bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Mechanism of Exercise Preventing Skeletal Muscle Atrophy
Authors: Theilen Nicholas , Kunkel George , Jeremic Nevena , Tyagi Suresh 
Published: November 2023

BackgroundSkeletal muscle atrophy is the consequence of protein degradation exceeding protein synthesis. This arises for a multitude of reasons including the unloading of muscle during microgravity, post‐surgery bedrest, immobilization of a limb after injury, and overall disuse of the musculature. Mitochondrial dysfunction is associated with skeletal muscle atrophy and contributes to the induction of protein degradation and cell apoptosis with the loss of organelle function. The development of therapies to enhance mitochondrial function prior to skeletal muscle atrophy settings to diminish protein degradation is scarce.ObjectiveWe are investigating whether an exercise treatment prior to an atrophic setting will diminish the skeletal muscle atrophy incurred during hindlimb suspension (HLS) in mice.MethodsMale C57BL/6 (wild‐type) mice between 11–14 weeks of age were assigned to control, HLS only (HLS‐only), exercise only (Ex‐only), and exercise prior to HLS (Ex+HLS), groups. The exercise protocol consisted of 14 progressive exercise sessions over an 18‐day period and the HLS protocol lasted 7 consecutive days. At the end of treatments mice were first anesthetized and blood flow imaging of the hindlimb was done using laser Doppler technology. Mice were then sacrificed and the soleus and gastrocnemius muscle were excised and analyzed for muscle weight. Immunohistochemistry staining was done to detect fiber cross‐sectional area. Future measurements will assess concentrations of mitochondrial function proteins in the excised muscle tissue through western blotting techniques.ResultsHLS‐only resulted in reductions in soleus and gastrocnemius muscle weight of 33.6% and 25.4%, respectively, while exercising prior to HLS led to a decrease in soleus and gastrocnemius weight of 5.1% and 10.8%, respectively, compared to controls. A standardization measurement of soleus muscle weight (mg) to bodyweight (g) ratio decreased 32.7% (.218±.018) in HLS‐only while decreasing 8.1% (.298±.004) in Ex+HLS. Immunostaining revealed greater cross‐sectional area, continuity, and uniformity in Ex+HLS soleus and gastrocnemius muscle fibers compared to HLS‐only. Laser Doppler imaging suggests blood flow in the lower hindlimbs is greater in Ex+HLS mice compared to the HLS only group.ConclusionsData indicates the time before an atrophic setting, particularly caused by muscle unloading and disuse, is a useful period to intervene progressive exercise training to prevent skeletal muscle atrophy which we may be associated with enhanced mitochondrial function.Support or Funding InformationNIH Grant HL74185 to SCT
Anti‐inflammatory Cytokine Receptor Prevents Muscle Atrophy
Authors: Kwon Young‐Won , Son Young Hoon , Park Sun‐Dong , Lee Ju‐Hee 
Published: November 2023

Skeletal muscle plays a leading role in the metabolism and concurrently functions as a repository of protein and amino acids. In many serious diseases such as cancer cachexia and sepsis, excessive secretion of cytokines exacerbates skeletal muscle wasting and metabolic imbalance. Excessively increased cytokines due to disease and tissue damage are regulated by anti‐inflammatory cytokines. However, the precise mechanisms of anti‐inflammatory cytokine in skeletal muscle atrophy have not been fully elucidated. Interleukin‐10 (IL‐10) is an anti‐inflammatory cytokine that improved insulin resistance in high fat diet and aging. The physiological effects of IL‐10 in skeletal muscle were known, but the study of IL‐10 receptor (IL‐10R) was unknown. Our hypothesis was that IL‐10R regulates muscle atrophy in vitro model. In our study, we found that IL‐10 mRNA levels were significantly elevated in various muscle atrophy conditions including the treatment of H2O2, dexamethasone, and cancer cell conditioned media. This is the regulation for suppressing the pro‐inflammatory cytokine, but the mechanism of IL‐10R is unidentified. In order to confirm the directly role of IL‐10R in skeletal muscle, we used the IL‐10R siRNA in C2C12 myotubes. Knockdown of IL‐10R increased the protein level of Atrogin‐1 by Foxo dependent activation, but MuRF1 level by NF‐κB dependent activation remained unchanged. Increased Atrogin‐1 is associated with the reduction of Akt signaling. Declining Akt activity leads to decrease in overall protein synthesis. Using puromycin incorporation, we proved that suppression of IL‐10R reduced the protein synthesis in myotubes. As a result, inhibition of IL‐10R implies a deficit of protein synthesis due to reducing Akt activation. According to our data, the inhibition of IL‐10R is caused by activation of E3 ligase via inhibition of insulin signaling. Our findings suggest that activation of IL‐10R may exert the potential therapeutic effect of skeletal muscle atrophy.Support or Funding InformationThis work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (Ministry of Education) (No.2015R1D1A1A01060340).
Impact of Metaboreflex Activation on Cerebrovascular Reactivity Index in Healthy Young Men
Authors: Maia‐Lopes Paulo Marcelo , Teixeira André L , Antonino Diego , Souza Mayara C , Ricardo Djalma R , Ramos Plinio S , Vianna Lauro C 
Published: November 2023

