bluuebunny/crossref_metadata_2025 huggingface dataset:
Stabilization of Cx43 mRNA by RNA-binding protein HuR enhances intestinal epithelial barrier function
Authors: Rao Jaladanki , Wang Shelley , Mallard Caroline , Cairns Cassandra , Xiao Lan , Chung Hee , Yu Ting-Xi , Wang Jian-Ying
Published: May 2023

BACKGROUND & AIMS: Connexin 43 (Cx43) acts as a gap junction protein and is involved in many aspects of different cellular processes including intercellular communication. The levels of cellular Cx43 change markedly in response to various pathobiological stresses, but the exact mechanism underlying Cx43 expression in the intestinal epithelium remains largely unknown. The RNA-binding protein HuR regulates the stability and translation of target mRNAs and is identified as a biological regulator of the intestinal epithelium homeostasis. In this study, we tested if HuR regulates Cx43 expression at the posttranscription level and further examined the influence of HuR/Cx43 interaction on the intestinal epithelial barrier function. METHODS: Studies were conducted in differentiated IEC-Cdx2L1 and Caco-2 cells. HuR binding to the Cx43 mRNA was determined by mRNP/IP assays, and the stability of Cx43 mRNA was examined by its half-life with qPCR analysis. Functions of HuR and its regulator Chk2 kinase were examined by their gene silencing or overexpression. Epithelial barrier function was assayed by transepithelial electrical resistance (TEER) and membrane-impermeable trace FITC-dextran. RESULTS: HuR directly bound to the Cx43 mRNA through its 3’-untranslated region (UTR) rather than 5’-UTR and coding region. HuR silencing decreased Cx43 levels by destabilizing Cx43 mRNA and caused the epithelial barrier dysfunction, as evidenced by a decrease in TEER and an increase in paracellular flux of FITC-dextran. In contrast, Cx43 overexpression rescued the epithelial barrier function in HuR-silenced cells. HuR mediated-Cx43 expression was regulated by ChK2 dependent HuR phosphorylation since decreasing the levels of phosphorylated HuR by silencing ChK2 lowered Cx43 levels and disrupted the barrier function. Reduction in phosphorylated HuR levels by polyamine depletion also inhibited HuR binding to the Cx43 mRNA and decreased Cx43 protein by destabilizing the Cx43 mRNA, which was associated with the epithelial barrier dysfunction. Ectopic overexpression of ChK2 in polyamine-deficient cells not only rescued Cx43 expression but also restored the barrier function. CONCLUSIONS: These results indicate that the Cx43 mRNA is a novel target of HuR and that HuR-induced expression of Cx43 via stabilization of its mRNA plays a critical role in the maintenance of intestinal epithelial barrier function.

US Department of Veterans Affairs and NIH

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Fibroadipogenic progenitor-derived Gdf10 regulates neuromuscular junction and fat content in tongue muscles
Authors: Choo Hyojung , Kim Seung-Hyun , Du Delia
Published: May 2023

Obstructive sleep apnea (OSA) is the most prevalent sleep disorder globally 4.5% in men and 2.5% in women. OSA increases the risk of more severe diseases such as heart attack, high blood pressure, type 2 diabetes, obesity, mild cognitive impairment, and depression. The known craniofacial anatomical changes leading to OSA are relaxed muscles and/or enlarged soft tissues by fat infiltration in the soft palate, pharynx, and particularly tongue, which blocks the upper airway during sleep. Although obesity is one of the main causes to induce OSA, the underlying mechanism of those changes has not been researched. The objective of our study is to understand the mechanism leading to those craniofacial changes that generate foundations to develop potential therapeutics for OSA. We hypothesize that high-fat diet-induced obesity regulates the fibroadipogenic progenitors, which are critical for neuromuscular interaction and is mainly responsible for increased fat content in skeletal muscles. To test this hypothesis, we used a mouse model fed with a high-fat diet to induce obesity or a normal diet (control group) for 6 months. Then we isolated tongue muscles for histology analysis, such as muscle size, neuromuscular junction integrity, and adipocyte content.We found that a high-fat diet leaded adipocyte hypertrophy and reduced intact neuromuscular junction in tongue muscles. To investigate the role of fibroadipogenic progenitors for tongue phenotypes by a high-fat diet, we isolated fibroadipogenic progenitor cells to measure transcript levels of Gdf10, also known as Bmp3b, since fibroadipogenic progenitor-derived Gdf10 has been known to stabilize Schwann cells for neuromuscular integrity in muscles. The role of Gdf10 has been suggested to protect from obesity by limiting adipocyte hypertrophy. Using single-cell RNA sequencing analysis, Gdf10 is specifically expressed in fibroadipogenic progenitors but not adipocyte or Schwann cells. We found that Gdf10 transcript levels are significantly reduced by a high-fat diet in tongue fibroadipose progenitors. Taken together, the reduced Gdf10 of fibroadipogenic progenitors by a high-fat diet reduces neuromuscular integrity but induces fat infiltration in tongue muscles in a paracrine manner. Therefore, targeting to increase Gdf10 expression is a potential therapeutic to reduce OSA by maintaining healthy tongue muscle.

