ABSTRACT
BACKGROUND: Pharmacogenomics (PGx) plays a central role in the selection of targeted therapies that underpins precision-medicine. We investigated the prevalence of three important pharmacogenetic variants of VKORC1, CYP2C9, and CYP3A5 genes among Pakistani populations. METHODS: A total of 1104 individuals were included representing thirteen major ethnicities. Samples were genotyped by using PCR-RFLP analysis. The allelic and genotypic frequencies of the three SNV's were calculated and were compared with the world's population data (ALFA, gnomAD, and 1000Genome, 1 K databases), using the chi-square test. RESULTS: We found overall frequencies of functional-alleles of VKORC1 0.43, CYP2C9 0.94, and CYP3A5 0.14 in our population. Data showed a low prevalence of homozygous functional genotypes of VKORC1 (0.18; 0.0-0.45) and CYP3A5 (0.04; 0.0-0.22), and a high frequency of CYP2C9 (0.885; 0.80-1.0) across ethnicities. Genotyping distribution of VKCOR1 functional genotype was varied across ethnic groups such as 0.0-0.10 in Brahuis and Mohanas, Sindhis, Rajputs, and Gujjars populations, 0.11-0.20 in Makranis, Parsis, and Burusho populations, and 0.20-0.30 in Kalash, Kashmiris and Baloch populations. The highest VKORC1 (CC) was found in Pathans (0.45) and Hazaras (0.39) populations. Interestingly, we found a high prevalence of functional genotype CYP2C9 (rs1799853; C) and non-functional genotype of CYP3A5 (rs776746; T) across various ethnic groups of Pakistan. CONCLUSION: Data regarding prevalence of clinically important pharmacogenomics SNVs could be useful in drug adjustment and avoiding adverse drug reactions in a specific ethnic population. This could help in moving current medical practices toward precision medicine in our part of the world.
Subject(s)
Aryl Hydrocarbon Hydroxylases , Ethnicity , Humans , Ethnicity/genetics , Vitamin K Epoxide Reductases/genetics , Pharmacogenomic Variants , Cytochrome P-450 CYP3A/genetics , Pakistan , Aryl Hydrocarbon Hydroxylases/genetics , Cytochrome P450 Family 3/genetics , Cytochrome P-450 CYP2C9/genetics , Prevalence , Genotype , Anticoagulants/therapeutic useABSTRACT
The demonstration that spray-induced gene silencing (SIGS) can confer strong disease resistance, bypassing the laborious and time-consuming transgenic expression of double-stranded (ds)RNA to induce the gene silencing of pathogenic targets, was ground-breaking. However, future field applications will require fundamental mechanistic knowledge of dsRNA uptake, processing, and transfer. There is increasing evidence that extracellular vesicles (EVs) mediate the transfer of transgene-derived small interfering (si)RNAs in host-induced gene silencing (HIGS) applications. In this study, we establish a protocol for barley EV isolation and assess the possibilities for EVs regarding the translocation of sprayed dsRNA from barley (Hordeum vulgare) to its interacting fungal pathogens. We found barley EVs that were 156 nm in size, containing predominantly 21 and 19 nucleotide (nts) siRNAs, starting with a 5'-terminal Adenine. Although a direct comparison of the RNA cargo between HIGS and SIGS EV isolates is improper given their underlying mechanistic differences, we identified sequence-identical siRNAs in both systems. Overall, the number of siRNAs isolated from the EVs of dsRNA-sprayed barley plants with sequence complementarity to the sprayed dsRNA precursor was low. However, whether these few siRNAs are sufficient to induce the SIGS of pathogenic target genes requires further research. Taken together, our results raise the possibility that EVs may not be mandatory for the spray-delivered siRNA uptake and induction of SIGS.
