bluuebunny/crossref_metadata_2025 huggingface dataset:
Optogenetic therapy on cardiac vagal dysfunction-related ventricular arrhythmia in type 2 diabetes
Authors: Hu Wenfeng , Tu Huiyin , Wadman Michael , Li Yulong , Zhang Dongze
Published: May 2023

Withdrawal of cardiac vagal activity is associated with ventricular arrhythmias-related sudden cardiac death and high mortality in T2DM patients. Although vagal nerve stimulation (VNS) has emerged as a promising therapy for ventricular arrhythmias, VNS-induced off-target side effects due to a lack of organ specificity severely limit its prescription in the clinic. To avoid the limitations of the VNS, we employed an optogenetic technique that combines with a miniaturized bio-optoelectronic implant with genetic targeting strategies to achieve cardiac-specific vagal activation in T2DM rats. We hypothesize that optogenetic activation in cardiac vagal postganglionic (CVP) neurons can restore vagal control of cardiac function, and further reduce susceptibility to ventricular arrhythmias in T2DM. Rat T2DM was induced by a high-fat diet plus streptozotocin injection. AAV-channelrhodopsin-2 (ChR2, 2 μl, 5x1012 vg/ml), an excitatory light-sensitive opsin gene, was in vivo transfected into CVP neurons located in the atrioventricular ganglion (AVG). At three weeks after opsin gene (i.e., AAV-ChR2) transfection, continual optogenetic stimulation in CVP neurons was applied twice daily (10 Hz, 50% duty cycle, 5 mW for 1 hour) by illuminating a LED probe that is controlled and powered wirelessly in conscious rats. Our data from immunofluorescence staining showed that microinjection of AAV-ChR2 into the AVG induced expression of ChR2-mcherry in almost all CVP neurons. Optogenetic activation of CVP neurons resulted in a negative inotropic reaction on the left ventricular systolic pressure in a frequency-dependent manner in anesthetized rats. Data from spectral analysis of heart rate variability demonstrated that optogenetic stimulation gradually restored T2DM-reduced high-frequency power (an index of cardiac vagal activation) from one to three days after optogenetic therapy in vivo, whereas it has no effect on low-frequency power (an index of cardiac sympathetic activation). Additionally, data from 24-hour continuous ECG recording in conscious rats demonstrated that optogenetic stimulation in CVP neurons improved the T2DM-impaired heterogeneity of ventricular electrical activity, which was measured by evaluating ventricular arrhythmia-related ECG parameters at three days after optogenetic therapy in vivo. These data suggested that optogenetic activation in CVP neurons might be an effective intervention against cardiac vagal dysfunction-related ventricular arrhythmias in the T2DM state.

This study was supported by the Great Plains IDeA-CTR Pilot Grant (to DZ), NIH-NHLBI (R01HL144146 to YLL), and AHA Career Development Award (851929 to DZ).

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.
Downregulation of hepatic lncRNA Gm19619 improves gluconeogenesis and lipogenesis following vertical sleeve gastrectomy in mice
Authors: Fang Zhipeng , Fan Mingjie , Yuan Dongqiang , Jin Lihua , Wang Yangmeng , Xu Senlin , Zhang Eryun , Chen Zhen , Huang Wendong
Published: May 2023

Long non-coding RNAs (lncRNAs) are emerging important epigenetic regulators in metabolic processes. Whether they contribute to the metabolic effects of vertical sleeve gastrectomy (VSG), one of the most effective treatments for sustainable weight loss and metabolic improvement, is unknown. Herein, we identified a novel hepatic lncRNA Gm19619, which was strongly repressed by VSG but highly up-regulated by diet-induced obesity and overnight-fasting in mice. Forced transcription of Gm19619 in the mouse liver significantly promoted hepatic gluconeogenesis with the elevated expression of G6pc and Pck1. In contrast, AAV-CasRx mediated knockdown of Gm19619 in the HFD-fed mice liver significantly improved hepatic glucose and lipid metabolism. Mechanistically, Gm19619 was enriched along genomic regions encoding leptin receptor (Lepr) and the transcriptional factor Foxo1, as revealed in chromatin isolation by RNA purification (ChIRP) assay. Moreover, Gm19619 was confirmed to promote gluconeogenesis by activating the Foxo1 pathway, facilitate the lipogenesis and repress lipolysis by inhibiting the leptin receptor signaling in the mouse liver. In summary, we have idenfied and characterized a new hepatic lncRNA which may mediate VSG effects to modulate gluconeogenesis and lipid metabolism in the liver.

This study was supported partially by the George & Irina Schaeffer, the John Hench, and the Ella Fitzgerald Foundations and the National Institutes of Health grants (R01DK124627 to W.H. R01HL145170 and R01GM141096 to Z.B.C. and COH P30CA33572 to COH).