NIH R01AR071397

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Inhibition of Ferroptosis in the Subacute Phase of Ischemic Stroke Worsens Aversive Learning In Diabetic Rats: A Randomized Double-Blind Preclinical Trial
Authors: Edgerton-Fulton Mia , Phoenix Ashley , Abdelsaid Kareem , Abdul Yasir , Jamil Sarah , Li Weiguo , Ergul Adviye
Published: May 2023

Diabetes increases the risk of hemorrhagic transformation as well as post-stroke cognitive impairment (PCSI). We have shown that iron chelation in the subacute phase improves stroke cognitive outcomes in experimental models of diabetes. We hypothesized that inhibition of ferroptosis, iron-induced cell death, in the post-stroke period will prevent PSCI in diabetic animals. Methods: Male rats, housed in reverse light cycle, underwent sham or 60-min middle cerebral artery occlusion surgery 8 weeks after diabetes onset. After MRI, rats that met the preset inclusion criteria (adhesive removal time > 35 sec. and either a modified Bederson score <= 6 or weight loss > 10% on Day 3) were randomized to ferroptosis inhibitor UAMC-3 (2mg/kg) or vehicle treatment for 2 weeks (n=8-12). Sensorimotor and cognitive outcomes were monitored for 8 weeks in the dark (active) cycle. Results: As confirmed by MRI, inclusion criteria predicted successful stroke surgery in 95% of the animals. There were significant acute neurological deficits. Long-term weight gain and survival were better in this cohort as compared to our historical data collected in regular light cycle experiments. Blood glucose levels were comparable. In contrast to our previous data, there were no significant differences in indices measured by novel object recognition (NOR), Y-maze, and sucrose preference tests after stroke but there was a trend for a greater number of animals showing a cognitive decline in treated cohorts. Step-through latency in the passive avoidance test (PAT) was lower in the treated stroke group. Open field (OF) suggested anxiety-like behavior in RX group. Conclusions: Preset inclusion criteria were effective in controlling for stroke severity. Ferroptosis inhibition impaired aversive learning and appeared to worsen cognitive outcomes in some of the animals. Better post-stroke weight gain/maintenance and greater engagement of animals in behavioral tests conducted in the “dark” cycle may explain the lack of a progressive memory decline after stroke. While further studies are required to better understand whether ferroptosis and housing lighting impacts stroke recovery in diabetes, based on current findings, inhibition of ferroptosis with UAMC-3 is not desirable.

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Xanthine oxidase mediates stress-induced Alzheimer's Disease progression in triple transgenic mice
Authors: Prabhu Saina , Burrage Emily , Luthman Jenna , Oudomvilay Crystal , Luna Natalia , Childers Ryan , Hanshew Alec , Englund Phillip , Tierno Vincent , Hoover Jacob , Simpkins James , Kelley Eric , Chantler Paul
Published: May 2023

Alzheimer’s disease (AD) is a progressive disorder associated with oxidative stress and neuroinflammation promoting the deposition of β-amyloid (Aβ) plaques and neurofibrillary tau tangles. Xanthine oxidoreductase (XOR) is a molybdoenzyme responsible for the metabolism of hypoxanthine and xanthine to uric acid. Under inflammatory conditions, high plasma uric acid levels upregulate XOR leading to increased free radical production and promoting cerebrovascular dysfunction. Chronic stress induces cerebrovascular dysfunction and cognitive decline in C57BL/6 mice mediated by XOR, suggesting a link between chronic stress and dementia. However, there is no published data that link XOR and stress to AD pathology and progression. Thus, we tested the hypothesis that chronic stress accelerates AD pathology via the XOR pathway.At 4 months of age, male and female WT (B6129) and triple transgenic (3xTg) AD mice underwent the Unpredictable Chronic Mild Stress (UCMS) model paradigm for 8 weeks. Mice were euthanized at two different time points at 6 and 9 months of age for both control and UCMS groups, and the tissues were harvested. Brain tissue lysates were homogenized, and the total tau and XOR protein was quantified using Western blot and normalized to β-actin. Aβ (1-40) levels in mouse brain homogenates using Aβ ELISA kit. Immunohistochemical staining was performed to study the colocalization of XO and CD-31 in WT and 3xTg coronal sections and analyzed using Fiji ImageJ.UCMS accelerated Aβ(1-40) expression levels (p<0.05) at both 6 and 9 months of age in the 3xTg mice. Tau levels were significantly increased at 6 months of age (p<0.05), but showed no significant differences in protein expression at 9 months of age. XOR levels were significantly upregulated (p<0.05) in the UCMS group at 6 months of age. At 9 months of age, no significant differences were seen in XOR expression across groups indicating that mice taken off from the UCMS protocol had normal levels of XOR due to reduced oxidative stress buildup in the brain. At 6 months of age, a significant decrease in microvessel density (p<0.05) was seen in 3xTg-UCMS mice vs 3xTg controls, with no significant differences seen at 9 months of age, indicating the role of chronic stress on the decline in cerebrovascular functions. Thus, the study establishes the premise that chronic stress mediated by XOR accelerates AD pathology in our early-onset AD model.

