bluuebunny/crossref_metadata_2025_split huggingface dataset:
Extracellular Nucleotide Signaling Stimulates Vascular L‐Type Ca2+ Channel Activity And Vasoconstriction During Diabetic Hyperglycemia
Authors: Prada Maria Paz , Nystoriak Matthew A , Syed Arsalan , Nieves‐Cintron Madeline , Navedo Manuel F 
Published: November 2023

Elevated extracellular glucose (i.e. hyperglycemia; HG) is a hallmark metabolic abnormality in diabetes and a major risk factor of vascular complications such as hypertension, stroke, and end organ damage. We recently discovered that HG amplifies intracellular Ca2+ concentration ([Ca2+]i) in vascular smooth muscle via PKA‐mediated potentiation of L‐type Ca2+ channels (LTCCs). Whereas elevation of [Ca2+]i by HG is prevented by ectonucleotidase activity, in this study, we tested the hypothesis that extracellular nucleotide signaling is required for PKA‐dependent potentiation of LTCC and vasoconstriction in response to HG. Using patch clamp electrophysiology and pressurized cerebral arterial diameter measurements, we found that HG‐potentiated LTCC current and endothelium‐independent vasoconstriction was associated with enhanced phosphorylation of CaV1.2 serine 1928 (S1928), a putative PKA target site in LTCCs. Consistent with our hypothesis, the increase in S1928 phosphorylation, vascular LTCC activity and vasoconstriction in the presence of HG was prevented by apyrase and a PKA inhibitory peptide, suggesting a mechanism involving the release of extracellular nucleotides and activation of PKA. Inhibition of the Gq‐coupled purinergic receptor P2Y6, which has been implicated in HG‐mediated increase in [Ca2+]i, failed to prevent the HG effects on S1928 phosphorylation, LTCC activity and vasoconstriction in response to HG. Altogether, our results indicate that extracellular nucleotide and PKA signaling is responsible for CaV1.2 S1928 phosphorylation, LTCC potentiation and vasoconstriction in HG. Considering our findings, we propose a potential functional association between PKA‐coupled purinergic receptors promoting LTCC activation and vasoconstriction in HG.Support or Funding InformationThis work was supported by grants NIH HL098200 and HL121059, and AHA‐14GRNT18730054 to MFN.
Enhanced Mobilization of Endothelial Ca2+ by SKA‐31 Contributes to the Restoration of Agonist‐mediated Vasorelaxation in Resistance Arteries from Type 2 Diabetic Rats
Authors: Kyle Barry D , Mishra Ramesh C , Braun Andrew P 
Published: November 2023

Endothelial dysfunction is a common early pathogenic event in patients with type 2 diabetes (T2D). In isolated hearts from T2D Goto‐Kakizaki (GK) rats, we have observed that SKA‐31, a positive modulator of the endothelial Ca2+‐activated K+ (KCa) channels KCa2.3 and KCa3.1, increases total coronary flow and restores agonist‐evoked elevations in flow to the levels observed in Wistar control hearts. The goal of the current study was to investigate the cellular mechanisms by which SKA‐31 restores vascular responsiveness in T2D vessels. In cannulated, myogenically active cremaster and cerebral resistance arteries from 24 week old, male T2D GK rats, and small intra‐thoracic arteries from T2D patients, a threshold concentration of SKA‐31 (0.3 μM) enhanced the ability of 0.3 μM acetylcholine and 0.1 μM bradykinin to inhibit developed tone at 70 mmHg. This effect of SKA‐31 was not disrupted by treatment with L‐NAME (0.1 mM) and indomethacin (10 μM), demonstrating that endothelial nitric oxide synthase and cyclooxygenase activities do not contribute to SKA‐31 mediated enhancement of agonist‐evoked vasorelaxation in T2D arteries. Using single cell Fura‐2 fluorescence imaging, we observed that Ca2+ mobilization evoked by the muscarinic agonist carbachol (1 μM) was significantly impaired in acutely isolated endothelial cells from GK arteries compared with Wistar controls and that treatment with 0.3 μM SKA‐31 was able to reverse this defect in response. Ca2+ mobilization evoked by the SERCA inhibitor cyclopiazonic acid (20 μM) was not different in endothelial cells from Wistar and T2D GK arteries, suggesting that the internal Ca2+ store, per se, is not dysfunctional in GK endothelial cells. In summary, we have identified a novel cellular mechanism to restore agonist‐mediated inhibition of myogenic tone in T2D resistance arteries that involves “priming” of endothelial KCa channels by a small molecule activator (e.g. SKA‐31). Our data further reveal that SKA‐31 is able to augment agonist‐evoked Ca2+ mobilization in T2D endothelial cells, which likely contributes to the functional restoration of agonist‐evoked vasorelaxation in T2D arteries.Support or Funding InformationThis study was supported by research funding to APB from the CIHR.
Dynamic Regulation of Endothelial Cell‐Specific Molecule 1 in Diabetic Mouse Kidney
Authors: Zheng Xiaoyi , Soroush Fariborz , Hall Evan , Adishesha Puneeth , Bhattacharya Sanchita , Kiani Mohammad , Bhalla Vivek 
Published: November 2023

