新烟碱类杀虫剂吡虫啉对大鼠卵巢功能的影响

Effects of neonicotinoid insecticide imidacloprid on ovarian function in rats

目的 探讨新烟碱类杀虫剂吡虫啉(IMI)对大鼠卵巢功能的影响。方法 将30只21日龄的雌性SD大鼠随机分为3组,每组10只,根据IMI暴露的浓度分为低浓度组(19 mg·kg^(-1)·d^(-1))和高浓度组(38 mg·kg^(-1)·d^(-1)),对照组则给予同等体积的生理盐水。连续灌胃30 d,对动物状态进行记录;采用电化学发光法测定大鼠血清中孕酮和雌二醇(E_(2))的含量,Western Blot法检测大鼠卵巢中胆固醇侧链裂解酶(P_(4)50scc)和芳香化酶(Aromatase)的表达量,行卵巢组织切片苏木精-伊红(HE)染色以观察卵泡形态、统计各级卵泡数量,同时进行抗苗勒管激素(AMH)免疫组化染色观察其表达量的变化。结果 各组大鼠灌胃期间毛发、进食情况、活动情况均无明显异常。随IMI暴露剂量增加,大鼠血清孕酮和E_(2)水平也逐渐增加;与对照组相比,低浓度组和高浓度组孕酮水平略增高,但均无显著性差异(P>0.05);与对照组相比,高浓度组血清中E_(2)水平显著升高(P<0.05)。Western Blot结果显示,IMI暴露后大鼠卵巢组织中P_(4)50scc和Aromatase表达量随IMI浓度增加而升高,与对照组相比,低浓度组中P_(4)50scc和Aromatase的表达量虽有增加但无显著性差异(P>0.05),高浓度组中P_(4)50scc和Aromatase的表达量显著增加(P<0.01)。卵泡计数结果显示,与对照组相比,低浓度组和高浓度组大鼠卵巢中总卵泡数均显著减少(P<0.001);与对照组相比,高浓度组原始卵泡比例显著降低(P<0.001),低浓度组生长卵泡比例显著增加(P<0.05)。免疫组化染色结果显示,与对照组相比,低浓度组和高浓度组的AMH表达均下降,IMI高浓度组AMH下降更明显。结论 IMI暴露后会导致大鼠卵巢甾体激素的生成增加,并改变卵泡发育的进程。

Objective:To investigate the effects of neonicotinoid insecticide imidacloprid(IMI)on ovarian endocrine function and follicular development in rats.Methods:Thirty 21-day-old female SD rats were randomly divided into 3 groups with 10 rats in each group.According to the concentration of IMI exposure,they were divided into low concentration group(19 mg·kg-1·day-1)and high concentration group(38 mg·kg-1·day-1),and the rats in the control group was given the same volume of normal saline,continuous gavage for 30 days.The serum levels of progesterone and estrogen(E_(2))were detected by electrochemiluminescence.Western Blot was used to examined the protein expression levels of two key enzymes for steroid hormone synthesis:cytochrome P_(4)50scc enzyme(P_(4)50scc)and aromatase.HE staining was used to observe the morphology of follicles and count the number of follicles at all stages.Immunohistochemical staining of anti-Mullerian hormone(AMH)was performed to observe the changes in its expression.Results:There were no significant abnormalities in hair,food intake,and activity of rats in each group during intragastric administration.With the increase of IMI dose,the serum progesterone and E_(2) levels in rats gradually increased.Compared with the control group,the progesterone levels in the low dose group and the high dose group were slightly higher,but there was no significant difference(P>0.05).Compared with the control group,the serum E_(2) level in the high concentration group was significantly higher(P<0.05).Western Blot results showed that the protein expression of P_(4)50scc and aromatase increased with the increase of IMI concentration.Compared with the control group,the expressions of P_(4)50scc and aromatase in the low-dose IMI group increased but there was no significant difference(P>0.05).The expressions of P_(4)50scc and aromatase in the high-dose IMI group increased significantly(P<0.01).The follicle count results showed that compared with the control group,the total number of follicles in the low-dose group and high-dose group decreased significantly(P<0.001),the proportion of primordial follicles in the high-dose group decreased significantly(P<0.001),and the proportion of growing follicles in the low-dose group increased(P<0.05).The immunohistochemical results showed that AMH expression in the ovaries decreased after IMI exposure compared with the control group,and the AMH expression in the high-dose IMI group decreased obviously.Conclusions:IMI exposure affects the synthesis and secretion of steroid hormones in the ovary of rats and may alter the course of follicular development.