氯氰菊酯和甲基对硫磷混配对大鼠内分泌和免疫系统的影响——Ⅰ.剂量-效应关系

目的探讨农药氯氰菊酯(Cyp)和甲基对硫磷(MP)混配对大鼠生殖激素、甲状腺激素和免疫功能的影响及其剂量-效应关系。方法健康2月龄Wistar大鼠80只,随机分为4组,氯氰菊酯和甲基对硫磷剂量分别为(0、1/600、1/135和1/30)LD50混配,即Cyp0·0、0·4、1·8和8·0mg/kg bw+MP0·0、0·0115、0·0518和0·2300mg/kg bw;对照组用色拉油,隔日对大鼠灌胃1次,共30天。测量大鼠体重增长,称量脏器湿重;用放射免疫法测定血清生殖激素指标促黄体生成激素(LH)、促卵泡成熟激素(FSH)、雌二醇(E2)和睾酮(T);甲状腺激素指标(T3、T4和TSH),以及免疫指标IgG和IgA;取血测定淋巴细胞转化率、中性粒细胞吞噬率。结果未观察到2种农药混配对大鼠体重增长的影响;肾上腺相对重量各剂量组比对照组增加(P<0·05)。血清FSH和E2水平中、高剂量组比对照组升高(P<0·05);血清TSH含量随混配农药剂量升高有上升趋势(rs=0·327,P=0·004)。淋巴细胞转化率各剂量组比对照组显著降低(P<0·01),中性粒细胞吞噬率各剂量组比对照组升高(P<0·01),血清IgG水平中、高剂量组比对照组显著降低(P<0·01);IgA水平雌鼠中、高剂量组比对照组升高(P<0·01),而雄鼠低剂量组比对照组降低(P<0·05)。以上改变均呈现剂量-效应关系。结论氯氰菊酯与甲基对硫磷混配可干扰大鼠生殖激素和免疫系统,尤其是使雌二醇水平明显增高。

Effects of mixed cypermethrin and methylparathion on endocrine hormone levels and immune functions in rats: Ⅰ. dose-response relationship

ObjectiveTo study dose-response relationship effects of mixed cypermethrin and methyl parathion on reproductive hormones, thyroid hormones, and immune functions in rats.Methods Eighty 2-month old Wistar rats (40 males and 40 females) were divided randomly by bodyweight into 4 groups. Four doses (0, 1/600 LD_ 50 , 1/135 LD_ 50 and 1/30 LD_ 50 ) were chosen for the combined exposure representing respective doses of cypermethrin 0, 0.4, 1.8 and 8.0mg/kg body weight and of methylparathion 0, 0.0115, 0.0518 and 0.2300mg/kg body weight. The control group received vehicle solvent only. All groups were force-fed every two days for 30 days with these dose combinations. Body weight gain and organ weights were determined. Serum levels of IgG and IgA, reproductive hormones (luteinizing hormone (LH), follicle stimulating hormone (FSH), estradiol (E_2), and testosterone), as well as the thyroid hormones (triiodothyronine (T_3), tetraiodothyronine (T_4), and thyroid stimulating hormone (TSH) were measured using radioimmunoassay (RIA). In addition, two immunological parameters (rate of neutrophil phagocytosis, rate of lymphocyte transformation) were being measured in blood samples.Results The body weight gains were similar in all 4 groups. The weights of adrenal glands in exposed rats were heavier than those in control (P<0.05). Serum FSH and E_2 levels in exposed rats were higher than those in the control group (P<0.01). Serum TSH levels were proportionally increasing with higher pesticide doses (r_s=0.329, P<0.01). Lymphocyte transformation rates in all exposed animals were lower than that of the control group (P<0.01). To the contrary, rates of neutrophil phagocytosis in all exposure groups were higher than those of the control group (P<0.01). Furthermore, serum IgG levels of all exposed animals were lower than that of the control (P<0.01) and serum IgA levels in exposed females were higher than that of the control(P<0.01). Dose-response relationships for these changes were significant (rank correlation statistics P<0.05 or <0.01).Conclusion Our results showed that exposure to different mixtures of cypermethrin and methyl parathion disrupted the endocrine hormone levels, and immune functions in rats.