Performing glomerular gene expression profiling in diabetic mouse models with differential susceptibility to nephropathy (DN), we identify endothelial cell‐specific molecule 1 (Esm‐1) as a novel candidate gene in the development of DN and sought to understand the functional role of Esm‐1 and how it may be regulated in diabetes. Esm‐1 is proposed to disrupt the interaction of lymphocyte function‐associated antigen 1 (LFA‐1) with intercellular adhesion molecule 1 (ICAM‐1) in vitro, suggesting Esm‐1 potentially blocks leukocyte infiltration, a known risk factor for DN. Therefore, we hypothesize Esm‐1 deficiency promotes leukocyte infiltration in susceptible mice and causes DN. Esm‐1 mRNA and protein expression profiles were tested in streptozotocin‐induced diabetic mice, and the functional relevance of Esm‐1 was tested in a bioinspired microfluidic assay (bMFA) which models leukocyte‐endothelial interactions ex vivo.ResultsIn bMFA, pre‐treatment of leukocytes with Esm‐1 inhibits rolling and transmigration in a dose‐dependent manner. Consistent with the diminution of leukocyte infiltration in vitro, 4 weeks after induction of diabetes, Esm‐1 mRNA is markedly attenuated in glomeruli from DN‐susceptible, DBA/2J, compared to DN‐resistant, C57BL/6J, mice (relative fold: 0.085 ± 0.012, p<0.05). Secretion of glomerular Esm‐1 is also lower in DN‐susceptible mice (132.6 ± 41.6 vs 226.4 ± 79.3 pg/mL, p<0.05). These changes occurred in the background of a dynamic response of kidney Esm‐1 to diabetes. Urine Esm‐1 excretion increases in diabetic vs. non‐diabetic mice (307.7 ± 51.6 vs 102.3 ± 29.7 pg/mg creatinine, p<0.05), despite no increase in urine albumin and a ~50% decrease in circulating Esm‐1 in diabetic mice. Further in vitro studies in cultured glomeruli show that hyperglycemia significantly increases Esm‐1 mRNA and protein, but significantly less so in DN‐susceptible mice. In contrast to serum mouse Esm‐1, glomerular‐derived Esm‐1 is partially glycosylated, and the level of glycosylation is increased in DN‐susceptible vs. DN‐resistant mice. Glomerular conditioned media from DN‐susceptible vs. DN‐resistant mice also degrades Esm‐1 preferentially.ConclusionEsm‐1 is a potential blocker of leukocyte infiltration in glomeruli. High urine Esm‐1 level in diabetes is associated with diabetes/hyperglycemia stimulated glomerular Esm‐1 over‐production. But attenuated glomerular Esm‐1 over‐production is associated with high DN‐susceptibility. These data suggest that increased production of glomerular Esm‐1 would be sufficient to attenuate leukocyte infiltration and consequently, DN. Furthermore, we propose urine Esm‐1 as a non‐invasive candidate biomarker for resistance to DN.Support or Funding InformationLarry L. Hillblom Foundation;Holmgren Family;NIDDK
Exercise Improves Microvascular Reactivity in the Comorbidity between the Metabolic Syndrome and Depression
Authors: Branyan Kayla , DeVallance Evan , Lemaster Kent , Chahal Ikttesh , Frisbee Jefferson , Chantler Paul 
Published: November 2023

