bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of the lateral hypothalamic leptin circuit on cardiorespiratory control
Authors: Jiang Jingwei , Singh Uday , Cui Huxing
Published: May 2024

In addition to its well-known roles in regulating metabolic homeostasis, leptin signaling in the brain has also been critically involved in cardiovascular and respiration functions. Although the central mechanisms mediating leptin’s effect on metabolic control have been extensively studied and elucidated, the neural substrates by which leptin exert its effect on cardiovascular and respiratory functions remain incompletely understood. Leptin receptors (LepRs) are expressed distinct hypothalamic nuclei, including the lateral hypothalamic area (LHA), a brain region historically known as the “feeding center”. We recently performed anterograde tract-tracing of LHA LepR-positive neurons and observed a broad but regionally enriched pattern of projections throughout the brain, including, but not limited to the brain regions involved in sympathetic control of cardiovascular function and breathing, such as the periaqueductal gray and ventrolateral medullar. Based on these preliminary neuroanatomical observations, we hypothesized that the LHA leptin circuit is critically involved in cardiorespiratory control. To test this hypothesis, we generated mice expressing hM3Dq-mCherry or mCherry (control) specifically in LHA LepR+ neurons by performing stereotaxic microinjection of Cre-dependent AAV-DIO-hM3Dq-mCherry or AAV-DIO-mCherry into the LHA of LepR-Cre+ mice. These mice were then subjected to radiotelemetry recording of blood pressure and whole-body plethysmography to evaluate the respiratory function. We found that chemogenetic activation of LHA LepR+ neurons by intraperitoneal injection of deschloroclozapine (DCZ, 0.5 mg/Kg) significantly elevated blood pressure (p<0.01) and heart rate (p<0.01) independently of locomotor activity. Whole-body plethysmography further revealed that activation of LHA LepR+ neurons also drastically increased the respiratory rate (p<0.0001) and minute ventilation (p<0.001) without a significant change in the tidal volume. Increased respiratory rate was associated with shortening both inspiratory and expiratory durations. These results identify the LHA as a novel hypothalamic node through which the circulating metabolic hormone leptin might influence cardiorespiratory control.

This work is supported by the grants from the National Institute of Health (HL127673 and HL153274 to HC).

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.
Evolution of the peroxiredoxin gene family: an antioxidant enzyme in the context of hypoxia-induced by aquatic mammals dives
Authors: Selleghin-Veiga Giovanna , Nery Mariana
Published: May 2024

Peroxiredoxins are a group of antioxidant enzymes that play a crucial role in eliminating hydrogen peroxide (H2O2) produced during cellular metabolism. In conditions such as tissue ischemia/reperfusion, H2O2 production is heightened. This scenario is recurrent in aquatic mammals, such as cetaceans and pinnipeds, when they perform breath-hold dives that lead to depletion of oxygen stores and cell hypoxia due to prolonged submersion. In such circumstances, peroxiredoxins are essential for regulating metabolism and preventing oxidative damage. Thus, our objective was to investigate evolutionary patterns of the peroxiredoxin gene family among aquatic mammalian species. Accordingly, we identified the number of ortholog and paralog genes among mammals, examining events of gene duplication, patterns of chromosomal distribution, and adaptive selection. We found that most subtypes of peroxiredoxins are characterized by single-copy genes with minimal missing data, with PRDX1, the most highly expressed subtype found in both the nucleus and cytoplasm, exhibiting an increase in gene copies in aquatic mammals, particularly in pinnipeds. The distribution of the copies was dispersed along the genome and the majority were retrocopies of the main coding sequence with little divergence among them. We also found evidence of positive selection in the PRDX3 gene, especially in a convergent mutation among two deepest-diving species, cuvier’s beaked whale and southern elephant seal in which the amino acid had radical physical-chemical property change, possibly affecting the protein function. These results suggest that the peroxiredoxin gene family has a role in the evolution of aquatic mammals by reducing oxidative damage intrinsic to diving behavior in these species.

FAPESP - São Paulo Research Foundation.

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.
Pre-sympathetic C1 RVLM neurons drives sleep disordered breathing in heart failure through activation of central chemoreceptors
Authors: Del Rio Rodrigo , Diaz-Jara Esteban , Toledo Camilo , Olivares Maria , Bernal Ignacio
Published: May 2024

