bluuebunny/crossref_metadata_2025_split huggingface dataset:
Activation of PACAP+ vagal motoneurons following remote ischemic pre-conditioning
Authors: Rostami Cyrus , Hornung Eden , Robbins Shaina , Vadigepalli Rajanikanth , Schwaber James 
Published: May 2024

The Dorsal Motor Nucleus of the Vagus nerve (DMV) provides parasympathetic innervation of the intrinsic cardiac nervous system (ICN), and it has been shown that DMV activity is required for the cardioprotection induced by remote ischemic pre-conditioning (RIPC) against the pathological effects of myocardial infarction. However, the mechanism behind the DMV’s cardioprotective effects is not well understood. Previous literature has shown that the DMV and the other vagal motor nuclei, the nucleus ambiguus (NA), innervate distinct cells within the ICN. DMV neurons project to many other organs in addition to the heart. The cardioprotective neuropeptide Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) has been found to be expressed in the fibers innervating the ICN, where it is co-localized with the parasympathetic marker, ChAT. While we have found PACAP to be expressed in cardiac-projecting DMV neurons, it is unknown whether these neurons are preferentially activated in response to RIPC. To assess the activity of these neurons following RIPC, we performed immunofluorescence staining of brainstem tissue containing DMV neurons for both PACAP, and c-FOS, a neuronal activity-dependent marker. We hypothesized that PACAP+ DMV neurons would have increased activity following RIPC, and therefore increased c-FOS intensity and increased co-localization with PACAP compared to sham control. Our results suggest that PACAP+ neurons in the DMV show increased activity following RIPC compared to sham, as defined by increased c-FOS fluorescence intensity and co-localization with PACAP. These results suggest that PACAP+ neurons are activated during the cardioprotective response to remote ischemic pre-conditioning. Funding was provided by the R01 HL161696 grant through National Heart, Lung, and Blood institute and the National Institutes of Health Common Fund SPARC Program Grant OT2OD030534. 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.
Targeted activation of Nrf2 prevents losses in leg muscle mass and strength during 2 weeks of immobilization in young adults
Authors: Wilcox Isaac , Fermoyle Caitlin , Lewis Matthew , Craig Jesse , Mckenzie Alec , Bisconti Angela Valentina , Hanson Brady 
Published: May 2024

Introduction: Leg immobilization results in substantial losses in muscle mass and strength. Strategies aimed at minimizing these losses have proven largely ineffective. Elevated oxidative stress has been identified as a potential mechanism contributing to these losses. Therefore, we tested the hypothesis that PB125, an activator of Nrf2 (the master regulator of the endogenous antioxidant system), and MitoQ, a mitochondrial-targeted antioxidant, would decrease the deleterious effects of limb immobilization on muscle mass and strength. Methods: A double-blind, placebo-controlled trial was performed in a cohort of twenty young healthy adults (6M/14F, Age: 28±7 y; Height: 169±7 cm; Mass: 70±14 kg). Participants were randomized into either placebo (n=7), PB125 (n=6), or MitoQ (n=7). Supplementation and measures of physical activity using an accelerometer began 2 weeks prior to single leg immobilization and continued through 2 weeks of immobilization. Knee extensor muscle strength was tested before and after immobilization using isometric maximal voluntary contractions (MVC) and isokinetic contractions (120 and 60 degrees/s). Muscle mass was determined by MRI, and thigh lean muscle volume from image slices between the patellar tendon and gluteal muscle were assessed. Results: Physical activity, measured by steps per day, decreased by 55-65% during limb immobilization for all groups (p <0.05). Isometric muscle strength was significantly decreased following placebo (145±40 to 119±27 kg; p <0.05) and MitoQ (148±36 to 118±36 kg; p <0.05), but not PB125 (140±55 to 144±71 kg, p=0.7). Similarly, isokinetic muscle strength measured at 120 and 60 degrees/s was significantly decreased in placebo and MitoQ but preserved with PB125. Lean muscle volume in the immobilized limb significantly decreased by ~4% in placebo (p<0.05) and MitoQ (p<0.05) but was preserved with PB125 (p =0.55). Conclusions: Targeted activation of Nrf2 with PB125 preserved muscle mass and strength following 2 weeks of leg immobilization. In contrast, both placebo and MitoQ had no impact on immobilization-induced losses in muscle mass and strength. These findings provide novel evidence that targeting Nrf2 offsets the detrimental skeletal muscle effects of limb immobilization in young, healthy individuals. NIH-R01HL142603 and VA Merit-I01CX001999. 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.
Neuromodulatory co-expression in cardiac vagal motor neurons of the Dorsal Motor Nucleus of the Vagus
Authors: Hornung Eden , Robbins Shaina , Srivastava Ankita , Achanta Sirisha , Schwaber James , Vadigepalli Rajanikanth 
Published: May 2024

