Higher Basal Metabolic Rate Research Articles

Divergent selection for basal metabolic rate in mice affects the abundance of UCP1 protein: implications for translational studies.

Low basal metabolic rate (BMR) is a risk factor for obesity, whereas elevation of non-shivering thermogenesis (NST) is a promising means to combat obesity. Because heat generated by NST covers thermogenic needs not fulfilled by BMR, one can expect the presence of a negative relationship between both parameters. Understanding of the mechanisms underlying this relationship is therefore important for interpretation of the results of translational experiments and the development of anti-obesity treatments. We studied two lines of laboratory mice divergently selected for high or low level of BMR, raised at 23°C and subsequently acclimated to different ambient temperatures (30, 23 and 4°C). Mice selected for low BMR accumulated more fat but simultaneously showed higher NST capacity and more uncoupling protein-1 (UCP1) in interscapular brown adipose tissue (iBAT), to compensate for their lower heat production through BMR. The between-line difference in UCP1 protein abundance was significant even in mice acclimated to 30°C when the level of UCP1 is very low. Differences in NST capacity between selected lines and acclimation temperatures were explained by UCP1 iBAT abundance. Our results reveal that BMR is inversely correlated with UCP1 protein abundance and NST, even after acclimation to thermoneutrality. Thus, low values of BMR can increase both obesity risk and the magnitude of NST, i.e. the process whose activation has been proposed to mitigate obesity risk. All these effects should be taken into account in the design and interpretation of translational studies on mice models of metabolic diseases. KEY POINTS: Basal metabolic rate (BMR) and non-shivering thermogenesis (NST) based on the activity of uncoupling protein-1 (UCP1) are two main sources of heat in laboratory mice. Both BMR and UCP1 can affect obesity risk in laboratory rodents and humans. Here we studied BMR, NST, and the abundance of UCP1 in laboratory mice selected divergently towards either high or low BMR. We showed that BMR is negatively correlated with UCP1 abundance and this effect is not removed even after acclimation to thermoneutrality. The pattern described reveals that BMR can affect not only obesity risk but also the magnitude of UCP1-mediated NST. Since activation of NST was proposed to mitigate obesity risk, variation in BMR should be taken into account in translational studies of mouse models of metabolic diseases.

Can High Temperatures Affect Body Size in Insects? The Case of Rubyspot Damselflies in the Colombian Western Andes

Basal metabolic rates (BMRs) increase with temperature and body mass. Environmental temperatures rapidly change in tropical mountains due to elevation (macro scale) and vegetation structure (micro scale). Thus, tropical mountains are good settings for testing the effects of temperature on BMRs. We measured the BMRs at four temperature ranges on six territorial and closely related species of Rubyspot damselflies (Hetaerina, Calopterygidae), which also share very similar behavior and morphology and are segregated by habitat and elevation across the Western Colombian Andes. We analyzed the effects of body mass, habitat, elevation, temperature, and sex on their BMRs, using a phylogenetic framework. We found that the main factors regulating their niche partition seemed to be environmental temperature, body size, and BMR. We found differences in their BMRs related to elevation when the temperatures were close to those experienced by the damselflies at their elevational range. As predicted, the larger species associated with colder habitats, forests, and highlands had higher BMRs. However, at high stressful temperatures, only the body mass was positively related to the BMR, showing that smaller individuals can keep their BMRs lower under high temperatures compared to bigger ones. Habitat use was not associated with changes in the BMR. Finally, phylogenetic reconstruction showed all species clustered in three clades. Each clade in the phylogenetic tree shares similar habitat preferences, pointing to a mixture of evolutionary history, thermal adaptations, and body mass differences as a possible explanation for the great diversity of these damselflies in a small area. Under the global warming scenario, we expect Rubyspots with smaller body sizes to be favored since they will tolerate higher temperatures, which would ultimately lead to populations with smaller body sizes overall, which could negatively affect their fitness.

Metabolic Rate and Oxidative Stress as a Risk Factors in the Development of Colorectal Cancer.