Sleep-disordered breathing is closely linked to heart failure (HF) morbidity and mortality. Recently, we showed that photo-stimulation of pre-sympathetic motor neurons located within the rostro ventrolateral medulla (RVLM) drive sleep-disordered breathing in healthy conditions. However, the neural circuitry required for these effects and whether this pathway is relevant for HF pathophysiology is not known. Accordingly, we aimed to determine: i) if the generation of RVLM-induced altered breathing encompasses the activation of chemoreceptor neurons from the retrotrapezoid nucleus (RTN), and ii) if selective ablation of RVLM neurons improves breathing control and sleep architecture in HF rats. Sprague-Dawley rats received stereotaxic injections of a lenti-viral vector containing a light-sensitive cation channel (Channelrhodopsin2) in the RVLM and a Substance P-saporin toxin conjugate into the RTN. Then, 200 mm fiber optics were implanted for RVLM neurons photo-stimulation. A second group underwent volume overload to induced HF and ablation of RVLM neurons was performed using a DbH-saporin toxin (DbH-SAP). EEG and EMG leads were implanted, and rats allowed to recover before sleep/breathing studies. We found that photo-stimulation of RVLM neurons triggered breathing disorders only in the presence of a functional RTN neurons. Indeed, breathing irregularity score following RVLM photo-stimulation showed a two-fold increase (9±2 vs. 20±3, pre vs. post-stimulation) and this was absent in the presence of Substance P-saporin (10±3 vs. 12±3, pre vs. post-stimulation with Substance P-saporin). Compared to Sham rats, HF animals showed overt signs of disordered breathing and sleep fragmentation and ablation of RVLM neurons using DbH-SAP significantly improves both breathing and sleep function in HF. Our results showed that RVLM drives breathing disorders through activation of the RTN and that selective ablation of RVLM neurons offer salutary benefit for the control of sleep and irregular breathing patterns in the setting of HF.

Fondecyt 1220950.

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.
Neuraminidase-3 Inhibition Improves Vascular Function in Diabetic Mice
Authors: Foote Christopher , Ramirez-Perez Francisco I. , Power Gavin , Morales-Quinones Mariana , Lazo-Fernandez Yoskaly , Augenreich Marc , Cairo Christopher
Published: May 2024

In type 2 diabetes (T2D), endothelial dysfunction and arterial stiffening play a significant role in the development of cardiovascular disease. A central mediator of vascular dysfunction is degradation of the endothelial glycocalyx, a semipermeable mechanosensitive structure that separates the endothelium from the flow of blood and shear forces associated with it. Neuraminidase, a sialidase that cleaves sialic acid from the terminal branches of glycoproteins and glycolipids, is implicated in glycocalyx degradation. However, its role in mediating vascular dysfunction in the setting of T2D remains relatively unexplored. Herein, we tested the hypothesis that pharmacological inhibition of neuraminidase-3 (Neu3i) improves glycocalyx integrity, ameliorates endothelial dysfunction, and reduces arterial stiffness in diabetes. In support of this hypothesis, we report that, relative to vehicle-treated cells, endothelial cells exposed to Neu3i for 24hr have increased glycocalyx components including sialic acid and N-acetylglucosamine (GlcNAc), one of the amino sugars comprising the N-acetyllactosaminoglycans chains within the glycocalyx, as assessed with fluorescent lectin staining using MAA/Mal I+2 and WGA, respectively. We further show that treatment of diabetic ( i.e., db/db) mice with Neu3i for 28 days reduced aortic pulse wave velocity, with no change in blood pressure, when compared to vehicle-treated mice. Neu3i also reduced the stiffness of aortic explants, as assessed via atomic force microscopy. Excised arteries were also assessed for flow-mediated dilation and vascular stiffness using pressure myography. Diabetic mice treated with Neu3i had increased flow-mediated dilation and reduced incremental modulus of elasticity, indicative of improved endothelial function and reduced arterial stiffness. Collectively, these data support the hypothesis that Neu3 is a potential therapeutic target for the amelioration of vascular dysfunction in T2D.

National Institutes of Health grant: R01HL153264 to LM-L and JP.

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.
P311 KO Mice are Protected from Experimentally Induced Lung Fibrosis
Authors: Aramgam Sree Latha , Vaddi Damodara Reddy , Badri Kameswara
Published: May 2024

Pulmonary fibrosis (PF) is a fatal chronic interstitial lung disease and one of the most irreversible forms of tissue/organ fibrosis. Idiopathic pulmonary fibrosis is a very progressive disease accompanied by inflammatory damage with a median survival of less than 5 years. Etiology of IPF is still elusive with potential reasons being genetic predisposition and environmental exposures including particulates, radiation, and SARS-CoV-2. Recent studies indicate that about 50% of COVID19 associated acute respiratory distress syndrome survivors develop PF. There are very limited treatment options with no curative therapies available for PF apart from invasive lung transplantation. P311 is an 8 kDa protein previously shown to have a key role in lung regeneration. As P311 overexpression in fibroblasts induced myofibroblast phenotype, we hypothesized that P311 has a role in tissue fibrosis. We induced PF by intra-tracheally instilling bleomycin (BL) in P311 knockout (KO) mice and wild type (WT, C57BL/6) control mice and collected lungs after 2-5 weeks. P311 KO mice showed significantly less fibrosis. After intra-tracheal instillation of BL, the lungs of P311 KO mice (D21) had significantly reduced number of myofibroblasts as indicated by reduced SM α-actin expression and collagen deposition as indicated by Masson trichrome staining compared to their WT counterparts. We further observed reduced levels of TGF-β1-3 and Smad-2 and -3 along with decreased epithelial to mesenchymal transdifferentiation markers in the lungs of bleomycin treated P311 KOs compared to WT controls. Further bronchoalveolar lavage fluid (BALF) was collected (D14) and utilized to determine the pulmonary inflammation by determining the total and different immune cell populations in the BALF and lung samples by FACS analysis. Even though we saw a significant increase in the BALF cellularity, we did not observe significant changes in T-cell, macrophage, and neutrophil numbers between WT and P311KOs. However, lung cell isolates showed significantly increased CD3 and CD4 positive cells indicating increased T-cells and helper T-cells in fibrotic P311KO lungs compared to WT lungs. In conclusion, bleomycin administration resulted in lung fibrosis in WT mice, but P311 KO mice are protected.