Subject(s)
Crop Protection/methods , Hordeum/genetics , Hordeum/microbiology , RNA, Small Interfering/administration & dosage , Cytochrome P450 Family 3/genetics , Disease Resistance/genetics , Extracellular Vesicles/genetics , Extracellular Vesicles/microbiology , Gene Silencing , Host Microbial Interactions/genetics , Plant Diseases/genetics , Plant Diseases/microbiology , Plant Diseases/prevention & control , RNA Interference , RNA, Plant/genetics , RNA, Plant/isolation & purification , RNA, Small Interfering/isolation & purificationABSTRACT
KEY MESSAGE: A U-box E3 ubiquitin ligase GhPUB17 is inhibited by GhCyP3 with antifungal activity and acts as a negative regulator involved in cotton resistance to Verticillium dahliae. E3 ubiquitin ligases, the key component enzymes of the ubiquitin-proteasome system, which contains the most diverse structural and functional members involved in the determination of target specificity and the regulation of metabolism, have been well documented in previous studies. Here, we identify GhPUB17, a U-box E3 ligase in cotton that has ubiquitination activity and is involved in the cotton immune response to Verticillium dahliae. The expression level of GhPUB17 is downregulated in the ssn mutant with a constitutively activated immune response (Sun et al., Nat Commun 5:5372, 2014). Infection with V. dahliae or exogenous hormone treatment, including jasmonic acid and salicylic acid, significantly upregulated GhPUB17 in cotton roots, which suggested a possible role for this E3 ligase in the plant immune response to pathogens. Moreover, GhPUB17-knockdown cotton plants are more resistant to V. dahliae, whereas GhPUB17-overexpressing plants are more susceptible to the pathogen, which indicated that GhPUB17 is a negative regulator of cotton resistance to V. dahliae. A yeast two-hybrid (Y2H) assay identified GhCyP3 as a protein that interacts with GhPUB17, and this finding was confirmed by further protein interaction assays. The downregulation of GhCyP3 in cotton seedlings attenuated the plants' resistance to V. dahliae. In addition, GhCyP3 showed antifungal activity against V. dahliae, and the E3 ligase activity of GhPUB17 was repressed by GhCyP3 in vitro. These results suggest that GhPUB17 negatively regulates cotton immunity to V. dahliae and that the antifungal protein GhCyP3 likely interacts with and inhibits the ligase activity of GhPUB17 and plays an important role in the cotton-Verticillium interaction.
Subject(s)
Antifungal Agents/pharmacology , Cytochrome P450 Family 3/antagonists & inhibitors , Gossypium/metabolism , Plant Immunity/physiology , Ubiquitin-Protein Ligases/drug effects , Verticillium/pathogenicity , Cyclopentanes , Cyclophilins , Cytochrome P450 Family 3/genetics , Disease Resistance/genetics , Disease Resistance/immunology , Down-Regulation , Gene Expression Regulation, Plant , Gene Knockdown Techniques , Gene Silencing , Oxylipins , Plant Diseases/immunology , Plant Immunity/genetics , Plant Proteins/genetics , Plant Proteins/immunology , Plant Proteins/metabolism , Plant Roots , Recombinant Proteins , Salicylic Acid , Ubiquitin-Protein Ligases/genetics , UbiquitinationABSTRACT
Hepatic steatosis is the early stage of alcoholic liver disease (ALD), may progress to steatohepatitis, fibrosis even cirrhosis. Polydatin, the primary active component of Polygonum cuspidatum Sieb. et Zucc, has been recognized to possess hepatoprotective and anti-inflammatory properties. To investigate whether polydatin alleviates ethanol induced liver injury and to elucidate the underlying molecular mechanisms, zebrafish larvae at 4 days post-fertilization (dpf) were exposed to 350 mmol/L of ethanol for 32 h, then treated with polydatin for 48 h. Oil red O, Nile Red and H&E staining were used to analyze the pathological changes in liver. The mRNA levels were measured by quantitative PCR and the antioxidant capacity was detected using H2O2-specific fluorescent probe. Here, polydatin strongly alleviated hepatic steatosis and decreased the expression levels of alcohol and lipid metabolism-related genes, including CYP2Y3, CYP3A65, HMGCRa, HMGCRb and FASN. Additionally, polydatin inhibited oxidative stress in the liver according to fluorescent probe. Moreover, significantly up-regulated expression of DNA damage-related genes (CHOP, GADD45αa) revealed that polydatin attenuated hepatic apoptosis in larvae. In conclusion, polydatin may improve the liver function of zebrafish with acute alcoholic liver injury through attenuating hepatic fat accumulation, ameliorating lipid and ethanol metabolism and reducing oxidative stress and DNA damage.