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.
Neuropeptide Y potentiates T-Lymphocyte inflammation after psychological trauma
Authors: Lauten Tatlock , Reed Emily , Elkhatib Safwan , Moshfegh Cassandra , Clopp Amelia , Case Adam
Published: May 2023

Post-traumatic stress disorder (PTSD) is a psychiatric disorder characterized by severe behavioral alterations, but also demonstrates elevated levels of systemic inflammation, sympathoexcitation, and a potentiated risk for autoimmune and cardiovascular diseases. These physiological changes suggest perturbations to the immune system, however, the signaling mechanisms linking psychological trauma to the immune system are not well understood. Utilizing a pre-clinical mouse model of PTSD known as repeated social defeat stress (RSDS), we previously demonstrated that psychological trauma causes robust T-lymphocyte-driven inflammation in the spleen as evidenced by increased pro-inflammatory cytokine production (primarily interleukin 17A, IL-17A), inflammatory polarization, and enhanced mitochondrial reactive oxygen species. Moreover, targeted denervation of the spleen was able to completely ablate this T-lymphocyte inflammatory response after psychological trauma, suggesting the signal was autonomic and neural in nature. Given that the splenic nerve possesses only sympathetic neurons (no direct parasympathetic innervation), we hypothesized that psychological trauma mediates splenic T-lymphocyte inflammation via enhanced release of sympathetic neurotransmitters. To test this, we first exposed naïve primary T-lymphocytes to various sympathetic catecholamines, including dopamine, norepinephrine, and epinephrine. Contrary to our original hypothesis, we observed no significant changes in IL-17A expression or mitochondria reactive oxygen species. Next, we assessed the physiological response of naïve T-lymphocytes exposed to neuropeptide Y (NPY) given its role in both sympathoexcitation as well as in PTSD. Interestingly, naïve T-lymphocytes treated with NPY also demonstrated no effect, but when NPY was given in combination of norepinephrine, we observed both an increase in IL-17A gene expression (~2 fold) and intracellular redox (~2 fold). To further investigate this effect, we examined NPY levels in our RSDS mouse model over-time. Circulating NPY levels spiked immediately after only one day of RSDS (~4.5 fold, p=0.0317) but steadily declined over the remaining 10 day psychological trauma induction. Intriguingly, NPY levels were strongly correlated with both circulating IL-17A and T-lymphocyte mitochondrial reactive oxygen species levels after RSDS, supporting our in vitro observations. Overall, these data suggest NPY may be playing a critical role in shaping the inflammatory milieu after psychological trauma, which may enhance the likelihood of inflammatory comorbidities.

NIH R01HL158521

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.
Novel sensory pathway from bone marrow to ventrolateral periaqueductal gray regulates blood pressure in the hypertensive rat
Authors: Koutsikou Stella , Zubcevic Jasenka
Published: May 2023

Introduction: A range of pathophysiological conditions present with dysfunctional immune and autonomic nervous system (ANS), including hypertension. Here, we present new data from a hypertensive rodent model that demonstrate an altered afferent communication between the bone marrow (BM), a major hematopoietic organ, and midbrain autonomic regions that regulate blood pressure. Considering that BM is pro-inflammatory in hypertension, we propose a dysfunctional BM-brain communication will be present in hypertensive rodents. Methods: Male adult (12-14wo) spontaneously hypertensive rats (SHR) and their age-matched normotensive controls, the Wistar-Kyoto (WKY) rats, were used in this study. Rats were anesthetized with isoflurane (1.5%) and mean arterial pressure (MAP) and heart rate (HR) were monitored in real time via a femoral arterial catheter and ECG leads in Spike2 (CED UK). Electrical stimulation (100 square pulses, 20Hz; 5mA, 500us) was applied inside the femoral bone cavity for stimulation of BM afferents, before and after a unilateral bicuculline (BIC) microinjection (100nl, 0.4mM) in the dorsolateral, lateral, or ventrolateral periaqueductal gray (PAG) separately. Results: Electrical BM stimulation produced an immediate stimulation-dependent decrease in MAP and HR that was of similar amplitude in the WKY versus SHR (WKY, from baseline: ΔMAP=-8±1mmHg, ΔHR=-1± 4bpm; SHR, from baseline: ΔMAP=-9±2mmHg, ΔHR=-6±4bpm; P=0.5 ANOVA). However, these responses were significantly enhanced in the SHR, but not the WKY, immediately following an injection of BIC in the ventrolateral PAG (vlPAG; WKY, from baseline: ΔMAP=-9±1mmHg; SHR, from baseline: ΔMAP=-31±3mmHg; ****P<0.0001 ANOVA). Conclusion: We demonstrate a novel BM-vlPAG afferent neural pathway in regulation of blood pressure. This neuronal circuitry may be dampened in hypertension due to elevated GABA signaling in the vlPAG.

1) University of Kent Deputy Vice-Chancellor's Partnership Fund to SK and JZ; 2) The Physiological Society UK to SK; 3) NIH R01 HL152162 to JZ

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.
Core temperature decline prior to sleep onset is associated with nocturnal heart rate variability
Authors: Cleveland Emily , Bigalke Jeremy , Barkstrom Elyse , Nicevski Jennifer , Tikkanen Anne , Carter Jason
Published: May 2023