BackgroundThe control of cerebral perfusion during exercise appears to be highly complex and remains incompletely understood. During isometric exercise, activation of metabolically sensitive skeletal muscle afferents (muscle metaboreflex) markedly increases mean arterial pressure (MAP), and MAP is sustained when the ischemia is maintained following the cessation of exercise (post‐exercise muscle ischemia, PEI). Stimulation of muscle metaboreflex has been implicated in the brain blood flow responses to exercise, but this remains unclear.AimTo determine the influence of muscle metaboreflex activation on pressure reactivity index (PRx) and intracranial pressure (ICP) in healthy young men.MethodsFifteen healthy young men (24 ± 5 years, mean ± SD) randomly performed two protocols. In the experimental protocol the muscle metaboreflex was activated during 3‐min period via PEI, whereas during control protocol the muscle metaboreflex was not activated. Measurements were made at baseline and following isometric handgrip exercise (IHG) with or without PEI for experimental and control protocols, respectively. Participants completed a single bout of IHG at 40% of maximum voluntary contraction for 90 seconds. Heart rate (HR) and arterial BP was monitored on beat‐to‐beat basis using finger photoplethysmography (Human NIBP, AD instruments). In addition, ICP was monitored noninvasively via BrainCare Research 1.5 (BrainCare Health Technology, São Carlos, Brazil). Briefly, small deformations in the surface of the cranium caused by beat‐to‐beat ICP oscillations was captured by strain gauge type sensor (SR‐4) who was placed in contact to the surface of head and connected to personal monitor. PRx is determined by calculating the correlation coefficient between 40 consecutive, time averaged data points of ICP and MAP.ResultsBaseline physiological variables were similar between protocols (P>0.05). During PEI, however, MAP significantly increased from rest (Δ28±3 mmHg, P<0.01) whereas mean ICP, HR (69 ± 3 bpm, P>0.05), and PRx (0.19 ± 0.08, P>0.05) were unchanged. During control protocol, MAP (Δ2±1 mmHg, P>0.05) returned to baseline values following IHG exercise and mean ICP, HR and PRx were unchanged from rest.ConclusionDespite the robust and sustained elevation in systemic blood pressure during selective activation of metabolically sensitive skeletal muscle afferent fibers, the PRx is preserved, indicating that the cerebrovascular is normally reactive.Support or Funding InformationCAPES, FAPDF, CNPq.
Cholinergic signaling in the forebrain regulates peripheral inflammation
Authors: Pavlov Valentin A. , Lehner Kurt R. , Chavan Sangeeta S. , Prado Vania F. , Prado Marco A.M. , Tracey Kevin J. 
Published: November 2023

The brain regulates physiological functions integral to survival. Relatively little is known about the brain neuronal regulation of peripheral immune function. Brain cholinergic signals have been implicated in controlling peripheral inflammation, but specific insight is lacking. Here, utilizing neuron‐and receptor‐specific approaches, we studied the role of forebrain cholinergic signaling and the M1 muscarinic acetylcholine receptor (M1 mAChR) in the regulation of peripheral inflammation. Forebrain‐specific Cre‐loxP‐based ablation of the vesicular acetylcholine transporter (required for synaptic acetylcholine release) and vagotomy abolished the suppression of serum TNF by the centrally‐acting cholinergic drug galantamine in murine endotoxemia. Basal forebrain cholinergic neurons innervate areas with abundant M1 mAChR localization. Enhancement of acetylcholine action on the brain M1 mAChR with the selective positive allosteric modulator benzyl quinolone carboxylic acid (BQCA) suppressed serum TNF levels in endotoxemia. Peripheral administration of the centrally‐acting BQCA also suppressed TNF levels and improved survival in endotoxemia, effects abolished in M1 mAChR KO mice. Optogenetic stimulation of basal forebrain cholinergic neurons in the medial septum reduced serum TNF in endotoxemic mice as compared to sham stimulation. These findings provide novel insights into brain regulation of peripheral inflammation and are of interest for developing new brain‐based treatments for inflammatory conditions.Support or Funding InformationThis work was supported by the following grants from the National Institute of General Medical Sciences, NIH: RO1GM089807 (to VAP and KJT) and RO1GM057226 (to KJT).
Excessive Thiol Nitrosylation Predisposes to Western Diet‐Induced Redox Imbalance and Erectile Dysfunction
Authors: La Favor Justin , Soetkamp Daniel , Venkatraman Vidya , Bivalacqua Trinity , Van Eyk Jennifer , Burnett Arthur 
Published: November 2023

