Energy Metabolism In Rats Research Articles

Photoperiod and food restriction differentially affect reproductive and immune responses in Siberian hamsters Phodopus sungorus

Summary 1. Organisms must contend with seasonal fluctuations in energy availability. To maintain a positive energy balance year‐round, a number of adaptations have evolved including seasonal changes in reproduction, energetics and immunity. Photoperiod is the primary environmental signal most animals use to predict seasonal events. Despite the established link between energetics and immune function, little is known regarding how changes in energy availability affect immunity. 2. The goal of the present study was to determine the effects of food restriction on photoperiodic changes in reproduction and immune function in the Siberian hamster (Phodopus sungorus). Adult hamsters were housed in long or short days and were food restricted or fed ad libitum. Immune responses were quantified by measuring specific antibody production and bacterial killing capacity. 3. Food restriction decreased body and relative reproductive masses in long‐day animals. Antibody responses, but not bacterial killing ability, were enhanced in food restricted short‐day animals as compared with ad libitum fed controls. We also found differential effects of body fat on immune responses depending on the immune measure. 4. The effects of food restriction on immune function appear to vary based on the restriction regimen, the response measured, and the physiological state of the organism including energy balance, metabolic rate and reproductive status. 5. In conclusion, these results suggest that a wide range of factors can differentially affect immune function. In addition, these effects may vary based on the specific response examined. Future studies should include a variety of measurements to provide a more integrative and accurate picture of reproductive, energetic, and photoperiodic effects on immune function.

The expression of genes PKM2 and CAST in the muscle tissue of pigs differentiated by glycolytic potential and drip loss, with reference to the genetic group

The present studies aimed at an analysis of the expression level of genes PKM2 and CAST in Longissimus lumborum [LL] muscle tissue of pigs differing as regards the glycolytic potential [GP] and drip loss [DL] from the LL muscle, with reference to the genetic group. The studies covered a total of 65 pigs: 20 purebred Landrace [L], 22 crossbreeds of Landrace with the Yorkshire [L × Y] and 23 three-breed crosses (Landrace × Yorkshire) × Duroc [(L × Y) × D]. In the case of gene PKM2 one may observe in (L × Y) × D crossbreds, compared to L × Y crossbreds, an increased expression, closely related with the increase in dry matter content, including intramuscular fat, as well as a more favourable progress of glycolytic and energy metabolism during the early time post mortem (pH 45 and R 1). Compared with Landrace animals, the lower expression of the CAST gene observed in (L × Y) × D pigs is manifested by a marked improvement of meat quality ( R 1 pH 45 pH 24, pH 48), arising from the rate of glycolytic and energy metabolism, typical for normal meat, that in effect results in its higher culinary and technological value.

Dietary Blueberry Attenuates Whole-Body Insulin Resistance in High Fat-Fed Mice by Reducing Adipocyte Death and Its Inflammatory Sequelae1–3

Adipose tissue (AT) inflammation promotes insulin resistance (IR) and other obesity complications. AT inflammation and IR are associated with oxidative stress, adipocyte death, and the scavenging of dead adipocytes by proinflammatory CD11c+ AT macrophages (ATMΦ). We tested the hypothesis that supplementation of an obesitogenic (high-fat) diet with whole blueberry (BB) powder protects against AT inflammation and IR. Male C57Bl/6j mice were maintained for 8 wk on 1 of 3 diets: low-fat (10% of energy) diet (LFD), high-fat (60% of energy) diet (HFD) or the HFD containing 4% (wt:wt) whole BB powder (1:1 Vaccinium ashei and V. corymbosum) (HFD+B). BB supplementation (2.7% of total energy) did not affect HFD-associated alterations in energy intake, metabolic rate, body weight, or adiposity. We observed an emerging pattern of gene expression in AT of HFD mice indicating a shift toward global upregulation of inflammatory genes (tumor necrosis factor-α, interleukin-6, monocyte chemoattractant protein 1, inducible nitric oxide synthase), increased M1-polarized ATMΦ (CD11c+), and increased oxidative stress (reduced glutathione peroxidase 3). This shift was attenuated or nonexistent in HFD+B-fed mice. Furthermore, mice fed the HFD+B were protected from IR and hyperglycemia coincident with reductions in adipocyte death. Salutary effects of BB on adipocyte physiology and ATMΦ gene expression may reflect the ability of BB anthocyanins to alter mitogen-activated protein kinase and nuclear factor-κB stress signaling pathways, which regulate cell fate and inflammatory genes. These results suggest that cytoprotective and antiinflammatory actions of dietary BB can provide metabolic benefits to combat obesity-associated pathology.