Subject(s)
Anti-Inflammatory Agents , Antioxidants , Glucosides/pharmacology , Lipid Metabolism/drug effects , Liver Diseases, Alcoholic/drug therapy , Liver Diseases, Alcoholic/metabolism , Oxidative Stress/drug effects , Phytotherapy , Stilbenes/pharmacology , Zebrafish , Animals , Aryl Hydrocarbon Hydroxylases/genetics , Aryl Hydrocarbon Hydroxylases/metabolism , Cell Cycle Proteins/genetics , Cell Cycle Proteins/metabolism , Cytochrome P450 Family 3/genetics , Cytochrome P450 Family 3/metabolism , DNA Damage/genetics , Fallopia japonica/chemistry , Gene Expression/drug effects , Glucosides/isolation & purification , Glucosides/therapeutic use , Lipid Metabolism/genetics , Liver Diseases, Alcoholic/genetics , Liver Diseases, Alcoholic/pathology , Nuclear Proteins/genetics , Nuclear Proteins/metabolism , Oxidoreductases, N-Demethylating/genetics , Oxidoreductases, N-Demethylating/metabolism , Stilbenes/isolation & purification , Stilbenes/therapeutic use , Zebrafish Proteins/genetics , Zebrafish Proteins/metabolismABSTRACT
The Ustilaginaceae family of smut fungi, especially Ustilago maydis, gained biotechnological interest over the last years, amongst others due to its ability to naturally produce the versatile bio-based building block itaconate. Along with itaconate, U. maydis also produces 2-hydroxyparaconate. The latter was proposed to be derived from itaconate, but the underlying biochemistry and associated genes were thus far unknown. Here, we confirm that 2-hydroxyparaconate is a secondary metabolite of U. maydis and propose an extension of U. maydis' itaconate pathway from itaconate to 2-hydroxyparaconate. This conversion is catalyzed by the P450 monooxygenase Cyp3, encoded by cyp3, a gene, which is adjacent to the itaconate gene cluster of U. maydis. By deletion of cyp3 and simultaneous overexpression of the gene cluster regulator ria1, it was possible to generate an itaconate hyper producer strain, which produced up to 4.5-fold more itaconate in comparison to the wildtype without the by-product 2-hydroxyparaconate. By adjusting culture conditions in controlled pulsed fed-batch fermentations, a product to substrate yield of 67% of the theoretical maximum was achieved. In all, the titer, rate and yield of itaconate produced by U. maydis was considerably increased, thus contributing to the industrial application of this unicellular fungus for the biotechnological production of this valuable biomass derived chemical.
Subject(s)
4-Butyrolactone/analogs & derivatives , Biosynthetic Pathways/genetics , Cytochrome P450 Family 3/genetics , Genetic Enhancement/methods , Metabolic Engineering/methods , Succinates/metabolism , Ustilago/physiology , 4-Butyrolactone/metabolism , Gene Expression Regulation, Fungal/genetics , Metabolic Networks and Pathways/genetics , Succinates/isolation & purification , Up-Regulation/genetics , Ustilago/classificationABSTRACT
Genomic and transcriptomic analyses have well established that the major fraction of the mammalian genome is transcribed into different classes of RNAs ranging in size from a few nucleotides to hundreds of thousands of nucleotides, which do not encode any protein. Some of these noncoding RNAs (ncRNAs) are directly or indirectly linked to the regulation of expression or functions of 25,000 proteins coded by <2% of the human genome. Among these regulatory RNAs, microRNAs are small (2125 nucleotides) RNAs that are processed from precursor RNAs that have stemloop structure, whereas noncoding RNAs >200 nucleotides are termed long noncoding RNAs (lncRNAs). Circular RNAs (circRNAs) are newly identified lncRNA members that are generated by back-splicing of primary transcripts. The functions of ncRNAs in modulating liver toxicity of xenobiotics are emerging only recently. Acetaminophen (N-acetyl-para-aminophenol, paracetamol or APAP) is a safe analgesic and antipyretic drug at the therapeutic dose. However, it can cause severe liver toxicity that may lead to liver failure if overdosed or combined with alcohol, herbs, or other xenobiotics. This review discusses the role of ncRNAs in acetaminophen metabolism, toxicity, and liver regeneration after APAP-induced liver injury (AILI).