Dorsal Motor Nucleus of the Vagus (DMV) activity is required for cardioprotection from physiological interventions such as remote ischemic pre-conditioning (RIPC). Herein, we discover the transcriptomic phenotypes of cardioprotective DMV neurons, by combining high throughput transcriptomics, 3D anatomical mapping, and neural tracing in 12 week old male and female Sprague Dawley rats. We find that DMV neurons appear to participate in neuromodulatory co-expression, including those that project to the heart. To distinguish potential mechanisms of cardioprotection, we highlight the functional significance of several transcripts in cardiac-projecting DMV neurons and we begin to validate these findings at the protein level. In our sc-RNAseq data we find that Snca (α-synuclein), the cardioprotective neuromodulator Adcyap1 (PACAP), and the neuropeptide Cartpt (CART) are enriched in cardiac-projecting DMV neurons. To contrast our molecular findings in cardioprotective DMV neurons, we have also collected single neuron HT-RTqPCR data from the other source of cardiac vagal motoneurons, the Nucleus Ambiguus (NA). Catecholaminergic transcripts, including Slc18a2 (VMAT2), Ddc, and Th, are enriched in cardiac-projecting DMV neurons relative to those of the NA. These findings implicate catecholaminergic processes, synuclein, and these secreted neuropeptides in cardioprotection. At the protein level, we found PACAP, CART, SNCA and TH enrichment, as well as co-localization of PACAP, TH, and ChAT, in cardiac-projecting DMV neurons. There is consistency between our findings from three spatial transcriptomics techniques and across sexes. Based on these results, we propose a 3D anatomical and molecular map of cardiac vagal motoneurons. This work fills a major gap in the understanding of the cellular mechanisms by which parasympathetic drive provides cardioprotection and provides a future translational path to emulating the positive vagal neuromodulatory effects on heart health. Funding was provided by the R01 HL161696 grant through National Heart, Lung, and Blood institute and the National Institutes of Health Common Fund SPARC Program Grant OT2OD030534. 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 CD8 T-cell transfer on biomechanics of post-myocardial infarction scar formation
Authors: Dasgupta Shaoni , Learmonth Maya , Corker Alexa , Troncoso Miguel , Broughton Philip , Baicu Catalin , Bradshaw Amy 
Published: May 2024