Metabolic syndrome (MetS) is increasing in prevalence at an alarming rate to where one out of every five Americans has multiple components of the disease. These components include dyslipidemia, hypertension, insulin resistance, and a chronic pro‐inflammatory state. Another disorder that is steadily rising is depression and it is estimated that 15.7 million adults in the United States suffer from its symptoms. Much is known about each disorder separately, but there is little evidence on comorbidity between the two. Both disorders are known to increase the risk of vascular dysfunction, and therefore also lead to an increase risk for poor cardiovascular outcomes. It is also known that exercise can be used as an intervention for MetS and depression. To determine if the comorbidity between MetS and depression have a confounding effect on microvasculature, specifically the gracilis arteriole, obese Zucker rats (OZRs) and lean Zucker rats (LZRs) were used as a model of MetS and healthy controls, respectively. An Unpredictable Chronic Mild Stress (UCMS) protocol was administered to mimic daily, chronic stress. OZRs and LZRs were then separated into experimental groups including: control, UCMS, exercise, and UCMS plus exercise. The gracilis arteriole was isolated and then hung in a pressurized vessel myobath to be exposed to increasing doses of acetylcholine, to assess endothelial function, and phenylephrine to examine adrenergic constrictor response. OZRs had a decreased overall gracilis reactivity from that of LZRs (p<0.01). The LZR‐UCMS group had decreased reactivity as compared to their controls (p<0.01) whereas OZR‐UCMS only had a slight decrease in gracilis reactivity. Exercise alone improved the gracilis reactivity in OZRs by 20% (p<0.01) but there was a significant increase in reactivity in the LZRs. In OZRs that were stressed and exercised, reactivity was recovered to control values. LZRs on the other hand had a 10% decrease in reactivity compared to their controls but exercise increased reactivity slightly when compared to the LZR‐UCMS group (p<0.01). TEMPOL only had an effect in the OZR groups which may suggest that adding a radical scavenger does not provide extra improvement in already healthy vasculature. These data suggest that the comorbidity between MetS and depression may have a confounding effect on healthy vasculature, but it does not necessarily increase microvascular dysfunction in already impaired vessels. It also suggests that exercise and radical scavenger intervention may be beneficial in improving microvascular reactivity in these disorders.Support or Funding InformationAHANIH
Increased mTORC1 signaling in the vasculature of diet‐induced obese mice and obese humans
Authors: Reho John J , Guo Deng‐Fu , Wegman‐Points Lauren , Pierce Gary L , Rahmouni Kamal 
Published: November 2023

Obesity‐induced hypertension is associated with vascular endothelial dysfunction. Recently our laboratory has implicated the mammalian target of rapamycin complex 1 (mTORC1) signaling in the regulation of the cardiovascular system. Specifically, activation of central mTORC1 triggered a significant increase in arterial pressure. Therefore, we tested the hypothesis that dysregulation of mTORC1 signaling is involved in the vascular endothelial dysfunction associated with obesity in mice and human patients. In diet induced obese mice (DIO), whole aortic homogenates demonstrated a significant increase in the mTORC1 signaling pathway compared to control as indicated by the increased phosphorylated levels of mTOR and its downstream targets S6‐kinase and S6 ribosomal protein (p<0.05) by Western blot. Immunohistochemical analysis, using a phospho‐S6 ribosomal protein antibody, of aortas from DIO mice revealed a substantial increase in mTORC1 signaling in the smooth muscle and the endothelium. Next, we isolated venous endothelial cells from normal‐weight (body mass index, BMI <25 kg/m2) and obese (BMI ≥30 kg/m2) humans and found increased levels of phosphorylated S6 ribosomal protein in obese compared with normal weight subjects (p<0.05), consistent with increased mTORC1 signaling. Stimulation of mTORC1 in cultured mouse aortas and resistance mesenteric arteries with the branched amino acid Leucine significantly increased mTORC1 signaling in both the endothelium and smooth muscle. Interestingly, cultured aortas stimulated with Leucine exhibited impairment in acetylcholine induced relaxation (Max. relaxation: 71.3 ± 2.1% vs 63.5 ± 1.9%; p<0.05), but no changes in relaxation responses evoked by sodium nitroprusside (Max. relaxation: 77.3 ± 2.3% vs 76.0 ± 4.5%) suggesting endothelial, but not smooth muscle, dysfunction. In order to selectively disrupt mTORC1 signaling in the vascular endothelium, we have generated endothelial‐specific mTORC1 knockout mice by breeding Tie‐2Cre mice with mice harboring floxed alleles of the unique regulatory associated protein of mTOR (Raptor) subunit (Tie‐2Cre/raptorf/f). Preliminary immunohistochemical analysis suggests endothelial specific knockout of mTORC1 signaling in these mice. Studies are ongoing to characterize the vascular function of these mice. We speculate that selective dysregulation of endothelial mTORC1 signaling is contributes to obesity‐induced endothelial dysfunction in both mice and humans.Support or Funding InformationP01 HL084207
Comparison of Subjective Perception of Balance to Ocular Counter Roll in Veterans
Authors: Michalik Justyna , Migdal Kamila , Serrador Jorge , Fox Apollonia 
Published: November 2023