Effects of diet quantity restriction on indices of lipid and energy metabolism in rats during diurnal variation

Effects of diet quantity restriction on indices of lipid and energy metabolism in rats during diurnal variation

A body composition model to estimate mammalian energy stores and metabolic rates from body mass and body length, with application to polar bears

Many species experience large fluctuations in food availability and depend on energy from fat and protein stores for survival, reproduction and growth. Body condition and, more specifically, energy stores thus constitute key variables in the life history of many species. Several indices exist to quantify body condition but none can provide the amount of stored energy. To estimate energy stores in mammals, we propose a body composition model that differentiates between structure and storage of an animal. We develop and parameterize the model specifically for polar bears (Ursus maritimus Phipps) but all concepts are general and the model could be easily adapted to other mammals. The model provides predictive equations to estimate structural mass, storage mass and storage energy from an appropriately chosen measure of body length and total body mass. The model also provides a means to estimate basal metabolic rates from body length and consecutive measurements of total body mass. Model estimates of body composition, structural mass, storage mass and energy density of 970 polar bears from Hudson Bay were consistent with the life history and physiology of polar bears. Metabolic rate estimates of fasting adult males derived from the body composition model corresponded closely to theoretically expected and experimentally measured metabolic rates. Our method is simple, non-invasive and provides considerably more information on the energetic status of individuals than currently available methods.

PICTORIAL COGNITIVE TASK RESOLUTION AND EXPIRED MINUTE VENTILATION, OXYGEN CONSUMPTION, CARBON DIOXIDE PRODUCTION AND HEART RATE

To assess the impact of cognitive task solving on respiratory and cardiovascular parameters. The ML870B80 Exercise Physiology System was used to record concurrently with EEG, the cardiorespiratory and metabolic functions of subjects during cognitive activity. The Expired Minute Ventilation (VE), Oxygen Consumption (VO2), Carbon Dioxide Production (VCO2) and Average Heart Rate (BPM) were ascertained for four periods: (1) rest or starting period, (2) reference period, (3) cognitive task solving period and (4) recovery period. Each period was defined by the type of presented visual stimuli and by the prearranged cognitive activity related to visual stimuli. The personality traits of participants were also determined. The momentary functional state of subject's brain (i.e. the period of the experiment) determined the average values of all measured parameters. During the cognitive task solving period the average VE, VO2 and VCO2 reached the lowest values while the HR behaved reversely--it was the highest in the cognitive task solving period. Further, the average VE, VCO2 and HR values but not VO2 value differed significantly from average values for the same variable measured in the rest period. The changes in respiratory variables during the cognitive task solving period predicate the whole-body metabolic rate rather than the energy metabolism of the brain alone. However, the heart rate related to some personality traits of the subject has a tighter relation to brain's energy metabolic rate during the cognitive task solving--it affects the oxygen supply of the brain.

Comparison of mycelial proteomes of two Verticillium albo-atrum pathotypes from hop

Verticillium wilt diseases caused by Verticillium spp. are known in many important crops and can seriously threaten their production. We studied Verticillium albo-atrum by comparative analysis of the proteome of four hop isolates, classified by the severity of wilt symptoms as mild and lethal pathotypes, from two geographic origins. A two-dimensional electrophoresis reference map of mycelium proteins was first established, resolving up to 650 protein spots on Coomassie-stained gels in a range of pH 4–7 and MW 14 – 116 kDa. The average coefficient of variance for the 268 matched protein spots was 16% and 15%, respectively, for technical and biological variability. Principal component analysis (PCA) discriminated the geographic origin of the isolates and between the two pathotypes and showed a closer relationship among English isolates than Slovene ones. The two-dimensional electrophoresis patterns of one mild (PG1) with one lethal pathotype (PG2) from Slovenia and one mild (M) with one lethal pathotype (PV1) from England were compared. A total of 27 and 30 spots were found differentially expressed between the pathotypes, which were analysed by tandem mass spectrometry. Fifty-three proteins were identified, of which 17 matched proteins with annotated functions. The lethal pathotypes showed increased expression of peroxiredoxine and ascorbate peroxidase, a higher level of cytoskeleton components and regulators, and a higher rate of protein synthesis and energy metabolism. These results reveal differences in the expression level of the identified proteins between the two pathotypes and are discussed in relation to virulence.

