bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of the δ‐Opioid Antagonist Naltrindole on the Antinociceptive and Behaviorally Disruptive Effects of Oxycodone in Squirrel Monkeys
Authors: Withey Sarah Louise , Bergman Jack
Published: June 2021

Opioids remain the most commonly prescribed drug class for the management of moderate to severe pain. Often, high doses that are required for effective analgesia have unwanted effects, ranging from tolerance and dependence, to less severe but still debilitating behavioral disruption. Although most opioid analgesics exert both analgesic and adverse effects primarily through μ‐opioid receptors, recent studies also suggest a role for modulatory interactions between μ‐ and δ‐opioid receptors. For example, δ‐agonists have been proposed to enhance the analgesic potency and efficacy of μ‐agonists, and δ‐antagonists to prevent or diminish the development of tolerance induced by μ‐agonists. Based on these observations, the development of new opioid ligands possessing mixed μ/δ–opioid receptor efficacy has emerged as a novel approach to analgesic drug development. Here, we further study the interaction of these two receptor subtypes by determining whether the δ‐opioid antagonist naltrindole modifies the acute effects of oxycodone on tail withdrawal latency and food‐maintained behavior (reinforcement density, response rate) in squirrel monkeys, using an apparatus for concurrently assaying both behavioral measures.

Daily sessions comprised four 5‐min response components, each preceded by a long timeout (10‐min) during which cumulative doses of drugs could be administered. During each component, the completion of ten leverpress responses [fixed‐ratio 10 (FR10)] in the presence of stimulus lights initiated food delivery and a 30‐sec short timeout (STO) during which stimulus lights were off and tail withdrawal latency was measured.

Results show that naltrindole (1.0 and 3.2 mg/kg) did not significantly alter oxycodone's dose‐effect function for tail withdrawal latency. However, 3.2 mg/kg naltrindole caused a significant rightward shift in the dose‐effect functions for decreases in food‐maintained behavior. ED50 ratios (i.e., the ratio of ED50 values for the two measures) were calculated as a preclinical estimate of therapeutic utility. Values >1 suggest antinociceptive effects are present at doses that do not cause significant food‐maintained behavioral disruption. The ED50 ratios were 1.26 and 3.92 for oxycodone alone and following 3.2 mg/kg naltrindole, respectively.

These results support previous findings that δ‐antagonists may reduce the unwanted adverse effects of μ‐opioid agonists at doses that do not heighten the antinociceptive effects of morphine‐like opioids. Additionally, they provide baseline data for studies of repeated exposure to this type of μ/δ–opioid combination on similar or other behavioral endpoints.

Support or Funding Information

Supported by NIDA Grant DA035857

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Hydrogen‐Deuterium exchange reveals distinct activation states of PLCβ2 by G‐proteins
Authors: Fisher Isaac , Jenkins Meredith , Tall Greg , Burke John , Smrcka Alan
Published: June 2021

G‐protein coupled receptors (GPCRs) are an important class of cell surface receptors that transduce extracellular stimuli to intracellular signaling events via G‐proteins. One major effector of G proteins is phospholipase C (PLC), which hydrolyzes Phosphatidylinositol 4,5 bisphosphate (PIP2) into Diacylglycerol (DAG) and Inositol 1,4,5, trisphosphate (IP3). PLCβ2 and PLCβ3 isoforms are directly activated by binding Gαq, Gβγ or both. The mechanism of activation of PLCβ2 by Gβγ is unknown, and the binding site(s) for Gβγ on PLCβ remain controversial.

Here, we use hydrogen‐deuterium exchange mass spectrometry (HDXMS) to understand the conformational dynamics of PLCβ and to answer open questions in the field concerning the mechanism of activation of PLC by Gβγ and Gαq. For these experiments, several complexes were examined with HDXMS: PLCβ2 alone, PLCβ2+ PIP2/Phosphoethanolamine (PE)/Phosphatidylserine (PS) vesicles, or PLCβ2+ PIP2/PE/PS vesicles plus Gβγ or Gαq‐AlF4. Incubation of PLCβ2 with PIP2/PE/PS vesicles strongly protects regions in the C‐terminus, confirming that this region is involved in membrane binding. In the presence of Gαq‐AlF4, PLCβ2 shows protection from deuterium exchange in the helix‐loop‐helix region of the proximal C‐terminal domain (CTD) and the EF‐hand domain on PLCβ2 that exactly correspond to regions shown to interact with Gαq in the Gαq‐PLCβ3 crystal structure. These data validate that our approach accurately reports bona fide protein‐protein and protein‐lipid interactions. Incubation of Gβγ with PLCβ2 does not reveal any regions of strong protection, but rather causes strong increases in deuterium exchange in the of the CTD of PLCβ2, indicating that the CTD of PLC undergoes a large conformational rearrangement upon Gβγ binding. This increase in deuterium exchange of the CTD of PLC is not seen upon Gαq activation. This indicates that there are distinct conformational states of PLCβ induced by Gαq and Gβγ interactions, suggesting that Gαq and Gβγ use different mechanisms for activation of PLCβ. Finally, these data suggest a mechanism for activation of PLC by Gβγ, where Gβγ binding to PLC breaks an autoinhibitory interaction involving the CTD of PLC and either the membrane or another portion of PLCβ2.