There is growing evidence that the body's energy expenditures constitute a significant risk factor for the development of most deadly diseases, including cancer. Our aim was to investigate the impact of basal metabolic rate (BMR) on the growth and progression of colorectal cancer (CRC). To do so, we used a unique model consisting of three lines of laboratory mice (Mus musculus) artificially selected for high (HBMR) and low (LBMR) basal metabolic rate and randomly bred individuals (non-selected, NSBMR). The experimental individuals were implanted with human colorectal cancer cells DLD-1. The variation in BMR between the lines allowed for testing the impact of whole-body metabolism on oxidative and antioxidant parameters in the liver throughout the cancerogenesis process. We investigated the dependence between metabolic values, reactive oxygen species (ROS) levels, and Kelch-like ECH-associated protein 1-based E3 ligase complexes (Keap1) gene activity in these animals. We found that the HBMR strain had a higher concentration of oxidative enzymes compared to the LBMR and NSBMR. Furthermore, the growth rate of CRC tumors was associated with alterations in the levels of oxidative stress enzymes and Keap1 expression in animals with a high metabolic rate. Our results indicate that a faster growth and development of CRC line DLD-1 is associated with enzymatic redox imbalance in animals with a high BMR.

Analysis of Genetic Risk Factors Associated with Charcot Foot Based on the FinnGen Study R9 Data: A Wide-angle Mendelian Randomization Study.

Charcot foot or Charcot neuropathic joint disease (CN) is a rare and complex foot disease with unknown pathogenesis, hindering early identification and intervention. The study aimed to clarify the causal association between all predominant risk factors and CN. Two-sample Mendelian Randomization (MR), Multivariate MR, and Bidirectional MR analyses investigated the causal association between 36 modifiable risk factors and CN. The causal relationship between CN and Inflammatory cytokine and immune cells was also analyzed. Genetic factors associated with obesity and genetic susceptibility to various autoimmune diseases and non-cancerous thyroid diseases increased the risk of CN (P < .05), genetically associated high basal metabolic rate and high total cholesterol decreased the risk of CN (P < .05). In addition, we found a bi-directional causal relationship between CN and diabetes. In further immune cell analysis, we found 8 CN related immune cells, and in inflammatory cytokine analysis, we found 2 CN related inflammatory cytokines. This comprehensive MR Study supports the causal role of Obesity-related factors, diabetes, autoimmune-related factors, and smoking in the development and progression of CN. This study identifies a potential cause of CN that has not been identified in previous studies and provides a new direction for further research.

Pain intensity, spine structure, and body composition in patients with acute discogenic lumbar radiculopathy

ObjectiveThis study aimed to compare the pain intensity, spine structure, and body composition according to functional disability levels in patients with acute discogenic lumbar radiculopathy (DLR). MethodsA total of 118 women (n = 83) and men (n = 35) patients with acute DLR (mean age: 51.87 ± 13.38 years) were included in the study. The function ability was measured with the Oswestry Disability Index, pain intensity was measured with the Visual Analogue Scale, spine structure was measured with the Spinal Mouse® device, and body composition was measured with the Bioelectrical Impedance Analysis System. ResultsPatients with mild functional disability levels had significantly lower activity (p˂.001) and night pain intensity (p = 0.001) than patients with moderate, severe, and completely functional disability levels, and patients with completely functional disability levels had significantly higher rest pain intensity (p = 0.005) than patients with mild, moderate, and severe functional disability levels. Patients with mild functional disability levels had significantly better spine check scores (p = 0.001), posture (p = 0.005), and mobility (p = 0.003) than patients with moderate, severe, and completely functional disability levels. Patients with mild functional disability levels had significantly lower fat percentage (p = 0.032), and higher basal metabolic rate (p = 0.024) than patients with moderate, severe, and completely functional disability levels. ConclusionPain intensity, spinal structure, and body composition of acute DLR patients differ greatly according to their functional disability levels. Although it is known that the level of functional disability of patients is a result of the severity or prognosis of the disease, performing different treatment methods aimed at decreasing the functional disability level of patients by health professionals may be important in terms of coping with the disease.

Causal relationship between basal metabolic rate and intervertebral disc degeneration: a Mendelian randomization study.