Common symptoms of vestibular dysfunction are dizziness, nausea, feelings of vertigo as well as imbalance. Since these symptoms occur in many disorders, vestibular disorders are often under diagnosed in primary care settings (Grill, 2014). Vestibular dysfunction can lead to a greater difficulty in daily tasks and increase the risks of falls. While there are many risk factors for falls, loss of vestibular function greatly increases fall risk. We have previously assessed vestibular function in healthy adults from 21–97 by measuring ocular torsion (OT), a reflexive eye movement in response to body tilt (Serrador, 2009). Age was related to a significant reduction in OT. In addition, lower OT was strongly correlated with increased postural sway that has previously been found to predict fall risk. Previous literature has shown that veterans exposed to blasts and head injuries demonstrate vestibular symptoms, making veterans an ideal model to test for vestibular dysfunction. In the current study, we explored vestibular hypofunction by comparing ocular torsion (OT), an objective measure of otolith function, to a subjective perception of balance in veterans who have been exposed to blast and had head injuries as well as those who have not.25 veterans (19 males; 6 females) from different conflicts volunteered for this study, ages 26–70 (mean age 52 ± 13.12). To measure ocularcounter roll, subjects were rotated ±25 deg in the roll plane while theirocular torsion was assessed using eye‐tracking goggles. For subjective perception of balance, participants were asked to complete several surveys about their balance and dizziness. The surveys consisted of an “Activities‐Specific Balance Confidence Scale”, “Dizziness Handicap Inventory” and “Vertigo SymptomScale”. 14 veterans were found to have low OT (below .14 degrees) while 11 were found to have normal ocular torsion. Out of the 14 veterans that were found to have low OT, 12 did not report having any balance issues or in conveniences during their day‐to‐day tasks across the various surveys used. A linear regression was run between the otolith function and questionnaires (R2 = .201, p=. 224). Interestingly, despite the lack of correlation, some questions, for example “riding an escalator without holding the rail”, showed a better correlation to the OT value, consistent with a task that would require otolithinputs. These data suggest that the self‐report questionnaires assessing balance function do not appear to provide a good assessment of otolith hypofunction. Thus future work is necessary to develop a questionnaire that would better assess otolithhypofunction.
Brain HMGB1 contributes to autonomic dysfunction
Authors: Masson Gustavo Santos , Nair Anand R , Dange Rahul , Soares Pedro Paulo Silva , Michelini Lisete Compagno , Francis Joseph 
Published: November 2023

Pro‐inflammatory cytokines and activated microglia in the hypothalamic paraventricular nucleus (PVN) are involved in autonomic and cardiovascular control. Recently HMGB1 was identified as cytokine‐like peptide in the brain, which through the CXC receptor 4 (CXCR4) causes neuroinflammation and neurodegeneration. However, its role in autonomic dysfunction have been never investigated. We tested the hypothesis that intracerebroventricular (icv) administration of HMGB1 in normotensive rats causes microglia activation, autonomic dysfunction and cardiovascular abnormalities. Twelve‐week‐old male Sprague‐Dawley rats were implanted with a chronic lateral ventricle cannula and after 5‐days recovery, an arterial and venous catheters were inserted one day before recording. After baseline recordings in conscious freely‐moving rats, HMGB1 (0.38 and 3.8 μg icv) was injected and cardiovascular and autonomic parameters were continuously measured for 30 minutes. In another experimental group, HMGB1 was administered following pretreatment with icv AMD3100 (5 and 50 μg), a CXCR4 antagonist. Rats were euthanized; brains were quickly collected and PVN tissue harvested for western blotting and immunofluorescence assays. HMGB1 (3.8 μg icv) markedly increased baseline arterial pressure, heart rate, systolic arterial pressure variability and vasomotor sympathetic activity; these effects were accompanied by decreased vagal outflow and increased sympathetic activity to the heart, reduced baroreflex sensitivity and attenuated heart rate variability. In the PVN, administration of HMGB1 icv, rapidly activated microglia, increased the phosphorylation of p42/44 MAPK and IκB‐α and augmented TNF‐α and IL‐6 protein expression. All the hemodynamic function and PVN responses to HMGB1 were completely abolished by pretreatment with 50 μg AMD3100 given icv. These finding indicate that HMGB1 induces microglia–CXCR4–p42/p44MAPK–NF‐κB cascade, and contribute to the autonomic dysfunction.Support or Funding InformationThis work was supported by a LSU‐SVM Corp grant for Dr. Francis
Does Chronic Sweetener Intake Affect Learning?
Authors: Morales Esmeralda , Contreras Irazú , Estrada José A. 
Published: November 2023

