| Phoxim as an efficient, broad-spectrum, low toxicity organophosphate insecticide, has been widely used in agriculture, forestry, animal husbandry and other production areas, New Manual of fishery drugs also explicitly states that phoxim can be used as a fishery drug for fish farming. However, the metabolism of phoxim in fish had not been reported, and the metabolism of exogenous compounds exist species differences in vivo, reports indicated that metabolites of some organophosphorus pesticide could generate more toxic than the parent. Therefore, this research project reported that the relationship of dose-effect and time-effect between phoxim and cytochrome P450 (CYP450) enzymes; Reserch on mechanism of phoxim stress injury in the body by observe microstructure and ultrastructure of tissue damage; The major metabolites of phoxim in Carassius Auratus Gibebio was investigated using high-performance liquid chromatography combined with IT/TOF mass spectrometry (LC/MS-ITTOF), and speculated the possible metabolic pathways.1 Effect of phoxim on CYP450 enzymes in Carassius auratus gibebioThe detection of CYP450 content and NCCR activity showed that there were no significant difference (P>0.05) between the exposed groups and the control group; For ERND, different concentration groups compared with the control group exposed to 3～5 d inhibition significantly different (P<0.05), exposed for the first 5 d, the low concentration group with the control group inhibition difference significant (P<0.05); for APND exposure 1d-5d, enzymes inhibition rate in each exposure group compared with the control group, there was no significant difference (P>0.05) in the entire exposure process. APND was not sensitive to the middle dose, but when exposure 3～7 d high dose group showed strong inhibition, after that the inhibitory effect was level off; the activity of AH was detected on the rise at 2～5 d, the results indicated that phoxim may be a inducer at a certain period of time.Compared with the control group, the AH activity of the high dose group were 81.0%,72.5%,72.4% at 9 d,14 d,21 d exposured, inhibition rates were 19.0%,27.5%,27.6%. What’s more, there were significant differences (P<0.05) between them. The enzyme activity recovery experiments indicated that the NCCR, APND, AH had varying degrees of recovery, the activity of ERND showed irreversible recovery and compared with the groups that before the recovery experiment, the recovery differences were not significant (P>0.05).2 Pathological damage of major tissue in Carassius auratus gibebioBy using HE staining and electron microscopy, microstructure and ultrastructure of tissue damage were observed after 40d and 60d semi-static exposure administration of phoxim. HE staining results showed that liver, gills, brain tissue damage of the exposure groups were different. The degree of tissue damage in the high dose group was greater than the low dose group, and as exposure time goes on,the damage would increase; TEM observations showed liver, gill, brain cells were visible to varying degrees of damage in the exposured groups; however, there was no significant lesions in brain tissue by SEM observing.3 Metabolism of phoxim in Carassius auratus gibebioCarassius auratus gibebio were administered phoxim intraperitoneal injection with a single dosage of 10 mg/kg. The method using LC/MS-ITTOF had been developed for the analysis phoxim and its metabolites in water, liver, blood and muscle. The results showed that four metabolites were detected after administration of phoxim in water, and phoxim was accompanied detected; phoxim was only detected in the blood, its metabolites were not detected; two metabolites in the liver were detected after 12 h administered of phoxim, didn’t find metabolites after 24 h; no metabolites was detected after 12 h and 24 h administration of phoxim in muscle tissue. |
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