NIH, NINDS BINP R01 NS117754, Psychosocial Stress-Induced Vascular Contributions to Cognitive Impairment and Alzheimer's Disease: The Role of Xanthine Oxidase

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Effects of food insecurity on nutrition, stress, and resilience
Authors: Bubis Sabrina , Chowdhury Ushima , Nagorny Katerina , Welch Megan , Rosenberg Lexis , Begdache Lina
Published: May 2023

Food Insecurity is a pressing issue that impacts many Americans, specifically the college student population. Along with the various burdens that come with university life, lacking adequate access to nutritious dense foods poses a serous threat to the resilience and stress levels of students. However, there is a lack on research addressing the relationship between food insecurity, stress and resilience among college students. To assess how food insecurity and low income impact stress, resilience, and diet, an anonymous online survey targeting 18 and older was distributed via social media and emails. This survey included demographic questions and several validated scales such as Food Insecurity Experience Scale, Brief Resilience Scale, Academic Motivation Scale, Kessler Psychological Distress Scale, Stress Mindset Measure, and Perceived Stress Scale. A total of 1005 participants completed the survey. The data were analyzed using Pearson’s Correlation Coefficient in SPSS version 25.0. The results indicate that there is a positive correlation between food insecurity and consumption of pre-packaged food. A negative correlation exists between food insecurity and consumption of fruits, dark green leafy vegetables, whole grain products, and frequent breakfast consumption. This suggests that those who are food insecure are more likely to be deficient in essential nutrients that accompany a well-balanced diet. Additionally, there is a positive correlation between stress and food insecurity as well as a negative correlation between food insecurity and resilience. This indicates that students who are food insecure are more likely to feel stressed and less confident in their ability to handle their personal problems. On the other hand, consuming dark leafy vegetables has a negative correlation with hopelessness, and consuming fruits has a negative correlation with feelings of stress and nervousness. This points to a strong relationship between food insecurity, stress, resilience, and diet. In conclusion, the lack of nutritious foods consumed stemming from food insecurity negatively impacts college students by increasing their stress levels and lowering their resilience.

Binghamton University

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Glucagon-like peptide 1 (GLP1) neurons provide highly collateralized axonal input to multiple brain regions
Authors: Rinaman Linda , Zheng Huiyuan
Published: May 2023

GLP1-immunopositive axons are present within a large number of subcortical brain regions in rats and mice. GLP1 neurons are activated/recruited by stress-related stimuli, and central GLP1 receptor signaling contributes to a variety of behavioral and physiological stress responses. GLP1-positive axons originate from a small cluster of glutamatergic GLP1 neurons, whose cell bodies occupy the hindbrain caudal nucleus of the solitary tract (cNTS) and intermediate reticular nucleus (IRt). The present study sought to determine whether GLP1 axonal inputs to distinct brain regions arise from distinct subsets of these hindbrain neurons. We recently developed and characterized a new knock-in Sprague Dawley rat model (Gcg-Cre) in which GLP1 neurons within the cNTS and IRt express iCre (DOI: 10.1016/j.molmet.2022.101631 ). Using this rat model, specific hypothalamic and limbic forebrain nuclei that receive GLP1 input were stereotaxically microinjected with Cre-dependent retrograde AAVs (i.e., AAVrg-EF1a-DIO-hChR2:mCherry and AAVrg-EF1a-DIO-hChR2:EYFP). These AAVs fully label the cell bodies, dendrites, and axon collaterals of Cre-expressing neurons that project to each injection site. AAVrg injections into the paraventricular nucleus of the hypothalamus (PVN) labeled GLP1-positive neurons within the cNTS and IRt. Interestingly, labeled axon collaterals of PVN-projecting GLP1 neurons were present within not only the PVN, but in every brain region previously described as containing GLP1-positive axons. Similar results were obtained after AAVrg was injected into the bed nucleus of the stria terminalis. While labeling generated from other AAVrg injection sites remains to be examined, results thus far suggest that individual GLP1 neurons have widely branching axons that target multiple CNS regions. The data suggest that GLP1 neurons broadcast signals simultaneously to multiple subcortical targets, consistent with GLP1 receptor-mediated modulation of overall behavioral state, rather than elicitation of specific behaviors or physiological processes.

NIH grant MH059911

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Sex-specific effects of mild to moderate renal dysfunction on vascular endothelial function and large elastic artery stiffness
Authors: Coppock McKinley , Darvish Sanna , Murray Kevin , Craighead Daniel , Seals Douglas , Chonchol Michel , Rossman Matthew
Published: May 2023

