Changes in cytochrome P450 gene expression and enzyme activity induced by xenobiotics in rabbits in vivo and in vitro

Abstract

As considerable inter-species differences exist in xenobiotic metabolism, developing new pharmaceutical therapies for use in different species is fraught with difficulties. For this reason, very few medicines have been registered for use in rabbits, despite their importance in inter alia meat and fur production. We have developed a rapid and sensitive screening system for drug safety in rabbits based on cytochrome P450 enzyme assays, specifically CYP1A1, CYP1A2 and CYP3A6, employing an adaptation of the luciferin-based clinical assay currently used in human drug screening. Short-term (4-h) cultured rabbit primary hepatocytes were treated with a cytochrome inducer (phenobarbital) and 2 inhibitors (alphanaphthoflavone and ketoconazole). In parallel, and to provide verification, New Zealand white rabbits were dosed with 80 mg/kg phenobarbital or 40 mg/kg ketoconazole for 3 d. Ketoconazole significantly increased CYP3A6 gene expression and decreased CYP3A6 activity both in vitro and in vivo. CYP1A1 activity was decreased by ketoconazole in vitro and increased in vivo. This is the first report of the inducer effect of ketoconazole on rabbit cytochrome isoenzymes in vivo. Our data support the use of a luciferin-based assay in short-term primary hepatocytes as an appropriate tool for xenobiotic metabolism assays and short-term toxicity testing in rabbits.

Effect of hydroxylated and methylated flavonoids on cytochrome P450 activity in porcine intestinal epithelial cells

“…For comparison, well-known CYP inducer and inhibitor compounds have also been applied on some cells. A group of cells was treated with 500 μM phenobarbital (general CYP inducer), while others received 25 μM ketoconazole (CYP1A1 and 3A4 inhibitor) (Palócz et al, 2017). Phenobarbital was also applied in combination with the different flavonoids.…”

Alteration of avian hepatic cytochrome P450 gene expression and activity by certain feed additives

“…Quantity, A260/ A280 and A260/A230 ratios of the extracted RNA were determined using a NanoDrop ND-1000 Spectrophotometer (Thermo Scientific, Wilmington, USA). Quantitative real-time PCR (qPCR) was performed as described previously (Palócz et al, 2017). The tested genes of interest were the avian cytochrome P450 1A4 (CYP1A4, formerly known as CYP1A1), cytochrome P450 2C23a (CYP2C23a, formerly known as CYP2H1), cytochrome P450 2C45 (CYP2C45) and cytochrome P450 3A37 (CYP3A37).…”

“…The CYP1A4, CYP3A and CYP2C activities of liver microsome samples were measured using the P450-Glo™ substrates (Luciferin-CEE, Luciferin-IPA, Luciferin-ME; Promega, Madison, USA) (Palócz et al, 2017). The assays were performed according to the manufacturer's recommendation; the luminogenic substrates and the NADPH regeneration system (Promega, Madison, USA) were added to each 5-fold diluted microsome sample, respectively.…”