bluuebunny/crossref_metadata_2025_split huggingface dataset:
PTSD induced inflammation negatively impacts cardiac homeostasis
Authors: Corker Alexa , Troncoso Miguel , Broughton Philip , Sidles Sara , Kelly Ryan , LaRue Amanda , DeLeon-Pennell Kristine 
Published: May 2023

Multiple studies indicate that post-traumatic stress disorder (PTSD) is a risk factor for cardiovascular disease (CVD), however the mechanisms behind this correlation is unknown. We hypothesize that PTSD stimulates recruitment of monocyte-derived macrophages to the heart, resulting in increased cardiac fibrosis and resetting cardiac homeostasis. To induce experimental PTSD, male C57BL/6 mice were given 5 different foot-shocks (IFS; 1.0 mA, 1 sec duration) in 6 min. Before each shock, a tone was played to act as the PTSD-associated trigger. Control mice were also placed in the IFS chambers for 6 min but did not receive foot shocks. Behavioral testing was performed to characterize mice into non-responders (NR; IFS mice that do not demonstrate PTSD-like behavioral characteristics) and PTSD-like mice. Terminal timepoints selected were 4-weeks (4.6±0.7 months old) and 13-weeks (8.2±0.0 months old) post-IFS. Doppler echocardiography was collected at the 4-week time point. Histological and immunoblot assessments were collected at 13-weeks post-IFS to determine chronic alterations in cardiac homeostasis. Doppler measurements revealed that 4-weeks post-IFS, PTSD-like mice had decreased aortic ejection time (p<0.05) and trended toward increased isovolumetric relaxation (p=0.080) and contraction (p=0.088) time compared to controls. Interestingly at 13-weeks post-IFS, cardiomyocyte size was also elevated in PTSD-like mice compared to controls (p<0.05), suggesting the functional changes observed at 4-weeks reflect elevations in myocardial stress. A decrease in spleen weight at 4- (p<0.05) but not at 13-weeks (p=0.30) post-IFS indicate potential recruitment of immune cells acutely in PTSD-like mice. In line with spleen weights, at 4- and 13-weeks post-IFS, macrophage staining showed elevated levels in the LV of PTSD-like mice but not NR compared to controls (p<0.05 for all). In addition, matrix metalloproteinase (MMP)-9 protein levels were increased in the LV of PTSD-like mice compared to controls 13-weeks post-IFS (p<0.05). Collagen volume fraction was elevated at 13-weeks post-IFS in PTSD-like and NR mice compared to controls (p<0.05 for all). Our data indicates PTSD-induced cardiac stress is leading to macrophage recruitment and cardiac fibrosis which likely over time will lead to deterioration of myocardial function. This work was supported by the National Institutes of Health T32GM123055; the American Heart Association Innovator Project IPA35260039; the Biomedical Laboratory Research and Development Service of the Veterans Affairs Office of Research and Development Award IK2BX003922; and South Carolina Translational Research Center UL1TR001450 This is the full abstract presented at the American Physiology Summit 2023 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.
Hyperinsulinemia alters Notch1 and ZO-1 expression in human brain microvascular endothelial cells
Authors: Khan Sabina , Altman Robin 
Published: May 2023

Alzheimer’s disease (AD) is an irreversible disease of aging that progressively impairs cognitive function. Although the pathogenesis of AD remains elusive, dysfunction of the blood-brain barrier (BBB) appears to be an important contributing factor. Of the cells that form the BBB, brain microvascular endothelial cells play an important role in maintaining the integrity of the barrier. Disruption of endothelial tight junctions may contribute to the BBB dysfunction observed in AD. Complete understanding of how this may occur remains unclear, but the intersection between AD and type 2 diabetes mellitus (T2DM) suggests possibilities. Individuals with T2DM are at greater risk of developing AD, and the hyperinsulinemia that characterizes untreated T2DM may contribute to endothelial damage and BBB dysfunction by disrupting tight junctions. The cellular mechanisms by which this dynamic occurs continue to be explored, but one signaling pathway that may be involved is the Notch signaling pathway. The objective of this study was to investigate the effects of hyperinsulinemia on Notch1 and zonula occludens-1 (ZO-1, a key tight junctional protein) expression in human brain microvascular endothelial cells. We hypothesized hyperinsulinemia disrupts tight junctions in brain endothelial cells by decreasing ZO-1 protein expression in a Notch1-dependent manner. To explore this hypothesis, human cerebral microvascular endothelial cells (hCMEC/d3 cell line) were exposed to hyperinsulinemic conditions (100 nM) for 0.5, 1, 2, and 4 hours. Following treatment, total cellular protein was isolated, quantified, and separated by SDS-PAGE. Notch1 and ZO-1 protein expression were analyzed by western blot, and expression levels normalized to GAPDH. Our results indicate hyperinsulinemia increased protein expression of Notch1 by almost 5-fold and decreased ZO-1 expression by 3-fold in a time-dependent manner compared to untreated control cells. These results demonstrate hyperinsulinemia alters both Notch1 and ZO-1 protein expression along a parallel timeline, suggesting ZO-1 expression may be dependent on Notch1 signaling; however, further studies are needed to determine whether Notch1 signaling is required for decreased ZO-1 expression during hyperinsulinemic conditions. Disruption of cerebral microvascular endothelial tight junctional integrity due to hyperinsulinemia in T2DM may negatively impact BBB functionality, lending insight into the development and progression of AD. This is the full abstract presented at the American Physiology Summit 2023 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.
