苯并[α]芘对新生幼鼠的海马组织ATP酶及钙离子的影响

Effects of benzo(a)pyrene exposure on the ATPase activity and content of Ca^(2+) in the hippocampus of neonatal SD rats

目的:探讨苯并[α]芘染毒是否对新生幼鼠海马组织ATP酶及钙离子产生影响。方法:将120只(雌雄各半)新生4日(postnatal day 4,PND4)龄SD幼鼠随机分为5组:空白对照组、溶剂对照组(给予花生油)、低剂量苯并[α]芘(0.02 mg/kg)组、中剂量苯并[α]芘(0.2 mg/kg)组、高剂量苯并[α]芘(2 mg/kg)组。将苯并[α]芘溶于花生油后,灌胃染毒,染毒时间自PND4持续到PND20。染毒期间,检测各组幼鼠的神经反射、神经肌肉发育情况及运动功能。染毒结束后,分光光度法检测Ca2+-ATP酶和Ca2+-Mg2+-ATP酶活性;荧光标记法测定海马突触内Ca2+浓度。结果:行为学结果显示:在PND12龄,中剂量苯并[α]芘组幼鼠平面翻正用时长于对照组(P<0.05);PND14,PND16龄时,高剂量苯并[α]芘组平面翻正用时明显长于对照组(P<0.05)。高剂量苯并[α]芘组的Ca2+-Mg2+-ATP酶和Ca2+-ATP酶活性明显低于对照组;随染苯并[α]芘染毒剂量的增加Ca2+-ATP酶活性降低(P<0.05)。中、高剂量苯并[α]芘组突触内Ca2+浓度明显高于对照组;突触内Ca2+浓度随着染毒剂量的增加有增加趋势(P<0.05)。结论:苯并[α]芘染毒导致海马组织ATP酶活性降低,突触内Ca2+超载,造成新生幼鼠神经神经发育损伤。

Objective: To investigate the eff ect of benzo(α)pyrene on the ATPase activity and content of Ca2+ in the hippocampus of neonatal SD rats.Methods: Sixty male and 60 female 4-days-old neonatal SD rats were randomly divided into 5 groups(n=24): a blank control group, a vehicle control group(peanut oil), 3 benzo(α)pyrene groups(0.02, 0.2 and 2 mg/kg, respectively). SD rats were given benzo(α)pyrene(dissolved in peanut oil) by gavage daily from postnatal day 4(PND4) to PND20. T h e nerve ref lex, the conditionof neuro-muscle development and motion function were examined in the period of treatment. The colorimetric technique was used to detect the activity of Ca2+-ATPase and Ca2+-Mg2+-ATPase in hippocampus after the treatment. The concentration of Ca2+ of synapse in the hippocampus of rats was detected by fluorescent labeling. Results: The results from the behavior tests showed that duration of surface reflex latency in rats with medium dose of benzo(α)pyrene was longer compared with that in the control group in PND12. The duration of surface reflex latency in rats with high dose of benzo(α)pyrene is longer in PND 14 and PND 16 compared with that in the control group(P<0.05). Compared with the rats in the control group, the activities of Ca2+-Mg2+-ATPase and Ca2+-ATPase in hippocampus in rats with high dose benzo(α)pyrene were significantly decreased, and the degree in the decrease of Ca2+-ATPase activity was dose-dependent(P<0.05). The contents of Ca2+ in the hippocampus in rats with medium or high dose of benzo(α)pyrene were significantly increased compared with that in the control group(P<0.05), which showed a dose-dependent manner(P<0.05).Conclusion: Benzo(α)pyrene exposure led to the decrease in ATPase activity as well as Ca2+ overload of the synapse in the hippocampal tissue, which in turn results in the nerve damage of newborn SD rats.