bluuebunny/crossref_metadata_2025_split huggingface dataset:
Brainstem Dopamine Controls Gastric Tone And Motility
Authors: Toti Luca , Travagli R.Alberto 
Published: June 2021

Gastrointestinal (GI) dysfunctions, such as gastroparesis, are prodromic to Parkinson's disease (PD). Upper GI functions are modulated by neurons in the dorsal vagal complex (DVC); recently, we reported a monosynaptic dopaminergic connection between the substantia nigra pars compacta (SNpc) and the DVC, activation of which modulates gastric tone and motility via dopamine (DA)1 receptors. The effects of DVC application of DA on gastric tone and motility, however, have not been characterized.Gastric tone & motility were recorded in rats using strain gauges sewn onto the anterior gastric wall. DA (0.1pmoles‐10nmoles/60nL; N=10‐16) microinjected in the left DVC decreased tone & motility in both the corpus (at 1nmole, tone: ‐152±21mg; motility: ‐57±6% of baseline) and in the antrum (at 1nmole, tone: ‐222±22 mg; motility: ‐41±6% of baseline, respectively; P<0.05 for all).Equivalent doses of DA induced a larger decrease in antrum compared to corpus tone, while motility was affected similarly. The effects of DA were blocked by ipsilateral vagotomy (N=4) and by application of DA2 (L741626), but not DA1 (SCH23390), antagonists (both at 45nM, N=7).DVC application of the dopamine uptake inhibitor, benztropine (100nmoles, N=2‐6), decreased tone (‐76±24 and ‐245±85mg) but increased motility (23±7 and 41±18% of baseline) in corpus and antrum, respectively.Our data indicate that the dopaminergic innervation of the DVC modulates gastric tone and motility differentially: when exogenous DA is applied, the effects are mediated mainly via DA2 receptors, which are also tonically active in setting gastric tone; conversely, a tonic DA1 input modulates gastric motility. We would like to suggest that this latter pathway is involved in the reduced gastric motility observed in PD.
UDCA modulates monocyte/epithelial cell interactions
Authors: O Dwyer Aoife , Ward Joseph , Greene Catherine , Keely Stephen 
Published: June 2021

Monocytes play a key role in the pathogenesis of inflammatory bowel disease (IBD) as they release pro‐inflammatory mediators that can compromise epithelial barrier function. Among these mediators is IL‐8, which has been implicated in the initiation and perpetuation of IBD. UDCA is a naturally occurring bile acid, which is used for the treatment of liver inflammation. The current study aimed to investigate the effects of UDCA on IL‐8 release from monocytes and examine its effects on monocyte induced loss of barrier function.IL‐8 release from U937 monocytes was induced with either lipopolysaccharide (LPS) [1 µg/mL] or the pro‐inflammatory cytokine, TNFα[5 ng/mL] for 24 hrs, either in the absence or presence of UDCA. Supernatants were then analysed for IL‐8 by ELISA. IL‐8 mRNA expression was assessed by qPCR. Epithelial barrier function was measured by transepithelial resistance (TER). Statistical analysis was performed by one way ANOVA with the Tukey‐Kramer post test.Treatment of U937 monocytes with TNFα or LPS induced 9.8 ± 1.2 and 7.9 ± 1.6 fold increases in IL‐8 release, respectively (n = 5–7; p < 0.001). UDCA [100 µM] reduced TNFα‐driven IL‐8 release to 3.5 ± 0.4 fold (n = 5; p < 0.001) and inhibited IL‐8 mRNA expression (n = 4; p < 0.05). In contrast, UDCA had no effect on LPS‐driven IL‐8 release. UDCA also specifically reduced TNFa‐, but not LPS‐, induced activation of NFkB (n = 4; p < 0.05). In further experiments, co‐culture of U937 monocytes with T84 cell monolayers resulted in a loss of barrier function, as indicated by a 68.9 ± 3.8% drop in TER. This effect was reversed by co‐treatment with UDCA (n = 5; p < 0.05).Taken together, our data suggest that UDCA, by virtue of its anti‐inflammatory effects on monocytes and consequential protective effects on epithelial cells, may prove to be a useful therapeutic target for IBD.
Exploring GPCR Biased Signaling from inside and outside the Cell
Authors: Trejo JoAnn 
Published: June 2021