CD8+ T-cells are adverse regulators of post-MI remodeling, resulting in attenuated cardiac function and overall survival. Based on previous studies, we hypothesize that CD8+ T-cells impair cardiac function by altering scar composition. MI was induced by ligating the left anterior descending coronary artery on C57BL6/J wildtype (WT; 3-7 months of age, n≥2/sex) and CD8atm1mak (CD8−/−; 3-7 months of age, n≥2/sex/ group) mice. CD8−/− mice were injected with either vehicle or naïve splenic CD8+ T-cells via tail vein, 4-hours post-coronary artery ligation to assess potential effects on the scar. On day 7 post-MI, infarct tissue was collected, undergoing either passive stretch biomechanical analysis or histological and biochemical assays for collagen composition. Effects of granzyme (Gzm) B and K on collagen cleavage were tested using a fluorogenic collagen cleavage assay to examine possible mechanisms of scar alteration. Mice lacking CD8+ T-cells had improved ejection fraction and decreased dilation compared to WT mice at post-MI Day 7. This protective effect was lost in CD8−/− mice that received splenic CD8+ T-cells. Biomechanical analysis demonstrated CD8−/− mice had a 2-fold increase in regional stiffness compared to WT mice. Re-supplementation with splenic CD8+ T-cells decreased scar tissue stiffness mimicking biomechanics of WT mice. Picrosirius red staining surprisingly showed no significant differences in total collagen levels (p=0.51). Immunoblotting for Collagen 1 trended an increase in the 250 kDa band in CD8−/− mice that decreased after supplementation indicating a loss of pro-collagen formation (p=0.051). Ex-vivo cleavage assay demonstrated GzmK cleaved collagen in a concentration (0-50 AU) and temporal-dependent manner (0-24 hrs). Moreover, GzmK demonstrated a 10-fold greater capacity in collagen cleavage compared to GzmB at 25 AU, indicating the role GzmK plays during post-MI remodeling may be distinctly separate from that of GzmB. In conclusion, our data demonstrates that CD8+ T-cells regulate cardiac fibrosis potentially in part through the release of granzymes, leading to alterations in biomechanical capability of the left ventricle. This work was supported by the National Institutes of Health T32GM123055, R25GM113278; the Biomedical Laboratory Research and Development Service of the Veterans Affairs Offce of Research and Development Award IK2BX003922 and BX003922; and South Carolina Translational Research Center UL1TR001450. 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.
Chronic kidney disease alters tryptophan metabolite concentrations in male and female Sprague Dawley rats
Authors: Irsik Debra L. 
Published: May 2024

Kynurenine is the first stable metabolite of tryptophan degradation. An increased ratio of kynurenine (KYN) to tryptophan (TRP) has been implicated in many disease states including chronic kidney disease (CKD) in humans. We hypothesized that we would see a similar increase in KYN/TRP in a CKD model in male and female rats. We induced CKD with a 0.25% adenine diet for 15 weeks and then measured a variety of renal parameters. Serum and kidneys were collected at sacrifice. We found that GFR was better preserved in CKD female rats compared to males (0.232 ± 0.056 vs. 0.081 ± 0.019 ml/min/100g BW) but was decreased significantly compared to controls (0.739 ± 0.048 female, 0.635 ± 0.099 male). Urine volume was elevated significantly in CKD rats compared to controls (80.0 ± 6.9 ml/day male CKD, 72.5 ± 4.7 female CKD vs. 13.3 ± 1.1 male CTL and 22.0 ± 1.8 female CTL). However, male CKD rats consumed significantly more water than female CKD (104.1 ± 7.3 ml/day male vs. 81.0 ± 5.1 female), although water consumption was similar in controls in both sexes (30.9 ± 2.6 male and 30.1 ± 2.5 female). Weekly food consumption and body weight were similar between same sex groups. Both male and female rats showed increased KYN/TRP in CKD compared to controls (0.102 ± 0.010 in male and 0.105 ± 0.011 in female CKD vs. 0.049 ± 0.005 and 0.033 ± 0.002 CTL). Similarly, kynurenic acid was elevated significantly in both sexes in CKD (305.7 ± 76.7 nmol/L male and 669.2 ± 140.7 female) compared to controls (92.3 ± 17.7 and 118.1 ± 14.7) respectively. These data show that the adenine feeding model of CKD reproduces many of the characteristics of human disease including alterations in TRP metabolites. This model will allow study of TRP metabolites in CKD progression. This work was supported by Career Development Award IK2 BX004997 from the United States Department of Veteran Affairs, Biomedical Laboratory Research and Development Service. 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.
Crosstalk Inhibition Between 5-HT2A and Adenosine 2A Receptor-Induced Phrenic Motor Facilitation
Authors: A. Burrowes Kayla , S. Mitchell Gordon 
Published: May 2024