Bioflavonoid luteolin normalizes pathways implicated in preeclampsia vascular dysfunction
Authors: Eddy Adrian , Spradley Frank , Rajakumar Augustine , Granger Joey , Rana Sarosh 
Published: May 2023

Preeclampsia (PE) is a pregnancy disease characterized by maternal hypertension and vascular dysfunction. PE is believed to originate from the ischemic/hypoxic placenta that activate local HIF-1α-mediated release of anti-angiogenic sFlt-1 and release of inflammatory cytokines, such as TNF-α. Signaling from both sFlt-1 and TNF-α-induced NF-κB activation result in upregulation of the potent vasoconstrictor ET-1. Antagonism of ET-1 signaling has been shown to relieve symptoms in animal models of PE, but these treatments are contraindicated in pregnancy. Luteolin is a naturally occurring bioflavonoid that has been studied for its use as an anti-inflammatory and anti-hypertensive agent but has never been studied in PE. In this in vitro study, we tested the hypothesis that luteolin may attenuate pathways involved in vascular dysfunction by attenuating HIF-1α increase (via upstream PI3K and ERK) as well as TNF-α-induced NF-κB activation. To study HIF-1α inhibition by luteolin, placental explants from normotensive patients were treated under normoxic (20%) and hypoxic (2%) conditions with luteolin (10μM) for 72 hours, in the presence and absence of relevant inhibitors; PI3K inhibitor (LY294002, 50μM) and ERK inhibitor (U0126, 20μM). Western blots were used to measure HIF-1α protein changes. HUVEC cells were stimulated by TNF-α in the presence or absence of luteolin to determine NF-κB nuclearization by immunofluorescence.Hypoxic incubations significantly increased HIF-1α compared to normoxia (1.44 + 0.43 vs 0.55 + 0.21 arbitrary units (AU); p<0.001). Although HIF-1α expression remained unchanged regardless of treatment in normoxic samples, hypoxic samples treated with luteolin had a significant reduction of HIF-1α expression (1.44 + 0.43 vs 0.51 + 0.09 AU; p<0.01). Similarly, HIF-1α expression was reduced by PI3K inhibitor treatment in hypoxia (1.44 + 0.43 vs 0.56 + 0.18 AU; p<0.01) and ERK 1/2 inhibitor (1.44 + 0.43 vs 0.66 + 0.24 AU; p<0.05). The combination of luteolin and inhibitors did not result in an additive effect. NF-κB nuclearization increased significantly after stimulation with TNF-α (0.38 + 0.13 vs 1.07 + 0.45 AU; p<0.01), which was ameliorated by luteolin to 0.51 + 0.18 AU (p<0.05).Maternal vascular dysfunction is a final common pathway in the pathogenesis of PE, stimulated by upregulation of ET-1. Signaling by ET-1 is promoted by upregulation of HIF-1α-induced sFlt-1 and TNF-α activation of NF-κB. Luteolin, based on our data, is capable of targeting these pathways of ET-1 upregulation and has the potential to serve as a therapeutic for PE. This work was supported by NIH 1R56HL157579-01. This is the full abstract presented at the American Physiology Summit 2023 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.