This study was partially supported by research funding to KB, from American Lung Association, DA-196629-N.

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.
Store-operated calcium entry is necessary for sustained K+-induced capillary-to-arteriole dilation in the brain
Authors: Lavanderos Boris , Sanchez Alfredo , Trebak Mohamed , Earley Scott
Published: May 2024

Neurovascular coupling (NVC) is a physiological process that directs blood flow to the most active regions of the brain. The extensive network of capillaries in the brain acts as a sensory web that detects local neuronal activity and orchestrates the dilation of upstream arterioles to meet the brain’s metabolic demands. Activation of inwardly rectifying K+ (KIR) channels on brain capillary endothelial cells (cECs) by modest concentrations of extracellular K+ initiates retrograde propagating hyperpolarizing signals that induce vasodilation and increase blood flow. Brain capillaries exhibit diverse and dynamic patterns of Ca2+ signaling in vivo, but little is known about their origins or physiological function. Store-operated Ca2+ entry (SOCE) is fundamental to Ca2+homeostasis in non-excitable cells, but the contribution of SOCE to capillary-to-arteriole dilation has not been explored. Here, we report that brain cECs express the endoplasmic reticulum-resident Ca2+ sensing protein stromal interaction molecule 1 ( Stim1) and the Ca2+-selective Orai1 and Orai3 channels. Ca2+ imaging experiments using brain cECs from transgenic mice expressing GCaMP8 in the endothelium or loaded with Fluo-4 showed that these cells exhibited robust SOCE that was blocked by the Orai1 inhibitor Synta66. Using EC-specific knockout (ecKO) mice, we found that Stim1 and Orai1 but not Orai3 are required for SOCE. Ex vivo brain microvascular preparations consisting of cannulated and pressured parenchymal arterioles with intact capillary beds were used to examine the role of SOCE in capillary-to-arteriole dilation. Arteriole dilation in response to a train of K+ pulses applied to capillaries exhibited dramatic run-down when preparations were treated with Snyta66 or when tissues from Stim1-ecKO mice were used. Preparations from Orai3-ecKO mice did not demonstrate run-down. Moreover, inhibition of Ca2+-activated K+ (SK and IK) channels also induced run-down, suggesting that SOCE activates SK and IK channels to boost KIR-induced hyperpolarizing signals to dilate upstream arterioles during multiple stimulations. We conclude that brain cECs exhibit SOCE that requires Stim1 and Orai1. Our data further show that brain cEC SOCE is necessary for capillary-to-arteriole dilation during repeated stimulations, suggesting an essential role for SOCE in NVC.

R35HL155008, R33NS115132, and P20GM130459 (to SE).

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.
Exploring student perceptions of course resources in an undergraduate animal physiology course
Authors: Pressey Jessica , Shi Wenyangzi , Izvorean Alexa
Published: May 2024

There has been a significant shift in student learning needs and strategies during and after the COVID-19 pandemic (Becker et al., 2022). In this context, traditional resources and approaches may not be suffcient to satisfy the new needs of students. This study, set in the post-pandemic landscape, focuses on an undergraduate physiology course where students struggled with learning despite having access to the same resources as before the pandemic. Our main objective was to understand students’ experiences with the existing course resources in the post-pandemic era and gather their suggestions for improvements. Using focus groups, we garnered insights into the student experience and perceptions in a second-year animal physiology course. The analysis of focus group interview data indicated that students faced various challenges utilizing the existing resources for understanding concepts and preparing for exams. The focus group also provided recommendations on how the resources related to the lecture content, assessment, and lab operation can be improved to enhance student learning experiences. Results from this study will be used to inform the development of innovative teaching resources to satisfy student demands in undergraduate-level physiology learning.

University of Toronto Faculty of Arts and Science Pedagogical Research Grant.