The role of basal metabolic rate (BMR) in intervertebral disc degeneration (IVDD) is still uncertain. To address this gap, we conducted a Mendelian randomization (MR) study to comprehensively explore the causal relationship between BMR and IVDD. BMR data were obtained from a large genome-wide association study (GWAS) database, while IVDD data were derived from the FinnGen project. The causal relationship between IVDD and BMR was investigated using MR, with inverse-variance weighting (IVW) as the primary estimate. MR-Egger weighed median and weighed mode were employed for robustness. Sensitivity analyses, including the Cochran Q test, leave-one-out analysis, and MR-Egger intercept analysis, were conducted. Furthermore, the study also identified causal relationships between IVDD and factors associated with BMR (hyperthyroidism, type 2 diabetes, standing height, weight, and body mass index). Multivariable MR was applied to further assess the direct effect of BMR on IVDD. Genetic predisposition to BMR (after removing outliers OR: 1.49; 95% CI: 1.37-1.63; P = 5.073e-21) were associated with an increased risk of IVDD. Additionally, IVDD risk increased with greater height, weight, and BMI. No causal relationship was observed between hy/thy and T2D and intervertebral disc degeneration (IVDD) (P > 0.05). In multivariable MR, a significant causal association between BMR and IVDD persisted, even after adjusting for BMI, height, and weight. In this study, we successfully identified that a higher BMR is independently and causally linked to IVDD, indicating an increased risk of developing IVDD. These findings suggest that managing BMR could potentially mitigate the risk of IVDD.

Predictive Roles of Basal Metabolic Rate and Muscle Mass in Lung Function among Patients with Obese Asthma: A Prospective Cohort Study.

The metabolic-status-related mechanisms underlying the deterioration of the lung function in obese asthma have not been completely elucidated. This study aimed to investigate the basal metabolic rate (BMR) in patients with obese asthma, its association with the lung function, and its mediating role in the impact of obesity on the lung function. A 12-month prospective cohort study (n = 598) was conducted in a real-world setting, comparing clinical, body composition, BMR, and lung function data between patients with obese (n = 282) and non-obese (n = 316) asthma. Path model mediation analyses for the BMR and skeletal muscle mass (SMM) were conducted. We also explored the effects of the BMR on the long-term lung function in patients with asthma. Patients with obese asthma exhibited greater airway obstruction, with lower FEV1 (1.99 vs. 2.29 L), FVC (3.02 vs. 3.33 L), and FEV1/FVC (65.5 vs. 68.2%) values compared to patients with non-obese asthma. The patients with obese asthma also had higher BMRs (1284.27 vs. 1210.08 kcal/d) and SMM (23.53 vs. 22.10 kg). Both the BMR and SMM mediated the relationship between obesity and the lung function spirometers (FEV1, %FEV1, FVC, %FVC, and FEV1/FVC). A higher BMR or SMM was associated with better long-term lung function. Our study highlights the significance of the BMR and SMM in mediating the relationship between obesity and spirometry in patients with asthma, and in determining the long-term lung function. Interventions for obese asthma should focus not only on reducing adiposity but also on maintaining a high BMR.

Association between CD4+T lymphocyte and body composition with physical frailty among elderly HIV-infected patients in Chongqing City

Objective: To identify the association between CD4+T lymphocyte (CD4) counts and physical frailty among HIV-infected people aged 65 years and older, and evaluate whether this association will be modified by the indicators of body composition. Methods: From May to October 2022, 485 elderly HIV-infected patients receiving antiretroviral therapy (ART) were recruited from 7 antiviral treatment sites in Jiangjin District Center for Disease Control and Prevention, Chongqing. The data of basic characteristics (age and gender), living habits (smoking and drinking) and disease history (metabolic diseases, cardiovascular and cerebrovascular diseases, respiratory disease and malignant tumors) were collected through the face-to-face investigation with self-made questionnaires. Fried Frailty Scale was used to evaluate the status of physical frailty. Physical fitness (walking speed, grip strength, height, and weight) and body composition (skeletal muscle mass, body fat mass, and basal metabolic rate) were measured. The antiretroviral treatment data were obtained from the China AIDS Integrated Prevention and Treatment Data information management system. The prevalence of physical frailty was calculated among the HIV-infected patients. The potential effects of CD4 counts on physical frailty were explored by using multivariate logistic regression. Subgroup analyses were repeated in the logistic regression with muscle mass, body fat mass, and other indicators of body composition as subgroup variables to determine whether the association might be modified by body composition. Results: The age of 485 patients were (72±5) years old, of which 48.2% (234 cases) were>70 years old and 70.9% (344 cases) were male, and all of whom had initiated the ART treatment. The prevalence of physical frailty among these patients was 7.4% (36/485). Multivariate logistic regression showed that after adjusting for age, sex, smoking, drinking, body composition index, ART duration, viral load and the number of comorbidities, increased CD4 cell level was associated with decreased prevalent risk of physical frailty among elderly HIV-infected patients. For every increase of 5.0×107 CD4 cells/L, the prevalent risk of physical frailty decreased by 12% [OR (95%CI): 0.88 (0.76-1.01)]. Compared with the low CD4 cell level group, the risk of physical frailty in those with normal CD4 cell level decreased by 69% [OR (95%CI): 0.31 (0.10-0.92)]. Subgroup analysis of body composition indicators showed that the protective effect of normal CD4 cell level on physical frailty was more pronounced in the high skeletal muscle mass and high basal metabolic rate group (Pinteraction<0.05). Conclusion: The prevalence of physical frailty among elderly HIV-infected patients is relatively lower in Chongqing, and the CD4 cell level, skeletal muscle mass and basal metabolic rate are related to physical frailty.