Impaired thermoregulation is associated with poor sleep and autonomic dysfunction. Previous studies demonstrate an association between core body temperature (CBT) dipping and an increase in heart rate variability (HRV) prior to sleep onset. However, the relationship between the rate of CBT decline prior to sleep onset and nocturnal HRV has not been established. The purpose of this study was to investigate the relationship between the rate of CBT decline prior to sleep onset and nocturnal HRV in objectively poor sleepers. We hypothesized a blunted pre-sleep CBT decline would correspond to reduced nocturnal HRV. Fifteen participants (9 males, 6 females; age, 33±4 years; BMI 27±1 kg/m2) underwent an 8-hour overnight sleep opportunity with continuous polysomnography (PSG) and 2-lead electrocardiogram monitoring. A temperature monitoring pill (CoreTempTM, HQ Inc., Palmetto, FL) was ingested with a standardized dinner to record CBT every 10 seconds throughout the sleep period. Core temperature was sampled every 5 minutes from the core temperature tracing one hour prior to sleep onset until final awakening. The rate of CBT decline prior to sleep onset was measured as the slope of CBT values from 1 hour prior to lights out until PSG sleep onset. Nocturnal HRV measures including the root mean squared of successive differences (RMSSD), percentage of R-R intervals (RRI) varying by greater than 50 ms (pNN50), and the high frequency (HF) power of the RRI were determined across the night in stage 2 (N2), stage 3 (SWS), and rapid eye movement (REM) sleep stages. Bivariate correlations were performed to assess the association between CBT rate of decline and nocturnal HRV measures. An inverse correlation was observed between the rate of CBT prior to sleep onset and the RRI in N2 (R= -0.743, p=0.002), SWS (R = -0.730, P = 0.002), and REM (R = -0.708, P = 0.003). Additionally, the rate of pre-sleep CBT decline was inversely correlated with time domain HRV measures in N2 (pNN50: R= -0.598, p= 0.019; RMSSD: R = -0.557, P = 0.031) and SWS (pNN50: R = -0.542, P = 0.037; RMSSD: R = -0.591, P = 0.020). A blunted rate of CBT was further correlated to decreased HFlog10 in N2 (R= -0.592, p= 0.020) and REM (R= -0.602, p= 0.018). Our results indicate an association between blunted core temperature decline prior to sleep onset and reduced nocturnal HRV. These findings suggest that adequate thermoregulation prior to sleep onset may have lasting associations with nocturnal cardiac autonomic function.

Support is provided by the National Institutes of Health (AA-024892, U54GM115371; P20GM103474).

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.
Store-operated calcium entry inhibition ameliorates Ang II induced podocyte apoptosis and mitochondria respiratory dysfunction
Authors: Tao Yu , Parisa Yazdizadeh Shotorban , Ma Rong , Inman Denise
Published: May 2023

Purpose and hypothesis: Podocyte injury induced by Angiotensin II (Ang II) is the key factor contributing to proteinuria and glomerulopathy in many kidney diseases including diabetic nephropathy and hypertensive kidney disease. Recent studies suggest that mitochondria dysfunction mediates Ang II-induced podocyte injury. However, the mechanism for Ang II-induced podocyte mitochondria damage is poorly understood. Store-operated Ca2+ entry (SOCE) has multiple functions in both excitable and non-excitable cells. Ang II can activate SOCE by releasing endoplasmic reticulum Ca2+ through generation of IP3. In addition, Ang II also activates Transient Receptor Potential Conventional Member 6 (TRPC6) channel through diacylglycerol (DAG). Our previous study demonstrated that enhanced SOCE mediated high glucose-induced podocyte cytoskeleton remodeling. However, the role of SOCE in podocyte injury by Ang II is not clear. The present study was carried out to test the hypothesis that enhanced SOCE contributed to Ang II-induced podocyte apoptosis and mitochondria respiration dysfunction. Methods: All experiments were carried out using cultured immortalized human podocytes. BTP2 (4 μM) was used to inhibit SOCE. SAR 7334 (100 nM) was used to block TRPC6 channel. Podocyte apoptosis was determined by flow cytometry using Annexin V/Propidium iodide (PI) staining. The conventional whole-cell patch-clamp was performed to measure store-operated Ca2+ channel (SOC) currents. Mitochondrial respiration function and mitochondria ATP production were evaluated by oxygen consumption rate (OCR) using seahorse analysis. Results: Ang II (1 μM) evoked inward currents, which were significantly blunted by BTP2 (10 μM), an SOC channel blocker. Ang II (1 μM) treatments for 24 hours significantly increased podocyte apoptosis and reduced podocyte basal OCR, maximal OCR, spare capacity and mitochondria ATP production. All these responses were significantly blunted by BTP2. However, Ang II treatment for 30 min did not induce a significant response of OCR, but significantly reduced maximal respiration and spare capacity. These responses were also significantly inhibited by BTP2 (10 μM), but not by SAR 7334 (100 nM). Conclusion: SOCE contributed to Ang II-induced podocyte apoptosis and mitochondria respiratory dysfunction.

Translational Project Award from American Heart Association (20TPA35500045, to RM); National Institute of Diabetes and Digestive and Kidney Disease (DK115424-01, to RM); Predoctoral Fellowship from American Heart Association (903925, to YT).