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.
Teaching research skills to the undergraduate bioscience students through COVID-19 studies
Authors: Ahmed Ishfaq
Published: May 2024

Objective: To describe experience of teaching research skills to the undergraduate bioscience students through COVID-19 studies.Methodology: Undergraduate students taking physiology, microbiology or biomanufacturing at a public college in Kansas City Kansas, during spring 2020 to fall 2023 were encouraged and mentored to 1) do literature survey on COVID-19 2) read the COVID-19 related clinical case study 3) read the COVID-19 related review article 4) learn basic bioinformatics tools 4) prepare and present poster in scientific conference 5) prepare review article.Results: This exercise allowed the students to learn using search engines like PubMed to find reliable information about the disease such as COVID-19. In the fall semester of 2020, students prepared a research paper about the coronavirus, COVID-19 disease, its symptoms and transmission. In the fall semester of 2022, students performed literature survey using PubMed, prepare presentations on various aspects of COVID-19 and wrote a review article. Students read review article about COVID-19 in the Spring semester of 2023 and responded to the questions related to the article. In the fall of 2021, students learned about the clinical aspects of COVID-19 by reading a clinical case study. This also helped students to understand molecular techniques like polymerase chain reaction (PCR), serology tests and how they are used to diagnose the disease. Similarly, in spring of 2022 students learned using NCBI tools to find the genomic and protein sequence of SARS-CoV-2 and its spike protein respectively. They also learned to design primers for PCR for the detection of coronavirus. Finally, students prepared and presented the poster on COVID-19 in a scientific conference.Conclusion: The methodology adopted enabled training the students to learn many research skills like literature survey, write review article, thoroughly read articles, understand the mechanism behind PCR, learn basic bioinformatics, prepare research poster and give scientific presentations.

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 High Glucose Exposed Endothelial Cells BLNK and BTK are Novel Components of the Nuclear Factor-kappa B Pathway
Authors: Singh Madhu , Wong Thomas , Moorjani Sonia , Mani Arul , Dokun Ayotunde
Published: May 2024

Peripheral artery disease (PAD) is atherosclerotic occlusion of vessels outside the heart and most commonly affects the lower extremities. Diabetes worsens PAD outcomes, but the mechanisms involved are poorly understood. A key component of perfusion recovery in experimental PAD is induction of NFκB signaling in ischemic endothelial cells (EC). We have previously shown that prolonged exposure of ECs to high glucose before simulated ischemic exposure resulted in impairment of the canonical NFκB pathway through activation of protein kinase C β (PKCβ). However, the signaling pathways upstream of PKCβ involved in this high glucose induced desensitization of NFκB signaling are not known. We used arrays of antibodies to approximately 100 proteins known to participate in the NFκB pathway to identify the changes in their phosphorylation states in human umbilical vein endothelial cells (HUVEC). Cells grown for three days either in culture medium with normal glucose (NG) or high glucose (HG) were subjected to ischemia for 24 hours (NGI and HGI, respectively). Cell lysates from NG, HG, NGI and HGI groups were then incubated with the array of antibodies printed on glass slides and fluorescent signals were digitally recorded and normalized. The change in protein phosphorylation was calculated by dividing the intensity of the phosphorylated spots by the signal intensity of the corresponding non-phosphorylated spots for each protein. Differential expression between samples, were calculated by dividing the phosphorylation ratio of the NGI and HGI with that of the NG and HG controls, respectively. A combination of pathway analyses using bioinformatics tools on 65 modulated phosphorylation sites in HGI (represented by 35 genes) and analysis of differential phosphorylation between NGI and HGI samples suggested involvement of B cell linker/adapter protein (BLNK)/Bruton’s tyrosine kinase (BTK). BTK plays a key role in B cell antigen receptor (BCR)-coupled signaling by associating with the scaffold protein BLNK. However, neither of these proteins has been known to be expressed in ECs or play a role in EC function. In this study, we confirmed BLNK and BTK protein and transcript expression in ECs. Inhibition of BTK by a selective inhibitor terreic acid decreased PKCβ-S661 phosphorylation and restored NFκB activation through IκBα in ECs suggesting a critical role of BLNK/BTK in the EC. Thus, we have identified BLNK/BTK as potentially new components of the NFκB pathway in ECs that may be a therapeutic target to improve PAD outcomes in diabetes.

National Heart, Lung, and Blood Institute (R01 HL130399) to AOD.

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.
Hemorrhage Magnitude Correlates with Sympathetic Vasomotion in Conscious Rabbits
Authors: Pellegrino Peter Ricci , Zucker Irving H , Wang Hanjun , Schiller Alicia M
Published: May 2024

Each year, over 1.8 million people die from hemorrhagic shock, and the median time from onset to death is only two hours, making early recognition and prompt action the cornerstone of management. The sympathetic nervous system is the most rapid physiological hemodynamic compensatory mechanism, and we have developed a novel measure of sympathetic vascular control called sympathetic vasomotion which could serve as an early marker of hemorrhage. We performed unilateral renal denervation on six rabbits and instrumented these rabbits with bilateral renal flow probes and arterial pressure telemeters to allow for measurement of sympathetic vasomotion. After a two-week recovery period, the rabbits then underwent controlled blood withdrawal via an auricular arterial catheter. The differences in admittance gain and phase shift occurrence between the innervated and denervated kidneys increased significantly before any other hemodynamic changes. Over the first 15 minutes of hemorrhage, the differences in admittance gain and phase shift correlated with hemorrhage magnitude (r = 0.69 and 0.63, respectively), whereas the differences in coherence did not. The sum of the admittance gain and phase shift differences showed a slightly higher correlation with hemorrhage magnitude (r = 0.71). This data suggests that some features of sympathetic vasomotion may be useful as a biomarker for diagnosing early-stage normotensive hemorrhage and assessing treatment response. Further studies are needed to evaluate the utility of sympathetic nervous system monitoring in clinical contexts.