BACKGROUND: Cardiovascular disease (CVD) risk is elevated in patients with advanced chronic kidney disease (CKD). Vascular dysfunction, including vascular endothelial dysfunction and large elastic artery stiffening, is a key contributor to increased CVD risk in advanced CKD. Individuals with mild to moderately reduced renal function may also be at increased risk for CVD, but endothelial function and arterial stiffness are not well characterized in this group. Further, women with CKD have lower risk for CVD than men. Whether women are protected from renal dysfunction-related decreases in vascular function is unknown. PURPOSE: We sought to determine: i) whether individuals with mild to moderate renal dysfunction (MRD) have lower endothelial function and greater arterial (aortic) stiffness compared to healthy controls (HC) and ii) if the presence of vascular dysfunction in individuals with MRD is influenced by sex. METHODS & RESULTS: Fifty-nine adults were split into two groups based on renal function. Thirty-two adults (mean±SEM: 66±2 years; 16 women) were identified with MRD, characterized as an estimated glomerular filtration rate (eGFR) of 45-89 (CKD-EPI; 75.0±2.0 mL/min/1.73m2) and/or the presence of microalbuminuria (albumin: creatinine ratio between 30-300 mg/g). Twenty-seven adults (63±2 years; 13 women) were identified as HC with an eGFR >90 (CKD-EPI; 98.7±0.9 mL/min/1.73m2). Subject characteristics known to influence vascular function (e.g., blood pressure, cholesterol, blood glucose, etc.) were not different between groups (all p>0.05). Endothelial function, assessed by brachial artery flow mediated dilation, was not different between groups (MRD: 4.4±0.5%, HC: 4.6±0.5%, p=0.75). Aortic stiffness, assessed via carotid-femoral pulse wave velocity, also was not different (MRD: 950.7±50.6 cm/s, HC: 864.3±33.1 cm/s, p=0.18). When analyzed by sex, men with MRD had lower endothelial function (MRD: 2.8±0.4%, HC: 4.4±0.6%, p=0.04) and tended to have stiffer arteries (MRD: 879.0±42.7 cm/s, HC: 787.7±35.5 cm/s, p=0.11) compared to HC men. In women with MRD, there were no differences in endothelial function (MRD: 5.9±0.8%, HC: 4.8±0.8%, p=0.36) or aortic stiffness (MRD: 1022.3±89.9 cm/s, HC: 953.6±49.4 cm/s, p=0.55) versus HC women. CONCLUSIONS: Men with MRD exhibit vascular dysfunction, while women appear to be protected from MRD-related vascular dysfunction. The lower risk of CVD in women versus men with CKD may, in part, be due to resistance against renal dysfunction-related vascular dysfunction.

NIH K01DK115524 to MJR; 5T32DK007135-46 to KOM; K01HL153326 to DHC

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Processing body accumulation in aged muscle stem cells contributes to impaired self-renewal
Authors: Hettinger Zachary , Hu Sophia , Xing Jianhua , Ambrosio Fabrisia
Published: May 2023

Stem cell exhaustion is a pillar of aging hallmarks, mediated by an inability of the body’s stem cells to self-renew. In skeletal muscle, impaired self-renewal of muscle stem cells (MuSCs) manifests as a progressive decline in muscle regenerative capacities, leading to functional dependence in the aged. Self-renewal depends on preventing degradation of factors mediating pluripotency during division, thereby averting differentiation, however, mechanisms underlying the inability of MuSCs to self-renew in the aged are unknown. Here, we show processing bodies (p-bodies) accumulate in MuSCs isolated from old mice. As p-bodies canonically represent cellular depots for RNA degradation, our findings suggest age-related changes to RNA degradation may contribute to impaired self-renewal of old MuSCs. To investigate the consequence of p-body enrichment in old MuSCs on self-renewal, we utilized a computational-based lineage analysis termed Dynamo following single cell RNA-sequencing of MuSCs isolated from young and old mice. Dynamo incorporates the velocity of RNA to generate transcriptional vector fields, allowing for inference of lineage specification. Moreover, through characterization of each cell’s transcriptome, this framework also allows for investigation of changes to lineage specification as a result of genetic perturbation. We found that manipulation of scaffold proteins mediating p-body formation resulted in a pronounced effect on lineage specification. Specifically, our results showed that upregulation of LSM14a mRNA processing body assembly factor ( LSM14a) in young MuSCs resulted in a loss of cycling-related gene expression, and subsequently promoted differentiation. Moreover, we found that downregulation of LSM14a in old MuSCs oriented transcriptional vector fields towards a self-renewing phenotype and away from differentiation, mediated by increased expression of cycling-related genes and decreases in differentiation-related genes. Together, the accumulation of p-bodies in old MuSCs coupled with the ability of p-bodies to facilitate self-renewal, suggests that targeted interventions focusing on p-body assembly may be therapeutic in restoring old MuSC self-renewal, and thereby regenerative capacities in the aged.

This study was supported by NIA R01 AG061005 (FA), NIA R01 AG052978 (FA), and NIEHS R01 ES025529 (FA). Postdoctoral fellowship funding provided by P30AG024827 (ZH).

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Alpha 1-adrenergic-mediated vasoconstriction and functional sympatholysis in patients with heart failure with preserved ejection fraction
Authors: Alpenglow Jeremy , Bunsawat Kanokwan , Fancisco Michael , Broxterman Ryan , Craig Jesse , Iacovelli Jarred , Harrison Jonathan , Morgan David , Silverton Natalie , Ryan John , Ma Chisty , Wray D.
Published: May 2023