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.
Real-Life Scenario Blended Teaching Approach for Nurturing Inquisitive Learning of Central Nervous System in Medical Students
Authors: Narayanan Sareesh , Merghani Tarig
Published: May 2023

Among the various systems taught in the preclinical phases, the nervous system is more challenging to learn than other systems. In this report, a novel teaching methodology, ‘real-life scenario (RLS) blended teaching’ is described and its effectiveness in facilitating inquisitive learning in undergraduate medical students was evaluated. This mixed-method study was conducted among three groups (Group 1; n=83, Group 2; n=85, and Group 3; n=79) of undergraduate medical students (18-20 years) in the neurology and behavioral sciences module. RLS was presented to students in the form of demonstrations, role-plays, videos, and group activities. Group-1 students underwent traditional teaching-learning sessions. Group-2 students underwent RLS blended sessions and were provided with multiple mini-assignments in a vignette format. Group-3 students received RLS blended sessions, multiple mini-assignments, peer discussions, multiple formative assessments, and facilitator feedback sessions. The student performances on different exams were compared in terms of their Group, and their perceptions of RLS were documented. Students exposed to RLS sessions blended with multiple assignments, peer discussions, multiple formative assignments, and facilitator feedback sessions performed well in the final summative assessments (67.87%) compared to those exposed to RLS sessions and assignments (50.21%) or exposed to traditional teaching alone (50.34%). RLS sessions increased students’ curiosity and motivated them to learn the subject well. RLS sessions stimulated student interest and facilitated their learning. RLS along with effective use of multiple assignments, formative assessments and/or feedback sessions significantly improved student learning. This demonstrates the effectiveness of this active method in teaching various subjects with appropriate modifications.

No funding was received for this research work. The data presented in this abstract is from the original work carried out at the Department of Physiology, Ras Al Khaimah Medical and Health Sciences University, UAE and a manuscript containing the same data is under consideration for publication in Advances in Physiology Education journal.

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.
Approximate entropy showed greater tidal volume and breathing frequency variability during steady state exercise in healthy adolescents compared to adults
Authors: Welch Ryan , Casey Sarah , Kolbe John , Kevin Ellyett
Published: May 2023

Introduction: During incremental exercise breathing frequency (Bf) and tidal volume (VT) increase to ensure that minute ventilation (VE) meets the metabolic demands of exercise. The control of exercise ventilation, which comprises of feedback and feedforward mechanisms, is challenged during adolescence by physiological changes in respiratory system characteristics. Our previous work showed that healthy adolescents demonstrate unstable ventilation during incremental exercise compared to the relatively stable breathing patterns of healthy adults. However, we were unable to objectively quantify these breathing patterns due to the increasing workload profile of incremental exercise. Approximate entropy (ApEn) is a non-linear method which can be used to quantify the unpredictability of ventilatory data. Aim/hypothesis: The objective of this study was to apply ApEn analysis to quantify and compare breathing patterns during steady state exercise in healthy physically active adolescent and adult subjects. We hypothesised that ApEn would be greater (i.e. more variable) in adolescent compared to adult subjects. Method: Two groups were recruited: the adolescent group (n=12, 5M:7F) aged 12-14 years and the adult group (n=9, 4M:5F) aged 25-35 years. Participants performed 20-minutes of steady state exercise on a cycle ergometer at a workload of 1 W·kg-1 of body weight. ApEn was performed for VT, Bf and VE over the final 15-minutes of exercise to ensure steady-state exercise breathing patterns were adopted. The Mann-Whitney U test compared the between group ApEn results. Results: Significantly greater ApEn results were observed in the adolescent group compared to the adult group for VT (1.28 ± 0.05 vs. 1.12 ± 0.11, p<0.05) and Bf (1.31 ± 0.07 vs. 1.19 ± 0.11, p<0.01) but not VE (1.25 ± 0.13 vs. 1.03 ± 0.23). Conclusion: Using ApEn we showed greater variability of VT and Bf for healthy adolescents compared to healthy adults. This supports the results of our previous studies of maximal exercise. We suggest that the greater variability of breathing patterns observed in the adolescent group likely reflects the normal development and maturation of ventilatory control and should not be viewed as abnormal.

This research was supported by an award from The Green Lane Research and Education Fund Board.

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.
Proteinuria observed post-uninephrectomy stems from partial suppression of protein endocytosis along the proximal tubule
Authors: Edwards Aurelie , Ralph Donna , Lei Hillmin , Priver Taylor , McDonough Alicia
Published: May 2023

Living kidney donors are at higher risk of developing proteinuria, yet few studies have addressed the etiology. To investigate whether post-uninephrectomy (UNX) proteinuria was due to increased filtration and/or reduced endocytosis/reabsorption along the proximal tubule (PT), we compared renal function, morphology, and PT endocytic machinery in male Sprague Dawley rats before and after UNX.At 12 wk post-UNX, the weight of the remnant kidney rose by 50%, PT diameters by 30%, and single nephron GFR by 50% (based on 26% fall in creatinine clearance and 50% decrease in the number of nephrons). Urinary albumin excretion increased 10-fold post-UNX. Since the filtered load of proteins decreases in parallel with GFR post-UNX, increased albumin excretion likely reflects decreased endocytosis along the PT, a notion supported by a 50% reduction in abundance of albumin and plasminogen in renal cortex homogenates from remnant versus explant kidneys. We tested the hypothesis that the protein endocytic machinery was reduced following UNX. Immunoblot assays of renal cortex revealed decreased abundance of megalin and Dab2, two key mediators of protein endocytosis along the PT, and no change in cubilin abundance. Immunohistochemistry confirmed a 50% fall in megalin along the PT apical membrane.Mathematical modeling predicted that albumin uptake per nephron increases post-UNX, owing to higher single nephron GFR and PT hypertrophy, but is attenuated by the decrease in megalin abundance; moreover, modeling predicts that if the endocytic machinery were not partly suppressed, overall albumin excretion would remain at pre-UNX levels.In addition to albumin, urinary plasminogen and angiotensinogen were similarly increased post-UNX, while uromodulin (synthesized and secreted distally) was decreased post-UNX. Urinary biomarkers of renal injury, RBP4 and KIM-1, were increased post-UNX likely reflecting the impact of the increased endocytosis of albumin which can carry bound toxic lipids into the PT.Taken together, our findings suggest that the blunting of albumin endocytosis post-UNX, apparent as increased albuminuria, may serve to protect PT cells from albumin-induced cytotoxicity.