Effects of acute heat stress on skeletal muscle gene expression associated with energy metabolism in rats

Study objectives were to determine the effects of acute heat stress (HS) on the expression of genes associated with energy metabolism in type I and II skeletal muscles. Male Sprague Dawley rats (n = 12; 9 mo) were randomly assigned to either thermal neutral (TN; 21.1°C) or HS conditions (39.4°C) for 6 h. Rats were anesthetized and the soleus (type I; oxidative) and tibialis anterior (TA; type II; glycolytic) muscles were collected. Total RNA was isolated and cDNA generated for real‐time PCR analysis (iQ5 Real‐Time PCR detection system). Exposure to HS tended to increase soleus and decrease TA AMP‐activated protein kinase (AMPK) mRNA abundance. Hyperthermia increased and tended to increase PPAR‐γ Co‐activator ‐1α (PGC‐1α) gene expression in soleus and TA, respectively. Pyruvate dehydrogenase kinase 4 (PDK4) mRNA abundance was increased by HS in the soleus but was unaltered in the TA. Lactate dehydrogenase‐α (LDHα) gene expression tended to increase in TA during HS but LDHα mRNA abundance did not differ in soleus between treatments. In conclusion, exposure to HS induced the differential expression of several energy metabolism genes based on muscle type (soleus versus TA). Moreover, changes in gene expression are consistent with impaired cellular energy status, perhaps due to mitochondrial dysfunction, in oxidative compared to glycolytic muscle fibers during hyperthermia.

Dietary blueberry attenuates obesity‐associated insulin resistance by reducing adipocyte death and macrophage pro‐inflammatory activation in adipose tissue of high fat‐fed mice

Adipose tissue (AT) inflammation promotes insulin resistance (IR) and other obesity complications. AT inflammation and IR are associated with AT oxidative stress, adipocyte death, and the scavenging of dead adipocytes by M1‐polarized CD11c+ AT macrophages (ATMs). We test the hypothesis that blueberry (BB) supplementation of an obesigenic diet protects against these AT events. Male C57B/6j mice were fed one of three diets for 8 weeks: 10% fat (LF), 60% fat (HF) or HF containing 4% (w:w) BB powder (1:1 V. ashei and V. corymbosum). We assessed energy intake, metabolic rate, insulin resistance (insulin tolerance tests), body and AT weights, adipocyte size, adipocyte death, as well as AT gene expression by Q‐PCR of CD11c, inflammatory mediators and markers of oxidative stress (GPx3). Relative to the HF cohort, mice fed the HFB diet were significantly protected from insulin resistance. This protection was associated with enhanced antioxidant (GPx3) gene expression, reduced adipocyte death, attenuated expression of CD11c, and abrogation of ATM expression of TNF‐α and iNOS. BB supplementation had no effect on HF diet‐associated alterations in energy intake, metabolic rate, body / AT weight, adipocyte size or markers of alternative (M2) ATM activation. BB's salutary effect on IR may reflect beneficial actions of BB anthocyanins on antioxidant and inflammatory gene expression in adipocytes and ATM.Grant Funding SourceNIH (1RO1DKO74979) and the Highbush Blueberry Council

A unique pancreatic mitochondrial response to calcium and its role in apoptosis

The exocrine pancreas synthesises more protein per gram of tissue than any other mammalian organ (with the exception of the lactating breast) and produces 6–20 g of digestive enzyme per...

