Study On The Reproductive Toxicity And Toxic Mechanism Of Rat Exposed To Fenvalerate

Pesticides,a major category of environmental pollutant,pervasively exist in the world of production and living.Recently,because of high toxicity,high residue in environment and reverse pollute,phosphate pesticides and organochlorine pesticides are banned in use in many countries.Meanwhile,pyrethoid pesticides are widely used because of their high performance and low toxicity.Pyrethoid pesticides have an obvious reproductive toxicity,can affect the level of sex hormone and the activity of enzyme in blood and testicle.They are environment sex hormones,can play a sex hormone-like role. They also can interfere with the accommodation of hypothalarnus-gonadal axis through affecting the function of Sertoli cell and lead to damage the spermatogenesis oligospermia and aspermatism.Fenvalerate as aâ…¡type pyrethoid pesticide,has low toxicity and is widely used.So we choose fenvalerate to study its male reproductive toxicity and toxic mechanisms by animal experiments.This study evaluated the effect of fenvalerate(Fen) on sperm counts,sperm motility, sex hormones and toxic on spermatogenic cell of male rats.Different doses of Fen(0,20, 40 mg/kg) were administered orally to the adult male SD rats for 15 days or 30 days, respectively.The sperm counts and sperm motility were evaluated,and the level of serum follide stimul ating hormone(FSH),Iuteinizing hormone(LH),testosterone(T),estradiol (E₂) and testis homogenate T and E₂ were determined by radioimmunoassay and chemiluminescent immunoassay.Paraffin section of epididymis and testicle was stained by hematoxylin and eosin,and expressions of Bax and Bcl-2,two proteins associated with apoptosis,were examined in immunohistochemistry assay.We also uses molecular biology technique,western blot and real time PCR,to futher confirm the results of immunohistochemistry assay from level of protein and level of mRNA separately.After fifteen days treatment,the sperm counts markedly decreased in rats exposed to fenvalerate of 40 mg/kg group compared to control(Fen 0 mg/kg group)(P<0.01).In addition,T levels in testis homogenates markedly decreased in the rats exposed to 20 and 40 mg/kg groups(P<0.01,P<0.05),LH and FSH levels in serum were aiso elevated with the increased doses of fenval er ate but not statisti cally significant.On the other hand, FSH levels were increased in a dose-depended manner(P<0.05).Lumens diameter of contorted seminiferous tubules reduced with the increased doses of fenvalerate increased, and reached maximum in rats exposed to fenvalerate of 40 mg/kg group(P<0.01).The number of Ledig cells decreased,and were arranged densely,cellular atrophy,cytoplasm acidophil enhancement,nuclear condensed and anachromasised.In spermatogenic cell, the percentage of Bax positive was raised when the doses of fenvalerate increased with highest in fenval erate of 40 mg/kg group(P<0.01).Bcl-2 was weakened in rats exposed to fenvalerate of 20,40 mg/kg groups(P<0.05,P<0.01).Protein Bax increased in quantity with the doses of fenvalerate increased,especially in 40 mg/kg group; expression of gene bax enhanced with the doses of fenvalerate increased,but not statistically significant,express of gene bcl-2 has no differences.After thirty days treatment,the sperm counts had no statistically significant differences among three groups.Compared to control,grade(a+b) sperm motility of 40 mg/kg group decreased significantly(P<0.05),L H and FSH levels in serum elevated with the increased doses of fenvalerate,but not statistically significant(P>0.05). Lumens diameter of contorted seminiferous tubules markedly reduced in rats exposed to fenvalerate of 20,40 mg/kg group(P<0.01).The number of Ledig cells decreased,and were arranged densely,cellular atrophy,cytoplasm acidophil enhancement,nuclear condensed and anachromasised.In rats exposed to fenvalerate of 40 mg/kg group, spermatogenic epithelium decreased,defluvium of spermatogenic epithelium were acute in part of seminiferous tubules,and only a little Sertoli cells retained.In spermatogenic cell,the percentage of Bax positive was raised,with highest in fenvalerate of 40mg/kg group(P<0.01).Bcl-2 was weakened with the doses of fenvalerate increased,with lowest in fenvalerate of 40 mg/kg group(P<0.01).Protein Bax increased in quantity with the doses of fenvalerate increased,but not obviously;expression of gene bax markedly enhanced in rats exposed to fenvalerate of 40 mg/kg group(P<0.05),and expression of gene bcl-2 has no differences.All the results above show that,fenvalerate has obvious reproductive toxicity on male rats.The changes of hormones levels of serum and testis homogenate,and effects on spermatogenic cell to apoptosis,through bcl-2 gene family(involved gene bax) imply its toxigenic mechanism.