bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of endurance training under calorie restriction on the metabolic enzyme activity and transporter levels in mouse skeletal muscle and liver
Authors: Takahashi Kenya , Kitaoka Yu , Hatta Hideo
Published: May 2024

Although endurance training (ET) and calorie restriction (CR) induce metabolic adaptations in skeletal muscle, the interaction of them have yet to be clarified. This study investigated the effects of endurance training with calorie restriction on the metabolic enzyme activity and transporter levels in mouse skeletal muscle and liver. Ten-week-old male ICR mice were fed ad libitum or subjected to 30% CR. The animals were subdivided into sedentary and ET groups. The animals in the ET group performed treadmill running (20 m/min, 30 min) five days a week for five weeks. Respiratory gas analysis during 24 h of rest showed that CR, but not ET, reduced carbohydrate consumption. While ET enhanced hexokinase (HK) activity in the plantaris and soleus muscles, CR decreased HK, phosphofructokinase, and lactate dehydrogenase activities and monocarboxylate transporter (MCT) 4 protein content. Although ET and CR alone increased citrate synthase (CS) activity and MCT1 protein content in the plantaris muscle, no additive or synergistic effects were observed. In the soleus muscle, ET increased CS, β-hydroxyacyl-CoA dehydrogenase (β-HAD), and total carnitine palmitoyltransferase (CPT) activities; however, CR significantly decreased CS and β-HAD activities but enhanced total CPT activity. Additionally, CR enhanced the glucose transporter 4 protein content in the plantaris and soleus muscles. In the liver, CR enhanced the protein levels of glucose 6-phosphatase, fructose 1,6-bisphosphatase, and mitochondrial phosphoenolpyruvate carboxykinase. Moreover, ET partially normalized the CR-induced increase in fatty acid synthase and acetyl-CoA carboxylase. These observations suggest that CR enhances the capacity for glucose and fatty acid synthesis in the liver as well as the glucose and lactate uptake capacity in skeletal muscle while reducing carbohydrate consumption in skeletal muscle. It is suggested that CR partially interferes with skeletal muscle adaptations to ET.

This study was supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI (Grant numbers 20H04071, 21K21249, and 23K16718).

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Exogenous Thyroxine Increases Cardiac AS160 Phosphorylation in Insulin Resistant OLETF Rats
Authors: Yang Xue , Mendez Dora A. , Vazquez-Anaya Guillermo , Nishiyama Akira , Ortiz Rudy M.
Published: May 2024

Thyroxine (T4) is the most abundant thyroid hormone secreted by thyroid gland and contributes to glucose metabolism via both insulin and non-insulin dependent pathways. Akt substrate 160 (AS160) is a Rab-GDP activating protein and a downstream effector of protein kinase B (Akt) required for glucose transport and upregulation of GLUT4 activating vesicle (GSV). The phosphorylation of AS160 (p-AS160) is required for the regulation of GLUT4 translocation to the membrane. It is also involved in insulin-mediated traffcking of GLUT4 in skeletal muscle and adipose tissues. The accumulation of AS160 has also been implicated in promoting cardiac hypertrophy, which is commonly associated with the metabolic syndrome (MetS). This study explores how thyroid hormones can affect the phosphorylation status of cardiac AS160 during insulin resistance. Under normal conditions, AS160 is phosphorylated by Akt to upregulate GSV, allowing glucose to cross the cell membrane through GLUT4. We hypothesize that exogenous T4 increases cardiac phosphorylation of AS160 expression during insulin resistance. Insulin resistant, Otsuka Long Evans Tokushima Fatty (OLETF) rats were used to assess the effects of exogenous thyroxine (T4) on cardiac p-AS160. Rats were assigned to four groups: (1) lean, Long Evans Tokushima Otsuka (LETO; n=6), (2) LETO + T4 (8 μg/100g BM/d × 5 wks; n=7), (3) untreated OLETF (n=6), and (4) OLETF + T4 (n=7). Exogenous T4 did not significantly alter native AS160 protein expression among all four groups. However, p-AS160 was reduced in the non-treated OLETF group by 61% (p<0.01) compared to healthy LETO control group. Exogenous T4 increased p-AS160 by 16% (p<0.05) compared to non-treated OLETF group and by 36% (p<0.05) in treated LETO compared to control LETO group. We have previously demonstrated that exogenous T4 increased the translocation of cardiac GLUT4 and the present findings suggest that this increased translocation is mediated by activation of AS160, resulting in improved glucose metabolism in the heart during insulin resistance.

