Long-term exposure to aryl hydrocarbon receptor agonist neburon induces reproductive toxicity in male zebrafish(Danio rerio)

Neburon is a phenylurea herbicide that is widely used worldwide,but its toxicity is poorly studied.In our previous study,we found that neburon has strong aryl hydrocarbon receptor(AhR)agonist activity,but whether it causes reproductive toxicity is not clear.In the present study,zebrafish were conducted as a model organism to evaluate whether environmental concentrations of neburon(0.1,1 and 10μg/L)induce reproductive disorder in males.After exposure to neburon for 150 days from embryo to adult,that the average spawning egg number in high concentration group was 106.40,which was significantly lower than 193.00in control group.This result was mainly due to the abnormal male reproductive behavior caused by abnormal transcription of genes associated with reproductive behavior in the brain,such as secretogranin-2a.The proportions of spermatozoa in the medium and high concentration groups were 82.40%and 83.84%,respectively,which were significantly lower than 89.45%in control group.This result was mainly caused by hormonal disturbances and an increased proportion of apoptotic cells.The hormonal disruption was due to the significant changes in the transcription levels of key genes in the hypothalamus-pituitary-gonadal axis following neburon treatment.Neburon treatment also significantly activated the AhR signaling pathway,causing oxidative stress damage and eventually leading to a significant increase in apoptosis in the exposed group.Together,these data filled the currently more vacant profile of neburon toxicity and might provide information to assess the ecotoxicity of neburon on male reproduction at environmentally relevant concentrations.

Food emulsifier glycerin monostearate aggravates phthalates'testicular toxicity by disrupting tight junctions'barrier function in rats

Objectives:This study aimed to investigate the effect of the widely used food emulsifier glycerin monostearate(GM)on testicular toxicity caused by the mixture of three commonly used phthalate esters(MPEs)in rats,and further to explore the underlying mechanism.Materials and Methods:Thirty male Sprague-Dawley rats were randomly divided into three groups.Rats were orally treated with 160 mg/kg/d MPEs in the MPEs group;coinstantaneously treated with 160 mg/kg/d MPEs and 200 mg/kg/d GM in the MPEs+GM group;and treated with the excipient in the control group.The intervention lasted for 5 weeks.Testis weight,epididymis weight,testicular histopathology,and serum testosterone were detected for testicular toxicity evaluation.The testicular ultrastructure,the tight junction proteins zonula occluden(ZO)-1,and claudin were measured for the mechanism exploration.Results:The body weight,epididymis,serum testosterone level,and anogenital distance in the MPEs+GM group were significantly decreased compared with control group(P<0.05);Testicular histopathological observation showed that shed spermatids were observed in the MPEs+GM group.Ultrastructural observation of testicular cells showed that the cristae number was decreased in some mitochondria in the MPEs group,whereas the cristae were fused and disappeared in most mitochondria in the MPEs+GM group.The tight junctions were broken in the MPEs+GM group;meanwhile,the expression of ZO-1 and claudin were altered in the MPEs+GM group(P<0.01).Conclusions:The results from this study indicated that GM aggravated MPEs'testicular toxicity,which might relate to the injured mitochondria and damaged tight junctions in testicular tissue.