Subject(s)
Acetaminophen/toxicity , Analgesics, Non-Narcotic/toxicity , Chemical and Drug Induced Liver Injury/metabolism , RNA, Untranslated/genetics , Animals , Chemical and Drug Induced Liver Injury/etiology , Chemical and Drug Induced Liver Injury/genetics , Cytochrome P450 Family 3/genetics , Cytochrome P450 Family 3/metabolism , Humans , RNA, Untranslated/blood , RNA, Untranslated/metabolismABSTRACT
Fasting has been shown to regulate the expression of the cytochrome p450 (CYP) enzyme system in the liver. However, the exact mechanism behind the fasting-induced regulation of the CYP's remains unknown. In the present study we tested the hypothesis that the peroxisome proliferator-activated receptor gamma coactivator 1α (PGC-1α), which is a key-regulator of energy metabolism, is responsible for the fasting-induced regulation of the CYP's. Lox/lox and liver specific PGC-1α (LKO) mice of both sexes, fasted for 18 h and the content of the CYP's as well as the hepatic metabolome was assessed. Fasting increased the mRNA content of Cyp2a4, Cyp2e1, Cyp3a11 and Cyp4a10. The fasting-induced response in Cyp4a10 mRNA content was different between lox/lox and LKO mice, while the absence of PGC-1α had no effect on the fasting-induced response for the other Cyp's. Moreover, the fasting-induced response in mRNA content of Sirtinus 1 and Perilipin 2 was different between lox/lox and LKO mice. Only the CYP1A isoform showed a fasting-induced response at the protein level. Absence of hepatic PGC-1α had no effect on the apparent metabolome, where fasting vs fed was the only discriminate in the following multivariate analysis. In conclusion, hepatic PGC-1α is not essential for the fasting-induced regulation of hepatic CYP's.
Subject(s)
Cytochrome P450 Family 2/metabolism , Cytochrome P450 Family 3/metabolism , Cytochrome P450 Family 4/metabolism , Food Deprivation , Liver/metabolism , Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha/metabolism , Animals , Cytochrome P450 Family 2/genetics , Cytochrome P450 Family 3/genetics , Cytochrome P450 Family 4/genetics , Gene Expression Regulation/physiology , Mice , Mice, Knockout , Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha/genetics , RNA, Messenger/genetics , RNA, Messenger/metabolismABSTRACT
OBJECTIVE: To identify genetic variants that influence steady-state etonogestrel concentrations among contraceptive implant users. METHODS: We enrolled healthy, reproductive-age women in our pharmacogenomic study using etonogestrel implants for 12-36 months without concomitant use of hepatic enzyme inducers or inhibitors. We collected participant characteristics, measured serum etonogestrel concentrations, and genotyped each participant for 120 single nucleotide variants in 14 genes encoding proteins involved in steroid hormone (ie, estrogens, progestins) metabolism, regulation, or function. We performed generalized linear modeling to identify genetic variants associated with steady-state etonogestrel concentrations. RESULTS: We enrolled 350 women, who had a median serum etonogestrel concentration of 137.4 pg/mL (range 55.8-695.1). Our final generalized linear model contained three genetic variants associated with serum etonogestrel concentrations: NR1I2(PXR) rs2461817 (ß=13.36, P=.005), PGR rs537681 (ß=-29.77, P=.007), and CYP3A7*1C (ß=-35.06, P=.025). Variant allele frequencies were 69.4%, 84.9%, and 5.1%, respectively. Our linear model also contained two nongenetic factors associated with etonogestrel concentrations: body mass index (BMI) (ß=-3.08, P=7.0×10) and duration of implant use (ß=-1.60, P=5.8×10); R for the model =0.17. CONCLUSION: Only BMI and duration of implant use remained significantly associated with steady-state etonogestrel concentrations. Of the three novel genetic associations found, one variant associated with increased etonogestrel metabolism (CYP3A7*1C) causes adult expression of fetal CYP3A7 proteins and can consequently alter steroid hormone metabolism. Women with this variant may potentially have increased metabolism of all steroid hormones, as 27.8% (5/18) of CYP3A7*1C carriers had serum etonogestrel concentrations that fell below the threshold for consistent ovulatory suppression (less than 90 pg/mL). More pharmacogenomic investigations are needed to advance our understanding of how genetic variation can influence the effectiveness and safety of hormonal contraception, and lay the groundwork for personalized medicine approaches in women's health. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, NCT03092037.