American Heart Association.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Transcutaneous evaluation of hemoconcentration response to hypoxia simulated and hypobaric hypoxia of 5050 m
Authors: Moraga Fernando , Riquelme Sylvia , Lopez Ivan , Calderon-Jofré Rodrigo , Pedreros Andres , Langer Vania , Sanzana Francisco
Published: May 2024

Objective: To evaluate the effect of normobaric and hypobaric hypoxia of 5050 m on hemoconcentration response in population without experience to hypoxia and acclimatized population to chronic intermittent hypobaric hypoxia (CIHH). Materials and Methods: 16 subjects without experience to altitudes over 1500 m (9 women/7 men) and 39 subjects acclimatized workers to CIHH at high altitude (5050 m, 9 women/32 men) were recruited. Normobaric hypoxia were performed in 3 steps: 5 min breathing ambient air, 20 min breathing hypoxic air (11,5% O2, equivalent to 5050 m) and 5 min of recovery breathing ambient air. CIHH condition represents a normal exposure characterized by 8 days working at high altitude and 6 days resting at low altitude (<1500 m). Subjects were evaluated at sea level and 5-6th day of exposure to CIHH at 5050 m. In each condition, Hemoglobin concentration (Hb), Carboxyhemoglobin (COHb), Methemoglobin (MetHb), Pulse oximetry (SPO2), heart rate (HR) were measured using a transcutaneous sensor (Rad 67 pulse Co-Oximeter, Masimo). Results: In evaluations performed at sea level, both groups of hypoxia (normobaric and CIHH) exhibited a lower hemoglobin concentration in women in comparison with men. During exposure to simulated hypoxia, a significative increase in hemoglobin concentration was showed, associated to decrease in SpO2 and increase in HR. However, an increased level of MetHb in women and men and only increased level of COHb in women were observed. During hypobaric exposure, Hb concentration increased, with reduced SpO2, and increased HR in comparison to sea level. Lower HR was observed in men respect of women. Lower level of COHb was observed in men respect of women. In addition, in women was observed an increase of level COHb related with time of exposure, in contrast, a tendency to reduction in level of COHb and MetHb in men was observed. Conclusion: The use of transcutaneous sensor to measure SpO2 and Hb showed an increase in hemoglobin concentration in normobaric and hypobaric hypoxia, in agreement with previous results from our laboratory. In addition, we reported new information about level of COHb and MetHb in two different model of exposure simulated hypoxia and hypobaric hypoxia at extreme altitude.

SUSESO ACHS 279-2022.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
During exposure to 3%, 5%, and 7% CO2, both Behaviorally Inhibited and Non-Behaviorally Inhibited individuals increased minute ventilation through different mechanisms
Authors: Ehlert Luke , Wiseman Connor , Poff Hannah , Talens Kate , Martino Paul , Miller Daniel P. , Miller Justin R.
Published: May 2024

Behavioral inhibition (BI) is a temperament associated with increased vulnerability to stress compared to their non-behaviorally inhibited (NBI) counterparts. Previous studies have demonstrated that BI individuals have a higher stress response than NBI individuals, suggesting that BI individuals have significantly less parasympathetic nervous system output at rest. However, this study only compared room air to 7% carbon dioxide (CO2) concentrations. The difference in the sympathetic nervous system activation between BI and NBI individuals under constant increasing stress is still unknown. Our current study tested the hypothesis that BI individuals will have an increased stress response as the inhaled CO2 concentration increases. In humans, we tested the effect of increasing CO2 concentrations on tidal volume, breathing rate, heart rate, and blood pressure. BI individuals were identified through self-reported questionnaires, such as The Adult Measure of Behavioral Inhibition (AMBI). A 15-minute control period of room air breathing was completed followed by 5 minutes each of 3% and 5% inspired CO2, and 3 minutes of 7% inspired CO2. Preliminary results indicate that BI individuals breathe differently at a physiological level and differ in their stress response.

Thank you to Carthage College's Student Travel Grant as well as the Neuroscience and Biology department for supporting this research.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Mapping the Vagus Nerve with Anatomical Scaffolds
Authors: Christie Richard , Lin Mabelle , Chopovda Valerie , Nickerson David , Hunter Peter
Published: May 2024

Phase 2 of the Stimulating Peripheral Activity to Relieve Conditions (SPARC) program ( https://commonfund.nih.gov/sparc ) aims to build a comprehensive map of the anatomy and functional connectivity of the human vagus nerve, allowing comparisons of inter-subject variability, and helping guide experiments on vagus nerve stimulation and the development of neuromodulation devices. Following approaches used in Phase 1 of the SPARC program, segmented nerve and fascicle data (using various imaging modalities) of vagus nerves from a large number of human subjects will be registered into an Anatomical Scaffold. This is a geometric model of the vagus nerve providing a common coordinate system across subjects. Registration is achieved by fitting a subject-specific vagus scaffold to digitized subject data, using standardized annotations for trunks, branches, fixed landmarks and orientation marks in the data and for the corresponding features of the Scaffold. We report here on progress and issues in the early stages of the study. A particular complication of the vagus is inter-subject variability. While the left and right vagus trunk are quite consistent across subjects, the number and locations of branches innervating a particular organ or target is quite different from one subject to another. This dictates generating a scaffold for each subject with its own unique branching structure. Once data is available for a reasonable number of subjects these will be remapped to a common or representative vagus scaffold. At the conclusion of this study all vagus imaging, plus derived data including the scaffold and embedded fascicles, their groupings and distributions will be freely available on the SPARC Portal ( https://sparc.science/ ). Mapping to a common scaffold allows these data to be compared and visualized at equivalent locations across all subjects in the study.

