| Monocrotophos pesticides is a kind of organophosphorous pesticides with high efficiency, it is also a of preferred controlled pollutants and showed potential threat to aquicolous organism and human health. In order to elucidate the harm of monocrotophos pesticides, our laboratory have done many researches about the toxicity and environmental estrogen effects of monocrotophos pesticides on fish. Our studies showed that monocrotophos pesticides could induce the vitellogenin (VTG) in male goldfish and have environmental estrogen activity. Monocrotophos pesticides, which is water-soluble, has complicated components include 40% monocrotophos (active ingredient), amides, monochlorides and so on. However, it's not clear that which ingredient acts as environmental estrogen. In this paper, Goldfish (Carassius Auratus) was selected as experimental organism for its wide distribution, readily available, and easily handling, etc., we expose goldfish to 0.01,0.10 and 1.00 mg·L-1 monocrotophos for 21 days. Parameters such as serous VTG, Ca2+ content and total protein content in serum, gonadosomatic index (GSI), ultrastructure of testis, the activities of several characteristic enzymes in testis were investigated to discuss the environmental estrogen effects of monocrotophos on fish, which would be used to explain whether the active ingredient in monocrotophos pesticide has environmental estrogen effect. The results showed as follows:(1) Following exposure to monocrotophos(0.01,0.10,1.00 mg·L-1) for 21 days, The qualitative result of the Western Blot, determining the VTG in blood plasma of goldfish, showed that male goldfish was induced to synthesize VTG, which had four main protein bands with relative molecular weights of 154kDa, 136kDa, 85kDa and 81kDa, respectively. At the same time, both the Ca2+ content and total protein content in blood plasma increased significantly suggesting the increase of VTG. The results proved that monocrotophos, which was the active ingredient in monocrotophos pesticides, has environmental estrogen activity. (2) Following exposure to monocrotophos for 21 days, the GSI decreased gradually with the increase of concentration of monocrotophos. Thereinto, the GSI of male goldfish of 0.01 and 0.1 mg·L-1 monocrotophos decreased significantly (P<0.05), and the GSI of male goldfish in 1.00 mg·L-1 monocrotophos decreased remarkably (P<0.01), indicating that the monocrotophos delayed the development of testis obviously. The ultrastructure of the testis in male goldfish was performed using the Transmission Electron Microscope, the result showed that monocrotophos not only affect the development but also damnify the structure of testis, mainly including: the head of sperm deformed, the plasma membrane of head dissolved, centriolar complex and mitochondrial dissolved, plasma membrane of flagellum edemaed and dissolved,"9+2"structure dissolved; Sertoli cells swelled, nuclear membrane and cell membrane dissolved, mitochondrial's number increased and cristae dissolved, lysosome accumulated, rough endoplasmic reticulum edemaed, vacuole and myelin-like figure occurred, but the increase of necrotic sperm was not obviously. The results suggest that main effect of monocrotophos to sperms and sertoli cells is the damage to membrane system, which is same as monocrotophos pesticides.(3) After exposed to monocrotophos of different concentration, the activities of characteristic enzymes in testis were detected in different degree. In the control and treated goldfish (0.01, 0.10, 1.00 mg·L-1 monocrotophos), the lactate dehydrogenase (LDH) activities were 1.26±0.07, 1.33±0.16, 1.62±0.21 and 1.11±0.13 U·mg-1pro; the LDH-X activities were 0.53±0.08, 0.61±0.07, 0.64±0.02 and 0.57±0.08 U·mg-1pro. The activities of LDH and LDH-X were induced by monocrotophos in low concentration, but were inhibited in high concentration. With the increase of exposed concentrations, the activities ofγ-glutamyl transpeptidase (γ-GTP), acid phosphatase (ACP), alkaline phosphatase (ALP) were declined obviously. The results elucidate that the changes of characteristic enzyme activities in testis treated by monocrotophos will interrupt the energy metabolism and affect the function of sertoli cells, result in further interruption the seminiferous process.In conclusion, we use western blot to ascertain that male goldfish could be induced to synthesize VTG by monocrotophos. It showed that monocrotophos, which was the active ingredient in monocrotophos pesticides, has environmental estrogen activity. Afterwards, ultrastructures of testis were observed, activities of characteristic enzymes in testis were measured, and the result showed that monocrotophos could damnify the structures and functions of testis. The effects of monocrotophos on the testis in male goldfish is conform with monocrotophos pesticides, which included the damage of membrane system of sperms and sertoli cells, the effects of activities of characteristic enzymes, the interruption of the seminiferous process. It is considered that monocrotophos has reproductive toxicity.
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