Mechanism Of Beta-Cypermethrin Regulation On Male Mice Reproductive Function

Cypermethrin is a type of pesticide broad-spectrum used in agriculture,domestic and veterinary applications because of its high performance and low toxical.β-cypermethrin(β-CP)is a mixture ofα-cypermethrin(α-CP)andθ-cypermethrin(θ-CP),the activity ofβ-CP is lower thanα-CP but higher than other cypermethrin.Usingβ-CP as investigational agent and adult mouse(30-35g)as a model,we investigated exactly effects ofβ-CP on male reproductive function and studied the mechanism ofβ-CP of regulation.Mice were fed with different dose ofβ-CP by oral method.First of all,definiting the median lethal dose(LD50)at 61.12mg/kgwt.d through acute experiment.According to the oral LD50,the dose used in the following experiment was based on LD50.Sixty adult Kunbai male mouse weighing about 30～35 g were grouped at random as follows:Group-Ⅰ:(0mg/kgwt.dβ-CP),Group-Ⅱ:(1mg/kgwt.dβ-CP) Group-Ⅲ:(10mg/kgwt.dβ-CP),Group-Ⅳ:(20mg/kgwt.dβ-CP),Group-Ⅴ:(20mg/kgwt.dβ-CP + 15mg/kgwt.d VE),Group-Ⅵ:(15mg/kgwt.d VE).All animals were administrated by 35days.Initially,all animals decreased the input of food and water and all showed spiritless,drowsiness.After a few days(seven days),all animals of Group-Ⅰrestored normal.Beta-CP did not produce any gross effect at Group-Ⅱand Group-Ⅲ,but the animals of Group-Ⅳstill had signs of prolonged depression followed by occasional pawing,or burrowing and decreased motor activity.Besides producing any gross effect,the level of serum testosterone also changed.In the study,different concentrations ofβ-CP had different effect on serum testosterone.At the lower dose,such as 1mg/kgwt.d,β-CP had no significant effect on serum testosterone(P＞0.05).At the higher dose,β-CP reduced serum testosterone level at 10mg/kgwt.d,20mg/kgwt,d significantly(P＜0.05).Vitamin E reduced the effect ofβ-CP(P＜0.05).To further study the influence ofβ-CP on testosterone composition,we detect the protein level of StAR.and foundβ-CP had negative effect on the expression of SrAR,Vitamin E could reduced the effect ofβ-CP.Different doses ofβ-CP could diminish the weight differently.The weight of testis depressed at Group-Ⅱ,Group-Ⅲand Group-Ⅳ.and s spermatogenic cell of all stages showed dilating and cells sloughed,even vacuolated in seminiferous tubules,desmoplasia occurrenced between seminiferous tubules, the quantity of sperm reduced.The data of Group-Ⅲand Group-Ⅳdecreased significantly than Group-Ⅰ(~aP＜0.05),Vitamin E could reduced the effect ofβ-CP(~bP＜0.05),but have significant deviation according Vitamin E only(~aP＜0.05).We detect the ultrastructure of Leydig cell.Mitochondrion and smooth endoplasmic reticulum began to swell lightly and bouncary of nuclear membrane is unclear.At the higher dose,many smooth endoplasmic reticulum degenerated and mitochondria swelled,showed tendency of transparence..At Group-ⅣMany smooth endoplasmic reticulum formed cocenric circle.The change of the structure of Leyding cell is the straight reason that testosterone composition descent and the expression of StAR.Study the oxidative stress and antioxygen ability.β-CP at low dose(1mg/kgwt.d)could sublime the level of MDA,and at higher dose,it could also sublime the level of NO(P＜0.05).Vitamin E could reduced the effect ofβ-CP(P＜0.05).β-CP sublime the level of NO through strengthen the iNOS.We also found CAT,GSH-Px,T-SOD and TAOC descended while the dose increased,this variation expressed significantly at Group-Ⅲand Group-Ⅳ(P＜0.05).We detect the variation of the activity of MAPK,and found the level of ERK1 and ERK2 advanced while the dose advanced.Vitamin E could reduced the effect ofβ-CP.On the whole,we get these conclusion:(1)β-CP at higher doses could destroy the structure of the testis and the ultrastructure of the Leydig cell:(2)β-CP at higher doses could cause oxidative stress,increase the level of MDA,NO,TNOS and iNOS,and reduce the antioxygen ability and depress the level of CAT,GSH-PX,SOD and TAOC,and depress the expression of StAR and the synthesis of testosterone;(3)ERK participate in the regulation ofβ-CP on the function of testis:(4)Vitamin E could reduced the oxidative stress and protect reproduction of mail animals.