A Preliminary Study On Hepatic Microsomal Cytochrome P450 In Carassius Auratus

Cytochrome P450 is a large superfamily of heme-containing isozymes responsible for the metabolism of a huge number of drugs. Research on cytochrome P450 system is fundamental both for drug therapy and for drug development. However, only relatively few papers about cytochrome P450 enzyme system have been reported in food-producing animals up to date. Currently, there are no reports on drug-metabolizing P450 enzymes in Carassius auratus. In this article, primary study on hepatic microsomal cytochrome P450 in Carassius auratus was performed to provide theoretical foundation for further research of piscine CYP450 and clinical application of drugs in aquiculture.1 Study on determination of hepatic microsomal CYP450 system in Carassius auratusTen normal fish were selected to establish a method for determination of hepatic microsomal cytochrome P450. Liver microsomes were prepared by differential ultracentrifugation. Microsomal protein content was determined using the Lowry method. Activities of cytochrome P450 were measured by spectrophotometry. Results showed that protein concentration in hepatic microsome was 5.238±0.397 mg/g liver, total content of cytochrome P450 is 0.319±0.032 nmol/mg microsomal protein, the activity of NCCR was 2.145±0.181 nmol/min/mg protein, the activity of APND was 1.775±0.084 nmol/min/mg protein, the activity of ERND was 0.906±0.073 nmol/min/mg protein, and the activity of AH was 0.063±0.007nmol/min/mg protein. The results suggested that the established method for determining the contents and activities of hepatic microsomal cytochrome P450 in Carassius auratus was sensitive, reliable with good reproducibility.2 Effects of various agents on hepatic cytochrome P450 in Carassius auratusThe effects of phenobarbital (PB), dexamethasone (DEX), enrofloxacin (ERFX) and sarafloxacin (SRFX) on the hepatic microsomal cytochrome P450 enzymes in Carassius auratus were investigated. The fish were pretreated with PB (40mg/kg i.p.) and DEX (2mg/kg i.p.) once daily for 4 days or with ERFX (100mg/kg p.o.) and SRFX (100mg/kg p.o.) once daily for 5 days. Animals were killed by a sharp blow to the head 24 hours after the last treatment and livers were excised for further assays. Although a slight increase in content of cytochrome P450 and activity of ERND in fish treated with DEX were observed,...