| Drugs are often detected in the water environment due to their direct excretion of animals and incomplete removal of sewage treatment plants.Drugs in the water environment may interfere with the endocrine system of aquatic organisms.Most current studies focus on how estrogen and androgens interact with the endocrine system,and few studies have reported the ecotoxicological effects of progesterone on fish and their potential risks.Carp and crucian are precious freshwater fish in China,delicacies on the table,the main source of protein intake and are commonly speciesused to detect chemicals.This paper mainly uses carp and crucian as experimental animal models to study the reproductive endocrine disrupting effect of progesterone(P4)on carp and crucian embryos and juveniles.The main results are as follows:1.The aim of this study was to investigate the effects of P4(10 ng/L,100 ng/L,1000 ng/L and 10000 ng/L)on the early embryonic morphological development stage of carp and crucian as well as the effects of P4(5 ng/L、50 ng/L and 100 ng/L)on the transcriptional expresssion levels of genes related to hypothalamic--pituitary-gonadal(HPG)axis and circadian rhythm in the early embryonic development stage of carp and crucian.It was shown that P4(10 ng/L,100 ng/L,1000 ng/L and 10000 ng/L)did not induce any acute toxic effects on embryonic development of carp and crucian.However,for carp,all P4(5 ng/L,50 ng/L and 100 ng/L)exposed groups significantly down-regulated the expression of Gnrh3 at 24 h(h).A significant up-regulatedthe expression of Hsd3β was observed at 5 ng/L or higher concentrations of P4 at different time points.The expression of several other HPG-axis related genes were affected with various degrees.Regarding the genes related to circadian rhythm,5 ng/L or higher concentrations of P4 significantly up-regulated the expression of Clock1,Arntl1,Cry2,Per2 and Nr1d1 genes at 24 h,and then significantly down-regulated the expression of these genes.For crucian,the expression of Lhβ,Cyp11 a and Cyp19 a genes were significantly up-regulated at 5 ng/L or higher concentrations of P4 at different exposure time points as well as the expression of other HPG-axis related genes were affected to varying degrees.Regarding the genes related to circadian rhythm,5 ng/L or higher concentrations of P4 significantly up-regulated the expression of Clock1 and Nr1d1 genes.The results indicate that P4 at environmentally relevant concentrations interfere with the expression of HPG axis and circadian rhythm-related genes of carp and crucian,which may affect the reproductive endocrine system of carp and crucian.2.In this paper,we investigated the effects of P4(5 ng/L,50 ng/L and 100 ng/L)on HPG and circadian rhythm-related gene expression,gonadal histology and sex ratio in juvenile carps and crucian.The results showed that the 5 ng/L or higher concentrations of P4 significantly up-regulated the expression of HPG axis-related genes at most time points,and the expression of circadian rhythm-related genes were also affected to varying degrees.In addition,both the carp and the crucian,100 ng/L P4 exposure group showed the presence of oocytes in the spermatozoa.And more females were produced in the higher concentration P4 exposure group.In summary,during the embryo and juvenile development stage of carp and crucian,P4 at environmentally relevant concentrations can interfere with the expression of HPG-axis related genes,and the change in the expression of these genes may lead to the occurrence of oocyte in the spermatozoa and the sex ratio is biased towards females.Furthermore,P4 at environmentally relevant concentrations can lead to the disorder of gene expression related to circadian rhythm,which may further lead to the disorder of cell and physiological metabolism,thus affecting its reproductive function. |