Subject(s)
Contraceptive Agents, Female/therapeutic use , Cytochrome P450 Family 3/genetics , Desogestrel/therapeutic use , Drug Implants , Genetic Variation , Adult , Cohort Studies , Desogestrel/blood , Female , Follow-Up Studies , Healthy Volunteers , Humans , Linear Models , Retrospective Studies , Young AdultABSTRACT
Pulsatillae radix, a traditional Chinese medicine (TCM), is often used in combination with florfenicol for treatment of intestinal infection in Chinese veterinary clinics. Anemoside B4 (AB4) is the major effective saponin in Pulsatillae radix. This study aimed to investigate whether the pharmacokinetics of florfenicol in broilers was affected by the combination of AB4. In this study, broilers were given AB4 (50 mg/kg BW), or 0.9% sodium chloride solution by oral administration for 7 days. They were then fed florfenicol orally (30 mg/kg BW) on the eighth day. The results showed that the AUC(0-∞), MRT(0-∞), t1/2z and Cmax of florfenicol were significantly decreased, and the Vz/F and CLz/F were significantly increased by AB4; the mRNA expression levels of CXR, CYP3A37 and MDR1 (except CXR and CYP3A37 in the liver) were up-regulated by AB4. In conclusion, AB4 altered the pharmacokinetics of florfenicol, resulting in lower plasma concentrations of florfenicol, this was probably related to the mRNA expression of CXR, CYP3A37 and MDR1 in the jejunum and liver (except CXR and CYP3A37) increased by AB4. The implications of these findings on the effect of traditional Chinese medicine containing AB4 on the effectiveness of florfenicol in veterinary practice deserve study.
Subject(s)
Gene Expression/drug effects , Saponins/pharmacology , Thiamphenicol/analogs & derivatives , ATP Binding Cassette Transporter, Subfamily B, Member 1/genetics , ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism , Administration, Oral , Animals , Aryl Hydrocarbon Hydroxylases/genetics , Aryl Hydrocarbon Hydroxylases/metabolism , Avian Proteins/genetics , Avian Proteins/metabolism , Chickens , Cytochrome P450 Family 3/genetics , Cytochrome P450 Family 3/metabolism , Drug Interactions , Glucuronosyltransferase/genetics , Glucuronosyltransferase/metabolism , Male , RNA, Messenger , Receptors, Cytoplasmic and Nuclear/genetics , Receptors, Cytoplasmic and Nuclear/metabolism , Saponins/administration & dosage , Thiamphenicol/administration & dosage , Thiamphenicol/blood , Thiamphenicol/pharmacokineticsABSTRACT
Enrofloxacin (ENR) is the most commonly used antibiotic in crustacean farming in China. Diet supplementation with lactic acid (LA) may, however, affect the efficacy and safety of ENR-based drugs. The aims of this study were to investigate the effects of LA on drug residues and elimination of oral ENR in Chinese mitten crab (Eriocheir sinensis) and to determine ENR and gene expression levels of drug-metabolizing enzymes in the hepatopancreas. To this end, ENR was orally administered to the crabs at a dose of 10.0â¯mgâ¯kg-1 body weight on the eighth day after feeding diets supplemented with 0.3%LA. The results showed that ENR levels in the hepatopancreas were significantly different at 1 and 12â¯h between the ENR and ENRâ¯+â¯0.3% LA groups (Pâ¯<â¯0.05). Lactic acid did not significantly affect the expression of CYP2A (phase I). However, the expressions of CYP3 (phase I) and GST (phase II) were significantly up-regulated by LA during the elimination process of ENR (6-24â¯h). At Tmax (1â¯h), the expression of phosphoenolpyruvate carboxykinase (PEPCK) was induced and expression of succinate dehydrogenase (SDH) was inhibited by LA. Both of these enzymes were significantly inhibited during the elimination process of ENR. The results suggest that LA contributes to the elimination of ENR, and thus, enhances hepatopancreas biotransformation and anti-injury capacity in E. sinensis.