Support or Funding Information

This work is supported by NIH R01 GM081772 to AVS.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Identifying Potential Biomarkers, Mechanisms and Protective Strategies for General Anesthetic‐Induced Neurotoxicity in the Developing Nonhuman Primate
Authors: Slikker William , Han Xianlin , Liu Fang , Zhang Xuan , Gu Qiang , Liu Shuliang , Paterson Tucker A. , Paule Merle G. , Hanig Joseph P. , Wang Cheng
Published: June 2021

It has been reported that commonly used general anesthetics such as sevoflurane induce neurotoxicity in developing brains. However, there has been limited research evaluating whether and how anesthetic agents affect bio‐lipids, the most abundant components of the brain other than water. Thus, assessing lipid profiles from blood samples may assist in the early detection of general anesthesia‐induced neurotoxic effects.

Postnatalday (PND) 5 or 6 monkeys were randomly assigned to control (room‐air; n=4) and sevoflurane‐exposed(n=4) groups. Sevoflurane was delivered using an agent‐specific vaporizer for 9 hours at a clinically‐relevant concentration of 2.5%. Blood samples were collected at 0, 2, 4, 8 and 9 hours during exposure from both the control and sevoflurane‐exposed groups. Lipid extractions and analyses were performed using a mass spectrometer. Four hours after completion of anesthetic exposures front alcortical tissue was collected for histochemical and Western blot analyses. In addition, to evaluate potential protective strategies monkey infants were exposed to sevoflurane in the presence or absence of acetyl‐L‐carnitine(mitochondrial stabilizer), and microPET scanning using [18F]‐FEPPA was carried out to repeatedly visualize and quantify aspects of neurotoxicity.

Serumlipidomic analyses demonstrated that the levels of critical lipid components including acylcarnitines, phosphatidylcholines and phosphatidylethanolamines were significantly decreased during prolongedexposure to sevoflurane. In contrast, the amounts of triglyceride and 4‐hydroxynonenal were increased to abnormally high levels in sevoflurane‐exposed monkeys. Consistently, histochemical staining and Western blot analyses of Bax protein revealed increased neuronal apoptotic damage after sevoflurane exposure. Co‐administration of acetyl‐L‐carnitine effectively blocked the neural damage (increased [18F]‐FEPPA signal)‐induced by prolonged sevoflurane exposure.

These data suggest that prolonged exposure of neonatal monkeys to a clinically‐relevant concentration of sevoflurane resulted in significant changes in lipidmetabolism and subsequently, neuronal apoptotic damage. Monitoring specificlipid changes may provide insights into the molecular mechanism(s) underlying generalanesthetic‐induced neurotoxicity and serve as sensitive biomarkers for the early detection of anesthetic‐induced neuronal damage. Acetyl‐L‐carnitine may act to preserve cellular membrane integrity and play critical roles in mitochondrial oxidation of long‐chain fatty acids, and thus protect neurons from sevoflurane induced damage.

Support or Funding Information

Supported by NCTR/FDA

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Evaluating the effects of HIPK2 Inhibition on Castration‐Resistant Prostate Cancer Cells
Authors: Camacho‐Hernández Elaine Marie , Thomas Phillip , Ledet Russell , Garabedian Michael J. , Logan Susan K.
Published: June 2021

Prostate cancer is the second leading cause of death in men in the United States. It depends on the signaling by the androgen receptor (AR), which is activated by testosterone. AR signaling promotes normal prostate development as well as cancer. Current treatments for prostate cancer include prostatectomy and androgen deprivation therapy. Although androgen deprivation is effective in halting prostate cancer growth, a group of men are often diagnosed with castration resistant prostate cancer (CRPC), which is refractory to hormone deprivation. Therefore, new targets are needed to stop prostate cancer growth. In this study, we investigated whether Homeodomain‐interacting protein kinase 2 (HIPK2) affects AR signaling and prostate cancer cell growth. To do this, we utilized doxycycline‐induced shRNA‐mediated silencing of HIPK2 expression in 22Rv1 and LNCaP‐95, two cell lines that are refractory to androgen deprivation, and demonstrated substantial knockdown of both HIPK2 mRNA and protein. In addition, we observed significant changes in AR target gene expression. To determine the effects of HIPK2 knockdown on AR subcellular localization, we fractionated control and doxycycline‐treated 22Rv1 and LNCaP‐95 cells. We observed modest changes in chromatin‐bound AR upon HIPK2 depletion, suggesting that HIPK2 influences AR chromatin occupancy and in turn AR‐dependent transcription. We also tested HIPK2 catalytic inhibitors by examining their effects on 22Rv1 and LNCaP‐95 cellular proliferation, and phosphorylation a HIPK2 substrate, SIAH2. We found that HIPK2 inhibitors modestly affected the proliferation and substrate phosphorylation. Thus, HIPK2 can modulate AR activity, highlighting the role of HIPK2 as a new drug target for prostate cancer.