Differences in the range of thermoneutral zone between mouse strains: potential effects on translational research.

Laboratory mice are commonly used for studies emulating human metabolism. To render human energetics, their ratio of daily (DEE) to basal (BMR) energy expenditure of 1.7-1.8 should be maintained. However, the DEE/BMR ratio strongly depends on whether a given study using a mouse model is carried out above, or below the lower critical temperature (LCT) of the thermoneutral zone, which is rarely considered in translational research. Here, we used mice artificially selected for high or low rates of BMR along with literature data to analyze the effect of ambient temperature on possible systematic bias in DEE/BMR. We demonstrated that the estimated LCTs of mice from the high and low BMR lines differ by more than 7°C. Furthermore, the range of variation of LCTs of mouse strains used in translational research spans from 23 to 33°C. Differences between LCTs in our selected mice and other mouse strains are mirrored by differences in their DEE-to-BMR ratio, on average increasing it at the rate of 0.172°C-1 at temperatures below LCT. Given the wide range of LCTs in different mouse strains, we conclude that the energetic cost of thermoregulation may differ greatly for different mouse strains with a potentially large impact on translational outcomes. Thus, the LCT of a given mouse strain is an important factor that must be considered in designing translational studies.

Particularities of coronary physiology in patients with atrial fibrillation: insights from combined pressure and flow indices measurements.

Symptoms suggestive of myocardial ischemia are frequently encountered in patients with atrial fibrillation (AF) even in the absence of obstructive coronary artery disease. Nevertheless, an in-depth characterisation of coronary physiology in patients with AF is currently lacking. We aim to provide an insight into the characteristics of coronary physiology in AF, by performing simultaneous invasive measurements of coronary flow- and pressure- indices in a real-life population of patients with AF and indication of coronary angiography. This is a prospective open label study including patients with permanent or persistent AF and indication of coronary angiography showing intermediate coronary stenosis requiring routine physiological assessment (n = 18 vessels from 14 patients). We measured FFR (fractional flow reserve), and Doppler-derived coronary flow indices, including CFR (coronary flow reserve) and HMR (hyperaemic microvascular resistance). From the analysed vessels, 18/18 vessels (100%) presented a pathological CFR (<2.5), indicative of coronary microvascular dysfunction (CMD), and 3/18 (17%) demonstrated obstructive epicardial coronary disease (FFR ≤ 0.8). A large proportion of vessels (15/18; 83%) showed discordant FFR/CFR with preserved FFR and low CFR. 47% of the coronary arteries in patients with AF and non-obstructive epicardial coronary disease presented structural CMD (HMR ≥ 2.5 mmHg/cm/s), and were associated with high BMR and an impaired response to adenosine. Conversely, vessels from patients with AF and non-obstructive epicardial coronary disease with functional CMD (HMR < 2.5 mmHg/cm/s) showed higher bAPV. The permanent AF subpopulation presented increased values of HMR and BMR compared to persistent AF, while structural CMD was more often associated with persistent symptoms at 3 months, taking into account the limited sample size of our study. Our findings highlight a systematically impaired CFR in patients with AF even in the absence of obstructive epicardial coronary disease, indicative of CMD. In addition, patients with AF presented more prevalent structural CMD (HMR ≥ 2.5 mmHg/cm/s), characterized by reduced hyperaemic responses to adenosine, possibly interfering with the FFR assessment.