Heart failure with preserved ejection fraction (HFpEF) is characterized by peripheral vascular dysregulation at both rest and during exercise. Prior studies have demonstrated that blood flow to skeletal muscle is closely regulated by sympathetic (α-adrenergic) vasoconstriction and the interaction of vasoactive substances released locally during exercise that counteract α-adrenergic vasoconstriction. This phenomenon, known as “functional sympatholysis” helps facilitate exercise hyperemia and has been shown to decline via aging and disease-related changes in α1-adrenergic function but this has not been studied in HFpEF. Thus, the overall objective of this study was to characterize peripheral α1-adrenergic vasoconstriction in HFpEF. We hypothesized that both resting α1-mediated vasoconstriction and the magnitude of functional sympatholysis would be diminished in HFpEF compared to healthy, age-matched control (CON) subjects.Six patients with HFpEF (3 male, 70±3 yrs) and six CON (3 male, 67±1 yrs) completed this study. Leg blood flow (LBF, ultrasound Doppler) was evaluated at rest and during dynamic single leg knee-extension exercise (0, 5 and 10 Watts) before and after local, intra-arterial administration of Phenylephrine (PE, α1-adrenergic agonist). PE-mediated changes in LBF (%Δ) at rest and during exercise were compared between groups. The magnitude of functional sympatholysis was calculated as the difference between PE-induced %Δ LBF from rest to exercise.At rest, the PE-induced %Δ LBF was smaller in HFpEF (HFpEF: -17±2% vs. CON: -31±8%, P=0.01). While PE-induced %Δ LBF were similar between groups during exercise, when these responses were compared to %Δ LBF at rest, the calculated magnitude of sympatholysis was significantly reduced in HFpEF (0W: -4±3%, 5W: -5±4%, 10W: -8±3%) compared to CON (0W: -17±7%, 5W: -20±8%, 10W: -25±6%). These data demonstrate a marked diminution in both α1-adrenergic responsiveness at rest and the ability to attenuate α1-adrenergic mediated vasoconstriction during exercise (functional sympatholysis) in patients with HFpEF. Diminished α1-adrenergic signaling and impaired functional sympatholysis may represent an important aspect of HFpEF pathophysiology that likely contribute to vascular dysregulation in this patient group.

Funded in part by grants from the National Institutes of Health (T32HL139451) and the Veterans Health Administration (I01RX001311, IK2RX003670, IK2CX002114).

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Pompe mice have improved respiration during hypercapnic challenge following acute intermittent hypoxia
Authors: Roger Angela , Huston Meredith , Kehoe Sean , Smith Jennifer , Le Davina , ElMallah Mai
Published: May 2023

Pompe disease results in cardiorespiratory distress secondary to glycogen accumulation in the lysosomes of all muscle types and motor neurons. The only approved treatment is enzyme replacement therapy (ERT), which improves survival, however, it cannot completely correct skeletal muscle or motor neuron pathology, therefore respiratory failure persists. To prevent respiratory distress effectively in Pompe patients, there is a need to develop novel approaches that can improve respiratory muscle and motor neuron function. Acute intermittent hypoxia (AIH) is a non-invasive therapy capable of improving respiratory motor function and has has been successful in studies of spinal cord injury and ALS. The hypothesis of this study is that AIH will promote plasticity in skeletal muscle and motor neurons to improve respiration in Pompe mice.2-month-old Pompe and wildtype (WT) mice were exposed to 10 cycles of alternating room air (21% O2) and hypoxia (10% O2) for 5 minutes each, once per day for 7 consecutive days. After the initial week of exposures, mice were given a reminder dose twice per week. An additional group of Pompe and WT mice were only exposed to room air to serve as untreated controls. Mice underwent whole body plethysmography (WBP) immediately before and after the initial week of AIH exposure and again at 6 months of age. During WBP, unanesthetized mice were placed in a Plexiglas chamber and exposed to room air (21% O2) for 2 hours, during which a 5-minute baseline period of quiet breathing was recorded, then the mice were exposed to 3, 10-minute respiratory challenges, first hypoxic air (10% O2), then hypercapnic air (7% CO2), and finally hypoxic and hypercapnic air together. At 6 months of age, respiration (frequency, tidal volume, minute ventilation, and peak inspiratory flow) was slightly improved in Pompe mice receiving AIH during the hypercapnia and hypercapnia + hypoxia challenges compared to untreated Pompe mice. The next steps of this study include evaluating glycogen accumulation and subsequent pathology in the carotid bodies, characterizing proteins associated with hypoxia induced plasticity in the medulla and spinal cord, and analyzing the health and integrity of diaphragm neuromuscular junctions. Our conclusion is that AIH improved respiration under hypercapnia conditions in Pompe mice.

NIH/NHLBI K99HL161420

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Response patterns of NTS neurons during electrical stimulation of the superior laryngeal nerve: Influence of codeine
Authors: Bolser Donald , Rose Melanie , Wang Wei , Morris Kendall , Segers Lauren , Nuding Sarah , Valarezo Ashley , Shen Tabitha
Published: May 2023

Electrical or mechanical activation of laryngeal afferents elicits the laryngeal adductor reflex (LAR), an airway defensive behavior that adducts the vocal folds to protect the airway from aspiration. This behavior is mediated, in part, by neurons in the NTS (nucleus of the solitary tract) and is sensitive to suppression by codeine. We hypothesized that NTS neuron responses to electrical stimulation of the superior laryngeal nerve (SLN) would be reduced by codeine, consistent with an action of the drug at this level of the brainstem to suppress the LAR. We recorded extracellular activity of multiple NTS neurons simultaneously in three anesthetized, spontaneously breathing cats using multiple microelectrode arrays. We also recorded bilateral EMG activity of upper airway and chest wall muscles. The neurons were tested with electrical stimulation of the SLN (2 Hz, 0.1 ms pulse duration, 1.5X threshold for inducing the LAR) during vehicle and a cumulative dose response to codeine (0.1-10.0 mg/kg iv). A total of 35 NTS neurons were recorded; some were identified as premotor to laryngeal or upper airway motoneuron pools by spike triggered averaging. Prior to codeine administration, approximately 30% of cells had short latency excitatory responses to electrical stimulation of the SLN; no inhibitory responses were observed. After codeine doses, changes in spontaneous activity were observed in most neurons (~80%). In response to codeine, both enhancement and suppression of short latency excitatory responses were observed in cells that were excited by SLN stimulation during vehicle. The data support complex actions of codeine on NTS neurons that do not easily account for opioid-suppression of the LAR.