Support or Funding Information

New York University Langone Medical Center

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
A New Preventive Therapeutic Strategy for Liver Cancer
Authors: Lee Jin , Feng Gen‐Sheng
Published: June 2021

Liver cancer is the second most common cause of cancer‐related death with difficulties of immune therapeutics. When administered at pre‐cancer stages, the immunostimulatory synthetic double‐stranded RNA (dsRNA), polyinosinic‐polycytidylic acid (pIC) robustly induced tumor remission with no cytotoxic effect in either chemically‐induced or phosphatase and tensin homolog (PTEN) knockout‐induced liver cancer in mice by boosting multiple anti‐tumor immune activities, including natural killer (NK) cells and reprogramming of macrophage polarization. In contrast, a potent anti‐tumor dsRNA, in late stages of PTEN loss‐associated hepatosteatosis markedly increased tumor burden. Injection of dsRNA stimulated macrophage type II and regulatory T cells in PTEN‐knockout mice without affecting lipid accumulation, expression of α‐smooth muscle actin (α‐SMA) and cholangiocyte expansion at late stages. This study provides a new strategy for approaching immune therapeutics for the large population of at‐risk and liver cancer patients at different stages.

Support or Funding Information

We thank Drs. D. Brenner, J Bui, M. Kaplan, M. Karin, T. Kisseleva, B. Schnabl and colleagues in the Feng lab for helpful discussion, critical reading of the manuscript or reagents. This work was supported by R01CA176012 and R01CA188506 to (G.S.F.), and P30DK063491, and JDRF 2‐SRA‐2016‐306‐S‐B (to W.F.).

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Adiponectin regulates T‐cell maturation by modulating the thymic epithelial environment
Authors: Cao Handi , Sun Wai Yan , Zhang Yiwei , Xu Aimin , Wang Yu
Published: June 2021

Objective

Adiponectin is an adipokine possessing potent immunomodulatory activities. The present study investigated T‐cell development and maturation in the thymus tissue of FVB/N‐Tg( PyVT‐MMTV)634Mul/J mice with or without Adipoq allele expressions.

Methods

Different populations of lymphocytes were analyzed by flow cytometry. Protein expressions were evaluated by immunofluorescence staining and/or Western blotting. Gene expression and mRNA presence were measured by quantitative real time PCR and in situ hybridization respectively.

Results

Significant reductions of CD3+CD45+ and CD3+CD4+ cells were observed in the blood of FVB/N‐Tg(PyVT‐MMTV)634Mul/J mice lacking adiponectin (AKO), when compared to age‐matched mice with Adipoq allele expression (WT). An increased population of CD45+CD3−CD44high progenitor cells was present in the blood of AKO mice. The CD3+ cells were also significantly reduced in the thymus of AKO mice, where exhibited altered expression and distribution of epithelial markers including cytokeratin 5, cytokeratin 8, p63 and β5t when compared to those of WT mice. Adiponectin mRNA and protein expression were detected in thymus tissue sections and the thymic nurse cell (TNC) complexes of WT mice. The thymus of AKO mice contained significantly reduced amount of TNC complexes, leading to the accumulation of double positive thymocytes. Molecular interactions between adiponectin, CD100 and galectin‐3 might play a role in the engulfment of lymphocytes by TNC complexes.

Conclusion

Thymic adiponectin expression plays a key role in modulating the epithelial environment and T‐cell maturation in thymus.

Support or Funding Information

This work was supported in part by grants from Seeding Funds for basic research of the University of Hong Kong, Research Council Grants (17121714, HKU779712M, HKU780613M) of Hong Kong; And the National Basic Research Program of China (973 program 2015CB553603).

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Direct and Indirect Effects of Ephedrine on the Cardiovascular System
Authors: Docherty James R. , Alsufyani Hadeel A.
Published: June 2021

After many years of use of ephedrine, there is still confusion as to its exact mode of action: direct agonism (Liles et al., 2007) or actions as an indirect sympathomimetic, or both. We have previously shown that cardiovascular actions of the stimulant cathinone are largely indirect by release of noradrenaline (Alsufyani & Docherty, 2015). We have now investigated, using the same techniques, the cardiac and pressor responses to (±)‐ and (−)‐ephedrine in pentobarbitone anaesthetised male wistar rats. The tachycardiac responses to (±)‐ and (−)‐ephedrine were similar, but pressor responses to (−)‐ephedrine (10 mg/kg) were significantly greater than those to (±)‐ephedrine, and for both, the pressor response was followed by a small depressor response. Sympathectomy did not affect the pressor response, but significantly increased the later depressor response to both compounds. Sympathectomy did not significantly affect cardiac or depressor responses to the direct beta‐adrenoceptor agonist isoprenaline. Sympathectomy significantly reduced the tachycardia to (±)‐ephedrine. It is concluded, firstly, that (−)‐ephedrine is more potent than the racemate mixture at producing pressor responses. Secondly, since the depressor response to the direct agonist isprenaline was unaffected, sympathectomy presumably reduced a later pressor component to the response to (±)‐ and (−)‐ephedrine. Hence, the early pressor response to both (±)‐ and (−)‐ephedrine is direct, but the later pressor response is largely indirect. Ephedrine has both direct and indirect actions on blood pressure.

Support or Funding Information

Supported by King Abdelaziz University

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Aspirin Protects Heart Against Ischemia‐reperfusion Injury Via LKB1‐Sestrn2‐AMPK Signaling Cascade
Authors: Lu Shaoxin
Published: June 2021

Introduction

AMP‐activated protein kinase (AMPK) is a stress signaling enzyme that orchestrates the regulation of energy pathways. Intrinsic AMPK activation protects the heart against ischemic injury, but whether the pharmacologic AMPK stimulation by aspirin mitigates ischemia‐reperfusion (I/R) damage is unknown.

Hypothesis

Aspirin as an emerging AMPK agonist could stimulate the cardiac AMPK signaling pathway that attenuates myocardial ischemia‐reperfusion injury.

