Effect of weight loss on gene expression profiles and oxidative stress markers in the skeletal muscle of lactating beef cows.

Abstract

Elevated β‐oxidation leads to increased oxidative stress. Many genes can help protect from damage sustained during this physiological state. To investigate the effect of fat mobilization on oxidative stress and gene expression in skeletal muscle, Angus cows (n=26) were examined during weight loss and weight maintenance. At both physiological states, body weight, serum non‐esterified fatty acids (NEFA), erythrocyte superoxide dismutase (SOD) activity and mRNA levels of target genes in the Biceps femoris were measured. When cows were losing weight, serum NEFA's (P<.0001) were higher and SOD activity (P<.025) increased compared to weight maintenance. Expression of β‐oxidation genes, carnitine palmitoyltransferase 1 (2.8 fold), fatty acid‐binding protein 3 (4.6 fold), and acyl‐coenzyme A oxidase 1 (2.0 fold) were higher during weight loss compared to weight maintenance (P<.01). During weight loss cows also had higher expression (P<.01) of uncoupling proteins 2 and 3 (3.0 fold and 5.0 fold respectively), tumor protein 53 (1.9 fold), nuclear respiratory factor 1 (2.6 fold), estrogen‐related receptor α (2.4 fold), and peroxisome proliferator‐activated receptors α and γ (2.0 fold and 1.9 fold). Mobilization of body fat results in greater antioxidant activity in erythrocytes and increased expression of genes that play a key role in protecting skeletal muscle against oxidative stress.