Artificial sweeteners are considered innocuous dietary complements used to replace sugarin a variety of commercial products. These additives are also used for the preventionor treatment of chronic illnesses such as diabetes and obesity, as well as forlosing weight. Among the most commonly used sweeteners we have sucralose, which recent studies have related to showing unwanted effects on metabolism.Due to the essential demand for glucose to supply the energetic requirements of the central nervous system (CNS), a decrease in its bioavailability disturbs signal conduction in the CNS and alters functions dependent on the specific area of the brain affected. This is particularly relevant for areas where neurogenesisoccurs, such as the olfactory bulb, striatum and hippocampus, which are related to cognitive processes involved in learning and memory formation.The objective of this study is to test spatial learning and memory through the Morris water mazein female BALB/c mice. Spatial learning in this task involves multiple cognitive components, such as problem solving, enhanced selective attention, formation of internal representations of the external world and storage and retrieval of relevant information. Based on principles for the use of animals in research and education, we used three groups of 8 week‐old mice: a control group (without supplementation), a sucrose group and a sucralose group (with sweetener supplemented in drinking water). The animals were supplemented for 5 weeks. After supplementation, mice were tested in a Morris water maze, where mice were trained on five consecutive days and on tested on day 6.Our results show significant differences in the amount of time taken to reach the platform, as well as time spent searching in the platform area and number of crossings over the platformarea, between the sucrose group and the sucralose and control groups, with mice from the sucrose group taking more time to reach the platform and spending lesstime in the platform area during training (p<0.001) compared to the control and sucralose groups; however, we did not find a statistical difference among groups on the final day. This situation is interesting, since there appear to be differences in the learning process during training, but those differences disappear by the end of the study period. Whether these differences are due to a modified animal behavior during training or to a compensatory mechanism that may balance an initially apparent learning deficiency requires further investigation related to the temporal course of supplementation and the molecular mechanisms involved. We are currently assessing molecular targets that may be relevant for these processes in our model.
The role of inhibition and excitation in visual attention
Authors: Smith Matthew A , Snyder Adam C , Morais Michael 
Published: November 2023

The natural world contains more information than our brain has the capacity to process. We make use of selective attention to filter this information ‐ enhance the relevant and suppress the distracting. While the behavioral improvements due to attention are easy to quantify experimentally, the neural circuits that give rise to these improvements remain unclear. In the visual system, modulation of neural activity due to attention is ubiquitous in measurements ranging from scalp electroencephalography to extracellular recordings from single neurons. A number of recent models of attention have proposed that inhibition may play a key role in modulating the computational abilities of neural networks at the locus of attention. While the fundamental importance of inhibition in the nervous system has been known since Sherrington's work at the turn of the 20th century, the mechanisms by which inhibition and excitation interact in service of neural computation are not well understood. Computations in cortex take place in networks of noisy neurons, and modulation of that noise likely plays an important role in attention. Recent models of cortical networks, employing balanced excitation and inhibition, are able to control the level of noise in the system. One prediction from such a model is that the attended state may be mediated be the activity of inhibitory neurons which serve to both modulate the noise in the network while simultaneously increasing response gain. While such a model is easy to implement, it is difficult to test in awake, behaving animals because extracellular recordings are blind to the cell class of the recorded neuron. We developed a novel method of probabilistically classifying neurons based on multiple aspects of their waveform shape that correspond to known differences between cell classes. Using this method, we were able to achieve a high degree of certainty of the classification of 95% of recorded V4 neurons in two rhesus macaque monkeys performing a demanding spatial attention task. We found that inhibitory neurons had stronger effects of attention than excitatory neurons in three key measures: (1) firing rate modulation; (2) decorrelation of their pairwise spiking response; and (3) the match of their response profile to the task's temporal demands. These results suggest that inhibitory neurons are indeed the recipients of a shared signal during the attentive state, and that this signal leads to a decrease in correlation in the rest of the population. Our results thus provide a network‐level account for the role of inhibition in attention.Support or Funding InformationNIH Grants EY023456, EY018894, EY022928, EY008098 and DA023428