DK083785; Keck School of Medicine Dean’s Pilot Funding

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.
Maintaining Cerebral-Endothelial Integrity and Permeability Guard Against Uremic Toxins Induced Cognitive Impairment
Authors: Yang Jenq-Lin
Published: May 2023

Chronic kidney disease (CKD) is with a characterization of progressing loss of renal function; commonly, CKD progression leads to multiple comorbidities, including neurological dysfunction and immune disorders. Our previous study reported that accumulation of uremic toxins, including creatinine, blood urea nitrogen (BUN), indoxyl sulfate (IS), and p-cresol sulfate (PCS), could not only induce neuronal inflammation, but also NLRP3-inflammasome-correlated astrocytic inflammation; both neuronal and astrocytic inflammation significantly contribute to CKD-triggered cognitive impairment. Our study also demonstrated that AST-120, an IS and PCS absorbent, effectively reduced serum and hippocampal IS and PCS levels and hippocampal inflammation as well as reversed the cognitive function in CKD mice. The current study aims to understand how IS and PCS passing through endothelial cells and affecting endothelial physiology, consequently, compromises cerebral-endothelial and blood-brain-barrier (BBB) function. The results of Evans blue assay and Western blotting of this study have shown that 5/6 nephrectomy CKD mice occurred leakage of BBB and IS treatment could trigger NLRP3 inflammasome-mediated endothelial inflammation respectively. Moreover, Western blotting assay also indicated expression of endothelial tight-junction proteins was altered by IS and immunocytochemistry images showed that the aryl hydrocarbon receptor (AhR) was activated and relocated to nuclei of endothelial cells. Furthermore, images of immunocytochemistry revealed that the organic anion transporter (OAT) inhibiters, chloroquine and hydroxychloroquine, prohibit IS-induced AhR relocation to endothelial nuclei. Therefore, we postulated that IS and PCS pass through endothelial membrane via certain types of OATs/OATPs and activate AhRs relocating to nuclei, subsequently, induce endothelial inflammation, alter expression of tight-junction proteins, and dysregulate permeability of BBB. The goal of our study is to decipher mechanisms of aromatic uremic toxins, specially IS and PCS, induced cognitive impairment and find out possible treatments via blocking IS/PCS endothelial transcytosis, suppressing endothelial AhR activity, preventing endothelial inflammation, and maintaining endothelial permeability.

The study is funded by National Science and Technology Committee of Taiwan, grant number 111-2320-B-128A-004

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.
Swallowing disrupts tongue-jaw coordination during chewing in a rat model of Parkinson's disease
Authors: Gould Francois , Palhang Meejan , Charles Nicole
Published: May 2023

The primary motor symptoms of Parkinson’s disease, including bradykinesia, rigidity, and tremor, are associated with difficulties regulating transitions between motor behaviors due to basal ganglia dysfunction. Chewing and swallowing, which are disordered in most patients with Parkinson’s disease, are two complex motor behaviors which overlap in time and share some neuromuscular components. The objective of this study is to identify how Parkinson’s disease affects the coordination of chewing and swallowing. We hypothesize that as a result of impaired regulation of shift between motor patterns, chewing cycles that occur with a swallow will be more affected that chewing cycles occurring in isolation in a rat model of Parkinson’s disease. Four adult Lewis rats were treated with daily IP injections of rotenone for 7 days to induce Parkinsonian symptoms. Prior to injections radio opaque markers were implanted into the tongue and jaw. Animals were filmed using high speed (2oofps) videofluoroscopy before the first injection and on injection day 7. Markers in the tongue and jaw were tracked to measure chew cycle duration and tongue-jaw coordination. Swallows times were identified from videofluoroscopic recordings. We tested whether chews occurring before, during, or after a swallow were longer, and whether tongue jaw coordination changed in rats before and after treatment using linear mixed models and post hoc pairwise contrasts. Chews that co-occur with swallows are significantly longer after treatment than before (p=0.006), whereas the lengths of pre and post swallow chews do not changes. Tongue jaw coordination after treatment is different in post chew swallows (p=0.016). The effects of Parkinsonian neurodegeneration on chewing are most pronounced when chewing and swallowing co-occur, which is in line with expectation given the role of the basal ganglia in coordinating motor functions. Lingering impacts on tongue–jaw coordination after the swallow suggest that return to baseline function is also impaired. The coordination of overlapping motor functions in feeding is affected in Parkinson’s disease, with potential implications for feeding difficulties and dysphagia.