Age-related changes in cardiac contractility in a mouse model of Down syndrome
Authors: Vasileva Anastasiia , Vasilyev Mikhail , Tomasson Michael , DeRuisseau Lara , Bates Melissa 
Published: May 2023

Over the last couple of decades, the median survival of individuals with Down syndrome (Ds) increased from 30 to 60 years. The Ts65Dn mouse model recapitulates most of the cognitive and neural phenotypes described in Ds individuals and its use continues to expand into other fields. The Ds population is at risk for cardiovascular comorbidities. We hypothesized that contractility in Ts65Dn mice will be lower compared to controls, and differences between strains will become exacerbated with age. The aim of this study was to comprehensively access the cardiac function in the Ts65Dn model across the lifespan. Ts65Dn and C57BL/6J mice (n = 3-5) were tested at 3, 6, and 12 months of age. Left ventricular function was assessed in closed-chest mice using a microtip pressure-volume catheter (PVR-1030, Millar) which was introduced via the right carotid artery and coupled to a digital converter (ADInstruments). By transiently compressing the inferior abdominal vena cava, different preloads were induced, accessing hemodynamic assessment of the left ventricle. Finally, the heart was excised, trimmed, & weighed to assess the Fulton index. The end-diastolic pressure-volume relationship (ESPVR) increased at 12 months in Ts65Dn mice compared to controls. Comparison of the maximal velocity of pressure rise (+ dP/dt) did not differ between ages and genotypes. The maximal velocity of pressure fall (− dP/dt), however, was significantly lower in 12 months Ts65Dn compared to the 6-month group. Cardiac output (Q̇) decreased with aging in Ts65Dn mice compared to controls, therefore decreasing stroke volume (SV) and stroke work (SW). The index of arterial elastance (Ea) increased with aging in Ts65Dn mice compared to the control. Together, Ts65Dn mice have decreased systolic performance accompanied by increased contractility of the heart and increased aortic elastance, and these parameters are revealed as mice age. NIH R21HD099573 This is the full abstract presented at the American Physiology Summit 2023 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.
Skeletal muscle transcriptomic differences underlie blunted mitochondrial adaptions following combined aerobic exercise and metformin
Authors: Elliehausen Christian , Minton Dennis , Lande Kat , Spiegelhoff Audrey , Konopka Adam 
Published: May 2023

The multi-morbidity of aging limits the value of targeting any single age associated disease. Despite exercise and metformin individually improving physiological hallmarks of aging, we and others have shown that metformin inhibits adaptions to insulin sensitivity, skeletal muscle mitochondrial respiratory capacity, and cardiorespiratory fitness after aerobic exercise training (AET). The mechanisms underlying these antagonistic effects are unknown but highlight an important need to further understand the interaction between two leading health span treatments. Here, we performed an 8-week progressive AET regimen on 8-month-old male C57BL6/J mice with metformin (AET+MET) in the drinking water (~300mg/kg/day), without (AET), and sedentary control (SED) (n=3/group). Using high resolution respirometry with permeabilized muscle fibers, metformin prevented the increase in complex I (CI) linked respiration after AET. Additional analyses of site-specific hydrogen peroxide (H2O2) emissions in isolated muscle mitochondria revealed metformin increased H2O2 emissions at site IF of CI versus AET with no difference at site IQ. In this preliminary data set, we did not detect differences between AET or AET+MET in glucose tolerance, insulin sensitivity, or maximal exercise performance following exercise. To facilitate the development of hypothesis generating questions, we aimed to identify a skeletal muscle gene expression prolife that was associated with the effects of metformin on skeletal muscle mitochondrial bioenergetics. Globally the number of differentially expressed genes was blunted by the addition of metformin to aerobic exercise training. Both the upregulation (AET: 139 genes vs. AET+MET: 45) and down regulation of genes (AET: 138 genes vs. AET+MET: 108) was attenuated by the addition of metformin. We identified Nicotinamide Riboside Kinase 2 (NMRK2) as the greatest differentially expressed gene between AET and AET+MET. NMRK2 has a dual role in NAD+ biosynthesis and integrin signaling. Therefore, metformin may alter the transduction of mechanical stimuli to NAD+ homeostasis via NMRK2. While the current study is limited in sample size, we have an ongoing cohort to validate these initial findings. Collectively, our data suggest metformin inhibits skeletal muscle mitochondrial adaptations of aerobic exercise training, similar to our previous work in humans. Further, we have identified NMRK2 as a potential candidate mechanism that is associated with how metformin mediates mitochondrial adaptations to exercise. Nathan Shock Center, Salk Institute for Biological Sciences This is the full abstract presented at the American Physiology Summit 2023 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.