Supported by NIH P01 HL62222 and NIH F30 HL118974.

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.
Identifying protein domain(s) and interactors necessary for Mcrip2 function in brown adipocytes
Authors: Ambrocio Reina , Wade Alexa , Kralli Anastasia
Published: May 2024

High in mitochondria and oxidative capacity, brown adipose tissue (BAT) produces heat through the process of adaptive thermogenesis. Understanding the mechanisms that enable the high oxidative metabolic capacity in BAT can provide insight into and enhance current therapeutic approaches targeting conditions of metabolic dysfunction. Recently, the Kralli lab has identified a gene implicated in BAT thermogenesis that encodes the “mitogen-activated protein kinase (MAPK)-regulated corepressor interacting protein 2” (Mcrip2). Preliminary studies show Mcrip2 regulates the mRNA levels of genes involved in oxidative metabolism, including those involved in oxidative phosphorylation ( Uqcrfs1), fatty acid oxidation ( Acat1, Cpt2), and branched-chain amino acid catabolism ( Bcat2, Bckdha, Ivd, Echs1, Pcca). Interestingly, unbiased proteomic experiments in HEK203 cells have identified multiple Mcrip2 interactors (including Ddx6, Atxn2, Atxn2l) involved in RNA processing, translation and decay, suggesting that this regulation could be post-transcriptional. However, how Mcrip2 post-transcriptionally regulates these genes and the identity of the interactors Mcrip2 constitutes its effects through remains unknown. To elucidate the mechanism of action of Mcrip2, the lab created eight C-terminal HA-tagged Mcrip2 mutant constructs, with mutations targeting different evolutionarily conserved regions of the protein. These mutants will be expressed in primary brown adipocytes lacking Mcrip2 to determine if they complement wild-type and will also be used for co-immunoprecipitation. Results from such studies may provide further insight into the role of Mcrip2 in adipocyte oxidative metabolism and, more broadly, in BAT function.

NIH.

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.
Endothelin-1 Receptor Antagonism Attenuates Increased Uncoupling Protein-1 in Brown Adipose Tissue of Obese Mice
Authors: Mills Megumi , Miller Caroline , Wilson Natalie , Speed Joshua
Published: May 2024

Endothelin-1 (ET-1) is increased in patients and rodent models with obesity and promotes metabolic syndrome by causing inflammation and adipocyte dysfunction. Recently, our laboratory demonstrated that treatment of obese mice with Atrasentan (Atr) and Bosentan (Bos) significantly improved fasting blood glucose, insulin, and glucose and insulin tolerance; however, the mechanisms are not completely understood. Brown adipocytes express all components of the ET-1 system and are important in limiting adiposity though an increase in uncoupling protein-1 (UCP-1) leading to increased metabolism via thermogenesis. We hypothesized that ET-1 antagonism may improve metabolism in obese mice by regulating UCP-1 in brown adipose. Mice were fed either normal (NMD) or high fat diet (HFD) for 10 week and treated with either vehicle, Atr, or Bos for the final two weeks. HFD significantly increased ET-1 and tumor necrosis factor alpha expression in brown adipose tissue compared to NMD controls with no significant effect of either ET-1 receptor antagonists. Interestingly, brown adipose expression of UCP-1 was significantly increased in HFD fed mice compared to NMD, an effect that was significantly attenuated in mice treated with atrasentan and bosentan. These data suggest that ET-1 modulates brown adipose tissue function in obesity, a potential contributor to obesity induced cardio metabolic risk.

This work was supported by National Institutes of Health grant 5T32HL105324-14.

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.
Sexual Dimorphism in Substrate Metabolism During Exercise
Authors: Abo Stéphanie , Casella Elisa , Layton Anita
Published: May 2024

During aerobic exercise, women oxidize significantly more lipids and less carbohydrates than men. This sexual dimorphism in substrate metabolism has been attributed, in part, to the observed differences in epinephrine and glucagon levels between men and women during exercise. To identify the underpinning candidate physiological mechanisms for these sex differences, we developed a sex-specific multi-scale mathematical model that relates cellular metabolism in the organs to whole-body responses during exercise. We conducted simulations to test the hypothesis that sex differences in the exercise-induced changes to epinephrine and glucagon would result in the sexual dimorphism of hepatic metabolic flux rates via the glucagon-to-insulin ratio (GIR). Indeed, model simulations indicate that the shift towards lipid metabolism in the female model is primarily driven by the liver. The female model liver exhibits resistance to GIR-mediated glycogenolysis, which helps maintain hepatic glycogen levels. This decreases arterial glucose levels and promotes the oxidation of free fatty acids. Furthermore, in the female model, skeletal muscle relies on plasma free fatty acids as the primary fuel source, rather than intramyocellular lipids, whereas the opposite holds true for the male model.