G protein‐coupled receptors (GPCRs) are the largest family of cell surface receptors expressed in the mammalian genome and mediate vast physiological responses, making this receptor class the target of most drugs used clinically. GPCRs are dynamic molecules that assume multiple active states that bias signaling towards distinct G‐protein subtypes and beta‐arrestins. However, the mechanisms that regulate GPCR bias signaling remains unclear. Towards understanding the molecular basis of GPCR biased signaling, we examined the role of post‐translational modifications and plasma membrane compartmentalization. We discovered that N‐linked glycosylation of protease‐activated receptor‐1 (PAR1), a GPCR for the coagulant protease thrombin, regulates preferential coupling to specific G‐protein subtypes that control stress fiber formation and cellular proliferation. We also found that PAR1 distribution into caveolae in endothelial cells is critical for biased signaling induced by thrombin versus activated Protein C, an anti‐coagulant protease. Thrombin‐activated PAR1 coupled to G‐proteins and induced endothelial barrier permeability. In contrast, APC‐activated PAR1 signaled preferentially through beta‐arrestins to promote endothelial barrier stabilization, which required compartmentalization in caveolae. These studies reveal two different mechanisms that regulate GPCR biased signaling from inside and outside of the cell. In addition to her research, Dr. JoAnn Trejo is an experienced educator and leader of diversity efforts. She will also discuss the untapped potential: diversity and the advancement of science.
GPR171, a Newly Deorphanized Hypothalamic G Protein‐Coupled Receptor is Involved in the Regulation of Reward‐Related Behaviors
Authors: Bobeck Erin , Gomes Ivone , Fujita Wakako , Devi Lakshmi 
Published: June 2021

Recent neuropeptidomics studies have demonstrated that ProSAAS‐derived peptides, including BigLEN (b‐LEN) are abundant in the hypothalamus and enriched in the agouti related peptide (AgRP) neurons of the arcuate nucleus. Additional studies have implicated b‐LEN in acute feeding. Recently we deorphanized GPR171, as a G protein‐coupled receptor for b‐LEN. Overexpression of GPR171 leads to an increase and knockdown to a decrease in b‐LEN binding and signaling. In the hypothalamus GPR171 expression complements the expression of b‐LEN. Lentiviral shRNA‐mediated knockdown of GPR171 in the hypothalamus leads to alterations in food intake and metabolism. To further investigate the role of GPR171, we used a designer receptor exclusively activated by designer drugs (DREADD) approach to activate AgRP neurons leading to the release of b‐LEN (and other neuropeptides). As expected, activation of these neurons with clozapine‐N‐oxide leads to increases in food intake. Interestingly, this increase is attenuated by co‐administration of a GPR171‐selective small molecule antagonist. Given the known hedonic effects of activating these neuropeptide systems in the hypothalamus, we investigated additional reward‐related behaviors. We find that activation of AgRP neurons leads to a reduction in anxiety and depression. The specific role of b‐LEN/GPR171 in this phenomenon is currently being examined using GPR171 selective ligands. In addition, we find that stress alters GPR171 mRNA expresssion. In conclusion, GPR171 is the receptor for b‐LEN and plays a role in feeding and reward‐related behaviors.This work was supported in part by NIH grants NS026880 and DA019521 to L.A.D and a NIDA postdoctoral training grant DA007135 to E.N.B.
Pregnenolone Sulfate as a Modulator of Synaptic Plasticity
Authors: Sugunan Kavitha , Singh Rumani , Badolato Ryan , Shetty Syona , Zambrano Mateo , Duval Kayla , Adams John , Luebke Jennifer , Kumaresan Vidhya , Farb David 
Published: June 2021