SGLT2 Inhibition Alters the Hepatic and Circulating Metabolome of Mice Under a High-Milk-Fat Diet
Authors: Mendez Espinoza Ileana , Shepard Blythe 
Published: May 2023

Recent studies have shown that the inhibition of Sodium-glucose cotransporter 2 (SGLT2), which reabsorbs glucose in the renal proximal tubule, can aid in glycemic control under conditions of type 2 diabetes (T2D). Though it acts directly on the kidney, these inhibitors also lead to great improvement in liver function. Previously, we challenged TallyHo mice, an inbred polygenetic mice model that recapitulates T2D, with a high milk fat diet (HMFD) for 12 weeks in the continued absence or presence of Empagliflozin (EMPA), an FDA-approved SGLT2 inhibitor. Male mice showed a decrease in circulating triglycerides, hyperglycemia, and hepatic lipid and cholesterol esters (Kurtz et al 2022). However, the mechanisms that underlie this improved liver phenotype is unknown. Thus, we sought to characterize the hepatic and circulating metabolic and lipidomic profiles that are altered and/or restored in the presence of EMPA using targeted and untargeted LC-MS. Control, HMFD, and HMFD + EMPA liver tissues and plasma samples were dissolved in a methanol/water 50/50 extraction buffer that contained debrisoquine (DBQ) for the positive mode standard and 4-nitrobenzoic acid for the negative mode standard. For the untargeted liver and plasma samples, a UPLC-QTOF analysis was performed. MetaboAnalyst was used to quantify metabolite changes with inclusion criteria set to a fold change of 2 and a p-value <0.05. Of note, previous studies have shown that EMPA promotes the upregulation of ketone bodies including β-Hydroxybutyrate (BHB). We noted a similar upregulation of BHB in our metabolomic analysis and confirmed that EMPA led to a ~1.5-fold increase (p < 0.022) in this circulating ketone body. In addition, of those metabolites that met the inclusion criteria, we identified 12 that were downregulated and 9 that were upregulated +EMPA in the male samples. Out of these, orotate, sarcosine, tartrate, and dihydrofolate levels were restored to those of control levels. In the female samples, 6 were downregulated and 3 were upregulated +EMPA. Indoxyl sulfate, butylcarnitine, and valerylcarnetine were all restored to control levels. Of particular interest is the finding that EMPA treatment restores levels of key metabolites that are involved in the folate and pyrimidine biosynthesis pathways. Previous studies have determined that folate deficiency can promote insulin resistance and the urea cycle, a pathway that is integrated with pyrimidine biosynthesis, is upregulated under conditions of T2D and non-alcoholic fatty liver disease. Future studies are aimed at identifying the role of EMPA's hepatic protection in these metabolic pathways. NIDDK This is the full abstract presented at the American Physiology Summit 2023 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.