Genetically predicted thyroid function and risk of colorectal cancer: a bidirectional Mendelian randomization study.

Observational studies have reported an association between thyroid function and colorectal cancer (CRC), with conflicting results. Elucidating the causal relationship between thyroid function and CRC facilitates the development of new preventive strategies to reduce CRC incidence. We applied a two-sample Mendelian randomization (MR) method to evaluate the causal relationship between five thyroid-related indexes, including hyperthyroidism, hypothyroidism, thyroid stimulating hormone (TSH), free thyroxine (FT4) and basal metabolic rate (BMR), and CRC. Genome-wide association study statistics for thyroid-related phenotypes were obtained from the ThyroidOmics consortium, and summary statistics for genetic associations with CRC were obtained from the FinnGen consortium. We set a series of criteria to screen single nucleotide polymorphisms (SNPs) as instrumental variables and then performed bidirectional MR analysis, stratified analysis and extensive sensitivity analysis. Multiplicative random-effects inverse variance weighted was the primary analysis method, supplemented by weighted median and MR-Egger. We identified 12 SNPs for hyperthyroidism, 10 SNPs for hypothyroidism, 41 SNPs for TSH, 18 SNPs for FT4, and 556 SNPs for BMR. Genetically predicted hyperthyroidism, hypothyroidism, TSH, and FT4 were not associated with CRC risk (all P > 0.05). Sensitivity analysis revealed no heterogeneity or pleiotropy. Genetically predicted BMR was significantly associated with increased CRC risk after removing outlier (OR = 1.30, P = 0.0029). Stratified analysis showed that BMR was significantly associated with colon cancer (OR = 1.33, P = 0.0074) but not rectal cancer. In the reverse analysis, there was no evidence of an effect of CRC on thyroid function (all P > 0.05). Our bidirectional MR analysis provides new insights into the relationship between thyroid function and CRC. CRC prevention may benefit from enhanced screening of high BMR populations.

Thermal biology in the Upper Galili Mountain blind mole rat (Nannospalax galili) and an overview of spalacine energetics

Several hundred mammalian species thrive in complex burrow systems, which protect them from climatic extremes and predation. At the same time, it is also a stressful environment due to low food supply, high humidity, and, in some cases, a hypoxic and hypercapnic atmosphere. To face such conditions, subterranean rodents have convergently evolved low basal metabolic rate, high minimal thermal conductance and low body temperature. Although these parameters have been intensively studied in the last decades, such information is far from being well-known in one of the most studied groups of subterranean rodents, the blind mole rats of the genus Nannospalax. The lack of information is particularly noticeable for parameters such as the upper critical temperature and the width of the thermoneutral zone.In our study, we analysed the energetics of the Upper Galilee Mountain blind mole rat Nannospalax galili and found its basal metabolic rate of 0.84 ± 0.10 mL O2×g−1 × h−1, thermoneutral zone between 28 and 35 °C, mean Tb within the zone of 36.3 ± 0.6 °C, and minimal thermal conductance equal to 0.082 mL O2×g−1 × h−1 × C−1. Nannospalax galili is a truly homeothermic rodent well adapted to face lower ambient temperatures, because its Tb was stable down to the lowest temperature measured (10 °C). At the same time, a relatively high basal metabolic rate and relatively low minimal thermal conductance for a subterranean rodent of such body mass, and the difficulty of surviving ambient temperatures slightly above upper critical temperature, indicates problems with sufficient heat dissipation at higher temperatures. This can easily lead to overheating, that is relevant mainly during the hot-dry season. These findings suggest that N. galili can be threatened by ongoing global climate change.

