Acute cold and exercise training upregulate similar aspects of fatty acid transport and catabolism in house sparrows, Passer domesticus

Abstract

Summit maximum thermoregulatory metabolic rate (M sum ) and maximum exercise metabolic rate (MMR) both increase in response to acute cold or exercise training in birds. Because lipids are the main fuel supporting both thermogenesis and exercise in birds, adjustments to lipid transport and catabolic capacities may support elevated energy demands from cold and exercise training. To examine a potential mechanistic role for lipid transport and catabolism in organismal cross-training effects (exercise effects on both exercise and thermogenesis, and vice versa), we measured enzyme activities and mRNA and protein expression in pectoralis muscle for several key steps of lipid transport and catabolism pathways in house sparrows (Passer domesticus) during acute exercise and cold training. Both training protocols elevated pectoralis protein levels of fatty acid translocase (FAT/CD36), cytosolic fatty acid-binding protein, and citrate synthase (CS) activity. However, mRNA expression of FAT/CD36 and both mRNA and protein expression of plasma membrane fatty acid-binding protein did not change for either training group. CS activities in supracoracoideus, leg and heart, and carnitine palmitoyl transferase (CPT) and β-hydroxyacyl CoA-dehydrogenase activities in all muscles did not vary significantly with either training protocol. Both M sum and MMR were significantly positively correlated with CPT and CS activities. These data suggest that up-regulation of trans-sarcolemmal and intramyocyte lipid transport capacities and cellular metabolic intensities, along with previously documented increases in body and pectoralis muscle masses and pectoralis myostatin (a muscle growth inhibitor) levels, are common mechanisms underlying the training effects of both exercise and shivering in birds.

The role of temperature as a driver of metabolic flexibility in the Red-billed Leiothrix (Leiothrix lutea)

“…The morphological, physiological and biochemical changes induced Table 1 Linear regression statistics for log organ mass versus log body mass (minus wet mass of the organ) allometric equations (allometric correlations) and for log organ mass residuals versus log basal metabolic rate (BMR) residuals (residual correlations)-or log organ mass versus log BMR raw values if allometric equations were not significant-in the Red-billed Leiothrixs (Leiothrix lutea) after 28 days of temperature acclimation by cold temperatures may lead to energy expenditure, thereby enhancing the survival of the Red-billed Leiothrix in winter, the most energetically challenging time of the year. Good quality transcriptomic and metabonomic data is required to fully understand the complex mediation of physiological and biochemical processes that occurs during seasonal acclimatization (Teulier et al 2010;Stager et al 2015;Zhang et al 2015).…”

Context-dependent regulation of pectoralis myostatin and lipid transporters by temperature and photoperiod in dark-eyed juncos

“…We measured pectoralis mRNA expression for myostatin , TLL-1 , TLL-2 , FABPpm , and FAT/CD36 by qRT–PCR, as described in Swanson et al (2014a ) and Zhang et al (2015a , 2015b , 2015c , 2015d ), using glyceraldehyde-3-phosphate dehydrogenase ( GAPDH ) as a housekeeping gene. For these assays, we first extracted total RNA with β-mercaptoethanol and the RNeasy Fibrous Tissue Mini kit (QIAGEN, Valencia, CA, USA).…”

“…Prolonged shivering thermogenesis in birds is almost exclusively fueled by exogenous lipids from adipose tissues ( Swanson 2010 ). As a result, capacities for non-esterified fatty acid (NEFA) uptake into the myocyte and their subsequent transport to mitochondrial membranes are potential regulatory steps for lipid catabolic capacity in support of shivering ( Swanson 2010 ; Zhang et al 2015a ). Once circulating NEFAs reach the myocyte, plasma membrane-bound fatty acid binding protein (FABPpm) and fatty acid translocase (FAT/CD36) cooperate to transport NEFAs across the endothelium, the interstitial space, and the sarcolemma to enter muscle cells ( Kiens 2006 ; Glatz et al 2010 ).…”

“…Some studies showed elevated FAT/CD36 and FABPpm levels during migration compared to non-migrants ( McFarlan et al 2009 ; Zhang et al 2015c ), but others indicated stable FAT/CD36 and FABPpm during migration or wintering ( Zhang et al 2015c , 2015d ). Moreover, results from exercise and cold training studies suggest that responses of FAT/CD36 and/or FABPpm levels to increasing energy demands also vary among species ( Price et al 2010 ; Zhang et al 2015a ). Intramyocyte fatty acid transport in skeletal muscles is mediated by cytosolic fatty acid binding protein (FABP c ) ( Kiens 2006 ; Guglielmo 2010 ).…”

Non-Mammalian Vertebrates: Distinct Models to Assess the Role of Ion Gradients in Energy Expenditure

“…Accordingly, in the mouse, fatty acid translocase (cd36) knockout prevents the maintenance of body temperature in response to cold exposure ( 70 ). Moreover, cold acclimation in the sparrow increases pectoralis cd36 protein expression by 46% ( 71 ). In addition to acting as a carbon source, these lipids may modulate the degree of Ca ++ cycling.…”