Funding source: Rowan School of Osteopathic Medicine

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.
Ac-SDKP inhibits Tunicamycin-induced ER stress UPR's sensors and subsequently inflammation and fibrosis in human cardiac fibroblasts
Authors: SUHAIL HAMID , Peng Hongmei , Nour-Eddin Rhaleb
Published: May 2023

Background: Endoplasmic Reticulum (ER) stress, chronic inflammation and cardiac fibrosis are very common pathophysiologic processes found in hypertension and other cardiovascular diseases. Prolonged ER stress disturbs ER functional capacity, resulting from accumulated unfolded or misfolded proteins in ER lumen. Thereby, cells activate an adaptive mechanism ‘unfolded protein response (UPR)’ to restore ER normal function. Consequently, a series of downstream signaling pathways are activated. N-acetyl-seryl-aspartyl-proline (Ac-SDKP) is an endogenous tetrapeptide released from its precursor thymosin-β4 and found in circulation and organs including heart and kidneys. Previously, our in-vivo studies showed that Ac-SDKP inhibits inflammation and fibrosis through the mechanism that remains elusive. Methods and Results: Quiescent human Cardiac Fibroblast (hCFB) cells were treated with tunicamycin (TM; 0.25 μg/mL) in absence or presence of Ac-SDKP (10 nM) and Tauroursodeoxycholic acid (TUDCA; 500 μg/mL). Ac-SDKP inhibited TM-induced expression of ER stress and downstream mediated UPRs sensors IRE1ɑ, XBP1, ATF4 and CHOP encoding molecular chaperons and protein processing enzymes, at the transcriptional and translational levels [ IRE1α; Ctl (1.0 ± 0.39)***, TM (2.99 ± 0.34), Ac-SDKP +TM (1.9 ± 0.10)*** Tudca +TM (2.5 ± 0.20)***. XBP1; Ctl (1.0 ± 0.36)***, TM (8.56 ± 0.77), Ac-SDKP +TM (4.57 ± 0.4)***, Tudca +TM (5.1 ± 0.6)***. ATF4; Ctl (1.0 ± 0.17)***, TM (5.35 ± 0.63), Ac-SDKP +TM (3.0 ± 0.31)**, Tudca +TM (2.9 ± 0.36)**. CHOP; Ctl (1.0 ± 0.17)***, TM (3.1 ± 0.21), Ac-SDKP +TM (1.75 ± 0.24)***, Tudca +TM (2.0 ± 0.18)**]. The inhibition of ER and UPRs sensors subsequently prevented proinflammatory mediator NF-kB activation, cytokine IL-6 and fibrotic Collagen-I (Coll I) expression [ NF-κB; Ctl (1.0 ± 0.10)*, TM (1.6 ± 0.13), Ac-SDKP +TM (1.08 ± 0.11)†, Tudca +TM (1.09 ± 0.14)†. IL-6; Ctl (1.0 ± 0.18)***, TM (6.8 ± 1.4), Ac-SDKP +TM (1.24 ± 0.23***), Tudca +TM (1.3 ± 0.35)***. Coll I; Ctl (1.0 ± 0.02)*** TM (2.5 ± 0.43), Ac-SDKP +TM (1.13 ± 0.13)***, Tudca +TM (1.22 ± 0.18)***]. TM also induced collagen production (Hydroxyproline assay), which was significantly inhibited by Ac-SDKP. The common ER stress inhibitor, TUDCA, exhibited similar inhibitory profile as Ac-SDKP. Conclusion: Ac-SDKP prevents inflammation and fibrosis in hCFB, likely by blocking the overexpressed detrimental ER stress UPRs sensors and its downstream molecular chaperon. Notes: Data are shown a mean ± SEM, p values were calculated using one-way ANOVA compared to CTL. All the experiments are representative of n = 5 – 8.***:p ≤ 0.0001 vs TM; **:p ≤ 0.001 vs TM; *: p ≤ 0.05 vs TM; †:p ≤ 0.05 vs TM.

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.
A novel mouse model of systemic hypertension by neprilysin overexpression in myeloid cells
Authors: Hoshi Aoi , Giani Jorge , Bernstein Ellen , Ahmed Faizan , Cao DuoYao , Shibata Tomohiro , Khan Zakir , Saito Suguru , Bernstein Kenneth
Published: May 2023

There have been many hypertension mouse models created by transgenesis. The transgenesis technologies to create hypertensive mouse models mostly target the renin-angiotensin system (RAS). Here, we show that enhanced expression of neprilysin driven by the myeloid-specific c-fms promoter causes systemic hypertension in mice. [Method] Transgenic mice, termed Nep mice, were created with a construct containing the c-fms promoter and the neprilysin gene (MME). Blood pressure was measured by tail-cuff. Circulating vasoactive substances were analyzed by ELISAs. [Results] Nep mice showed higher systolic blood pressure compared with WT mice (117.0±1.75 vs. 107.1±2.373 mmHg, p=0.0018). The sodium concentration in a 24hr urine was significantly lower in Nep mice (0.2093±0.0039 vs. 0.2445±0.0054 μmol/μl urine, p=0.0004). The concentration of circulating neprilysin was significantly higher in Nep mice (3085±750.5 vs. 1098±197.1 pg/ml, p=0.0283). Notably, the plasma concentration of ANP showed no significant difference between Nep and WT mice although hypertension usually causes an ANP increase. [Conclusion] Overexpression of neprilysin in monocytes causes systemic hypertension associated with sodium and water retention. These mice might be useful for studying the pathologies of heart diseases and hypertension due to volume overload, and in addition, other neprilysin related diseases like Alzheimer’s disease to investigate the interaction with immune cells and beta-amyloid which is cleaved by neprilysin.