Methods

The cardioprotective activity of aspirin was evaluated in an in vivo regional I/R (45 min/24 hours) injury model in which the left anterior descending coronary artery (LAD) was occluded and released. The Langendroff perfused heart system was used to approach an ex vivo global ischemia and reperfusion model.

Results

Isolated mouse hearts ex vivo pre‐treated with aspirin had better recovery of left ventricular contractile function (55% vs. 29% of baseline heart rate‐pressure product; p<0.05) and less myocardial necrosis (56% reduction in infarct size; p<0.01) during post‐ischemic reperfusion. Pre‐treatment with aspirin in vivo attenuated myocardial infarction in C57BL/6J mice undergoing left coronary artery occlusion and reperfusion compared to vehicle (36% vs. 18%, p<0.05). Mouse hearts with genetically inactivated AMPK catalytic subunit were not protected by aspirin treatment, indicating the critical role of cardiac AMPK activation by aspirin in cardioprotection against ischemic injury. Moreover, pre‐treatment with aspirin in vivo increased the AMPK downstream phosphorylation and inactivation of eukaryotic elongation factor 2 (eEF2), preserved energy charge during ischemia and delayed the development of ischemic contracture. Aspirin treatment augmented the interaction between AMPK upstream LKB1 and Sestrin2‐AMPK complex, also enhanced activation of AMPK downstream endothelial nitric oxide synthase (eNOS) during ischemia, which partially attenuated myocardial stunning.

Conclusions

AMPK is a therapeutic target that can be stimulated by a direct‐acting small molecule in order to prevent injury during I/R. The use of aspirin may represent a novel strategy to protect the heart and other solid organs against ischemia.

Support or Funding Information

American Heart Association

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Rho Kinase inhibitors and hypoxia modulate expression of platelet activating factor (PAF) receptor and gene expression in fetal ovine pulmonary vascular smooth muscle cells.
Authors: Ibe Basil O. , Renteria Lissette S.
Published: June 2021

Hypoxia and PAF augment intracellular calcium flux in fetal ovine pulmonary vascular smooth muscle cells (PVSMC) indicating that high pulmonary vascular tone in fetal pulmonary vessels in utero is consequent on combined effects of hypoxia and PAF receptor (PAFR)‐linked vascular responses. PAFR internalization is said to inactivate PAF effects in PVSMC in vitro. Hypoxia increases PAFR expression, but Rho kinase (ROCK) inhibitors decrease the expression suggesting PAFR internalization may be one pathway to downregulate PAFR‐mediated responses in PVSMC. These findings also suggest that ROCK may act in synergy with PAF to modulate PAFR‐mediated pulmonary vascular responses. We studied effects of PAF, hypoxia and other modulators of pulmonary vascular reactivity in arterial (PA) and venous (PV) smooth muscle cells (SMC) to aid in understanding the signaling pathways of PAFR‐mediated fetal ovine pulmonary vascular reactivity in utero. We hypothesized that ROCK inhibitors attenuate PAFR expression in hypoxia leading to increased expression of the contractile proteins. Cells were cultured in normoxia or hypoxia, with and without 10 nM PAF or ROCK inhibitors (Y27632 and HA 1077, each 10 μM). Proteins were probed for PAFR, and Calponin, MLCK and Desmin, which are contractile protein modulators of PVSMC activity. PAF binding, PAFR protein and gene expression by qRT‐PCR were also determined. In normoxia, PAFR density (Bmax) in PA and PV SMC were 487±37 and 624±17 respectively, which increased by 30–35% in hypoxia, and higher in PV than PA in normoxia and hypoxia. The KD for PAF binding to PASMC was higher than for PVSMC, and then hypoxia decreased the KD of PAFR binding in both cell types. ROCK inhibitors attenuated PAFR binding with comparable effect to cycloheximide, but unlike PAFR inhibitor, CV3988, cycloheximide had no effect on pre‐synthesized proteins. ROCK inhibitors decreased PAFR expression, but increased expression of MLCK2, Calponin and Desmin in PASMC especially in hypoxia, with different effects in PVSMC. Generally, PAFR gene expression studied by qRT‐PCR was higher in PVSMC under all conditions. This study shows that hypoxia in conjunction with ROCK inhibitors modulate PAFR‐mediated signaling in PVSMC in vitro with different effects on cells from PA and PV. Increased expression of the contractive proteins in hypoxia indicates involvement of these proteins in PAF‐induced contractions in PVSMC.

Support or Funding Information

LABiomed

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Nardostachys jatamansi ameliorates doxorubicin induced cardiotoxicity via down regulation oxidative stress and inflammatory markers in rats
Authors: Madkhali Hassan A. , Ganaie Majid Ahmad , Raish Mohammad , Jan Basit Latief , Ahmad Ajaz
Published: June 2021