Neurosteroids such as pregnenolone have been implicated in the pathophysiology of neuropsychiatric disorders such as schizophrenia and cannabinoid addiction (1, 2). Our laboratory discovered that the unique negatively charged steroid pregnenolone sulfate (PregS), the product of pregnenolone metabolism via a single sulfation step, modulates fast excitatory synaptic transmission by potentiating NMDA receptor activity in a fashion that is balanced by AMPA receptor inhibition at micromolar concentrations. We recently reported finding a novel high affinity response to PregS (EC50 = 2 pM) that increases intracellular [Ca2+] and CREB activation in cultured rat cortical neurons. Here, we report that PregS increases glutamate receptor and PSD95 colocalized puncta, presumably on dendritic spines of hippocampal neurons, suggesting that PregS increases surface‐postsynaptic AMPARs and NMDARs. Whole cell recordings of primary rat hippocampal neurons revealed that PregS increases the frequency of spontaneous excitatory postsynaptic currents, suggesting an increase in glutamate release from presynaptic terminals or an increase in the number of activatable synapses. The results indicate that PregS acts within the physiological range of endogenous concentrations (3) to recruit AMPA receptors to postsynaptic sites, thereby altering synaptic plasticity.(1) Marx et al. (2009) Neuropsychopharmacology 34:1885‐1903(2) Vallée et al. (2014) Science 343(6166):94‐8(3) Rustichelli et al. (2013) J Chromatogr B Analyt Technol Biomed Life Sci. 930:62‐9
Lipid‐derived aldehyde, acrolein, is a critical mediator of alcohol‐induced gut‐liver injury in alcoholic liver disease
Authors: Chen Wei‐Yang , Zhang Jingwen , Barve Shirish , McClain Craig , Joshi‐Barve Swati 
Published: June 2021

Alcohol consumption can cause alcoholic liver disease (ALD). Chronic alcohol consumption causes a pro‐oxidant environment in the liver and increases hepatic lipid peroxidation. Acrolein (ACR) is the most reactive and toxic aldehyde generated through lipid peroxidation. ACR forms protein adducts and triggers endoplasmic reticulum (ER) stress and hepatocyte apoptosis, which are recognized etiologic factors in ALD. Moreover, recent evidence has established the critical role of the gut‐liver axis in ALD pathogenesis, wherein alcohol‐induced gut barrier dysfunction contributes to liver injury. This study investigates the pathogenic role of acrolein as a major mediator gut‐liver axis in ALD.Accumulation of ACR adducts was seen in response to alcohol consumption in mouse livers and intestines. Acrolein adduct accumulation correlated with hepatic steatosis, JNK activation, ER stress, apoptosis and liver injury. We used cultured hepatic and intestinal cells to examine the direct in vitro effects of acrolein exposure in comparison to alcohol exposure. Alcohol‐induced in vivo intestinal effects were mimicked by ACR in vitro in intestinal Caco2 cells; specifically, ACR down‐regulated tight junction proteins, resulting in disruption of TEER (transepithelial electrical resistance), and increased FD‐4 permeability. In vitro acrolein exposure in hepatic cells triggered ER stress and induced apoptotic cell death, indicating that acrolein may mediate the effects of alcohol. Notably, these effects were attenuated by acrolein scavengers suggesting their therapeutic potential in ALD.
Involvement of Prostaglandins in the Pharmacological Actions of L‐Cysteine in Ocular Tissues
Authors: Nguyen Olivia , Robinson Jenaye , Mitchell Leah , Opere Catherine , Ohia Sunny , Njie‐Mbye Ya Fatou 
Published: June 2021