Evidence for a maintenance cost for birds maintaining highly flexible basal, but not summit, metabolic rates

Reversible phenotypic flexibility allows organisms to better match phenotypes to prevailing environmental conditions and may produce fitness benefits. Costs and constraints of phenotypic flexibility may limit the capacity for flexible responses but are not well understood nor documented. Costs could include expenses associated with maintaining the flexible system or with generating the flexible response. One potential cost of maintaining a flexible system is an energetic cost reflected in the basal metabolic rate (BMR), with elevated BMR in individuals with more flexible metabolic responses. We accessed data from thermal acclimation studies of birds where BMR and/or Msum (maximum cold-induced metabolic rate) were measured before and after acclimation, as a measure of metabolic flexibility, to test the hypothesis that flexibility in BMR (ΔBMR), Msum (ΔMsum), or metabolic scope (Msum − BMR; ΔScope) is positively correlated with BMR. When temperature treatments lasted at least three weeks, three of six species showed significant positive correlations between ΔBMR and BMR, one species showed a significant negative correlation, and two species showed no significant correlation. ΔMsum and BMR were not significantly correlated for any species and ΔScope and BMR were significantly positively correlated for only one species. These data suggest that support costs exist for maintaining high BMR flexibility for some bird species, but high flexibility in Msum or metabolic scope does not generally incur elevated maintenance costs.

Effect of basal metabolic rate on lifespan: a sex-specific Mendelian randomization study

Observationally, the association of basal metabolic rate (BMR) with mortality is mixed, although some ageing theories suggest that higher BMR should reduce lifespan. It remains unclear whether a causal association exists. In this one-sample Mendelian randomization study, we aimed to estimate the casual effect of BMR on parental attained age, a proxy for lifespan, using two-sample Mendelian randomization methods. We obtained genetic variants strongly (p-value < 5 × 10–8) and independently (r2 < 0.001) predicting BMR from the UK Biobank and applied them to a genome-wide association study of parental attained age based on the UK Biobank. We meta-analyzed genetic variant-specific Wald ratios using inverse-variance weighting with multiplicative random effects by sex, supplemented by sensitivity analysis. A total of 178 and 180 genetic variants predicting BMR in men and women were available for father’s and mother’s attained age, respectively. Genetically predicted BMR was inversely associated with father’s and mother’s attained age (years of life lost per unit increase in effect size of genetically predicted BMR, 0.46 and 1.36; 95% confidence interval 0.07–0.85 and 0.89–1.82), with a stronger association in women than men. In conclusion, higher BMR might reduce lifespan. The underlying pathways linking to major causes of death and relevant interventions warrant further investigation.

Prediction of physiological state, cognition, sensory function, and biomarkers for frailty in patients aged 55 years or more with schizophrenia.

We explored the performance of demographic characteristics, physiological state, cognitive function, sensory function, and biomarkers when used as predictors of frailty for patients with schizophrenia. A cross-sectional study design was adopted. Demographic data and data on physiological state, cognitive function, sensory function, biochemical indices, and frailty status of patients with schizophrenia were collected. The data were analysed using descriptive statistics, a chi-square test, one-factor analysis of variance, and logistic regression. The results revealed that frailty was prevalent among patients with lower educational attainment, longer hospital stay, higher skeletal muscle mass, higher basal metabolic rate, lower cognitive function, the use of tranquillisers and sleeping pills, and the use of assistive equipment as well as having fallen in the past year. In addition, cognitive function (p < 0.05), use of a wheelchair (p < 0.05), and use of an assistive walker (p < 0.001) were used as predictors of frailty condition of patients with schizophrenia. Patients with schizophrenia have higher risk of having complications than patients with other chronic illnesses. Therefore, medical staff should regularly assess the levels of frailty risk to help patients with schizophrenia.

Seasonal variation in thermoregulatory capacity of three closely related Afrotropical Estrildid finches introduced to Europe

A species' potential geographical range is largely determined by how the species responds physiologically to its changing environment. It is therefore crucial to study the physiological mechanisms that species use to maintain their homeothermy in order to address biodiversity conservation challenges, such as the success of invasions of introduced species. The common waxbill Estrilda astrild, the orange-cheeked waxbill E. melpoda, and the black-rumped waxbill E. troglodytes are small Afrotropical passerines that have established invasive populations in regions where the climate is colder than in their native ranges. As a result, they are highly suitable species for studying potential mechanisms for coping with a colder and more variable climate. Here, we investigated the magnitude and direction of seasonal variation in their thermoregulatory traits, such as basal (BMR), summit (Msum) metabolic rates and thermal conductance. We found that, from summer to autumn, their ability to resist colder temperatures increased. This was not related to larger body masses or higher BMR and Msum, but instead, species downregulated BMR and Msum toward the colder season, suggesting energy conservation mechanisms to increase winter survival. BMR and Msum were most strongly correlated with temperature variation in the week preceding the measurements. Common waxbill and black-rumped waxbill, whose native ranges encompass the highest degree of seasonality, showed the most flexibility in metabolic rates (i.e., stronger downregulation toward colder seasons). This ability to adjust thermoregulatory traits, combined with increased cold tolerance, may facilitate their establishment in areas characterized by colder winters and less predictable climates.