ObjectivesBinding of nitric oxide (NO) to a cysteine thiol is termed S‐nitrosylation, which is emerging as an important means of NO‐mediated signal transduction independent of stimulation of soluble guanylate cyclase. However, the impact of S‐nitrosylation on erectile function remains unclear. S‐nitrosylation is a redox sensitive post‐translational modification, which is thought to be promoted by reactive oxygen species (ROS). Protein S‐nitrosylation levels are regulated in part by S‐nitrosoglutatione reductase (GSNOR), which acts to de‐nitrosylate protein thiols. The objectives of this study were to determine the role of GSNOR on maintenance of redox balance and erectile function in response to a Western diet (WD) high in fat and sugar.Materials and MethodsYoung male wild type (WT; n = 110) and GSNOR−/− (n = 108) mice were fed either a control diet or a WD ad libitum for 3, 6, 9, or 12 weeks. Following the dietary intervention, erectile function was assessed by measuring intracavernosal pressure (ICP) and mean arterial pressure (MAP) during cavernous nerve stimulation. In separate mice, in vivo ROS production was measured in the penis utilizing a novel microdialysis approach. Microdialysis probes were inserted into the penis of anesthetized mice and perfused with saline containing 100 uM Amplex Ultrared, 1 U/ml horseradish peroxidase, and 10 U/ml superoxide dismutase. ROS convert the reagents to a fluorescent byproduct resorufin, which was measured in the outflowing dialysate. Penile tissue was harvested from mice and processed for enrichment of nitrosylated thiols. Nitrosylated thiols were labeled with iodoTMT, and nitrosylated proteins were detected by mass spectrometry.ResultsNeither ROS generation (WT: 0.66 ± 0.09 vs. GSNOR−/− 0.96 ± 0.12 μM H2O2; p = 0.41) nor erectile function (WT:8.44 ± 1.4 vs. GSNOR−/− 9.6 ± 1.6 ICP area/MAP; p = 0.97) were different between genotypes fed the control diet. However, ROS were elevated following just 3 weeks of WD consumption in GSNOR−/− mice (1.44 ± 0.19; p = 0.01), whereas ROS increased following 6 weeks of WD in WT mice (1.29 ± 0.19; p = 0.02). Subsequent to increases in ROS, ED was evident after 6 weeks of WD in GSNOR−/− mice (5.0 ± 1.1, p = 0.04) and after 12 weeks of WD in WT mice (3.1 ± 0.6, p = 0.02). 249 unique peptides corresponding to 136 different proteins with nitrosylated thiol groups were identified by mass spectrometry.ConclusionsMice lacking GSNOR demonstrated an impaired ability to maintain redox balance in the face of the pro‐oxidant stimulus of the WD, prompting accelerated development of erectile dysfunction. These data implicate a protective role for GSNOR in the penis and suggest that excessive S‐nitrosylation may negatively regulate erectile function.Support or Funding InformationSupported by a mini grant from the National Kidney Foundation of Maryland and National Institutes of Health grant 1F32DK100082.
Endothelial Marker Expressing Stromal Cells Play a Critical Role in Recovery Following Acute Kidney Injury
Authors: Maringer Katie , Sims‐Lucas Sunder 
Published: November 2023