Evidence from our laboratory demonstrates that hydrogen sulfide (H2S) can exert pharmacological actions in ocular tissues, an effect that can be blocked by inhibitors of cyclooxygenase (COX).PurposeTo investigate whether H2S (using L‐cysteine as substrate) can alter prostaglandin E2 (PGE2) production in isolated bovine irides and retina.MethodsIsolated bovine irides and retinae were incubated in oxygenated Krebs buffer for 30 mins, prior to treatment with different concentrations of L‐cysteine (1 nM ‐ 10 µM) and norepinephrine (NE, 1 µM). After incubation and termination of reaction, tissues were homogenized and both homogenates and incubation media were collected and prepared for PGE2 Enzyme‐immunoassay (EIA) using a well‐established methodology.ResultsIn both bovine isolated irides and retinae, L‐cysteine elicited a concentration‐dependent (1 nM ‐ 10 µM) increase in PGE2 concentrations over basal levels. For instance, L‐cysteine (10nM; irides) and (10 µM; retina) produced an equi‐effective significant (p< 0.05) increase in PGE2 concentrations over basal levels. In bovine irides (but not retinae), L‐cysteine (10 µM) produced an increase in PGE2 levelsin the incubation media indicating a washout of prostanoids from tissues exposed to L‐cysteine. The positive control, NE (1µM) also caused an increase in PGE2 concentrations over basal levels in ocular tissues.ConclusionL‐cysteine can increase prostaglandin production in isolated bovine irides and retinae, affirming a role for these autacoids in the pharmacology of H2S in the eye.
Polyvinylpyrrolidone can be Used to Cost‐Effectively Increase the Viscosity of Culture Media
Authors: Denniss Steven , Rush James 
Published: June 2021

The objective of this study was to examine of effect of polyvinylpyrrolidone(PVP) on the viscosity of Dulbecco's Modified Eagle's Medium (DMEM), a common media base used in in vitro cell culture and ex vivo organ culture experiments. The viscosity of solutions of DMEM with either 0, 2, 4, 6, 8, 9, or 10% PVP (40000 molecular weight) w/v prepared at 37 ͦ C were measured (n=4‐6 per solution) using a viscosimeter assembled using commercially‐available laboratory equipment (consisting of a syringe pump, pressure transducers, and rigid tubing). The viscosities (measured in centipoise) of the prepared medias were as follows: 1.141±0.012 (approximately that of water), 1.477±0.013, 2.010±0.005, 2.658±0.024, 3.501±0.016, 4.044±0.011 (approximately that of blood), and 4.453±0.022 for the 0, 2, 4, 6, 8, 9, and 10% PVP‐DMEM, respectively. There was a roughly linear increase in viscosity across this 0‐10% range of PVP concentrations. PVP did not alter the pH of the media at any concentration. The cost of increasing the viscosity of DMEM to that of blood (i.e. ~ 4.0 centipoise) would have been ~ 5x more expensive to accomplish if using dextran, a compound commonly used by experimenters to increase the viscosity of the media in their experiments. These data demonstrate that PVP may be a cost‐effective way to increase the viscosity of culture media.Funded by NSERC.
Novel Insights into Anatomical and Functional Roles of Nucleus Retroambiguus in Respiratory Function
Authors: Jones Sarah , Stanić Davor , Dutschmann Mathias 
Published: June 2021

