The Study Of Embryonic Toxicity And Reproductive Toxicity In Offspring After Pregnant Rat Exposure To Combined Pesticides

Objective:To study the embryonic toxicity and reproductive development toxicity in offspring after pregnant rat exposure to methylparathion and cypermethrinMethod: Two hundreds healthy Wistar rats of Ten weeks ages,which includes 140 females and 70 males, mated according to the proportion of 1:1, vaginal smear examination was proceed the next morning,if sperms were seen, then recorded pregnant day O.The pregnant rats were divided randomly into 4 groups.Three exposure groups were force-fed one time a day from pregnant day 1 to 15 using 1/300 LD₅0 1/95 LD₅0 1/30 LD50 methylparathion plus the same equivalent doses of cypermethrin,respectively.Control group was force-fed vehicle solvent. Some rats were sacrified on pregnant day 19 to estimate the effects of embryonic toxicity: counted the quantity of luteum, checked minutely and counted the quantity of living fetus,later death fetus,earlier death fetus and absorbed fetus.Measured the body weight, body length and tail length of each living fetus. Observed the abnormality of appearance and checked monstrosity of viscera and bones of each living fetus. Others normal labor: counted the quantity of liveborn of each pregnant rat,on postnatal day 1,measured ganoenital distance of offspring to distinguish sex,also measured the body weight, body length and tail length. Postnatal day 30 started to examine vagina opening of young female rats; Postnatal day 40,the young females were sacrified and the viscera relative weight of womb and oophorus were measured. Postnatal day 25 started to examine testes descent of young male rats. Postnatal day 70,the young males were sacrified and measured the viscera relative weight of testes epididymidis and prostate, the quantity of daily sperm production of testes and the quantity of sperm of epididymidis were also measured.The level of serumgenital hormone Luteinizing Hormone(LH),Follicle Stimulating Hormone(FSH),Estradiol(E2) and Testosterone(T) were measured.Result: The ratio of living fetus of high dose group was lower than middle dose group and control groupC P<0.01), while the ratio of death fetus was higher than middle dose group and control group (P<0.01) . We did not find the effect on body weight, body length and tail length of each living fetus and newly born, also no effect on the quantity of liveborn and the proportion of sex; the effects to the viscera relative weight and the quantity of daily sperm production of testes and the quantity of sperm of epididymidis were also little. The ratio of vagina opening postnatal day 40 of middle dose group was higher than control group (P<0.05) .The level of Testosterone(T) of low dose group was higher than control and other dose groups (P<0.01 or P<0.05) ,and with dose rising,the level decreasing in three exposure groups (P<0.01)Conclusion: After pregnant rat exposure to Methylparathion and Cypermethrin,our result showed that:1. The ratio of living fetus of high dose group was lower than middle dose group and . control group (P<0.01)? while the ratio .of death fetus was higher than middle dosegroup and control group (P<0.01) .2. The ratio of vagina opening postnatal day 40 of middle dose group was higher than control group (P<0.05) .3. The level of Testosterone(T) of low dose group was higher than control.and other dose groups(P<0.01 or P<0.05 ),and with the dose rising,the level of Testosterone(T) decreasing in three exposure group (P<0.01) .