This work is supported by the NIH SPARC program under award number OT3OD025347.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Transposable element-derived double-stranded RNAs stimulate pro-inflammatory activation in human astrocytes
Authors: McEntee Cali , Cavalier Alyssa , LaRocca Thomas
Published: May 2024

Astrocyte-related inflammation contributes to neuroinflammation with brain aging and Alzheimer’s disease (AD), but the causes of pro-inflammatory astrocyte activation in this context are incompletely understood. One driver of pro-inflammatory signaling in astrocytes may be endogenous double-stranded RNA (dsRNA) derived from transposable elements (TEs). TEs make up more than 50% of the human genome, and recent evidence suggests a role for TEs in pro-inflammatory signaling with aging and neurodegenerative diseases. However, the role of TEs and/or TE-derived dsRNA in astrocyte-related inflammation, and the specific TEs involved, have yet to be investigated. Here, we increased the expression of TE transcripts in human astrocytes by suppressing ADAR1 (an enzyme involved in the suppression/regulation of endogenous dsRNA) and performed RNA-seq to broadly characterize resulting biological changes. Using a computational pipeline (SPRINT) to detect potential dsRNA transcripts through adenosine-to-inosine (A-to-I; a marker of ADAR1 activity) edits, we found that dsRNA transcripts were more likely to come from TEs compared to coding genes. Of these TEs, highly edited and increased transcripts consisted of the TE families Alu and LINE-1 (L1) elements. We confirmed the increase in L1 transcripts in vitro by characterizing colocalization of J2 (antibody for dsRNA) and an L1 element via fluorescence in situ hybridization. Increases in these TEs were associated with increases in pro-inflammatory signaling and decreases in expression of genes relating to astrocyte identity/function (e.g., synapse modifying and cholesterol-related genes). Lastly, we found similar increases in Alu and L1 transcripts in brain tissue of AD patients and older subjects. Together, these data suggest a role for TE-derived dsRNA in pro-inflammatory activation in astrocytes, and possibly in aging and AD. To expand on these findings, we have performed RNA immunoprecipitation sequencing to identify the specific TEs that form dsRNA with ADAR1 suppression in astrocytes, and we are developing an approach to mitigate their effects by increasing ADAR1 expression in the brains of old mice.

NIA: F31AG084330, R01AG078859.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Different subsets of V2a propriospinal neurons respond differently to spinal cord injury
Authors: Crone Steven
Published: May 2024

While propriospinal neurons play a crucial role in recovering function post-spinal cord injury, it remains unclear whether these neurons exhibit largely similar responses to injury or if their diversity requires distinct alterations in gene expression. Here, we focused on one population of spinal neurons, the V2a class, previously shown to be important for recovery of locomotor and respiratory function after spinal cord injury. Using single nuclei gene expression analyses, we delineate substantial molecular and cellular heterogeneity of V2a propriospinal neurons subtypes in adult mice and examine how individual subtypes are altered by injury. Remarkably, a subset of V2a neurons expressing Rbms3+/Nav3+ and enriched for synaptic transmission and axon guidance molecules were found to be nearly absent following injury. The remaining V2a populations exhibited distinctive transcriptional alterations, indicating a potential rewiring of cellular interactions within the spinal cord microenvironment. Thus, our study reveals the diverse responses of propriospinal neurons to injury. These analyses provide a foundation for understanding changes in propriospinal neurons that may lead to adaptive (or maladaptive) changes in circuit function following injury.

NIH R01 NS112255 (PI:Crone) Spinal Circuitry for Ventilatory Control and Compensation Craig H. Neilsen Foundation- Spinal Cord Injury Research on the Translational Spectrum (PI: Crone) Targeting propriospinal neurons to improve breathing following injury.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Interactive maps of nerve-organ anatomy and function on the SPARC Portal
Authors: Wu Man Chung , Brooks David , Yu Jianwei , Balachandran Keeran , Khorasanee Jesse , Sorby Hugh , Garny Alan
Published: May 2024

The integrated maps viewer of the SPARC Portal ( https://sparc.science ) provides interactive, modular, and continually-updated visualizations of nerve-organ anatomy and function. SPARC data and knowledge is registered onto two-dimensional flatmaps, and three-dimensional anatomical organ and whole-body scaffolds. Flatmaps are zoomable maps built from a range of sources and portray anatomy and nerve knowledge of a given species, and scaffold maps are geometric models able to represent the spatial distribution of connectivity knowledge, observed data, and computational models. These maps, and their annotations, are published as SPARC datasets and they are available for public viewing using the map viewers on the SPARC Portal ( https://sparc.science/maps ).The map viewers provide visual interfaces for exploring data and tools in the context of knowledge about neural connectivity. Visualization on the viewer can be customized using different settings. Search can be conducted on both the flatmap and scaffold maps to find and highlight specific features. Data and literature sources and other relevant information of a network and connectivity can be explored comprehensively based on standardized annotations. Multiple maps can be visualized simultaneously using a split-pane display system. Users are able to dynamically create permalinks to specific views, allowing knowledge and corresponding visualization to be shared and cited. Development of the map viewers are on-going and new features continue to be deployed to the SPARC Portal. Subject-specific vagus nerve exploration on the flatmaps and whole-body scaffolds is a key feature planned to be available later this year.