Individual response in body mass and basal metabolism to the risks of predation and starvation in passerines.

Wintering energy management in small passerines has focused on the adaptive regulation of the daily acquisition of energy reserves within a starvation-predation trade-off framework. However, the possibility that the energetic cost of living, i.e. basal metabolic rate (BMR), is being modulated as part of the management energy strategy has been largely neglected. Here, we addressed this possibility by experimentally exposing captive great tits (Parus major) during winter to two consecutive treatments of increased starvation and predation risk for each individual bird. Body mass and BMR were measured prior to and after each week-long treatment. We predicted that birds should be lighter but with a higher metabolic capacity (higher BMR) as a response to increased predation risk, and that birds should increase internal reserves while reducing their cost of living (lower BMR) when exposed to increased starvation risk. Wintering great tits kept a constant body mass independently of a week-long predation or starvation treatment. However, great tits reduced the cost of living (lower BMR) when exposed to the starvation treatment, while BMR remained unaffected by the predation treatment. Energy management in wintering small birds partly relies on BMR regulation, which challenges the current theoretical framework based on body mass regulation.

РЕЗУЛЬТАТЫ ПЕРВОГО ОПЫТА БИОИМПЕДАНСНОГО АНАЛИЗА СОСТАВА ТЕЛА НАСЕЛЕНИЯ РЕСПУБЛИКИ ТАДЖИКИСТАН

Objective: Evaluation of a pilot study results examining bioelectrical impedance analysis (BIA) of body composition of the population of the Republic of Tajikistan. Methods: The body composition of 1304 individuals was studied using bioimpedance measurements. The study included 718 women (55.1%) and 586 men (44.9%) with an average age of 41.1±13.6 years. The following variables were measured: fat mass (FM, kg), percent body fat (PBF, %), fat-free mass (FFM, kg), body cell mass (BCM, %), percent body cell mass (PBCM, %), skeletal muscle mass (SMM, kg), percentage of SMM (PSMM, %), total body water (TBW, kg), extracellular fluid (ECF, kg), bone mineral content (BMC, kg), basal metabolic rate (BMR, kcal/day) and mass-specific metabolic rate (msBMR, kcal/m2 /day). In addition to examining patients, we determined their body mass index (BMI) and waist-to-hip ratio (WHR) using the Adolphe Quetelet formula. Results: The average FM for all study subjects was 22.5±12.04 kg. Women displayed 24.2% more FM than men – 24.6±12.0 kg and 19.8±11.6 kg, respectively (p 0.001). LM in all subjects averaged 44.9±4.7 kg, in men and women – 46.3±3.6 kg and 44.0±4.3 kg, respectively (p 0.05). As a result, men had a higher BMR than women – 1735.5±102.1 kcal/day and 918.9±57.2 kcal/day, respectively (p 0.001). There were no significant gender differences in msBMR: for men and women, the average was 853.7±30.8 and 846.4±33.3 kcal/m2/day, respectively (p 0.05). There were also no gender differences in BMC for men and women: the average was 2.1±0.2 and 2.1±0.2 kg, respectively (p 0.05). The results showed positive significant (p 0.05) linear relationships between BMI categories and WHR (r=0.182), FM (r=0.933), PBF (r=0.855), FFM (r=0.262), BCM (r=0.159), TBW (r=0.259), ECF (r=0.440), BMC (r=0.522), BMR (r=0.161), and negative linear relationship – with PBCM (r= -0.042), SMM (r= -0.121), PSMM (r= -0.605) and msBMR (r=-0.521).Conclusion: BIA is a highly effective method for assessing body composition, allowing for accurate determination of fat and lean mass, total body fluid, and basal metabolic rates. The differences in the above indicators varied based on gender, age, and body weight of the examined cohort. Using bioimpedance instead of anthropometry provides a more accurate assessment of obesity. Keywords: Electrical impedance measurement, bioimpedance analysis, overweight, obesity, fat mass

TRH and NPY Interact to Regulate Dynamic Changes in Energy Balance in the Male Zebra Finch.