Nardostachys jatamansi (family Valerianaceae) is a perennial herb found in Alpine Himalayas. In Ayurveda system of medicine, rhizomes of Nardostachys jatamansi are used as a bitter tonic, stimulant and antispasmodic and to treat epilepsy, hysteria, and convulsions. In the Unani system of medicine Nardostachys jatamansi has been mentioned as hepatotonic, cardiotonic, diuretic and analgesic. In the present study, we have investigated the protective role of alcoholic extract of N. jatamansi on myocardial injury induced by doxorubicin (15 mg/kg body weight, intraperitoneal single dose). Pretreatment for 5 days with ethanolic extract of N. jatamansi (250 mg/kg body weight and 500 mg/kg body weight orally) showed moderate cardioprotective activity as evidenced by significant decline in the elevated levels of serum marker enzymes and lipid peroxide levels with restoration in myocardial endogenous antioxidants levels. Hyperlipidaemia induced by doxorubicin was also inhibited and inflammation markers TNF‐α, IL‐6, and myeloperoxidase [MPO]), were also assessed. Doxorubicin promoted the upregulation of cardiac cytokines (TNF‐α and IL‐6), and MPO activity were significantly down regulated upon ethanolic extract of N. jatamansi pretreatment. Histopathological changes ranging from edema to degenerative changes in cardiac tissue sections were also restored.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Model‐Based Estimation of Pulmonary Flow Heterogeneity from Observed Oxygen Transport Parameters in Exercise
Authors: Roy Tuhin K. , Secomb Timothy W.
Published: June 2021

The rate at which oxygen can be taken up into the bloodstream in the lung is a critical determinant of functional capacity, and can be affected by heterogeneity of pulmonary blood flow (leading to maldistribution and poor ventilation‐perfusion matching) as well as alterations in diffusing capacity. Under resting conditions, the high degree of reserve in the healthy lung leads to adequate oxygen uptake even in the face of increased heterogeneity or decreased diffusing capacity; under conditions of exercise, however, oxygen transport and utilization are contingent upon adequate lung function with relatively little reserve. A mathematical model of pulmonary oxygen uptake is used in this study to investigate the impact of pulmonary flow heterogeneity in exercise, which we characterize by the coefficient of variation (CV) of pulmonary capillary blood flow; under conditions of uniform alveolar ventilation, this is theoretically equivalent to impaired ventilation‐perfusion matching. We have previously demonstrated that any level of pulmonary heterogeneity up to a high degree (CV of approximately 3.0) is consistent with the observed level of arterial oxygen tension under resting conditions. We hypothesize that such high levels of heterogeneity would preclude the high oxygen uptake in the lung observed during exercise. In this study, literature data on humans under normoxic and hypoxic conditions was used to estimate the CV of pulmonary capillary blood flow under conditions of moderate and extreme exercise. With the assumption of a normal diffusing capacity, the best fit overall to aggregated data from five studies was found with a CV of 0.61. These results show that a high degree of pulmonary flow heterogeneity does not limit oxygen uptake at rest, but that in exercise much lower levels of heterogeneity are necessary to achieve observed oxygen fluxes. An important mechanism for reducing heterogeneity is flow regulation via hypoxic pulmonary vasoconstriction (HPV), which is activated at the low levels of venous oxygen tension in exercise. The results suggest that HPV plays an essential role in allowing high levels of pulmonary oxygen uptake in exercise.

Support or Funding Information

Supported by NIH U01 HL133362

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Endothelial Barrier Restoration after Inflammation‐Induced Hyperpermeability
Authors: Nepali Prerna Ramesh , Mujica Patricio E. , Kim David D. , Thomas Andrew P. , Duran Walter N.
Published: June 2021

Inflammation is characterized by an increase in endothelial barrier permeability (hyperpermeability) to macromolecules. Major efforts have focused on understanding the mechanisms involved in the hyperpermeability response of endothelial cells; however, less attention has been given to the restoration of vascular barrier integrity following hyperpermeability. Because many negative effects of hyperpermeability are due to its persistence beyond what is required for preserving organ function, we are investigating mechanisms that terminate hyperpermeability and thereby restore microvascular barrier properties. Understanding the mechanisms involved in the restoration of endothelial barrier integrity will have direct clinical impact because sustained inflammation is a hallmark in clinical disorders such as trauma and ischemia‐reperfusion. We demonstrated that eNOS translocation from plasma membrane to cytosol is required for the onset of hyperpermeability. We also demonstrated that stimulation of Epac1 (exchange protein activated by cAMP) contributes to restoration of basal permeability after ischemia‐reperfusion. In this study, we tested the hypothesis that 1) hyperpermeability induces delayed increase in cAMP concentration; and 2) cAMP stimulates Epac1 and VASP (vasodilator‐stimulated phosphoprotein) to promote translocation of eNOS back to the plasma membrane, and restores endothelial barrier properties. We use human microvascular (HMVEC) and mouse myocardial endothelial cells (Myend) to study the restoration of endothelial barrier after hyperpermeability induced by platelet‐activating factor (PAF). Myend VASP knockout (KO) endothelial cells (EC) have significantly greater baseline permeability to macromolecules as well as hyperpermeability response to PAF compared to wild type Myend cells. Stimulation of Epac1 in HMVEC inactivates their hyperpermeability response to PAF. However, Epac1 stimulation fails to inactivate PAF‐induced hyperpermeability in VASP KO Myend EC. PAF activates VASP by phosphorylation at Serine 157 and Serine 239. This phosphorylation is sensitive to eNOS inhibition indicating that PAF stimulates production of eNOS‐derived NO and VASP phosphorylation in a sequential manner. In addition, stimulation of Epac1 after the onset of PAF‐induced hyperpermeability translocates eNOS back from the cytosol to the plasma membrane in HMVEC and in control Myend. eNOS is preferentially located in the cytosol in Myend VASP KO cells. Lack of VASP prevents movement of eNOS associated with stimulation of Epac1. We conclude that VASP is a required protein for movement of eNOS and restoration of EC barrier.