This work is supported by the NIH SPARC program under award number OT3OD025347.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Gut Microbiome Response to the Reduction of Diet Induced Obesity by Vitamin B1 Supplementation
Authors: Dutta Disha , Ortañez Jericho , Leano John , Curras-Collazo Margarita , Deol Poonamjot , Sladek Frances , Degnan Patrick
Published: May 2024

Dietary deficiencies in vitamins such as thiamine (Vitamin B1) produce a range of deleterious health effects and can occur even in developed countries. We’ve hypothesized that a physiological deficiency in thiamine can exacerbate conditions like obesity, diabetes, and fatty liver that are associated with consumption of high fat diets rich in soybean oil (SO) and that one or more of these conditions might be associated with changes in the composition of the gut microbiota. We first evaluated the short-term effect of thiamine deficiency on the gut microbial composition in fecal pellets from C57BL/6N male mice. Mice provided a thiamine regime of 1 mg/kg of low-fat diet for 4 weeks showed marked decreases in fecal community diversity and are characterized by “missing”’ microbes compared to animals provided a standard low-fat thiamine diet (5 mg/kg). Combined with a LC/MS metabolomic analysis these data confirmed changes in the microbiome are coincident with changes of physiological levels of thiamine in the mice. To test the effect of thiamine availability directly on obesity, a separate cohort of C57BL/6N male mice were fed either a low-fat chow (OSD) or an obesogenic soybean oil high fat diet (SO-HFD), with or without supplementation with a thiamine analog (640 mg/kg of diet). Over an 18-week period we found that animals on the SO-HFD with the added thiamine analog gained ~40% less weight compared to animals on the SO-HFD only. Longitudinal sampling of fecal pellets at week 0, 10, 16 and 18 demonstrate major shifts in the microbial composition and diversity over time for animals in all four diet groups. A nested PERMANOVA of Bray-Curtis dissimilarities confirmed the microbiome differences between the SO-HFD and OSD diet (adonis, p = 0.001) and with and without the thiamine analog supplementation (adonis, p = 0.009) at week 16. Measures of microbial diversity show significant increases in diversity for animals consuming the thiamine analog (Kruskall-Wallis, q < 0.05), consistent with the trend observed in the short-term diet trial. Taxonomic classifications for species (ASVs) that significantly increased in these animals are primarily in the Lachnospiraceae family from the Bacillota (Firmicutes) phylum. Together, these data identify major compositional and inferred functional changes to the microbiome in response to the SO-HFD diet as well as thiamine supplementation that may contribute to the observed differences in body weight gain.

Funding: The Thiamine Advocacy Foundation. Acknowledgements: UCR Genomics Core.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Induced Ablation of Prmt1 in Endothelial Cells Causes Endothelial Dysfunction Associated with Pulmonary Thromboembolic Hypertension
Authors: Tran Thi Thuy Vy , Jeong Yideul , Kang Jong-Sun
Published: May 2024

Endothelial cells (ECs) play vital roles in regulation of vascular homeostasis, vascular tone, leukocyte traffcking, and barrier function to ensure pulmonary function. Endothelial dysfunction is a key factor for the progression of pulmonary pathogenesis. Protein arginine methyltransferase 1 (Prmt1) catalyzes asymmetric di-methylation of substrates on arginine residues and is implicated in a variety of cellular processes, including cardiovascular function. In the current study, we examined the role of Prmt1 in endothelial function by using tamoxifen-inducible EC-specific Prmt1 ablation (KO) mice. EC-specific Prmt1 ablation in adult mice (KO) for 8 weeks led to lethality, concurrent with pulmonary hypertension and thromboembolism. The lung bulk RNA sequencing and single EC RNA sequencing analyses revealed that Prmt1 ablation increased inflammation, endothelial junction disruption, apoptosis, and fibrosis. Comprehensive analysis through bulk RNA and single cell RNA sequencing revealed that Prmt1 ablation in ECs triggers homeostatic disturbance accompanied by inflammation and endothelial dysfunction, associated with hyperactivation of NFkB and Stat signaling. In conclusion, the current study suggests that Prmt1 plays a key role in pulmonary endothelial function and vascular homeostasis via the suppression of NFkB-induced endothelial dysfunction.

The National Research Foundation Grant funded by the Korean Government (MIST) (NRF-2022R1A2B5B02001482).