T32 HL134621, and NIH HL155721

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Inflammatory biomarkers throughout influenza infection associate with changes in cardiovascular measurements
Authors: Martin Brigitte , Martin Brigitte , Attipoe Esinam , Wu Wenji , Challagundla Lavanya , Showmaker Kurt , Garrett Michael
Published: May 2023

For better infectious disease surveillance, there is growing interest in the detection of subtle changes in cardiovascular physiology in response to viral infection. This is not only important for earlier diagnosis and better prognosis of symptomatic carriers, but also useful to diagnose asymptomatic carriers of the virus. In our previous study, we found changes in cardiovascular physiology induced in A/Puerto Rico/8/34 (PR8) influenza infections in female and male C57BL/6J mice. Reduction in activity, blood pressure (BP) and heart rate (HR) for females was observed approximately 3-13 days post infection (dpi) and males approximately 5-12 dpi. Additionally, we found sex differences in inflammatory maker expression in lungs at 7dpi with bulk RNA sequencing (RNA-seq) data of lungs and Bio-plex cytokine assay for blood. In this study, we aim to associate changes in cardiovascular measurements with biomarkers throughout infection. Blood, brain, heart, lung, kidney, and nasal septum were collected at 1, 3, 5, and 9 dpi from influenza infected and naïve C57BL/6J female and male mice (n=6 for each time point and experimental group). Using body weight loss as a marker for disease in mice, we found both females and males had significant decrease in body weight at 9 dpi, yet infected females had a significant increase in brain, lung, and kidney weight at 9 dpi compared to naïve females. We are currently in process of analyzing pathological impacts of each tissue with histology and differing patterns of inflammatory maker expression in lungs throughout infection by analyzing bulk RNA sequencing (RNA-seq) data of lungs and Bio-plex cytokine assay for blood. Both cardiovascular measurements and molecular markers throughout influenza infection help to distinguish sex differences caused by influenza virus infection for better, earlier disease diagnosis.

Hypertension and Cardiorenal Diseases Research Training Program T32HL105324 (NIH)

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Early life stress (ELS) induces aortic stiffening and increased cytokine production in mice
Authors: Kelly Gillian , Kellum Cailin , Washington LaTimberly , Pollock Jennifer
Published: May 2023

ELS exposure (childhood adversity such as household dysfunction, abuse, or neglect) is an independent risk factor for adult-onset cardiovascular disease (CVD). ELS exposure is associated with increased circulating inflammatory markers in humans, as well as elevated aortic inflammatory monocytes in mice. The cellular sources and mechanisms of excessive cytokine production behind these findings are still poorly understood. We hypothesized that mice exposed to ELS, maternal separation with early weaning (MSEW), will have greater arterial stiffening and greater reactive aortic macrophages leading to a larger cytokine response when activated with LPS than normally reared (NR) mice. The MSEW model includes pups separated from the dam 4h/day (postnatal day (PD) 2 to PD5), 8h/day (PD6 to 16), and weaned at PD17. NR pups remain with the dams until weaning at PD21. Pulse wave velocity (PWV), a measure of aortic stiffness, determined at 6 wks of age found that MSEW mice had elevated PWV as compared to NR (NR: 1.2±0.08 mm/sec, MSEW: 2.1±0.04 mm/sec, p<0.0001, n=4,6). In the aorta, total F4/80+ macrophages as well as cells expressing activation markers CD86 and MHCII were elevated in 14 wk old MSEW mice (%F4/80+: NR:2.73±0.34, MSEW 5.04±0.56, p=0.004, n=7,5; %CD86: NR: 0.12±0.03, MSEW: 0.52±0.09, p=0.004, n=7,5; %MHCII: NR: 1.14±0.09, MSEW: 1.92±0.22, p=0.001, n=7,5). MSEW mice showed significantly elevated levels of macrophages (%CD11c-CD11b+F4/80+ of CD45+) in the spleen red pulp (NR: 1.09±0.04, MSEW: 1.28±0.07, P=0.03, n=14,10). However, expression of activation markers CD86 and MHCII as well as TNFα, IL-1b and IL6 in splenic macrophages from 14 wk old MSEW mice did not significantly differ between the MSEW and NR cohorts. Finally, we isolated splenic macrophages, stimulated with LPS (100 ng/mL) for 24 hrs and cytokine secretion measured by cytokine array. The qualitative array showed that the total supernatant of macrophage cultures from MSEW sample had greater IL1-ra, IL-16, G-CSF, CXCL10, macrophage inflammatory protein 1B and 2, and TNFα compared to cultures from NR samples. These results suggest that macrophages of MSEW mice are primed for inflammatory responses and may secrete intracellular cytokines compared to macrophages from NR mice. Elevated PWV is an early indicator for the development of CVD, seen as early as 6 wks in MSEW mice. Taken together these findings suggest a greater propensity for those who have experienced ELS to develop CVD. Future studies will aim to elucidate the role of the elevated macrophage derived cytokines in arterial stiffening.