Subject(s)
Brachyura/drug effects , Enrofloxacin/pharmacokinetics , Inactivation, Metabolic/drug effects , Lactic Acid/pharmacology , Administration, Oral , Animals , Anti-Bacterial Agents/administration & dosage , Anti-Bacterial Agents/pharmacokinetics , Aquaculture , Aryl Hydrocarbon Hydroxylases/genetics , Aryl Hydrocarbon Hydroxylases/metabolism , Brachyura/enzymology , Cytochrome P450 Family 3/genetics , Cytochrome P450 Family 3/metabolism , Dietary Supplements , Energy Metabolism/drug effects , Energy Metabolism/genetics , Enrofloxacin/administration & dosage , Gene Expression Regulation/drug effects , Hepatopancreas/drug effects , Hepatopancreas/metabolism , Inactivation, Metabolic/genetics , Steroid Hydroxylases/genetics , Steroid Hydroxylases/metabolismABSTRACT
After oral route of administration, drug absorption is unpredictable and is governed by various factors such as multi drug resistance-1 (MDR1) an efflux transporter and drug metabolizing enzymes (like CYP3A4, CYP3A37, CYP2D6) at intestine and liver. Naturally available phyto chemicals like piperine and quercetin as well as some floroquinolones are known to inhibit MDR1 and CYP3A37 activity and increases bioavailability of co-administered drugs. This study was carried out to investigate the effect of piperine and quercetin alone or in combination with marbofloxacin on CYP3A37 and MDR1 mRNA expression levels in liver and intestine of broiler chicken. After oral administration of piperine and quercetin for 3 consecutive days followed by with or without oral administration of marbofloxacin for 5â¯days, CYP3A37 and MDR1 mRNA expression levels were determined using quantitative real-time PCR. Total of 36 broiler chickens in seven individual groups were treated with different regimen and the mRNA expression levels at duodenum and liver were analyzed with apt statistical tools. After piperine and quercetin combined treatment with marbofloxacin, CYP3A37 mRNA expression levels were significantly down regulated by 20.57 (pâ¯=â¯.034) and 25.95 (pâ¯=â¯.003) folds; and MDR1 mRNA expression levels were also significantly down regulated by 11.33 (pâ¯=â¯.012) and 33.59 (pâ¯=â¯.006) folds in liver and duodenum, respectively. Down regulation of CYP3A37 and MDR1 mRNA in liver and duodenum indicate the combined pretreatment of piperine and quercetin may be useful for improving the pharmacokinetics of orally administered drugs which are substrates for CYP3A37 and MDR1.
Subject(s)
ATP Binding Cassette Transporter, Subfamily B, Member 1/genetics , Alkaloids/pharmacology , Aryl Hydrocarbon Hydroxylases/genetics , Benzodioxoles/pharmacology , Chickens/physiology , Cytochrome P450 Family 3/genetics , Fluoroquinolones/pharmacology , Gene Expression Regulation/drug effects , Piperidines/pharmacology , Polyunsaturated Alkamides/pharmacology , Quercetin/pharmacology , ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism , Animals , Anti-Bacterial Agents/pharmacology , Antioxidants/pharmacology , Aryl Hydrocarbon Hydroxylases/metabolism , Avian Proteins/genetics , Avian Proteins/metabolism , Chickens/genetics , Cytochrome P-450 Enzyme Inhibitors/pharmacology , Cytochrome P450 Family 3/metabolism , Duodenum/drug effects , Duodenum/metabolism , Liver/drug effects , Liver/metabolism , RNA, Messenger/genetics , RNA, Messenger/metabolism , Random AllocationABSTRACT
P-glycoprotein ( P-GP: , encoding gene Abcb1) and Breast Cancer Resistance Protein ( BCRP: , encoding gene Abcg2) are transport proteins that play a major role in modulating the bioavailability of oral drugs in humans and rodents. It has been shown that rifampicin is the typical inducer of P-gp in rodents by activating the nuclear receptor. However, its effect on Abcb1, Abcg2, CYP3A, and chicken xenobiotic-sensing orphan nuclear receptor ( CXR: ) mRNA expression in broilers is poorly understood. This study explored the effect of rifampicin on mRNA expression of Abcb1, Abcg2, CYP3A37, CXR as well as its effect on the pharmacokinetics of enrofloxacin in broilers. The mRNA levels of Abcb1, Abcg2, CYP3A37, and CXR were significantly increased in the liver (except Abcg2), kidney, jejunum, and ileum (P < 0.05) but not significantly changed in the duodenum (P > 0.05) after treated with rifampicin. Further analysis revealed that the variation tendencies of Abcb1, Abcg2, and CYP3A37 expression levels were significantly correlated with CXR mRNA expression levels in liver, kidney, jejunum, and ileum. Coadministration of rifampicin significantly changed the pharmacokinetic behavior of enrofloxacin orally administered by showing clearly lower AUC0-∞, AUC0-t, and Cmax as well as longer Tmax. The bioavailability of orally administered enrofloxacin was decreased from 72.5% to 24.8% by rifampicin. However, rifampicin did not significantly change the pharmacokinetics of enrofloxacin following intravenous administration. Our study shows that rifampicin up-regulated the small intestinal level of P-gp and BCRP and suggests that P-gp and BCRP are key factors that affected pharmacokinetic behavior of orally administered enrofloxacin by limiting its absorption from the intestine in broilers.