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Sex-dependent cAMP signaling domains in vascular smooth muscle
Authors: Nieves-Cintron Madeline , Pereira Da Silva Eric Aian , Navedo Manuel F
Published: May 2024

The ubiquitous second messenger 3’,5’ monophosphate (cAMP) is essential for regulating vascular smooth muscle (VSM) function. Despite the overwhelming number of studies examining cAMP signaling compartmentalization in multiple cell types, no study has examined how biological sex regulates discrete cAMP pools and the functional implications in VSM. In this study, cAMP biosensors targeted to the cytosol (cyt), plasm membrane (PM), and sarcoplasmic reticulum (SR) were used to examine subcellular cAMP domains using live-cell FRET imaging. We uncovered a sex-specific distribution of cAMP signaling domains where cAMP pools are constrained in the SR of male but not in female mice. To test whether sexually dimorphic cAMP pools are mediated by sex hormones, we used WT male and sham or ovariectomized (OVX) WT female mice. cAMP subcellular distribution was like that of males in VSM from OVX female mice. Interestingly, aortic rings from males and OVX females showed less relaxation responses to isoproterenol compared to sham females. Our study highlights sex-dependent segregation cAMP pools in VSM that could contribute to the sex-specific regulation of vascular reactivity.

American Heart Association award 852984 Research Supplement to Promote Diversity in Science 23DIVSUP1069345.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Effects of Lifelong Exercise on Body Composition and Bone Density
Authors: Hughes Ryan , Raue Ulrika , Trappe Todd , Trappe Scott
Published: May 2024

Objective: The purpose of this study was to compare body composition and bone density among young exercisers (YE), lifelong exercisers (LLE), and old healthy non-exercisers (OH), as well as between men (M) and women (W). Hypothesis: A hierarchal pattern will emerge (YE > LLE > OH) for healthy body composition and bone density. Both body composition and bone density will differ between M and W. Methods: Healthy adults were separated into three groups: YE (n=20, 10M, 25±1yr, 67±10kg), LLE (n=28, 21M, 74±2yr, 75±12kg), and OH (n=20, 10M, 74±2yr, 77±14kg). Daily physical activity was indirectly assessed using a pedometer (YE: ~10,000steps/day; LLE: ~9,000steps/day; OH: ~6,000steps/day). LLE individuals completed aerobic exercise regularly ~5 days/week (~7 hrs/week) for 52±1yr. Further analysis was done between men and women to investigate potential sex differences (M: n=41, 62±25yr, 80±10kg; W: n=27, 58±28yr, 62±7kg). Dual X-ray absorptiometry (DXA) was used to assess body composition (fat and lean mass) and bone mineral density. Results: There was a hierarchal pattern of beneficial body composition related to total body fat (YE: 21±6% < LLE: 25±6% < OH: 37±7%; p<0.05) and lean mass (YE: 79±6% > LLE: 74±6% > OH: 62±7%; p<0.05). In addition, there were sex differences for both total body fat (M: 24±7%; W: 32±9%; p<0.05) and lean mass (M: 75±7%; W: 67±10%; p<0.05). Bone mineral density was not different among the three groups (YE: 1.26±0.10g/cm2; LLE: 1.27±0.18g/cm2; OH: 1.22±0.14g/cm2; P>0.05) but was different between men and women (M: 1.33±0.12g/cm2; W: 1.14±0.11g/cm2; p<0.05). Conclusion: These data suggest lifelong endurance exercise was beneficial for body fat and lean mass in both men and women. Bone mineral density, generally thought to decrease with age, was not impacted by aging or exercise status in this cohort. Women had lower bone mineral density compared to men, regardless of age, which may be related to distinct hormonal regulation between the sexes.

Funding Sources: This research was supported by the National Institutes of Health Grant R01-AG038576 and the Ball State University Human Bioenergetics Program.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Mast cell degranulation is greater when exposed to dialysate collected from exercising skeletal muscle
Authors: Abbotts Kieran , Mangum Joshua , Wiedenfeld Needham Karen , Sieck Dylan , Ely Matthew , Larson Emily , Minson Christopher
Published: May 2024

The effect of histamine is multifaceted and potentially triggers a broad range of cellular adaptations contributing to vascular function, cellular maintenance, metabolism, and inflammation. During exercise, histamine is released from skeletal muscle. This response and the subsequent actions of histamine appear important in obtaining many of the beneficial adaptations to exercise. Increases in exercising skeletal muscle histamine release, in part, occur due to mast cell degranulation. However, the direct effect of exercise on mast cell degranulation has yet to be elucidated. To that end, this preliminary study aimed to quantify in vitro mast cell degranulation when cells are exposed to dialysate taken from exercising and non-exercising skeletal muscle. We hypothesized that greater mast cell degranulation would occur when exposed to dialysate collected from exercising skeletal muscle compared to dialysate collected from non-exercising muscle. Ten subjects (5M/5F, age 26 ± 5 years, weight 76 ± 17 kg, height 168 ± 12 cm) completed 60 minutes of single-leg dynamic knee extension exercise. Prior to exercise, a microdialysis probe was inserted into the vastus lateralis of the exercising and non-exercising legs and perfused with saline at a rate of 5 uL/min. Dialysate was collected before and every 20 minutes during exercise and the subsequent one-hour recovery period. In the exercising skeletal muscle, mast cell degranulation (quantified via b-hexosaminidase release) was greater when exposed to dialysate during exercise versus dialysate collected pre-exercise (P < 0.05). Compared to non-exercising leg dialysate, degranulation was greater for exercising leg dialysate taken between minutes 20 and 40 into exercise (20.6 ± 2.7% vs 15.8 ± 2.0%, P < 0.05) and 40 and 60 into exercise (24.0 ± 2.6 % vs 15.0 ± 2.7 %, P < 0.001) and remained greater for dialysate taken in the first 20 minutes of recovery (21.4 ± 2.8% vs 15.2 ± 3.0%, P < 0.05). These data suggest that there is a soluble factor released from exercising skeletal muscle that causes mast cell degranulation in vitro. These preliminary findings establish a bioassay for further exploration of the identity of the soluble factor released from exercising skeletal muscle, which is responsible for mast cell degranulation in vivo.