Support or Funding Information

Rutgers School of Gradute Studies

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Mechanisms of Endothelial Dysfunction in Young Adults with Major Depressive Disorder: Influence of Sex
Authors: Greaney Jody L. , Santhanam Lakshmi , Saunders Erika F. , Alexander Lacy M.
Published: June 2021

Major Depressive Disorder (MDD) is associated with endothelial dysfunction, a primary causative event in the development of cardiovascular disease. In rodents, depression‐induced endothelial dysfunction is modulated by sex, with females demonstrating less severe impairments than males owing to increased nitric oxide (NO) bioavailability, secondary to greater antioxidant defense mechanisms. This relative preservation of endothelial function in female rodents occurs despite an increased behavioral susceptibility to depressive‐like behaviors. Women of reproductive age are more than twice as likely to suffer from MDD; however, the influence of sex on the molecular mediators of endothelial dysfunction in humans with MDD remains unexplored. We hypothesized that endothelial dysfunction would be less severe in otherwise healthy young women with MDD compared to men with MDD due to increased nitric oxide (NO) bioavailability, mediated by greater antioxidant mechanisms. Twenty healthy adults (HC; 10 men; 22±1 yr) and 23 adults with MDD (9 men; 20±0.3 yr; PHQ‐9 score 12±1) participated. Red blood cell flux (laser Doppler flowmetry) was measured during graded intradermal microdialysis perfusion of the endothelium‐dependent agonist acetylcholine (ACh; 10−10–10−1 M) alone and with the co‐perfusion of the NO synthase inhibitor NG‐nitro‐L‐arginine methyl ester (L‐NAME; 20 mM), the superoxide dismutase mimetic Tempol (TEM; 10 μM), or the NADPH oxidase inhibitor apocynin (APO; 100 μM). Endothelium‐dependent dilation (EDD) was expressed as a percentage of maximum cutaneous vascular conductance (CVC=flux·mmHg−1). Tissue oxidant stress markers were quantified in cutaneous tissue homogenates (Western blot). As expected, EDD was blunted in MDD and mediated by reductions in NO bioavailability and increases in oxidative stress. There were no sex differences in EDD in either HC (87±6% men vs. 93±9% women; P=0.07) or MDD (79±10% men vs. 76±9% women; P=0.70). In MDD, the NO‐dependent portion of the vasodilatory response was also not different between men and women (14±5% men vs. 16±5% women; P=0.78). Further, pharmacological scavenging of superoxide or inhibition of NADPH oxidase improved EDD to a similar extent men and women with MDD (TEM: 81±7% men vs. 95±3% women, P=0.10; APO: 91±3% men vs. 88±5% women, P=0.65). Nitrotyrosine and NADPH oxidase (p47phox) expression were increased in MDD but not different between sexes (both P>0.05). Although these data confirm significant vascular impairments in MDD via oxidant stress mechanisms, these preliminary findings suggest that sex does not modulate the mechanisms mediating endothelial dysfunction in otherwise healthy young adults with MDD.

Support or Funding Information

HL133414

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Cyclooxygenase Inhibition and Cerebrovascular Reactivity: Interaction of Aging and Aerobic Fitness
Authors: Corkery Adam T. , Miller Kathleen B. , Howery Anna J. , Carl Alexandra E. , Greisch Mackenzie L. , Eisenmann Nicole A. , Barnes Jill N.
Published: June 2021

The ability of the cerebral microvessels to respond to chemical or metabolic stimuli declines with age and this change may be one mechanism through which age‐related cognitive decline occurs. Prostaglandins play an important role in the control of vascular tone, therefore changes in prostaglandin synthesis or expression may be underlying the age‐related alterations in cerebral microvascular function. Additionally, we have previously shown that aerobic fitness was associated with a decrease in cerebral microvascular function after cyclooxygenase (COX) blockade; yet this was in a small sample size of healthy older adults who were not exercise trained. Thus, the purpose of our study was to evaluate the effect of age on cerebral microvascular reactivity to hypercapnia (CVR) and to determine if habitual exercise modifies the response to COX blockade. We recruited 45 younger (YA; age = 26±1 y) and 31 older (OA; age = 63±1 y) healthy adults, including 21 sedentary YA, 24 exercising YA, 12 sedentary OA, and 19 exercising OA. Aerobic fitness (VO2 max) was measured during an incremental cycle ergometer test. Middle cerebral artery blood flow velocity (MCAv) and end‐tidal CO2 (ETCO2) were continuously recorded. CVR was calculated as the linear slope of the relationship between ETCO2 and MCAv and was assessed before and after the administration of the COX inhibitor indomethacin (INDO). The change in CVR was calculated as pre INDO CVR – post INDO CVR. There were no group differences in MCAv pre INDO (YA: 65±3 cm/s vs. OA: 59±3 cm/s; p>0.05); however, YA had higher MCAv post INDO (YA: 45±1 cm/s vs. OA: 40±2 cm/s; p<0.05). OA had significantly greater change in CVR compared with YA (2.0±0.1 cm/s/mmHg vs. 1.5±0.2 cm/s/mmHg, respectively; p<0.05). There was also a significant effect of habitual exercise, such that sedentary adults had a greater change in CVR compared with exercising adults (2.0±0.2 cm/s/mmHg vs. 1.5±0.2 cm/s/mmHg, respectively; p<0.05). In addition, there was an inverse association between VO2 max and the change in CVR in OA (r=0.42, p<0.05), but not in YA (p>0.05). Our results indicate that older adults, regardless of exercise status, rely more on COX‐derived products for cerebral microvascular responses to hypercapnia. Our results also suggest that habitual exercise may alter the contribution of COX‐derived products to cerebral blood flow regulation.