NIH R25 DK 112731, NIH R25 DK 115353, NIH T32 DK 116672

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Pharmacological inhibition of the endocannabinoid anandamide metabolism alleviates cisplatin-induced acute kidney injury
Authors: Chen Chaoling , Wang Weili , Poklis Justin , Em Brandon , Lichtman Aron , Gewirtz David , Li Ningjun
Published: May 2023

Fatty acid amide hydrolase (FAAH) is the primary enzyme that degrades the endocannabinoid anandamide (AEA). Inhibition of FAAH by pharmacology or genetic approach has been shown to reduce inflammation in the brain, colon, heart and kidneys. Kidney medullary infusion of a FAAH inhibitor exerts diuretic and natriuretic effects. Faah knockout mice are protected from both post ischemia reperfusion injury and cisplatin-induced acute kidney injury (AKI) but through distinct mechanisms. The presented study tested the hypothesis that pharmacological inhibition of FAAH activity mitigates cisplatin-induced AKI and explored the potential renoprotective mechanism. Male wild type C57BL/6 (WT) were treated with oral gavage of a FAAH inhibitor (PF-04457845, PF, 5mg/kg) or vehicle (10% PEG200+5% Tween80+normal saline) at 72, 48, 24, 2-hr before and 24, 48-hr after a single dose of intraperitoneal injection of cisplatin (Cis, 25 mg/kg). Mice were euthanatized 72 hours after cisplatin treatment. PF-treated mice showed a decrease of cisplatin-induced plasma creatinine levels compared with vehicle (Veh)-treated mice (mean: 0.23±0.17, 1.98± 1.09, 0.31±0.16 and 1.11±0.56 mg/dL in Veh, Veh+Cis, PF and PF+Cis, respectively, p=0.02). Western blot analysis revealed that increased kidney injury molecule-1 (KIM-1) levels in kidney tissue of Veh-mice by cisplatin were reduced in PF-treated mice (2-fold increase vs. 1.1-fold in Veh+Cis vs. PF+Cis compared to the Veh-mice, respectively, p=0.04). Liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay showed that PF+Cis mice displayed enhanced AEA tone compared with Veh+Cis mice (1.3-fold increase vs. 2.9-fold in Veh+Cis vs. PF+Cis compared to the Veh-mice, respectively, p=0.03). These results suggest that the renal protection from oral gavage of the FAAH inhibitor against cisplatin nephrotoxicity may be associated with enhanced tone of AEA and that pharmacological inactivation of FAAH could be a novel strategy to prevent cisplatin-induced AKI.

NIH grant R01HL145163 and P30DA033934

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Acceleration of artery stiffness during childhood obesity in mice lacking lysosomal acid ceramidase
Authors: Zhang Fan , Zhang Fan , Yuan Xinxu , Li Guangbi , Zou Yao , Bhat Owais , Li Pin-Lan
Published: May 2023

Childhood obesity imposes significant risks of cardiovascular diseases in adulthood and the late life. Our previous studies found that the arterial calcification was developed in Asah1fl/fl/SMcre mice, a mouse model whose lysosomal acid ceramidase was tissue-specifically knocked out in smooth muscle cells. The present study was designed to investigate whether there occurred arterial stiffness, an early pathological event prior to the arterial calcification, and explore the underling mechanism in Asah1fl/fl/SMcre mice at their young age. The young obesity mice were generated by starting with feeding mother mice with high fat diet (HFD) during their gestation and lactation, followed by putting pups on HFD for 6 weeks after weaning. The arterial stiffness was assessed in vivo by pulse wave velocity (PWV) method using the ultrasound to measure velocity of arterial waveform traveling along the aorta. It was found that PWV was significantly increased, an indication of elevated arterial stiffness, in young obese Asah1fl/fl/SMcre mice than wild type mice. In the isolated aorta using wire and pressure myography, young obese Asah1fl/fl/SMcre mice were found to have much steeper force-diameter curve from wire myography, but much smaller maximal increases in aorta diameter compared to WT controls in pressure myography. To explore the mechanisms accelerating arterial stiffness in young obese Asah1fl/fl/SMcre, integrins level and their adhesion to fibronectin were examined. Immunohistochemistry showed that the aortic integrin staining significantly increased in the aorta from young obese Asah1fl/fl/SMcre mice. Confocal microscopy demonstrated that the colocalization coefficient of integrin with fibronectin was also markedly enhanced in the aorta from young obese Asah1fl/fl/SMcre mice. This increased integrin staining and integrin-fibronectin interactions were markedly attenuated when young obese Asah1fl/fl/SMcre mice were treated with amitriptyline (a lysosomal function enhancer), rapamycin (a lysosomal function enhancer) or ML-SA5 (a lysosomal TRP-ML1 channel agonist). In primary cultures of aortic smooth muscle cells (ASMCs) from Asah1fl/fl/SMcre mice, the recycling rates of integrin (labeled with Alexa 488 integrin antibody) to the cell membrane (stained with Alexa 594-wheat germ agglutinin) was shown markedly elevated in response to visfatin, compared to those ASMCs from WT mice. These results strongly suggest that the deficiency of lysosomal acid ceramidase accelerates arterial stiffness in young obese mice, which may be associated with enhanced integrin recycling back to cell membrane of ASMCs.