PurposeThe study aims to elucidate the role and contribution of nucleus retroambiguus (NRA) in generating or modulating the respiratory central pattern generator (rCPG). Previously we identified a putative rhythmogenic area 1.5 mm caudal to obex in the rat in‐situ perfused brainstem‐spinal cord preparation. Histological analysis indicated the putative rhythmogenic cell population resides at the level of the pyramidal decussation, therefore likely to overlap with the NRA. We investigated possible involvement of NRA in rhythmogenesis anatomically and functionally.MethodsAnatomical tracing: Anterograde neuronal tracer, biotinylated dextran amine, was injected into the NRA. Respiratory areas which contained labelled terminal fields received the retrograde tracer Fast Blue in subsequent experiments. Functional testing: Glutamate microinjections were made in a grid formation across the NRA region in the rat in‐situ perfused brainstem spinal cord preparation; with whole nerve recordings taken from phrenic and vagus nerves.ResultsAnterograde and retrograde tracing revealed anatomical connectivity between the NRA and respiratory nuclei, including the pre‐Bötzinger complex, parafacial respiratory group and Kölliker Fuse nucleus. Glutamate mapping in‐situ revealed two distinct responses to pharmacological stimulation. A tachypneic response was seen predominantly overlapping the NRA whilst a breath hold response was seen more frequently in the periphery, dorsal and lateral to the NRA.ConclusionAnatomical evidence shows that NRA can drive respiratory modulation via ascending projections to the rCPG. Therefore the NRA is not just a bulbospinal relay, but rather an integral part of the rCPG.Funding: Melbourne University
Transcriptional Control of Oscillatory Homocysteine Homeostasis by Nuclear Receptor SHP
Authors: yang zhihong , Lee Sangmin , Wang Li 
Published: June 2021

[Purpose]Hyperhomocysteinemia (HHcy) is often associated with metabolic diseases. This study aims at identifying transcriptional control of oscillatory homocysteine homeostasis.[Methods]Wild‐type (WT), Shp‐/‐, Bhmt‐/‐, and Bhmt‐/‐Shp‐/‐mice were used. HHcy was induced by alcohol‐ binge or chow diet supplied with drinking water containing 0.18% of DL‐Hcy. Serum and livers were collected over a 24h light/dark cycle. Assays: RNA‐seq, metabolomics (LC/MS, GC/MS), qPCR, adenovirus transduction, transfection, luciferase reporter assay, ChIP assay, Co‐IP, Western blots, and enzymatic assays.[Results]Loss of small heterodimer partner (SHP) induced a robust expression of betaine‐homocysteine S‐methyltransferase (Bhmt) and cystathionine γ‐lyase (Cth), and caused rhythmic alterations of other genes in the Hcy metabolic pathway. The induction of Bhmt and Cthwas blocked by Shp reexpression in Shp‐/‐liver. Consequently, the oscillatory productions of betaine, choline, cystathionine, cysteine, SAH and SAM, GSSG and GSH, were modulated by Shp‐deficiency or Shp‐reexpression. Forkhead box A1 (FoxA1) activated Bhmt and Cth promoter activities and expression, which was inhibited by Shp. Ethanol‐binge or homocysteine induced HHcy, glucose intolerance and ER stress response in WT mice, which was diminished in Shp‐/‐mice. However, ethanol‐binge triggered macrovesicular fatty changes in Bhmt‐/‐ and Bhmt‐/‐/Shp‐/‐ mice, but not in Shp‐/‐ mice.ConclusionsThe study sheds light on a new regulatory module to control one‐carbon metabolism in the liver, which may have significant clinical implications.[Grant support]NIH DK080440, AHA 13GRNT14700043, VA Merit Award 1I01BX002634.
Substrate Stiffness Regulates Cardiac Fibroblast Phenotype in Volume Overload Induced Heart Failure
Authors: Childers Rachel , Gooch Keith , Lucchesi Pamela 
Published: June 2021