Support or Funding Information

Supported by National Institute of Health grant HL118154

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Pharmacologically‐induced impairment of neurovascular coupling responses alters gait coordination in mice
Authors: Tarantini Stefano , Yabluchanskiy Andriy , Fulop Gabor Aaron , Hertelendy Peter , Valcarcel‐Ares Marta Noa , Kiss Tamas , Bagwell Jonathan M. , O'Connor Daniel , Farkas Eszter , Sorond Farzaneh , Csiszar Anna , Ungvari Zoltan
Published: June 2021

There is correlative evidence that impaired cerebral blood flow (CBF) regulation, in addition to promoting cognitive impairment, is also associated with alterations in gait and development of falls in elderly people. CBF is adjusted to neuronal activity via neurovascular coupling (NVC) and this mechanism becomes progressively impaired with age. To establish a direct cause and effect relationship between impaired NVC and gait abnormalities, we induced neurovascular uncoupling pharmacologically in young C57BL/6 mice by inhibiting the synthesis of vasodilator mediators involved in NVC. Treatment of mice with the epoxygenase inhibitor MSPPOH, the NO synthase inhibitor L‐NAME and the COX inhibitor indomethacin significantly decreased NVC mimicking the aging phenotype. Pharmacologically‐induced neurovascular uncoupling significantly decreased the dynamic gait parameter duty cycle, altered footfall patterns and significantly increased phase dispersion, indicating impaired interlimb coordination. Impaired NVC also tended to increase gait variability. Thus, selective experimental disruption of NVC causes subclinical gait abnormalities, supporting the importance of CBF in both cognitive function and gait regulation.

Support or Funding Information

This work was supported by grants from the American Heart Association, the National Center for Complementary and Alternative Medicine, and the National Institute on Aging

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Activation of cannabinoid (CB2) receptors and reactivity of cerebral arterioles
Authors: Mayhan William G. , Arrick Denise M.
Published: June 2021

While activation of cannabinoid (CB2) receptors has been shown to be neuroprotective, no studies have examined whether this neuroprotection is directed at cerebral arterioles and no studies have examined whether activation of CB2 receptors can rescue cerebrovascular dysfunction during a chronic disease states such as type 1 diabetes (T1D). Our goal was to test that hypothesis that administration of a CB2 agonist (JWH‐133) would improve impaired endothelial (eNOS)‐ and neuronal (nNOS)‐ dependent dilation of cerebral arterioles during T1D. In vivo diameter of cerebral arterioles in nondiabetic and diabetic rats was measured in response to an eNOS‐dependent agonist (adenosine 5′‐diphosphate; ADP), an nNOS‐dependent agonist (N‐methyl‐D‐aspartate; NMDA), and an NOS‐independent agonist (nitroglycerin) before and following JWH‐133 (1 mg/kg IP). Dilation of cerebral arterioles to ADP and NMDA was greater in nondiabetic than in diabetic rats. Treatment with JWH‐133 increased responses of cerebral arterioles to ADP and NMDA in both nondiabetic and diabetic rats. Responses of cerebral arterioles to nitroglycerin were similar between nondiabetic and diabetic rats, and JWH‐133 did not influence responses to nitroglycerin in either group. Thus, it appears that activation of CB2 receptors can influence vascular function of cerebral arterioles during physiologic and pathophysiologic states. We speculate that treatment with CB2 receptor agonists may have potential therapeutic benefits for the treatment of cerebral vascular disease via a mechanism that can increase cerebral blood flow.

Support or Funding Information

These studies were supported by funds from the Diabetes Action Research and Education Foundation

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Inhibition of p70 ribosomal S6 kinase (S6K1) reduces infarct size without improving microregional oxygen supply/consumption balance after cerebral ischemia‐reperfusion
Authors: Weiss Harvey R. , Chi Oak Za , Liu Xia
Published: June 2021

We tested the hypothesis that inhibition of p70 ribosomal S6 kinase (S6K1) would decrease infarct size and improve microregional O2 supply/consumption balance after cerebral ischemia‐reperfusion. This was tested in isoflurane anesthetized rats with middle cerebral artery blockade for 1 hr and reperfusion for 2 hr with or without PF‐4708671 (S6K1 inhibitor, 75 mg/kg, 15 min after blockade). Regional cerebral blood flow was determined using a C14‐iodoantipyrine autoradiographic technique. Regional small vessel (20–60 μm diameter) arterial and venous oxygen saturations were determined microspectrophotometrically. There were no significant hemodynamic or arterial blood gas differences between groups. The control ischemic‐reperfused cortex had a similar O2 consumption to the contralateral cortex. However, microregional O2 supply/consumption balance was significantly reduced in the ischemic‐reperfused cortex with many areas of low O2 saturation (48 of 80 veins with O2 saturation below 50%). PF‐4708671 did not significantly alter cerebral blood flow or O2 consumption. It also did not affect O2 supply/consumption balance in the reperfused area (41 of 80 veins with O2 saturation below 50%). However, this was associated with a significantly reduced cortical infarct size after S6K1 inhibition (12.9 ± 0.8% control vs 6.6 ± 0.3% PF‐4708671). This suggests that S6K1 inhibition is important for cell survival, but does not significantly improve local oxygen balance after cerebral ischemia‐reperfusion.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Flow‐Mediated Dilation in Obese Adolescents: Correlation with Waist Circumference and Systolic Blood Pressure
Authors: Hussid Maria Fernanda , Jordão Camila Paixão , Lopes‐Vicente Wanda Rafaela , Virmondes Leslie , Cepeda Felipe , Katayama Keyla , Franco‐de‐Oliveira Luis Vicente , de Oliveira Ezequiel F. , Colombo Fernanda Consolin , Trombetta Ivani Credidio
Published: June 2021