Rapid, activity-dependent co-release of GABA and glycine in the mouse brainstem
Authors: Gao Hong , Desmoulins Lucie , Molinas Adrien , Zsombok Andrea , Derbenev Andrei 
Published: May 2023

Presympathetic neurons in the ventrolateral and ventromedial medulla (VLM/VMM) control the sympathetic tone, and GABA was identified as a primary mechanism for sympathoinhibition. Intriguingly, there is evidence that both GABA and glycine efficiently inhibit sympathetic tone; however, the mechanism of glycine release is unknown. In this study, we tested the hypothesis that GABA and glycine are co-released in the VLM/VMM. Glycine is recycled by glycine transporter 2 (GlyT2), which is a reliable marker of glycinergic neurons. Therefore, we crossed heterozygous GlyT2Cre mice with floxed channelrhodopsin 2 (ChR2-EYFP) mice to generate GlyT2 reporter mice (GlyT2ChR2/EYFP), which were used to determine the mechanism of glycine release and reveal the location of glycinergic neurons. Whole-cell patch-clamp recordings from presympathetic VLM/VMM neurons revealed that GABA mediates most spontaneous inhibitory postsynaptic currents (sIPSCs); whereas increased activity of inhibitory inputs promotes the release of glycine. Light stimulation of glycinergic fibers expressing ChR2 in GlyT2ChR2/EYFP mice evoked IPSCs (eIPSCs) with glycinergic and GABAergic components. Bath application of GABAA receptors antagonist (bicuculline, 10 μM) decreased the amplitude of eIPSCs, suggesting that approximately 70% of the eIPSCs are generated by glycine. Moreover, blockade of GlyT2 partially diminished the glycinergic component of the light-evoked IPSCs. Using GlyT2ChR2/EYFP mice, we found that glycinergic fibers are abundant throughout the rostral brainstem, and GlyT2-expressing neurons were distributed within the ventral gigantocellular nucleus and medial reticular formation. Immunofluorescence labeling of glycine receptor subunits in the VLM/VMM revealed the expression of two prevalent forms of glycine receptors formed by α1 and α3. In summary, we found that GABA and glycine are co-released in the VLM/VMM, and blockage of GlyT2 decreased the amplitude of light-evoked IPSCs, suggesting that GABA and glycine are likely located in separate vesicles. Our data provide evidence for the co-inhibition of presympathetic neurons in the VLM/VMM by GABA and glycine and suggest that GABA controls the threshold excitability, while glycine is released on demand to increase the strength of inhibition. Supported by: NIDDK122842 and Tulane Brain Institute Marko Spark Innovation Research Fund This is the full abstract presented at the American Physiology Summit 2023 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.
The novel MYH6-E1584K tail domain variant associated with hypoplastic left heart syndrome leads to hypercontractility in vitro
Authors: Anfinson Melissa , Thareja Suma , Cavanaugh Matthew , Brown Ryan , Kim Min-Su , Liang Huan-Ling , Mitchell Michael , Fitts Robert , Tomita-Mitchell Aoy 
Published: May 2023

Hypoplastic left heart syndrome (HLHS) is a complex form of congenital heart disease (CHD) characterized by hypoplasia of the left ventricle and proximal aorta, as well as stenosis or atresia of the mitral and aortic valves. Our lab previously identified that rare, predicted-damaging variants in the gene encoding for α-myosin heavy chain ( MYH6, α-MHC), a key contractile protein in the heart, are enriched in HLHS. It has been shown that pathological variants in the MHC head domain directly alter force generation, but mechanisms by which tail domain variants cause contractile defects are less clear.In double-blind analyses, patient-specific induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) carrying the MYH6 E1584K tail domain variant (VAR) showed significant structural and functional deficits compared to wild-type (WT). Consistent with our previously reported findings in atrial tissue from a patient carrying MYH6 E1584K, VAR iPSC-CMs exhibited sarcomere disarray (p<0.001) and altered sarcomeric gene expression (p<0.05). VAR iPSC-CMs display a hypercontractile phenotype compared to WT, with increased amplitude (2.16μm VAR, 1.32μm WT; p<0.05) and duration (233 msec VAR, 173 msec WT; p<0.05) of contraction and elongated relaxation times (270 msec VAR, 190 msec WT; p<0.01). Hypercontractility was also observed in bulk culture, where VAR iPSC-CMs demonstrated increased amplitude (1413.4 a.u. VAR, 993.6 a.u. WT, p<0.05) and velocity of contraction (1493.7 a.u./msec VAR, 982.2 a.u./msec WT, p<0.05). Notably, this is different than our previous reports of iPSC-CMs carrying the head domain variant MYH6 R443P, which exhibited decreased contraction velocity.Our data demonstrate the mechanism of MYH6 pathogenicity is distinct between variants, emphasizing the importance of mechanistic studies to inform clinical decision-making. Furthermore, this work will direct future investigations into the genetic etiology and physiology of CHD and provide a framework upon which personalized treatment strategies can be developed. Future studies will examine the effect of myosin modulators omecamtiv mecarbil (OM) and mavacamten on MYH6 variant iPSC-CMs. Advancing a Healthier Wisconsin Endowment This is the full abstract presented at the American Physiology Summit 2023 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.