ObjectiveDetermine whether substrate stiffness contributes to the hypo‐fibrotic phenotype of cardiac fibroblasts (CFs) isolated from a volume overload heart failure model.MethodsPrimary (P0) CFs were isolated from left ventricle (LV) tissue of sham operated (control) rats and rats subjected to 4 weeks of volume overload surgically induced by Aortocaval Fistula (ACF). CFs were plated on polyacrylamide gels at a range of stiffness (0.2 kPa to 50 kPa) similar to LV stiffness in vivo. The alignment of f‐actin and αSMA was assessed by immunostaining and used as an indicator of the pro‐fibrotic myofibroblast phenotype. ImageJ was used to quantify fluorescent intensity and morphology. Changes in gene expression were assessed by qRT‐PCR.ResultsSubstrate stiffness differentially affected CF morphology and αSMA expression. CFs on soft gels had a smaller spread area; CFs on stiff gels displayed stellate morphologies and αSMA aligned stress fibers (Fig A). Compared to sham, there was ~50% reduction in ACF CFs differentiation towards a myofibroblast phenotype (Fig B) on stiff substrates. Substrate stiffness elicited significantly different patterns of αSMA (~5‐fold), BNP (~3‐fold) and PPAR‐γ (~12‐fold for sham; ~6‐fold for ACF) mRNA expression between sham and ACF (FigC‐E).ConclusionsThis study provides evidence that substrate stiffness plays an important role in phenotype regulation by affecting cytoskeletal organization and mRNA expression. The changes in αSMA, BNP, and PPAR‐γ could provide some explanation for the distinct phenotype in ACF.image
Overactivation of muscle mechanoreflex in human hypertension
Authors: Velasco Alejandro , Wang Zhongyun , Arbique Debbie , Smith Scott , Mitchell Jere , Vongpatanasin Wanpen 
Published: June 2021

Our previous study in patients with mild essential hypertension demonstrated that moderate level rhythmic handgrip (RHG) at 30% maximal voluntary contraction (MVC), which typically had no effect on sympathetic nerve activity (SNA) in healthy normotensive subjects, evoked asympathoexcitatory response in hypertensive subjects. This finding indirectly suggested that mechanoreflex function was enhanced in hypertension. However, mechanoreflex function has not been directly assessed in hypertensive patients.Accordingly, we measured SNA with intraneural microelectrodes in 5 subjects with untreated hypertension (HTN) and 6 age‐matched normotensive controls (NT) during passive arm cycling (PAC). PAC was used to preferentially stimulate the mechanoreflex. Surface electromyography was monitored during arm cycling to avoid inadvertent muscle contraction.We found that SNA increased significantly in HTN compared to NT within the first minute of PAC, which was sustained at 3 minutes (27±10 vs. 2±6% total activity, p < 0.05). The increase in SNA was accompanied by a significant increase in mean arterial pressure (MAP) from 102±4 to 106±3 mmHg in the HTN group (p <0.05), while MAP remained unchanged in NT group (96±3 vs. 96±3 mmHg, p = NS). Rhythmic handgrip at 30% MVC also induced greater increases in SNA in the HTN than NT group (46±14 vs. ‐1±6% total activity, p <0.05).Thus, our data represent the first direct evidence for enhanced mechanoreflex function in human hypertension.
Resting brachial artery shear rate is associated with exercise habituation in middle aged and older adults
Authors: Tanahashi Koichiro , Akazawa Nobuhiko , Choi Youngju , Kosaki Keisei , Sugawara Jun , Maeda Seiji 
Published: June 2021

Hemodynamic shear stress, a frictional force of blood on the arterial wall, decreases with aging. The reduction in shear stress involved in development and progression of vascular endothelial dysfunction, a risk factor of cardiovascular disease. Habitual exercise is an effective strategy to improve vascular endothelial function. However, the effect of habitual exercise on the resting shear stress is unknown. The aim of this study was to determine whether brachial artery shear stress correlates with exercise habituation in middle aged and older adults.A total of 112 healthy middle aged and older adults (50–76 years) participated in this study. We measured peak and mean brachial artery shear rates, as indices of shear stress, at rest. Daily step counts and maximum oxygen consumption (VO2max) were measured as an index of exercise habituation. Subjects were divided into the inactive group (< 7500 steps/day) and the active group (蠅 7500 steps/day).VO2max was significantly higher in the active group than in the inactive group (P < 0.01). Peak shear rate and mean shear rate in the active group were significantly higher than in the inactive group (P < 0.01 and P < 0.05). VO2max correlated significantly with peak (r = 0.362, P < 0.01) and mean shear rates (r = 0.302, P < 0.05). These associations were remained significant even when adjusted for age.These results suggest that habitual exercise may increase resting brachial artery shear stress in middle‐aged and older adults.