Supported by NIH grants HL057244 and HL075316

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Endothelin-1 Enhances Activities of Cav1.2 in Arterial Vascular Smooth Muscle Cells of Peripheral Artery Disease with Hindlimb Ischemia-Reperfusion
Authors: Zhang Xuexin , Qin Lu , Li Jianhua
Published: May 2023

Background and Objective: The ischemia-reperfusion (IR) injury is a main feature of pathophysiological process in peripheral artery disease (PAD). In PAD, an exaggerated blood pressure response increases cardiovascular and cerebrovascular risks for the disease. Considering that L-type voltage-gated calcium channel (Cav1.2) in arterial vascular smooth muscle cells (VSMCs) plays a crucial role in regulating blood pressure, the purpose of this study was to determine the activities of Cav1.2 following hindlimb IR as well as a contribution of endothelin-1 (ET-1), a potent vasoconstrictor, to the activities of Cav1.2. Hypothesis: We hypothesized that IR injury of PAD upregulates ET-1 signaling pathways in limb muscle and thereby amplifies the activities of Cav1.2 in VSMCs. Methods: An experimental PAD model with IR was induced by 6 hours of ischemia followed by 18 hours of reperfusion in rats (IR18h rats). ELISA and western blot analysis were used to examine the levels of ET-1 in the hindlimb muscle, and protein expression of Cav1.2 and ET-1 receptor ETA in VSM. Patch clamp was used to determine the Cav1.2 currents. Data are presented as mean ± standard deviation. Results: The hindlimb IR increased the levels of ET-1 in the hindlimb muscle, and expression of Cav1.2 and ET-1’s ETA in VSMCs. In particular, compared with the control group, there was a promising trend for the increasing Cav1.2 in VSM of the IR18h group (1.00±0.61 in control/n=4 vs. 8.77±8.04 in IR18h/n=5, P=0.09). Meanwhile, ETA expression was significantly higher in IR18h group than control group (1.00±1.12 in control/n=4 vs. 3.71±1.59 in IR18h/n=5, P<0.05). The hindlimb IR also increased amplitude of Cav1.2. In addition, ET-1 (1 μM) enhanced Cav1.2 current density in VSMCs of control rats from 0.47± 0.14 pA/pF to 0.68 ± 0.14 pA/pF (n=3; P<0.05) and from 0.54 ± 0.17 pA/pF to 0.74 ± 0.15 pA/pF (n=5; P<0.05) in the VSMCs of IR18h rats, respectively. Pretreatment of the VSMCs with an ETA antagonist, BQ-123 (1 μM), prevented the increasing effects of ET-1 on Cav1.2 current. In contrast, an ETB antagonist, BQ-788 (1 μM), had no distinct effects on the ET-1 increased-Cav1.2 current. Conclusions: ET-1 increases the activities of Cav1.2 in VSMCs via ETA receptor and upregulation of ET-1 signaling pathways in VSMCs of PAD is likely to lead to amplified blood pressure response via increasing the activities of Cav1.2.

NIH R01 HL141198 & HL164571; and American Heart Association grant # 940567

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Activation of the optogenetic pumps halorhodopsin and archaerhodopsin result in an unexpected potassium ion redistribution
Authors: Parrish R. Ryley , MacKenzie-Gray-Scott Connie , Jackson-Taylor Tom , Voipio Juha , Trevelyan Andrew
Published: May 2023

The optogenetic pumps halorhodopsin and archaerhodopsin are now common tools for directed silencing of specific neuronal cell classes. Halorhodopsin achieves neuronal silencing by pumping chloride ions into cells while archaerhodpsin silences cells by pumping out protons. Though these pumps are often targeted to specific cells within the neuronal network, the differential movement of ions across neuronal membranes can exert significant effects on neighboring cells. Furthermore, these ionic movements often result in secondary ion movements as the cells attempt to maintain electroneutrality. We, therefore, sought to determine to what extent these optogenetic pumps might result in secondary, unexpected movements of other ions. We hypothesized that there would be potassium redistribution occurring with both optogenetic pumps and secondary effects on cells not expressing the opsins. We explored this hypothesis through activation of these pumps, while recording with ion-selective microelectrodes and with current clamp recordings on cells not expressing the opsins. We found that both the chloride pump and the proton pump led to secondary redistribution of K+ ions into the cell, through tonically open, “leak” K+ channels. After the end of the activation with halorhodopsin, there was a large rise in extracellular K+, mediated by both the removal of K+ that had been driven into the cells, as well as by the cell’s extrusion of Cl- ions by the potassium chloride cotransporter, which uses the K+ gradient to remove Cl- ions from the cells. This secondary rise in extracellular K+ was much less with archaerhodpsin, presumably due to its activation not involving chloride loading of the neurons. We further found that during halorhodopsin activation, neighboring cells not expressing the opsin had greatly reduced excitability during illumination, likely due to the observed decrease in extracellular K+. Surprisingly, halorhodopsin also triggered cortical spreading depolarizations during and following illumination, when extracellular K+ was below physiological levels, an observation not replicated with archaerhodpsin activation. These results demonstrate that there are unexpected and significant effects on the neuronal network with use of optogenetic pumps. Despite the confounding issues inherent with using these tools, our results demonstrate new and exciting ways to address physiological questions with optogenetic tools.

Medical Research Council (UK)

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.