Episodic spinal serotonin receptor activation elicits phrenic motor facilitation (pMF), a form of respiratory motor plasticity. Although both intermittent 5-HT2 and 5-HT7 receptor activation elicit pMF, they do so via distinct cellular mechanisms known as the Q (5-HT2A/B) and S (5-HT7) pathways. The Q and S pathways interact via powerful crosstalk inhibition; thus, concurrent activation of both receptor subtypes diminishes/abolishes pMF. At least some of the molecules giving rise to mutually inhibitory interactions between 5-HT2 and 5-HT7 receptors have been identified. Although episodic spinal adenosine 2A (A2A) receptor activation also elicits pMF via the S pathway, we do not know: 1) if 5-HT2 and A2A receptors interact via similar crosstalk inhibition, nor 2) if they do so via the same signaling mechanisms. Thus, we tested the hypothesis that concurrent 5-HT2 and A2A receptor activation diminishes pMF via crosstalk inhibition. Selective 5-HT2A (DOI) and A2A receptor agonists (CGS21680) were delivered to the C4 intrathecal space (3, 6 μl injections, 5-min intervals) in urethane anesthetized, artificially ventilated, vagotomized and paralyzed Sprague Dawley rats. Integrated phrenic nerve burst activity was measured before (baseline), during and 90 minutes post-drug injection. Spinal 5-HT2A and A2A receptor activation both increased phrenic nerve burst amplitude when delivered alone (i.e., pMF); however, pMF was no longer apparent with concurrent receptor activation. The magnitude of pMF, expressed as a % change in phrenic burst amplitude from baseline to 90-min post-injection, was significantly lower with concurrent receptor activation (5-HT2A + A2A= 15 ± 7.7%; n=5) versus 5-HT2A (84 ± 12%; n=5, p=0.0047) and A2A (88 ± 16%; n=5, p=0.0085) alone. Thus, 5-HT2A and A2A receptors interact via crosstalk inhibition similar to 5-HT2 and 5-HT7 receptors. However, the mechanism underlying this crosstalk inhibition remains unknown. NIH HL148030. 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.
Vascular Endothelial Mitochondrial Oxidative Stress in Response to Placental Macrophages from Preeclamptic Pregnancies
Authors: Shields Corbin , Robbins Marcus , Deer Evangeline , Cornelius Denise 
Published: May 2024

Preeclampsia (PE), a hypertensive disorder of pregnancy characterized by maternal hypertension, fetal growth restriction (FGR), and chronic immune activation and inflammation, is a major cause of maternal and fetal morbidity and mortality worldwide. Prior clinical studies demonstrate that proinflammatory M1 macrophages are increased in women with PE. We do not understand the role that M1 macrophage polarization may play in PE pathophysiology. We set out to begin characterization of macrophages in patient samples obtained from the UMMC biobank and their ability to induce mitochondrial oxidative stress (ROS) in human umbilical vein endothelial cells (HUVECs). After obtaining informed consent, whole blood and placental tissues were collected from normal pregnant (n=5) and preeclamptic women (n=8) who delivered in the labor and delivery unit UMMC. Lymphocytes were isolated from blood on a Ficoll-Histopaque gradient and analyzed by flow cytometry for total and M1 macrophages. Total macrophages were isolated from digested placental tissue by magnetic bead separation using the Human Macrophage Isolation Kit (Miltenyi). Isolated macrophages were co-cultured with HUVECs overnight. After removal of culture inserts containing macrophages, HUVECs were serum-starved and incubated with MitoSox Red, collected, and analyzed on a flow cytometer. Total circulating macrophages were increased in placentas from PE women vs normal pregnant patients (10.8% PMBCs vs. 3.5% PMBCs, respectively, p<0.05). Furthermore, macrophage polarization to M1 macrophages was significantly higher in women with PE (15.02% of total macrophages) compared to NP women (6.23% of total macrophages, p<0.05 vs. PE). We also determined that mitochondrial ROS production was significantly elevated in HUVEC cells co-cultured with macrophages from PE pregnancies (15.37 A.U.) when compared to HUVECs co-cultured with normal pregnant control macrophages (7.788 A.U., p<0.05 vs. PE). Future studies will include enrollment of additional participants and determination of endothelial activation by measurement of adhesion molecules, growth factors, extracellular matrix proteins, and cytokines in HUVECs and conditioned media via Western Blot, ELISA, and multiplex analysis. These data show that PE placental macrophages induce mitochondrial ROS production in endothelial cells and may play a role to directly induce vascular dysfunction contributing to hypertension during a preeclamptic pregnancy. This work was supported by National Institutes of Health Grants T32HL105324 to C. A. Shields, and R01HL151407 to D. C. Cornelius. 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.
Inhalation of Aerosolized Fentanyl Induces Respiratory Disorder and Sudden Death in Anesthetized Rats
Authors: Zhuang Jianguo , Shi Shan , Xu Fadi 
Published: May 2024