This research was supported in part by National Institutes of Health Grants AG072805 and HL115027.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
A Meta Analysis of Whole-Body and Heart Mass Effect Sizes From a Long-Term Artificial Selection Experiment for High Voluntary Exercise
Authors: Schwartz Nicole , Garland Theodore
Published: May 2024

Effect sizes are a quantitative measure of the magnitude and direction of a phenomenon. These estimates can be compiled across multiple studies to summarize the weight of evidence for a particular alternative hypothesis, which is generally termed a meta-analysis. A meta-analytic approach allows one to summarize information from a wide array of similar studies and reach conclusions that may not be apparent on a case-by-case basis (e.g., to determine the overall effectiveness of a drug). Meta-analyses may be particularly useful in selection experiments, where the magnitude of a correlated response is necessarily expected to increase across generations, perhaps eventually reaching a plateau. Here, we examined the effect of artificial selection for high voluntary wheel running on heart mass in mice, which was expected to increase with selection for aerobic exercise behavior. The experiment spans nearly 30 years and 100 generations. All 4 of the replicate High Runner (HR) lines reached selection limits around generations 17-27, running approximately 2.5-3-fold more revolutions per day than the 4 non-selected Control (C) lines. These selection limits cannot be explained simply by a complete loss of heritability. Functional studies have tried to elucidate subordinate traits that affect motivational and/or ability for endurance exercise and have shown that HR mice differ from C in several other behavioral, physiological, and morphological traits. Several studies of heart ventricle mass have reported larger values in HR mice (with body mass as a covariate), but the differences often do not reach statistical significance (p<0.05). We compiled Least-Square Means, standard errors, F-statistics, degrees of freedom, and p-values from multiple studies. We also recorded pertinent information, such as: covariates used, age, generation, and whether other main effects were present (e.g., sex, wheel access). We calculated a common measure of effect size (Pearson’s R) and associated confidence intervals. This work is part of a larger meta-analysis to quantify effects of selection on various traits across multiple levels of biological organization. Preliminary results indicate that, despite a lack of statistical significance in many generations, HR mice have evolved larger hearts and smaller bodies relative to Controls. Moreover, a plateau in effect sizes for both of these traits coincide with the generational range during which the selection limit for wheel-running behavior was reached.

NSF IOS-2038528.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
In Vivo Silencing of Intestinal DMT1 Mitigates Iron Loading in β-thalassemia Intermedia (Hbbth3/+) Mice
Authors: Yu Yang , Yang Chunghua , Delellis Regina , Lee Jennifer , Ebea-Ugwuanyi Pearl , Shine Jacob , He Yue
Published: May 2024

β-thalassemia is an iron-loading anemia caused by homozygous mutations in the hemoglobin subunit beta gene. In β-thalassemia major, frequent blood transfusions and elevated absorption of dietary iron can lead to iron overload, which exacerbates pathological outcomes. Iron absorption is inappropriately high due to blunted expression of the iron-regulatory hormone hepcidin. Low hepcidin potentiates iron export from duodenal enterocytes by ferroportin (FPN); cellular iron depletion then secondarily increases expression of the iron importer, divalent metal-ion transporter 1 (DMT1). High expression of both transporters drives excessive iron absorption and ultimately, iron overload. In non-transfusion-dependent, β-thalassemia intermedia (βTI), hepcidin suppression and high iron absorption are the sole causes of iron loading. In this investigation, two parallel hypotheses were tested in βTI ( Hbbth3/+) mice: 1) Intestinal DMT1 drives elevated iron absorption and precipitates iron overload; and 2) In vivo silencing of intestinal DMT1 mitigates iron loading. Initial experiments revealed that intestine-specific ablation of DMT1 caused a pathophysiological shift from iron overload to an iron-deficiency phenotype with exacerbated anemia, thus proving that intestinal DMT1 is required for iron absorption in Hbbth3/+ mice. Subsequent studies utilized folic acid-coupled, ginger nanoparticle-derived lipid vectors to deliver functional DMT1 siRNAs to the duodenal epithelium of 4-week-old Hbbth3/+ mice daily for 16 days to assess the impact on iron loading. Knockdown of intestinal DMT1 blunted iron loading in Hbbth3/+ mice, thus supporting hypothesis 2. These notable experimental outcomes establish intestinal DMT1 as a plausible therapeutic target to mitigate iron overload in βTI and possibly other non-transfusion dependent, iron-loading anemias.