This work was supported by the Canadian Institutes of Health Research (CIHR) and the Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery award.

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.
Inflammatory Responses of the Remote Organs After Tourniquet-Induced Ischemia-Reperfusion in Mouse Hindlimb
Authors: Xu Linda , Klammer Abigail , Whitney Lauren , Tu Huiyin , Barksdale Aaron , Wadman Michael , Li Yu-Long
Published: May 2024

Tourniquet use is the most effective tool for controlling life-threatening extremity hemorrhage before other treatments and for creating bloodless operating fields in surgical procedures. However, tourniquet-induced ischemia-reperfusion (IR) also causes skeletal muscle injury and associated secondary end-organ damage. Our previous studies have demonstrated that there are involvements of inflammatory cytokines in tourniquet-induced skeletal muscle IR injuries. The objective of this study is to investigate the inflammatory responses of end-organs after tourniquet-induced mouse hindlimb IR. We hypothesized that tourniquet use would result in an inflammatory response in the remote organs. The unilateral hindlimbs of mice were subjected to 3 hours of tourniquet application by placing a rubber band at the hip joint. Then the rubber bands were released for reperfusion over different periods of time (1, 3, 7, and 14 days). The mRNA levels of IL-1β and TNFα (two inflammatory cytokines) in the lungs, liver, kidneys, and heart were measured using real-time RT-PCR analysis. In the lungs, the levels of IL-1β and TNFα mRNA were significantly elevated at day 1 after tourniquet-induced IR, then decreased at days 3 and 7, and returned to a high level at day 14. In the liver, the levels of IL-1β and TNFα mRNA were increased at day 1 and remained at a high level until day 14. However, tourniquet-induced hindlimb IR did not change the levels of IL-1β or TNFα mRNA in the kidneys or heart during the whole period of tourniquet-induced IR. In conclusion, these results suggest that the inflammatory response to tourniquet-induced hindlimb IR is different among distant organs, which will help to develop therapeutic strategies for different end-organs after tourniquet-induced hindlimb IR.

NIH/NIGMS 1R01GM145736 to Y-LL.

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.
Regulatory Effect of L-Cysteine on Testosterone Biosynthesis Genes in Leydig Cells and THP-1 Monocytes
Authors: Justin Margret Jeffrey , Jain Sushil K
Published: May 2024

Background: Spermatogenesis involves a series of complicated cellular events resulting in the production of mature spermatids. Leydig cells of the testis are essential to forming a spermatozoon. Leydig cells are the interstitial cells that reside between seminiferous tubules and their key role is in the biosynthesis of testosterone. Leydig cells also regulate testicular macrophage and are stocked with innate defense systems. CYP11A1 is a major enzyme in the biosynthesis pathway of testosterone which converts the cholesterol to pregnenolone in the mitochondria of Leydig cells. L-Cysteine (L-Cys) acts as a precursor of glutathione, an antioxidant that plays a vital role against oxidative stress damage. Previous animal studies report the protective effect of L-Cys against chemical/radiation-induced-testicular damage. This study examined the biochemical mechanisms by which L-Cys stimulates testosterone biosynthesis and relative expression of blood-testis barrier (BTB) genes in Leydig cells and THP-1 monocytes. Methodology: The THP-1 monocytes and Leydig cells were treated with L-Cys for 24 hours. Following treatment, RNA was extracted, and the expression of the testosterone biosynthesis gene and BTB genes was analyzed using quantitative RT-PCR. Data (n=4) is presented as mean ± SEM and p-values ≤0.05 are considered as significant. Results: Expression of CLDN1 (p=0.006), CLDN11 (p=0.03), and TJP1 (p=0.04) genes was significantly higher in Leydig cells than in the THP-1 monocytes. There is no significant change in the expression of testosterone-regulatory genes between Leydig cells and THP-1 monocytes. In THP-1 monocytes, L-Cys treatment significantly upregulated the expression of CYP11A1 (p=0.03), CYP19A1 (p=0.002), and BTB genes: CLDN1 (p=0.05), CLDN2 (p=0.001), CLDN4 (p=0.0006), CLDN11 (p=0.006), and TJP1 (p=0.03). Similarly, L-Cys (500uM) treatment significantly upregulated (p=0.03) the CYP11A1 gene expression in HLC, further, the expression of BTB genes: CLDN1 (p=0.03), CLDN11 (p=0.02), and TJP1 (p=0.02) was also upregulated. Conclusion: This study shows that L-Cys increases the expression of testosterone-related genes in both HLC and THP-1. The expression profile of the BTB genes was higher in HLC than in THP-1 monocytes. L-Cys supplementation upregulates the expression of the testosterone biosynthesis pathway gene which can increase spermatogenesis and reduce the male infertility risk.

