PSI-A-10 Correlations of NR3C1 Gene Expression with Pork Quality and Carcass Characteristics

Abstract

Abstract Genetic control of carcass and meat quality traits is of great interest to the pork industry, and Hypothalamic-Pituitary-Adrenal (HPA) activation has been reported to have an inverse relationship with lean carcass growth traits in swine. The objective of this study was to determine if transcript abundance of the glucocorticoid receptor (NR3C1) in liver is associated with carcass trait variation. The liver is a key player in energy partitioning towards muscle or adipose accretion, and hepatic glucocorticoid receptors that bind cortisol are known to play a role in glucose metabolism. We hypothesized that NR3C1 expression levels are associated with differences in pork quality and carcass traits. We collected liver tissue from 18 gilts at slaughter (avg. BW =127 kg, age at slaughter = 164 d). Additionally, we collected measurements of carcass traits including dressing percentage, loin muscle area, 10th-rib backfat depth, subjective color and marbling scores, Minolta Colorimeter measures of L*, a*, b*, 45-min and ultimate pH, and driploss (Table 1). We extracted RNA from liver samples using a Qiagen miRNeasy kit and performed qRT-PCR using a TaqMan assay to quantify NR3C1 transcript abundance, with ACTB and HPRT1 as reference genes. Pearson correlation analysis was conducted between the carcass traits and NR3C1 expression. While liver NR3C1 transcript abundance was not significantly correlated with a majority of these traits, it was found to have a significant positive correlation with dressing percentage (r = 0.606, t = 3.05, P = 0.008). In conclusion, transcript abundance of NR3C1 in liver does not appear have a relationship with carcass merit and meat quality, but does have a positive relationship with dressing percentage. Further investigation into tissue-specific expression of NR3C1 may reveal the molecular mechanisms underlying the reported associations between HPA activation and differences in pork quality and carcass traits.