Background

The increasing prevalence of obesity worldwide impacts childhood and adolescence, and this trend points to a significant growth rate of non‐transmissible chronic diseases in the near future. Endothelial dysfunction is an early marker of cardiovascular risk.

Objective

To determine a) whether obese adolescents have endothelial dysfunction and b) whether cardiovascular risk factors and obstructive sleep apnea (OSA) are associated with endothelial dysfunction.

Methods

We studied 20 obese adolescents (OA; median age 14 years, 100.9±20.3 kg), post pubescent, sedentary, not following any special diet or receiving any drug treatment, and compared them with 10 lean adolescents (LA, median age 15 years, 54.4±5.3 kg) paired for sex. Metabolic syndrome risk factors (MetS, International Diabetes Federation), vascular function (flow‐mediated dilation, FMD, and Reactive Hyperemia Index, RHI, by peripheral arterial tonometry, EndoPAT®), functional capacity and OSA using the apnea‐hypopnea index (AHI, polysomnography) were assessed.

Results

The OA presented higher waist (WC) and cervical circumference, as well as higher proportion of body fat, triglycerides, SBP, DBP, LDL‐c and lower HDL‐c than the LA group. In the OA, 35% presented MetS, which was absent in the LA group. OSA was present in 86.6% of the OA and 50% of LA (AHI>1 event/hour). There was no difference between groups in the AHI, VO2 peak and RHI. The OA presented lower FMD than LA (6.17±2.72 vs. 9.37±2.20%, p=0.005). There was an association between FMD and WC (r=−0.506, p=0.008) and FMD and SBP (r=−0.493, p=0.006).

Conclusion

OSA was observed in most adolescents, regardless of obesity. OA presented MetS and endothelial dysfunction. Increased WC and SBP seem to be involved in this alteration.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Mouse strains, sex, salt intake, AT1R activity and blood pressure
Authors: Wang Xiaoyan , Ma Xiaobo , Asico Laureano , Armando Ines , Jose Pedro
Published: June 2021

Male C57Bl/6J mice are salt‐sensitive while male SJL/J mice are salt‐resistant which is related to the functional state of the renal dopamine D1 receptor (D1R). Angiotensin II may be involved in the decreased renal expression of D1R of salt‐sensitive obese Zucker rats. However, the roles of the duration and amount of dietary salt intake and sex on salt sensitivity are not well known. Therefore, we studied the effect of sodium intake (<0.009, 0.6, 0.8,1.6, 4, 6, % NaCl) on the blood pressure (BP), renal dopamine and angiotensin receptors and sodium transporters in three different strains of male and female mice. We found that 4 or 6% NaCl diet given for 1 or 3 wks increased the BP of male C57Bl/6Jackson but not C57Bl/6Taconic, Balb/c, or SJL/J mice. The male C57Bl/6J mice with NaCl intake equal to or greater than 1.6% had increased BP. Similar to that reported in male C57Bl/6J mice, the BP (telemetry) of female C57Bl/6J mice was also increased by 4% NaCl diet (1 wk) which is associated with a decrease in serum renin but an increase in renal protein expression of angiotensin type 1 (AT1R). The salt‐induced increase in BP was ameliorated by angiotensin type 1 (AT1R) blockade with candesartan (1 mg/kg/day, subcutaneously administered with osmotic mini‐pumps, 1 wk) in both sexes. Except for the lower body weight of female than male mice, as expected, there were no differences in food/water intake, urinary excretions of water and electrolytes, and serum concentrations of creatinine and electrolytes, regardless of diets. In female C57Bl/6J mice on 6% NaCl diet, candesartan increased renal D1R and D5R but not D2R, D3R, or D4R protein expression while male C57Bl/6J mice had increased renal D5R protein expression, only. There was a similar decrease in renal protein expressions of sodium‐hydrogen exchanger isoform 3, sodium‐potassium‐2 chloride cotransporter, sodium‐chloride cotransporter, and α, β and γ epithelial sodium channel (ENaC) but not type 2 sodium phosphate cotransporter and α1Na+K+ATPase, in both male and female mice. We conclude that the salt sensitivity of BP of C57BL6/J mice is not sex‐related. However, the amelioration of high salt induced‐hypertension by AT1R blockade may be mediated by the differential increase in renal dopamine receptor expression and similar reduction in renal apical sodium transporters, leading to a decrease in renal sodium transport in male and female mice.

Support or Funding Information

This work was supported in part by grants from the National Institutes of Health, HL68686, HL23081, HL074940, HL092196, and DK039308. Dr. Xiaoyan Wang was supported, in part, by National Kidney Foundation of Maryland (Professional Development Award, 2014).

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.