In synthetic opioids, fentanyl (FNT) is the deadliest in clinical settings, resulting from respiratory disorder (RD) including ventilatory depression (dVE) and apnea. Rapid intravenous injection of FNT has been reported to cause immediately central and upper airway obstructive apnea that is mediated by vagal afferents in anesthetized rat (Zhuang J et al, 2012 and 2023). Here we asked whether acute inhalation of FNT also induced similar RD. EMGs of the internal and external intercostal muscles and thyroarytenoid muscles (EMGII, EMGEI, and EMGTA), minute ventilation (VE), heart rate and arterial blood pressure were recorded in anesthetized rats exposed to aerosolized FNT for 10 min. Immediately after exposure to FNT at 100 mg/m3, the rats showed apneas and remarkable prolongation of expiratory duration (TE) associated with hypotension and bradycardia. The apneas were characterized by cessation of EMGEI activity (central apnea) with enhanced tonic discharges of EMGTA (vocal closure, i.e., obstructive apnea) and EMGII (expiratory muscle constriction, i.e., chest wall rigidity). After a brief rebound at ~0.5 min exposure when the cardiorespiratory activities almost recovered to the baseline level, the rats presented gradual dVE by reduction of VT and fR, lasting for approximately 10 min. Apneas and ventilatory arrest subsequently occurred, leading to cardiac arrest a few minutes later. In contrast, FNT at 50 mg/m3 initially failed to significantly change VE, but subsequently developed gradual dVE (70% reduction) with significant TE prolongation, bradycardia and hypotension. These cardiorespiratory responses disappeared 30 min later. Our results suggest that acute exposure to a lethal dose of aerosolized FNT initially induces both central and upper airway obstructive apnea followed by dVE and ventilatory arrest, which is responsible for the sudden death in anesthetized rats. Supported by NIH R01 grants HL163512 and DA059063. 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.
Evaluating the Dynamics of Cyp3a11, MRP2 and MDR1 Modulation by IL-22
Authors: Delanne-Cuménal Améline , Flannigan Kyle L. , Hirota Simon A. 
Published: May 2024

Background: IL-22 is a cytokine produced by a number of immune cell populations, including type 3 innate lymphoid cells. We have shown previously that IL-22 suppresses the expression Cyp3a11 in the mouse intestine, a gene that encodes a drug metabolizing. In addition, IL-22 reduces the expression of MRP2 and MDR1, the gene that encodes as Multidrug resistance protein 2 or 1 involve in the drug detoxification. Modulation of these proteins can influence the oral bioavailability of drugs. Aims: The aim of this study was to define the existence of reversible modulation of IL-22 on Cyp3a11, MRP2 and MDR1 expression and protein level or activity in the intestinal epithelium. Methods: In vitro enteroids of the mouse small intestine were cultured in 3D in the presence/absence of IL-22 for 5 days. Cyp3a11, MRP2 and MDR1 transcript expression was evaluated by qPCR followed by protein analysis to define their modulation and activity at varying timepoints after IL-22 treatment cessation. Results: IL-22 reduced the expression and activity of Cyp3a11 which normalized soon after stopping IL-22 treatment. This action of IL-22 are made without any modulation of protein level of Cyp3a11. In the same way, IL-22 reduces the expression and the protein level of MRP2 and MDR1, an effect normalizes after treatment cessation. Conclusions: IL-22 suppresses the expression and the activity of Cyp3a11 without any modulation of the protein level unlike at the level of MRP2 and MDR1 which are reduced. These data suggest that regulation of gene expression, protein or enzyme activity by IL-22 may have variable effects: Cyp3a11 is ATP-independent, whereas MRP2 and MDR1 are ATP-dependent. This direct or indirect enzymatic modulation of these proteins must be taken into account when assessing the role of the drug in the biology of the intestinal mucosa. Dr. Lloyd Sutherland Chair in IBD/GI Research/Weston 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.