Funding source: NIH/NCCIH (5R33AT010637) and the Malcolm Feist Endowed Chair in Diabetes.

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.
Empagliflozin Mitigates TMAO-Induced NLRP3 Inflammation and Alters Transporter Expression in Renal Proximal Tubular Cells
Authors: Huang Chiang-Chi , Yang Jenq-Lin
Published: May 2024

The gut-microbe-derived metabolite, trimethylamine N-oxide (TMAO), not only exhibits elevated levels but also serves as a predictor of higher mortality in patients with chronic kidney disease (CKD). In additional to CKD, elevated TMAO levels were also observed in organic anion transporter 3 (OAT 3) knockout mice and in the presence of trimethoprim, an antibiotic known for inhibiting multiple transporters on renal proximal tubule (PT) cells. These findings suggest that plasma TMAO level is a marker for diminished transporter function in PT cells. Moreover, the pro-inflammatory effects of TMAO on PT cells is relatively underexplored. Besides reno-protective effect, a recent study has shown that the sodium-glucose cotransporter 2 (SGLT2) inhibitor empagliflozin attenuates hyperuricemia by enhancing efflux transporter function. Therefore, we propose that empagliflozin can ameliorate TMAO-induced inflammation in PT cells by regulating the expression of membrane transporters. Western blotting results revealed that empagliflozin mitigated TMAO-induced NLRP3 inflammatory cytokines IL-1β, and IL-18. Additionally, empagliflozin reduced the elevated serum levels of TMAO in a CKD mouse model resulting from 5/6 nephrectomy (5/6Nx). Immuno-fluorescent staining demonstrated that TMAO decreased the expression of the basolateral transporter organic anion transporter 1 (OAT1) but increased the expression of apical membrane transporters ATP-binding cassette super-family G member 2 (ABCG2) on the PT cells of 5/6Nx mice. Our in vitro study indicated that TMAO reduced the expression of basolateral membrane transporters OAT1 and OAT3. But empagliflozin significantly increased the expression of OAT3 and ABCG2 in TMAO-treated HK-2 cells. In summary, TMAO induced NLRP3 inflammation in PT cells, while empagliflozin ameliorated the inflammation. Empagliflozin also lowered TMAO levels and influenced transporter expressions in a CKD mouse model. In conclusion, we have shown that empagliflozin mitigate TMAO-induced NLRP3 inflammation. Beyond inhibiting SGLT2, empagliflozin possesses additional effect on the expression of membrane transporters in PT, particularly in CKD mice.

This research was funded by Chang Gung Medical Foundation CMRPG8K0011 and CMRPG8M0311.

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.
Serum Proteins Infer Molecular Protection Against Inflammation in Weddell Seal (Leptonychotes weddellii) Blood
Authors: Klink Amy C , Bagchi Aranya , Hindle Allyson G
Published: May 2024

Weddell seals ( Leptonychotes weddellii) are elite divers able to dive up to 900 meters deep and remain submerged for over 90 minutes. Weddell seals have a dramatic dive response to allow for longer, deeper dives including intense bradycardia and constriction of blood vessels, especially those supplying peripheral or visceral organs. Vasoconstriction, hypo-perfusion and subsequent re-oxygenation upon surfacing is known to induce tissue injury in terrestrial mammals via inflammation. Previous work interrogating the Weddell seal’s innate immune system suggested a component in the seal’s blood serum that protects against inflammation. We are using a mouse macrophage (RAW 264.7) cell model to characterize components of the seal’s blood that are anti-inflammatory to lipopolysaccharide (LPS). When exposed to 10 ng/mL LPS, RAW cells supplemented with deproteinated serum from adult Weddell seals lose their protection against inflammation, having 11-fold greater induction of interleukin-6 (IL-6) mRNA expression after a 6-h exposure compared to RAW cells supplemented with intact seal serum (T=3.29, p=0.01). To determine whether anti-inflammatory capacity of serum is innately present in Weddell seals or whether it is acquired in conjunction with development of diving capacity, we compared the protective effects of adult Weddell seal serum against serum from Weddell seal pups collected at approximately their age of weaning, when they had begun diving activities but do not yet dive deep. Following exposure to 10 ng/mL LPS, IL-6 expression was 69% lower in RAW cells supplemented with serum from adult seals compared to those supplemented with serum from pups (T=8.41, p=0.002), suggesting that ontogeny or diving behavior contributes to the development of anti-inflammatory serum. Analysis of adult (n=12) and pup (n=11) serum proteomes revealed a single protein, colony stimulating factor 2 receptor subunit beta (CSF2RB), with a 24-fold higher abundance in adults (PFDR<0.0001). CSF2RB is a pleiotropic cell surface receptor subunit with known functions in innate immunity, erythropoiesis, as well as tissue protection. Therefore, we hypothesize that it plays a role in the anti-inflammatory protection observed in adult seals. Defining the mechanism of action for this protein in seal serum could identify a protective adaptation that facilitates deep and long dives. In a broader context, lessons learned from an extreme diving mammals may identify anti-inflammatory strategies with new clinical relevance.

