| Monocrotophos is one of the environment hormones, because it can induce the production of vitellogenin in male goldfish. However, very few reports about the reproduction toxicity of monocrotophos exist in the literature. So the gonadosomatic index(GSI)of male goldfish (Carassius auratus) under monocrotophos treatment was tested in this paper. The activities of several characteristic enzymes in testis were then measured; the micro- and ultrastructure of testis were observed as well. The toxicity effect of monocrotophos to DNA and motility of sperm was evaluated via the investigation of the viability, the percentage and duration of motility of sperms by microscope, and the percentage of DNA in comet tail(Tail DNA%), the tail length(TL) and tail moment(TM) by comet assay of sperm comets. All the works aim at exploring the effect and mechanism of reproduction toxicity of monocrotophos on male goldfish. The data might give useful information to toxicological research of environment hormones on reproduction system of human.Exposure to monocrotophos led to the change of GSI and microstructure of male goldfish. After exposed to monocrotophos of various concentration(0.01,0.10,1.00 mg·L-1) for 21 days, the GSI of adult male goldfish decreased gradually with the increase of concentration of monocrotophos. The GSI of male goldfish in exposure concentration of 1.00 mg·L-1 decreased significantly compared to the control, indicating that the monocrotophos delayed the development of testis. As a result of monocrotophos exposure, dissolution of ground membrane, swelling of Leydig's and spermatogenous cell and enlargement of interstitial tissue were clearly observed. The changes in microstructure of testis may lead to the decline of sperm quantity.The alteration of ultrastructure and activities of several characteristic enzymes in testis of male goldfish treated by monocrotophos were further studied. In Sertoli's cell, monocrotophos induced the dissolution of nuclear membrane, accumulation of lipid droplet, increase of myelin-like figure and necrosis of sperm. To the sperms, the deformation of head, the dissolution of mitochondrial and plasma membrane and the fragment of tail were observed. The damage became severer with the increase of exposure concentration. In the control and treated goldfish which were exposed to 0.01, 0.10, 1.00 mg·L-1 monocrotophos, the lactate dehydrogenase (LDH) activities were1879.58±141.69, 1614.06±233.97, 1409.20±86.93, 1111.81±199.13U·mg-1pro separately, and the activities ofγ-glutamyl transpeptidase (γ-GTP) were 6.03±1.09, 4.33±0.87, 3.47±0.44, 3.08±0.56 U·mg-1pro respectively. So the activities of LDH andγ-GTP were inhibited by monocrotophos. The activities of acid phosphatase, alkaline phosphatase, sorbitol dehydrogenase declined, and the activity of superoxide dismutase increased as a result of monocrotophos exposure. It is supposed that the changes of ultrastructure and enzyme activities in testis of goldfish treated by monoccrotophos will interrupt the physiological courses such as energy metabolism, and further disturb the seminiferous process.The main function of male reproduction system is to produce sperms whose quantity is essential to healthy reproduction for generations. The exposure of sperms to monocrotophos(0.01 mg·L-1, 0.10 mg·L-1, 1.00 mg·L-1) in vitro for 3h didn't have any effect on viability of sperms. After exposed to monocrotophos at concentration of 0.10 and 1.00 mg·L-1 for 1h, the percentage of motility of sperms was 37.74±4.04% and 29.17±2.06%; the duration of motility was 70±3s and 63±5s, while that of control was 92.73±2.48% and 92±3s, respectively. The result showed that the monocrotophos reduced the motility of sperms. In the sperms of control and treated goldfish which were exposed to 0.01, 0.10, 1.00 mg·L-1 monocrotophos for 3h, the Tail DNA% was 1.17±0.81%,4.55±1.24%,14.60±2.17%,17.50±1.98% respectively; the TL of each group was 0.39±0.27, 0.70±0.38, 1.90±0.45, 4.47±0.33μm, and the TM was 0.39±0.27, 0.70±0.38,1.90±0.45,4.47±0.33μm respectively. The increase of DNA% in comet tail, tail length and TM implied that the DNA of sperm was damaged by monocrotophos.The micro- and ultrastructure of testis were observed at the histological level, the activities of characteristic enzymes in testis were measured at the biochemical level and the damage of DNA of sperms was tested at the DNA level. Finally, it is concluded that monocrotophos inhibits the seminiferous process via the damage to Leydig's cell, Sertoli's cell and mitochondrial of sperm and the changes in activities of characteristic enzymes. The monocrotophos can damage the motility and DNA of sperm as well, resulting in the harm to fertilization, development of embryo and the health of offspring.
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