More efficient mastication allows increasing intake without compromising digestibility or necessitating a larger gut: Comparative feeding trials in banteng ( Bos javanicus) and pygmy hippopotamus ( Hexaprotodon liberiensis)

The digestion of plant material in mammalian herbivores basically depends on the chemical and structural composition of the diet, the mean particle size to which the forage is processed, and the ingesta retention time. These different factors can be influenced by the animal, and they can presumably compensate for each other. The pygmy hippopotamus, a non-ruminating foregut fermenter, has longer mean retention times than ruminants; however hippos do not achieve higher (fibre) digestibilities on comparable diets, which could be due to ineffective mastication. We performed feeding trials with six pygmy hippos ( Hexaprotodon liberiensis) and six banteng cattle ( Bos javanicus) on a grass diet. As predicted, both species achieved similar dry matter, organic matter, crude protein and gross energy digestibilities. However, neutral and acid detergent fibre digestibility was lower in pygmy hippos. Apparently, in these species, fibre digestibility was more influenced by particle size, which was larger in pygmy hippos compared to banteng, than by retention time. In spite of their higher relative food intake, the banteng in this study did not have greater relative gut fills than the hippos. Ruminants traditionally appear intake-limited when compared to equids, because feed particles above a certain size cannot leave the rumen. But when compared to nonruminating foregut fermenters, rumination seems to free foregut fermenters from an intrinsic food intake limitation. The higher energy intakes and metabolic rates in wild cattle compared to hippos could have life-history consequences, such as a higher relative reproductive rate.

Mechanism-Based Modeling of Nutritional and Leptin Influences on Growth in Normal and Type 2 Diabetic Rats

Influences of genetic and nutritional factors on body weight, fat mass, and leptin production and effects of leptin were assessed in normal [Wistar-Kyoto (WKY)] and diabetic [Goto-Kakizaki (GK)] rats by mechanism-based modeling. The study included 60 WKY and 60 GK rats; half received high-fat diet (HF), and the others received normal rat chow (N). Body weights and food consumption were measured twice weekly. Six rats per group were sacrificed at 4, 8, 12, 16, and 20 weeks. Abdominal fat was weighed, and plasma leptin was measured by enzyme-linked immunosorbent assay. All data were comodeled using NONMEM version VI level 1.1 (first-order conditional estimation with interaction) (Beal SL, Boeckmann AJ, Sheiner LB, and NONMEM Project Group, NONMEM Users Guides, University of California, San Francisco, CA, 2007). Weight gain was modeled as differences between energy intake and metabolic rate based on allometrically scaled lean body mass (LBM). The GK had higher metabolic rates (1.15 kcal/day/g LBM(0.75)) than WKY-N (0.92) and WKY-HF (1.02) rats and higher efficiency in transforming energy into body weight. Leptin effect was modeled as inhibition of food consumption. Total body fat was estimated from abdominal fat. Leptin production from fat was 4.7-fold higher for GK (3.03 ng/ml/day/g) than WKY (0.66 ng/ml/day/g). Leptin production rate from LBM was 0.53 ng/ml/day/g for all groups. The IC(50) for inhibition of food intake by leptin was approximately 3-fold higher in GK versus WKY, indicating leptin resistance for the effect on food consumption in GK. The GK had similar intake of kilocalories but lower body weights and fat mass than WKY, possibly because of higher metabolic rates. Our mechanism-based model explains intrinsic reasons for differences in growth, food intake, and leptin concentrations among these two strains of rats.

QT intervals compared in small and large hibernators and humans

Small hibernating animals experience cycles of deep hypothermia followed by rewarming and feeding. This contrasts with bears, which remain in hibernation for four to seven months, experiencing large reductions in energy metabolism and heart rate, and small reductions in core temperature, and do not eat, drink, urinate, or defecate throughout. We measured the QT interval (QT) of the electrocardiogram (EKG) to determine whether the hearts of bears behave electrophysiologically more like classic hibernators or non-hibernators. We compared EKGs from grizzly and polar bears with small hibernators (marmots) and humans. Animal data were obtained using implanted radio capsules. EKGs of non-dormant marmots were characterized by a shortened QT (0.07–0.14 s); this held for grizzly and polar bears (0.14–0.23 s), but not for humans (0.39 s). Thus, the QT of bears resembles that of small hibernators. At the same heart rate, the QT of non-dormant bears and marmots differs in winter and summer.