BackgroundAcute Kidney Injury (AKI) is characterized by an abrupt decrease in renal function that can lead to renal failure, thus contributing to high percentages of morbidity and mortality. The kidney contains a complex and high degree of vascularization making it susceptible to ischemic injury, particularly the peritubular capillaries. We have identified a subset of endothelial marker expressing stromal (EMES) cells that contribute to the peritubular capillary endothelium. Subsequently, we hypothesize that EMES cells are important contributors to kidney recovery after AKI.MethodsWe confirmed the importance of EMES following ischemia reperfusion injury (IRI) via lineage tracing, using a TdTomato reporter (permanently labeling all EMES cells) and interrogated the percentage of EMES cells that were present in the IRI and contralateral control kidneys. Furthermore, we generated mice with a conditional deletion of Flk1 (Vegfr2, essential for vascular development) in the Foxd1cre positive renal stroma (Flk1ST−/−), and evaluated the tissue after both blood flow dependent AKI, utilizing ischemia reperfusion injury (IRI), and blood flow independent or nephrotoxic AKI utilizing the chemotherapy agent cisplatin and focused on the recovery phase (7, or 28 days) post injury.ResultsWe determined in control mice following IRI that developmental stromal genes were re‐expressed suggesting that the stroma may be undergoing de‐differentiation and subsequently driving EMES proliferation. Furthermore, using lineage tracing we found that EMES preferentially increase during the repair phase (7 days) of IRI. To evaluate the role of EMES cells following AKI, we used Flk1ST−/− animals subjected to IRI, and found that mutants had less perfusion and an increase in hypoxia and increased expression of hypoxia inducible factor 1a (HIF1a) at 7 days. The hypoxic environment caused exasperated kidney damage in the mutant animals. Furthermore, when animals were allowed to recover for 28 days, there was significant fibrosis, and damage in the injured kidney compared to the contralateral control. When these animals were subjected to cisplatin injections we found that while perfusion of the kidneys appeared unaffected, HIF1a was similarly increased and the stromal genes were re‐expressed.ConclusionsTaken together we determined that for repair after AKI the renal stroma requires de‐differentiation and re‐expression of developmental markers prior to proliferation and re‐differentiation. This cellular reprogramming event also requires EMES cell proliferation, which play an important role in mediating vascular perfusion, reestablishing normal oxygen concentrations and regulating HIF signaling to modulate repair and recovery.Support or Funding InformationF32 DK111165‐01K01 DK096996
Urine electrolyte excretion in a hypertensive population of East Africans
Authors: Dobrovolskaite Aiste , Rice Nancy A. 
Published: November 2023

According to the World Health Organization (WHO), chronic non‐communicable diseases (NCDs) cause 38 million deaths annually of which 75 % occur in low and middle income countries. Hypertension is a primary risk factor for cardiovascular disease (CVD), a leading chronic NCD. Kenya, a country in Sub‐Saharan Africa, has a high prevalence of hypertension of which only ~ 3 % is pharmaceutically controlled. Previous work from our lab identified a population of Kenyans with a high prevalence of hypertension that does not statistically correlate with any known risk factor for the disease such as hyperlipidemia or obesity. Therefore, we hypothesized that consumption of a high Na+ and low K+ diet may be involved in the etiology of hypertension in this community. To test this hypothesis, systolic and diastolic blood pressure levels and spot urine samples from 135 people were collected in the morning and evening, and subsequently analyzed for Na+, K+ and Cl− excretion using the Smartlyte Electrolyte Analyzer. Overall mean urine electrolyte excretion values for Na+, K+ and Cl− were 80.2 ± 42.0 mmol/L, 32.0 ± 21.1 mmol/L, and 87.7 ± 42.1 mmol/L respectively. These values fall well within the suggested levels for Na+ (40–220 mmol/L) and K+ (25–125 mmol/L), but under normal excretion levels for Cl− (110–250 mmol/L). Females exhibited higher overall electrolyte excretion when compared to males, with significantly higher excretion levels of K+ (p<0.05). Additionally, there is a significant difference between normotensive and stage I hypertensive individuals in both Na+ (57.9 mmol/L vs. 88.9 mmol/L; p<0.05) and Cl− excretion (65.5 mmol/L vs. 96.7 mmol/L; p<0.05).Support or Funding InformationThis work was funded by a WKU Graduate Studies research award to A. D. and a WKU RCAP award to N.A.R.
Vasoactive effects of P2X7 receptors in the aorta of control and hypertensive mice
Authors: Howarth Amelia Rose , Menzies R.I. , Conway B.R. , Bailey M.A. 
Published: November 2023