NIH R01 AI164519 (KEB, P.I.)

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.
High-resolution respirometry (HRR)-derived assessment of human skeletal muscle respiratory control confirms loss of metabolic flexibility with aging and type 2 diabetes
Authors: Waterman-Vandiver Kayla , Lukasiewicz Cole , Lindsay Keston , Lundby Carsten , Jacobs Robert
Published: May 2023

Compromised metabolic flexibility is linked to skeletal muscle respiratory control limitations and associated with human senescence and pathological conditions, like type 2 diabetes mellitus (T2D). However, demonstrable proof of compromised metabolic flexibility is limited in research studying aging and T2D, possibly because respiratory control per consensus is commonly assessed at 37°C when mitochondrial temperatures have been shown to reach ~50°C. Therefore, the study objective was to assess indices of skeletal muscle respiratory control and metabolic flexibility via high-resolution respirometry (HRR) in older individuals (OFM) and those diagnosed with T2D. Our hypothesis is that both populations, OFM and T2D, will present with diminished metabolic flexibility when compared to relative controls, young fitness-matched (YFM) or body-mass and BMI-matched middle-aged overweight or obese (MAOO) controls, respectively. Study methodology involved: i) Collecting published HRR-derived assessments of skeletal muscle state 3 respiration using complex I+II substrates obtained with standard experimental conditions at 37°C (OXPHOS37); ii) Temperature correcting published values to reflect mitochondrial temperatures ~10°C higher than contracting muscle (OXPHOS~50); and iii) Estimating metabolic flexibility by taking the difference of OXPHOS37 from OXPHOS~50. Data show that OFM (n = 170; age = 65 ± 6 y; Fitness Percentile = 48 ± 29%) express higher (p < 0.001) rates of OXPHOS37 than YFM (n = 154; age = 25 ± 5 y; Fitness Percentile = 43 ± 14%) with average rates of 123 ± 39 and 109 ± 31 ml/kg/min, respectively, but no observable difference (p = 0.113) between T2D (n=148, body mass = 99 ± 17 kg, BMI = 32 ± 5) and MAOO (n = 267, body mass = 97 ± 19 kg, BMI = 32 ± 6) with average rates of 96 ± 24 and 100 ± 25 ml/kg/min, respectively. Alternatively, temperature correction and determination of metabolic flexibility confirmed our study hypothesis in OFM v YFM (5.88 ± 1.57 and 6.32 ± 1.92 l/min, respectively, p = 0.026) as well as T2D v MAOO (115 ± 29 and 122 ± 31 ml/kg/min, respectively, p = 0.024). A summary of results confirms that OFM and T2D suffer from compromised metabolic flexibility. However, these findings were only observable after temperature correcting previously published HRR-derived data. Conclusions: This study further highlights the importance of maintaining muscle mass and relative fitness, respectively, to retain metabolic flexibility throughout life. Also, general standardized HRR methodologies may currently obscure some biological context and, thus, limit our full application of related research.

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.
Evolutionarily conserved mechanisms regulating hypoxia tolerance in Drosophila melanogaster
Authors: Zhou Dan , Xue Jin , Stobdan Tsering , Haddad Gabriel
Published: May 2023

Hypoxia is one of the critical pathological elements in many human diseases, including ischemic stroke, myocardial infarction and solid tumors. Understanding the mechanisms regulating hypoxia tolerance or susceptibility is essential for developing effective strategies for medical therapy. In this regard, we generated hypoxia-tolerant Drosophila melanogaster populations through experimental hypoxia-directed evolution in the laboratory, sequenced and analyzed their genomes. In parallel, we took advantage of the natural evolution of humans at high-altitude regions and analyzed the whole genomes of Ethiopian and Andean highlanders. Through a comparative genomic approach, we obtained a group of evolutionarily conserved genes (28 human/23 Drosophila genes) that are potentially involved in regulating hypoxia tolerance in both human highlanders and the hypoxia-tolerant flies. We confirmed that ubiquitous knocking down of the conserved genes, such as grn/ GATA3, inv/ EN1, Mkk4/MAP2K4, Pxt/DUOX1/DUOX2, pyd/TJP1, RapGAP1/RAP1GAP2, Shal/KCN and shep/RBMS3 dramatically enhanced hypoxia tolerance in vivo in Drosophila melanogaster. In addition, we found that glial-specific knocking down of Egfr, grn, pyd and Shal rescued hypoxia-induced lethality. Furthermore, we found that some of these conserved genes (i.e., bnl, croc, Mkk4 and shep) are required by Notch activation-conferred survival in hypoxic environment, whereas Egfr, grn, pyd and Shal regulating hypoxia tolerance through Notch-independent mechanisms. We believe that these evolutionarily conserved mechanisms are novel targets that have a strong potential to be translated into therapeutic strategies to treat or prevent hypoxia-related diseases.