NSF #1921491; #1853326; #2337400.

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.
Identifying associations of human surfactant protein A SNPs and allelic variants with retinopathy of prematurity
Authors: Colon Montanez Keishla , Brass Kelsey , Rousselle Dustin , Aston Christopher , Silveyra Patricia , Bhatti Faizah
Published: May 2024

Retinopathy of prematurity (ROP) is the primary cause of childhood blindness worldwide. Previous studies showed that allelic single nucleotide polymorphic (SNP) variants of the human surfactant protein A genes (SP-A1, SP-A2) are associated with the development of respiratory distress syndrome and bronchopulmonary dysplasia (BPD). In this work, we hypothesized that SP-A SNPs and allelic variants are associated with altered risk of ROP in prematurely born infants. To test this hypothesis, we used a modified PCR-based method to detect variants of the SP-A1 and SP-A2 genes in a cohort of preterm infants. Infants born at <32 weeks’ gestation and/or<1500 grams were enrolled. Scavenged blood samples or cheek swabs were collected and DNA was extracted using the QIAamp DNA Mini Kit. We measured SNPs in SP-A1 and SP-A2 using Taqman probes for allelic discrimination by PCR or PCR/RFLP/sequencing method. Associations of SP-A1 and SP-A2 SNP allele frequencies with ROP and BPD were determined using chi-square and logistic regression analyses. Our results show that, of the total patient cohort (n=59), 42 patients had a BPD diagnosis (23 with ROP and 36 without ROP). DNA analysis of these samples identified associations of SP-A1 and SP-A2 SNPs and variants with ROP. For SP-A1, the following SNP associations were found for ROP using chi-square: rs1059047 (p=0.44), rs1136450 (p=0.63), rs1136451 (p=0.21), rs1059057 (p=0.52). For SP-A2, the following SNPs associations were identified with ROP: rs1059046 (p=0.51), rs17886395 (p=0.050), rs1965707 (p=0.031), rs1965708 (p=0.46). Logistic regression analysis indicated an association of ROP with the SP-A1 6A2 variant (p-value = 0.47, OR (6A2/*)=0.8036, 95%CI [0.2299 - 2.8082], OR (6A2/6A2) = 0.4327, 95%CI [0.1063 - 1.7615]), which conferred protection, as well as an association of ROP with SP-A2 6A2 (p-value = 0.0055) with decreased risk when 1A2 variant is present. We conclude that SP-A1/SP-A2 polymorphisms are associated with the presence of ROP in infants with BPD. The 6A4 SP-A1 and SP-A2 1A2 appear to confer protection in babies against ROP. Further studies will determine the mechanisms of this protective effect.

Indiana University, University of Chicago Metcalf Internship Program Grant, The University of Oklahoma Health Sciences Center.

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.
Pathogenic Mechanisms Activated by NSD2 Translocations in Multiple Myeloma
Authors: Ma Guiru , Vasilyev Mikhail , Tripathi Chakrapani , Jedlicka Charles , Bates Melissa , Tomasson Michael
Published: May 2024

The NSD2 gene is overexpressed in multiple cancers and is associated with cancer cell proliferation, invasion, and metastasis. NSD2 gene is universally present in multiple myeloma (MM) patients with t(4;14) (p16;q32) translocation, a high-risk subtype. NSD2 is characterized by different breakpoints. NSD2Δ3 breakpoint is associated with shorter survival than other breakpoints. NSD2Δ3 contains non-coding RNA ACA11 within intron 18. Additionally, 80% of t(4;14) MM patients lack the retinoblastoma tumor suppressor gene (RB1). We hypothesize that ACA11 cooperates with RB1 loss in MM pathogenesis. Also, we hypothesize that NSD2Δ3 increases protein expression driving myeloma growth. To overexpress NSD2WT, snoACA11, and NSD2Δ3 in cells, we cloned NSD2WT, and NSD2Δ3 plasmid constructs in a murine stem cell virus (MSCV)-IRES- GFP vector. We isolated primary B cells from RB1 wild-type and knock-out mice by CD43 microbeads and transduced those cells using a virus containing ACA11 and NSD2WT. ACA11 overexpression significantly increased B cell proliferation in Rb1dKO mice. This hyperproliferative phenotype is induced by reactive oxygen species (ROS) levels. However, we did not find a further increase in B cell proliferation with co-overexpression of NSD2WT and ACA11 in Rb1dKO mice. We demonstrated increased protein stability by finding higher NSD2Δ3 protein expression compared to NSD2WT protein expression in HEK293T cells. These results support our hypothesis and demonstrate oncogenic role of ACA11 in t(4;14) MM. Future work will be done to determine the cell biological effects of NSD2Δ3 and establish its role in myeloma pathogenesis. Completion of this study will advance understanding of this epigenetic NSD2 gene and potentially develop targeted drugs for NSD2, providing more individualized treatment options for these patients.

University of Iowa Department of Internal Medicine.

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.