P2X7 receptors (P2X7R) are activated by extracellular ATP and have well defined pro‐inflammatory roles in immune cells. The receptor is also expressed in the vascular endothelium and we recently reported that systemic infusion of a P2X7R antagonist reduced blood pressure and increased renal perfusion in hypertensive rats (Menzies et al, Kidney International, 88, p1079, 2015). In the present study we performed a comprehensive immunlocalisation study of P2X7R expression in the mouse renal vasculature and examined the effect of P2X7R activation on the contractility of isolated aorta.Kidneys from male C57BL6 mice were fixed and P2X7R immunofluorescence performed using a rabbit anti‐P2X7 primary antibody (Alomone, 1:500). Immunofluorescence staining was also performed using antibodies against CD31 (endothelium marker); αSMA (vascular smooth muscle marker) and PDGFRβ (pericyte marker). This approach localised P2X7 to the endothelium of mouse renal arteries and glomerular capillaries, but not to the vascular smooth muscle. P2X7 was also seen to co‐localise with PDGFRβ at focal points in the renal medulla.To examine the functional role of vascular P2XR7 expression, we performed wire myography on thoracic aorta dissected from male C57BL6 mice (n=5). The P2X7R agonist, BzATP (50μM) induced a modest vasoconstriction, amounting to 20±5.2% of that induced by depolarisation with KCL. Preincubation with the P2X7R antagonist A438079 (10μM), blocked ~70% of the BZATP‐induced constriction.In a separate group of mice, we induced hypertension (Hypertensive mice: 136.5±3.2mmHg Control mice: 113.3±1.9mmHg) through a 4 week administration of ANGII (100ng/kg/min) and deoxycorticosterone (50mg), combined with high salt feeding. This regimen induced perivascular fibrosis but no albuminuria. In this setting, BZATP also induced a constriction, similar to that observed in non‐treated mice. However, pre‐incubation with the P2X7R antagonist amplified the constrictive response to BZATP.Our data confirm endothelial expression of P2X7R innormotensive mice and suggest that activation of the receptor exerts a modest vasoconstriction. In hypertensive animals, our data suggest that P2X7R exerts a vasodilatory tone.Support or Funding InformationThis work has been generously funded by the British Heart Foundation
EHD4 Regulates Renal Urea Handling In Mice
Authors: Rahman Shamma S , Storck Matthew , Band Hamid , Boesen Erika 
Published: November 2023

Eps15 homology domain‐containing protein 4 (EHD4) is an important regulator of endocytic recycling and is abundantly expressed within the inner medullary collecting duct (IMCD). We have previously found that global EHD4 knockout (EHD4‐KO) mice have a higher urine flow and lower urine osmolality as compared to wild‐type (WT) C57Bl/6 mice, but no significant difference in urinary sodium excretion. Urea transport is important in generating the medullary interstitial osmotic gradient that is required for concentrating urine. Baseline urinary urea excretion in EHD4‐KO on normal rodent chow (19% protein) was significantly higher than that in the WT mice, despite similar abundance of the key urea transporter UT‐A1 in the inner medulla by Western Blot. These data may suggest that EHD4 plays a role in regulating the subcellular distribution or activity of UT‐A1 or other urea transporters in the kidney, rendering renal urea handling dysfunctional in EHD4‐KO mice. The Berliner hypothesis predicts low‐protein diet‐induced restoration of urine‐concentrating ability in the absence of urea transporters in IMCDs. Accordingly, we hypothesized that due to impaired urea transport, the polyuric phenotype observed in the EHD4‐KO mice would be ameliorated by low protein intake and exacerbated high protein intake. To test this hypothesis, we provided female EHD4‐KO (n = 4) and WT littermate (n = 3) mice with either 6% (low), 20% (normal), and 40% (high) protein diet for 7 seven days. On day 8, mice were placed in metabolic cages with the corresponding food and water for 48 hours to acclimate followed by a 24 hours urine collection period. Urine flow remained higher in EHD4‐KO mice than WT mice on the normal protein diet (1.99 vs 1.05 ml/day in EHD4‐KO vs WT), which further increased on the high protein diet (3.67 vs 1.50 ml/day in EHD4‐KO vs WT) but was similar to WT mice on the low protein diet (1.34 vs 1.13 ml/day in EHD4‐KO vs WT) (Pgenotype=0.06, Pdiet<0.01, Pinteraction<0.01). These results indicate that renal urea handling is regulated by EHD4, possibly via a mechanism that involves the trafficking of the UT‐A1 to the apical plasma membrane of the IMCDs rather than regulating UT‐A1 abundance. Future studies will be designed to explore the mechanism of how EHD4 regulates urea transporter activity or localization.Support or Funding Information•American Heart Association Pre‐doctoral Fellowship (SR) (15PRE25580003)•Nebraska Center for Cellular Signaling Pilot Project Grant (EIB and HB)