MAXIMUM ENTROPY AND THE STATE-VARIABLE APPROACH TO MACROECOLOGY

The biodiversity scaling metrics widely studied in macroecology include the species-area relationship (SAR), the scale-dependent species-abundance distribution (SAD), the distribution of masses or metabolic energies of individuals within and across species, the abundance-energy or abundance-mass relationship across species, and the species-level occupancy distributions across space. We propose a theoretical framework for predicting the scaling forms of these and other metrics based on the state-variable concept and an analytical method derived from information theory. In statistical physics, a method of inference based on information entropy results in a complete macro-scale description of classical thermodynamic systems in terms of the state variables volume, temperature, and number of molecules. In analogy, we take the state variables of an ecosystem to be its total area, the total number of species within any specified taxonomic group in that area, the total number of individuals across those species, and the summed metabolic energy rate for all those individuals. In terms solely of ratios of those state variables, and without invoking any specific ecological mechanisms, we show that realistic functional forms for the macroecological metrics listed above are inferred based on information entropy. The Fisher log series SAD emerges naturally from the theory. The SAR is predicted to have negative curvature on a log-log plot, but as the ratio of the number of species to the number of individuals decreases, the SAR becomes better and better approximated by a power law, with the predicted slope z in the range of 0.14-0.20. Using the 3/4 power mass-metabolism scaling relation to relate energy requirements and measured body sizes, the Damuth scaling rule relating mass and abundance is also predicted by the theory. We argue that the predicted forms of the macroecological metrics are in reasonable agreement with the patterns observed from plant census data across habitats and spatial scales. While this is encouraging, given the absence of adjustable fitting parameters in the theory, we further argue that even small discrepancies between data and predictions can help identify ecological mechanisms that influence macroecological patterns.

Toxicity of ethylene glycol monomethyl ether: impact on testicular gene expression

Methoxyacetic acid (MAA), the active biological oxidation product of the industrial solvent ethylene glycol monomethyl ether (EGME), causes acute toxicity in several species including humans. MAA primarily affects tissues with rapidly dividing cells and high rates of energy metabolism, including testes, thymus and the fetus. Testicular toxicity, one of the most prominent consequences of EGME, and MAA, exposure, results from apoptosis of primary spermatocytes and is associated with changes in the expression of various genes and signalling pathways. This review of EGME metabolism and its organ-specific toxicities emphasizes genes and signalling pathways that are modulated by EGME exposure and their relevance to the molecular mechanisms underlying EGME and MAA toxicity. Of particular importance are the genes that code for oxidative stress response factors, protein kinases, and nuclear hormone receptors. Nuclear receptors and protein kinases regulate multiple cellular processes and are critical for signalling events required for spermatogenesis. De-regulation of their activity by EGME or MAA leads to inappropriate signalling in testicular cells. Oxidative stress in spermatocytes exposed to MAA triggers mitochondrial release of cytochrome C, activation of caspases and ultimately apoptosis. Detailed investigation of the molecular responses to MAA exposure may help elucidate the overall impact and extent of toxicity seen following EGME exposure. Finally, given the effects of EGME on multiple genes and signalling pathways in the testis, mixture studies combining EGME, or MAA, with other testicular toxicants may help identify toxicities that are aggravated by EGME exposure.

Is basal metabolic rate influenced by age in a long-lived seabird, the snow petrel?

Ageing is associated with a decline in basal metabolic rate (BMR) in many species, including humans. The evolutionary and physiological causes underlying the relationship between age and BMR are poorly understood. Studies of procellariiform seabirds may provide valuable insight because they have a longer maximum lifespan than expected from their body size and rates of energy metabolism. Such studies are rare, however, because there are few populations with a high proportion of individuals of known age. We performed a cross-sectional study of energy metabolism in relation to age in a long-lived seabird, the snow petrel Pagodroma nivea. In an Antarctic population that has been subject to a long-term research program, including annual banding of chicks since 1963, we measured BMR of individuals aged between 8 and 39 years. We show that the BMR of the snow petrel does not decrease with increasing age. BMR seems to be sustained at a fixed level throughout the investigated age-span. We review this result in light of the disposable soma theory of ageing, and we discuss whether species-specific relationships between age and basal metabolic rate can be related to differences in maximum lifespan.