This work was supported by grants R01 DK074867 from the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), and R01 DK109717 from NIDDK and the Offce of Dietary Supplements (to JFC).

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Optogenetic Engineering of STING Signaling to Remotely Control anti-Tumor Immunity
Authors: Liu Siyao
Published: May 2024

The cGAS-STING signaling pathway is regarded as a promising target for cancer therapeutics development. Here we present an ultra-light-sensitive optogenetic device, designated LiSmore for light-inducible SMOC-like repeats, that remotely control STING activation and downstream gene expression in antigen-presenting cells to mount innate immunity. We demonstrate that noninvasive light-triggered STING modulation effectively promotes dendritic cell (DC) maturation and antigen presentation, allowing T cells to be effectively sensitized to engage tumor antigens, thereby photo-boosting anti-tumor immune response. Importantly, combining LiSmore with immune checkpoint blocker (ICB) synergistically enhances antitumor effcacy in an immunosuppressive lung cancer model, which otherwise remains largely unresponsive to ICB treatment. Our findings establish that targeted optogenetic activation of STING signaling allows for the remote control of DC functions by boosting anti-tumor immunity at the tumor sites. Hence, LiSmore sets the stage for the development of wireless optogenetic immunomodulatory therapies in a light-switchable manner.

Acknowledgment: This work was supported by the Welch Foundation (BE-1913-20220331 to Y.Z.), the Cancer Prevention and Research Institutes of Texas (RP210070 to Y.Z.), and the National Institutes of Health (R01GM144986 to Y.Z., R01HL134780 to R01 Y.H., R01HL146852 to Y.H., and R01CA240258 to Y.H.). Images were created by Biorender.com.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Chloroquine Treatment Causes Diaphragm Muscle Denervation
Authors: Gulbronson Chloe I. , Jahanian Sepideh , Gransee Heather M. , Sieck Gary C. , Mantilla Carlos B.
Published: May 2024

Chloroquine (CQ), an antimalarial agent, inhibits autophagy by preventing the autophagosome from fusing with the lysosome, emulating the effects of aging. Autophagy is a cellular digestion process that contributes to homeostasis through degradation of cytoplasmic structures in the cell. Aging effects include autophagy impairment, leading to the accumulation of altered proteins and organelles, thus contributing to subsequent cell damage and death. Previous studies in phrenic motor neurons show an age-dependent increase in key autophagy proteins LC3 and p62, reflecting autophagy impairment and autophagosome accumulation. In addition, acute chloroquine administration in old mice decreases maximal transdiaphragmatic pressure generation, suggesting a neuromuscular effect in aging. We hypothesized that treatment with the autophagy inhibitor chloroquine alters pre-synaptic morphology and increases the proportion of denervated diaphragm muscle fibers. Adult male and female 6-month C57BL6 mice were used to examine diaphragm muscle neuromuscular junction (NMJ) morphology and denervation. The autophagy inhibitor chloroquine (10 mg/kg/d) or vehicle was administered via daily intraperitoneal injections for 7 days. Confocal microscopy was used to compare pre- and post-synaptic morphology and denervation. There was evidence of a decrease in pre-synaptic volume without evidence of post-synaptic volume changes in chloroquine treated mice compared to vehicle. As expected, vehicle treated mice did not show evidence of substantial denervation. In contrast, chloroquine treated mice showed an increased proportion of denervated NMJs. The morphological changes observed were similar to those previously reported in the diaphragm muscles of 24-month-old mice. These findings reveal the effects at the neuromuscular junction of inhibiting autophagy and implicate impaired autophagy as a mechanism of aging effects.

Supported by NIH R01 AG057052 and Mayo Clinic.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Role of adipocyte-hepatic stellate cell cross talk in liver fibrosis
Authors: Morgan Angelina , Herbert Lea , Robinson Takeriah , Kim Paul , Kim Audrey
Published: May 2024

Hepatic stellate cells (HSCs) are located in the space of Disse, between sinusoidal epithelial cells and hepatocytes. When the liver is injured chronically by alcohol, toxins, viruses, or nonalcoholic steatohepatitis, HSCs are activated. Activated HSCs are transdifferentiated into proliferative myofibroblasts which secrete extracellular matrix and exhibit contractile properties. HSCs may be an effective target to treat liver fibrosis. HSCs can communicate with neighboring cells such as hepatocytes, sinusoidal endothelial cells, Kupffer cells, and immune cells that regulate the activation of HSCs. The secretion of cytokines has led to HSC activation by the cell types mentioned, adipocytes are also known to release cytokines. The role of adipocytes in HSC activation has been rarely reported. This research aims to explore the roles of adipocyte-hepatic stellate cell crosstalk in liver fibrosis. At this annual meeting preliminary gene expression of activation markers, α-smooth muscle actin and type I collagen fiber, in HSCs will be discussed.