This project is supported by NIH grant 1R21NS120023-01A1.

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.
SLC40A1 is involved in iron accumulation in human lung fibroblasts
Authors: Dang Quanjin , Huang Chaoqun , Liang Yurong , Hewawasam Sankha , Liu Lin
Published: May 2023

Iron is an essential nutrient for almost all organisms. However, excess iron generates reactive oxygen species and causes tissue injuries. Iron has been shown to accumulate in alveolar macrophages and is implicated in idiopathic pulmonary fibrosis (IPF). In this study, we examined iron accumulation in lung fibroblasts and the underlying mechanisms. We hypothesize that the downregulation of Solute Carrier Family 40 Member 1 ( SLC40A1) results in iron accumulation in lung fibroblasts. Using a Prussian Blue iron staining, we found that iron accumulated in the fibrotic region of the lungs from IPF patients and mice with lung fibrosis induced by bleomycin and asbestos. Iron was partially co-localized with the fibroblast marker vimentin in IPF lungs. By using publicly available scRNA-seq data, we identified SLC40A1, the only known gene involved in iron export, as a down-regulated gene in alveolar fibroblasts. The downregulation of SLC40A1 was confirmed in the lung fibroblasts isolated from IPF patients and bleomycin-treated mice. The treatment of human lung fibroblasts with transforming growth factor-β1 (TGF-β1), a major cytokine elevated in IPF, reduced SLC40A1 mRNA and protein expression. TGF-β1 downregulated SLC40A1 expression via SMAD3 as determined by chromatin immunoprecipitation and luciferase promoter reporter assays. Knockdown of SLC40A1 using lentiviral shRNAs or TGF-β treatment induced iron accumulation in human lung fibroblasts as determined by live cell ferrous dye staining using a SiRhoNox-1 probe. Knockdown of SLC40A1 enhanced the iron-induced lung fibroblast activation. In summary, we conclude that the downregulation of SLC40A1 caused by TGF-β1 induces iron accumulation in lung fibroblasts, resulting in fibroblast activation.

R01 HL157450, R01HL135152 and P20GM103648

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.
Piezo1 and TRPV4 complementary contribute to [Ca2+]i homeostasis in collecting duct cells
Authors: Tomilin Viktor , Stavniichuk Anna , Pyrshev Kyrylo , Kordysh Mariya , Zaika Oleg , Pochynyuk Oleh
Published: May 2023

Mechanical stress arising from elevated fluid flow is an important regulator of the water-electrolyte transport in the collecting duct (CD). It is well established that mechano-sensitive TRPV4 Ca2+-permeable channel mediates intracellular Ca2+ ([Ca2+]i) responses to high flow in these cells. Piezo1, a Ca2+-permeable channel directly activated by the plasma membrane stretch, is a recent arrival at this scene. Piezo1 expression has been reported in the CD. However, its functional significance is yet to be determined. Here, we applied a combination of Ca2+ imaging and confocal microscopy in freshly isolated split-opened CDs to investigate a potential interplay between TRPV4 and Piezo1 in mediating [Ca2+]i signaling in the CD. Immunofluorescent analysis of split-opened CDs showed presence of Piezo1 in both AQP2-positive (principal cells, PC) and -negative (intercalated cells, IC) with higher intensity in the former. Importantly, Piezo1 was apparent on both apical and basolateral membrane of CD cells. Piezo1 agonists, Yoda-1 (20μM) and Jedi2 (500μM) acutely increase [Ca2+]i in both principal and intercalated cells. The responses were abolished when extracellular Ca2+ was buffered with EGTA suggesting a direct Ca2+ influx via Piezo1. Interestingly, we detected two disparate calcium responses to Piezo1 activation with the majority (70%) cells showing a fast transient response with a sustained plateau, whereas the remaining (30%) population had much slower gradual calcium increase to the same plateau level. Subsequent immunofluorescent analysis revealed that fast Ca2+ responses were attributed to PC, whereas responses with slow kinetics corresponded to IC. Consistently, PCs have ~3 fold higher Piezo-1 signal when compared to neighbor ICs. We next tested whether Piezo1 activity depends on TRPV4 status. Genetic deletion and pharmacological inhibition of TRPV4 with GSK2193874 did not affect Piezo1-dependent elevations in [Ca2+]i. However, high K+ diet, which is known to elevate the flow in the CD and augment both TRPV4 activity and expression, led to diminished Piezo1 responses to Yoda-1. In summary, our results are consistent with the view that Piezo1 and TRPV4 are functional in both principal and intercalated cells of the collecting duct and operate independently to modulate mechanosensitive [Ca2+]i signaling. We hypothesize that augmented TRPV4-dependent [Ca2+]i is compensated by the diminished activity of Piezo1 to account for elevated flow rate upon increased K+ intake.

This research was supported by NIH-NIDDK DK117865, DK119170, AHA EIA35260097 (to O. Pochynyuk) and AHA-19CDA34660148 (to V. N. Tomilin).

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.