600μg/kg B[a]P,respectively),of 8 animals in each group.Rats in the B[a]P treatment groups were administered by oral gavage with a mixture of B[a]P and corn oil at a dose of 0.2 mL/100 g body weight since day 1 of pregnancy until 21 days after delivery,while rats in the blank control group were given the same volume of coin oil by oral gavage.The BPDE-DNA adduct levels were measured and the pancreatic development was observed in the offspring rats 2 and 21 days and 12 weeks after birth,and the correlation between pancreas volume index and dose of exposure to B[a]P was examined using Spearman’s rank correlation analysis.In addition,glucose metabolism was measured in offspring rats 12 months after birth using glucose tolerance test(GTT)and insulin tolerance test(ITT).Results There was no abnormal appearance,death,abortion or preterm birth in pregnant or offspring rats in the five groups,and no significant differences were seen in activity,diet,drinking water or mental status in rats.The greatest level of BPDE-DNA adducts was measured in offspring rats 2 days after birth,with median levels(interquartile range)of1089.60(586.10)to 1405.49(346.47)pg/mL,and no BPDE-DNA adducts were found in offspring rats 12 weeks after birth.The pancreas volume index correlated negatively with the dose of exposure to B[a]P in offspring rats 2(r_(s)=-0.620,P=0.001)and 21 days after birth(r_(s)=-0.801,P-0.001).Hypoplasia of pancreas with loose tissues was seen in offspring rats 2 days after birth,while well pancreatic development was found in offspring rats 12 weeks after birth,with tight exocrine portion.GTT showed an increase in glucose levels in offspring rats in all five groups following abdominal injection of glucose and declined 30 min post-injection(F=365.578,P<0.001),and ITT showed a tendency towards a decline in glucose levels in offspring rats in all five groups(F=461.215,P<0.001).Conclusions The levels of BPDE-DNA adducts in offspring rats increase with the dose of intrauterine B[a]P exposure,and insulin resistance and impaired glucose tolerance occur 12 months post-exposure to B[a]P.Intrauterine B[a]P exposure affects pancreatic development in offspring rats and causes abnormal glucose metabolism in adult offspring rats.