Institutional Development Award (IDeA) from the National Institute of General Medical Sciences of the National Institutes of Health under grant #P20GM103424-21. Grambling State University Title 3 Program (Award #P01B220013).

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Allelic modulation of large (second-order) mesenteric artery mechanical properties in adult APOE3 & APOE4 Mice
Authors: Walton Isaiah , McMurray Shelby , Gusek Brikena , Stimpson Anna , Jones Carleton , Eckman Delrae
Published: May 2024

Previous studies from our lab have demonstrated age-related changes in vascular structure/function in posterior cerebral arteries (PCA) and left common carotid artery (CA) in male and female mice expressing human-APOE targeted replacement of APOE3 (B6.129P2-APOEtm2(APOE*3)MaeN8) and APOE4 (B6.129P2-APOEtm3(APOE*4)MaeN8) (Taconic Labs). Therefore, we hypothesize that similar changes may be observed in the systemic circulation. We isolated second-order mesenteric arteries (MA) from adult (6-month-old) male and female mice expressing APOE3 (n=3) and APOE4 (n=4). Mesenteric artery segments (5-8 mm in length) were rapidly isolated and cannulated on an arteriograph to assess mechanical properties: lumen diameter (LD), wall thickness (WT), wall:lumen ratio (W:L), distensibility, stress, strain, and stress versus strain (SvS) in the presence of Ca2+-free Krebs + diltiazem at intraluminal pressures ranging from 10mmHg–140mmHg. Phenylephrine and potassium-induced contractions were assessed in Ca2+-containing Krebs at intraluminal pressures ranging from 10-140mmHg. Data were analyzed using two-way ANOVA, Student’s t-test, and analysis of nonlinear fit. Values were considered statistically different at p<0.05. Our preliminary data indicated APOE4 mice had a greater WT and W:L compared to APOE3. Interestingly, there were no significant differences in the remaining passive mechanical properties (LD, distensibility, stress, strain, SvS). In addition, phenylephrine and potassium-induced contractions were similar in the APOE3 and APOE4 mice. This data suggests changes in passive mechanical properties in APOE4 mice which may resemble premature aging.

ABRC/ADHS18-205211 (DME, CBJ), Arizona Alzheimer’s Consortium (funded by the Arizona Department of Health Services, Contract No. CTR040636) and matching funds from Midwestern University (DME), Biomedical Sciences Program (IW, SM, DME), Biomedical Sciences Start-up Funds (DME).

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Pharmacological Modulation of Leg Shear Rate Profile in Young and Older Adults
Authors: Hanson Brady , Fermoyle Caitlin , Alpenglow Jeremy , LaSalle Taylor , Craig Jesse , Bunsawat Kanokwan , Broxterman Ryan
Published: May 2024

Aging alters the shear rate profile in the arm, characterized by increased oscillatory (bidirectional) shear, potentially from progressive increases in sympathetic nervous system activity. However, the extent to which the shear profile in the atheroprone vasculature of the leg is mediated by sympathetic overactivity via α-adrenergic receptor activation is unknown. We sought to determine how pharmacological modulation of α-adrenergic receptor activity alters shear in the femoral artery with aging. We hypothesized, within the leg, that increased α-adrenergic vasoconstriction would lead to a pro-atherosclerotic shear profile in young adults while α-adrenergic blockade would improve the shear rate profile in older adults, as previously reported in the arm. Resting femoral artery shear rate profiles were assessed in five young (4M/1F, 26±5 yr) and seven older (4M/3F, 65±7 yr) adults during saline (control), phentolamine (PHEN, nonselective α -adrenergic antagonist), and phenylephrine (PE, a selective α-adrenergic agonist) intra-arterial infusions using Doppler ultrasound. Under control conditions, there were no age-related differences in antegrade, retrograde, or total (antegrade + retrograde) shear rates. During PHEN infusion, antegrade shear increased in both young and older adults (Y: 597±214 v. 1011±313 s−1; O: 412±168 v. 648±334 s−1, p<0.05 for both), while retrograde (Y: 122±49 v. 62±21 s−1; O: 109±59 v. 54±43 s−1, p<0.05 for both), and oscillatory shear decreased (Y: 0.17±0.01 v. 0.06±0.01; O: 0.20±0.02 v. 0.09±0.02, p<0.05 for both) compared to control. Although the magnitude of change was similar between age groups, antegrade and total shear were greater in young following PHEN. Infusion of PE had no effect on antegrade (Y: p=0.16; Op=0.78,), retrograde (Y: p=0.83; O: p=0.17), and oscillatory shear (Y: p=0.25; O: p=0.09) but did cause an age-related separation in antegrade and total shear such that the young were greater following PE. Collectively, these preliminary data suggest withdrawal of α-adrenergic vasoconstriction with PHEN leads to a more favorable shear pattern (i.e., increased antegrade shear, and decreased retrograde and oscillatory) within the femoral artery, independent of age. Overall, these findings indicate that femoral shear rate may be influenced by the α-adrenergic system in a manner that is uniquely different from what has been previously reported in the arm.

R01HL142603, I01CX001999, IK2RX001215.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.