Differential Gene Expression across Breed and Sex in Commercial Pigs Administered Fenbendazole and Flunixin Meglumine

Abstract

Characterizing the variability in transcript levels across breeds and sex in swine for genes that play a role in drug metabolism may shed light on breed and sex differences in drug metabolism. The objective of the study is to determine if there is heterogeneity between swine breeds and sex in transcript levels for genes previously shown to play a role in drug metabolism for animals administered flunixin meglumine or fenbendazole. Crossbred nursery female and castrated male pigs (n = 169) spread across 5 groups were utilized. Sires (n = 15) of the pigs were purebred Duroc, Landrace, Yorkshire or Hampshire boars mated to a common sow population. Animals were randomly placed into the following treatments: no drug (control), flunixin meglumine, or fenbendazole. One hour after the second dosing, animals were sacrificed and liver samples collected. Quantitative Real-Time PCR was used to measure liver gene expression of the following genes: SULT1A1, ABCB1, CYP1A2, CYP2E1, CYP3A22 and CYP3A29. The control animals were used to investigate baseline transcript level differences across breed and sex. Post drug administration transcript differences across breed and sex were investigated by comparing animals administered the drug to the controls. Contrasts to determine fold change were constructed from a model that included fixed and random effects within each drug. Significant (P-value <0.007) basal transcript differences were found across breeds for SULT1A1, CYP3A29 and CYP3A22. Across drugs, significant (P-value <0.0038) transcript differences existed between animals given a drug and controls across breeds and sex for ABCB1, PS and CYP1A2. Significant (P <0.0038) transcript differences across breeds were found for CYP2E1 and SULT1A1 for flunixin meglumine and fenbendazole, respectively. The current analysis found transcript level differences across swine breeds and sex for multiple genes, which provides greater insight into the relationship between flunixin meglumine and fenbendazole and known drug metabolizing genes.

Human Food Safety Implications of Variation in Food Animal Drug Metabolism

“…Besides diseases, other factors, such as genetic polymorphisms, breed differences, the type of food, drug-drug interaction, and feedlot environment, may also affect M/D ratios and withdrawal times11121314. Recent studies have proposed population-based approaches, either population mixed-effect pharmacokinetic1516 or population PBPK modeling1718, to estimate withdrawal times of veterinary drugs in food animals because population-based approaches are stochastic modeling techniques that can consider all possible factors and incorporate all available data into analysis.…”

Genetic Parameter Estimates for Metabolizing Two Common Pharmaceuticals in Swine

“…Within this resource population, it was shown by Howard et al ( 2014 ) that differences in pharmacokinetic (PK) parameters exist across four major swine breeds (i.e., Duroc, Hamphsire, Yorkshire, and Landrace) and sex. This was further verified at the genomic level based on gene expression differences for genes previously shown to play a role in drug metabolism, which include SULT1A1 and CYP2E1 for flunixin meglumine and SULT1A1 for fenbendazole (Howard et al, 2015 ). Furthermore, across the liver transcriptome, multiple cytochrome P450 (CYP1A1, CYP2A19, and CYP2C36) genes displayed different transcript levels across animals administered a drug vs. untreated animals (Howard et al, 2017 ).…”

“…The resource population that was utilized to estimate genetic parameters was developed to investigate the phenotypic and genetic variability related to drug metabolism in swine (Howard et al, 2014 , 2015 , 2017 ). The animals consisted of crossbred female and castrated male nursery pigs ( n = 198) housed in individual pens (0.9 × 1.8 m) at a room temperature of 17–24°C.…”

“…For both drugs, our recent work suggest that CYP1A1 and CYP2E1 are primarily involved in phase one metabolism and phase two often involves sulfate ( SULT1A1 ) and possibly glucuronide conjugation. (Howard et al, 2015 , 2017 ). The objective of the current study is to determine the amount of phenotypic variation in fenbendazole and flunixin meglumine drug metabolism due to genetics.…”

Pharmacokinetics of 14C‐ortho‐phenylphenol following intravenous administration in pigs

“…As well as species differences, there may be breed differences in the activity of SULT1A1 and therefore the ability to produce sulfate conjugates. Howard et al () found significant basal gene expression differences across breeds of pigs for SULT1A1 when comparing Hampshire to Landrace and Hampshire to Duroc. Lin et al () observed that a substitution of A➔G at base 546 of SULT1A1 in pig liver caused a significant decrease in its sulfation activity.…”