Management of Uncontrolled Hemorrhagic Shock

Management of Uncontrolled Hemorrhagic Shock

Application of MRS to mouse models of neurodegenerative illness

The rapid development of transgenic mouse models of neurodegenerative diseases, in parallel with the rapidly expanding growth of MR techniques for assessing in vivo, non-invasive, neurochemistry, offers the potential to develop novel markers of disease progression and therapy. In this review we discuss the interpretation and utility of MRS for the study of these transgenic mouse and rodent models of neurodegenerative diseases such as Alzheimer's (AD), Huntington's (HD) and Parkinson's disease (PD). MRS studies can provide a wealth of information on various facets of in vivo neurochemistry, including neuronal health, gliosis, osmoregulation, energy metabolism, neuronal-glial cycling, and molecular synthesis rates. These data provide information on the etiology, natural history and therapy of these diseases. Mouse models enable longitudinal studies with useful time frames for evaluation of neuroprotection and therapeutic interventions using many of the potential MRS markers. In addition, the ability to manipulate the genome in these models allows better mechanistic understanding of the roles of the observable neurochemicals, such as N-acetylaspartate, in the brain. The argument is made that use of MRS, combined with correlative histology and other MRI techniques, will enable objective markers with which potential therapies can be followed in a quantitative fashion.

Feeding Scallop Shell Powder Induces the Expression of Uncoupling Protein 1 (UCP1) in White Adipose Tissue of Rats

Previously we found that the organic components in scallop shell promote lipolysis in differentiated 3T3-L1 and C3H10T1/2 adipocyte cells, and that incorporating scallop shell powder into the diet of rats reduced the amount of white adipose tissue. In this study, we used RT-PCR to investigate the effect of ingesting scallop shell powder on the gene expression profile of uncoupling proteins (UCPs) regulating energy metabolism in rats. Feeding of scallop shell powder increased mRNA levels of UCP1 and UCP2 in white adipose tissue. By contrast, scallop shell powder had no effect on the expression of UCP1 in brown adipose tissue, although the expression level of UCP2 mRNA decreased significantly. These results suggest that feeding scallop shell powder increases gene expression of UCP1 that may regulate energy metabolism in white adipose tissue, resulting in the observed reduction in weight of white adipose tissue.

Ischemic preconditioning improves liver regeneration by sustaining energy metabolism after partial hepatectomy under ischemia in rats

The protective effect of ischemic preconditioning (IPC) has been reported on improvement of survival, reduction of liver necrosis and enhancement of the regenerative capacity of hepatocytes after partial hepatectomy. This study was undertaken to confirm that IPC has a significant impact on regeneration of hepatocytes after partial hepatectomy in ischemically damaged liver. In addition, we sought to examine the role of adenine nucleotides in this process. Wistar rats were subjected to 60 min of total hepatic ischemia, followed by 70% hepatectomy. The animals were subdivided into an IPC (10/15 min) group and a non-IPC (control) group. Liver function tests and arginase activity were analyzed. Hepatic adenosine triphosphate (ATP), adenosine diphosphate and adenosine monophosphate were measured using gradient high-performance liquid chromatography. The liver regeneration was identified using relative liver weight and proliferating cell nuclear antigen (PCNA) labeling index. IPC treatment improved serum liver enzymes and tissue arginase activity (P<0.05) when compared with the control group. The preconditioned livers were associated with upregulation of ATP expression and also increased tissue energy charge. Regenerated liver weight in the IPC group was significantly higher than in the control group (P<0.05). The PCNA labeling index in the remnant livers in the IPC group was also significantly increased at 24 and 48 h after partial hepatectomy (P<0.05). These results suggest that IPC-augmented liver regeneration after hepatectomy, probably due to the stabilization of energy metabolism in rats.