In contrast to mammals, birds have a higher basal metabolic rate and undertake wide range of energy-demanding activities. As a consequence, food deprivation for birds, even for a short period, poses major energy challenge. The energy-regulating hypothalamic homeostatic mechanisms, although extensively studied in mammals, are far from clear in the case of birds. We focus on the interplay between neuropeptide Y (NPY) and thyrotropin-releasing hormone (TRH), 2 of the most important hypothalamic signaling agents, in modulating the energy balance in a bird model, the zebra finch, Taeniopygia guttata. TRH neurons were confined to a few nuclei in the preoptic area and hypothalamus, and fibers widely distributed. The majority of TRH neurons in the hypothalamic paraventricular nucleus (PVN) whose axons terminate in median eminence were contacted by NPY-containing axons. Compared to fed animals, fasting significantly reduced body weight, PVN pro-TRH messenger RNA (mRNA) and TRH immunoreactivity, but increased NPY mRNA and NPY immunoreactivity in the infundibular nucleus (IN, avian homologue of mammalian arcuate nucleus) and PVN. Refeeding for a short duration restored PVN pro-TRH and IN NPY mRNA, and PVN NPY innervation to fed levels. Compared to control tissues, treatment of the hypothalamic superfused slices with NPY or an NPY-Y1 receptor agonist significantly reduced TRH immunoreactivity, a response blocked by treatment with a Y1-receptor antagonist. We describe a detailed neuroanatomical map of TRH-equipped elements, identify new TRH-producing neuronal groups in the avian brain, and demonstrate rapid restoration of the fasting-induced suppression of PVN TRH following refeeding. We further show that NPY via Y1 receptors may regulate PVN TRH neurons to control energy balance in T. guttata.

The Role of Dietary Patterns and Dietary Quality on Body Composition of Adolescents in Chinese College.

There is limited evidence regarding the effects of dietary pattern and dietary quality on the risk of unhealthy weight status and related body composition in Chinese adolescence. In particular, studies using bioelectrical impedance analyzer (BIA) in these subjects are rare. The aim of this study was to evaluate the role of diet in body composition, to find a healthy dietary pattern for Chinese youth, and to promote the application of BIA among this population. A total of 498 participants aged from 18 to 22 years old were included. Dietary patterns were identified by principal components analysis. Energy-adjusted dietary inflammatory index (DII) and diet balance index (DBI) were calculated based on semi-quantitative food frequency questionnaire. Multivariate linear regression and logistic regression analysis were used to examine the relationship of dietary patterns, dietary quality with body mass index (BMI), fat mass index (FMI), fat-free mass index (FFMI), and the effect of dietary factors on BMI levels. The majority of participants with overweight and obesity had abdominal obesity, and there was 3.7% abdominal obesity in normal BMI individuals. Four dietary patterns were detected in the subjects. The pattern with the higher energy intake, which was close to the Western diet, was positively correlated with BMI (β = 0.326, p = 0.018) and FMI (β = 0.201, p = 0.043), while being negatively correlated with FFMI (β = −0.183, p = 0.021). Individuals who followed the pattern similar to the Mediterranean diet had a higher basal metabolic rate (BMR), and the highest fat free mass, soft lean mass, and skeletal muscle mass (p < 0.05) but the lowest FMI, visceral fat area (VFA), waist−hip ratio, and FMI/FFMI ratio (p < 0.05). Higher energy-adjusted DII was associated with high BMI. Higher bound score (HBS) (β = −0.018, p = 0.010) and diet quality distance (DQD) (β = −0.012, p = 0.015) were both negatively correlated with FFMI. In conclusion, fat or muscle indexes, such as BMR, FMI, and FFMI, had an important role in predicting overweight and obesity, which suggested the importance of applying BIA among Chinese college students. Students who followed healthful dietary patterns or the high-quality diet that is similar to the Mediterranean diet but not close to the Western diet were more likely to have a healthy BMI and normal body composition.