bluuebunny/crossref_metadata_2025 huggingface dataset:
Long Term Effects on Metabolic Parameters of Significant Weight Reduction (>25%) by Very Low Calorie Diet Compared to Roux-en-Y Gastric Bypass in Diabetic Obese vs Obese Without Diabetes (Patients vs Nonhuman Primates)
Authors: Harrison Daniel , Nguyen Tam , Shah Ria , Kavanaugh Megan , Mahler Raegan , Alford Nicholas , Hansen Barbara
Published: May 2023

Background: Obesity has similar effects in both monkeys and humans, including the development of metabolic syndrome, which is often followed by type 2 diabetes mellitus (DM). The effects of short term and intermittent very low-calorie diets (VLCD) suggest improvement in glycemic control, however, the long term (two year or more) effects of a VLCD have not been examined in obesity with or without diabetes. Methods: The metabolic and glycemic effects of major weight reduction in nonhuman primates using VLCD was compared to major weight reduction in humans using gastric bypass at 2 years post-surgery. In 14 spontaneously obese rhesus monkeys, half with overt T2DM were compared to 18 obese humans, ten with DM and eight without (OB). All humans underwent Roux-en-Y gastric bypass surgery and were followed for two years. The metabolic indices of the NHP and humans were obtained at the beginning and end of the two-year period. Results: All four groups experienced significant weight loss ranging from 22% to 37% reduction. Fasting glucose decreased significantly in both DM groups but were unchanged in both obese groups. In both humans and monkeys, fasting glucose of the DM and OB groups initially differed significantly from each other, but after surgery and after VLCD, did not differ. ß cell function, assessed by the acute insulin response to IV glucose, decreased in both OB groups and increased in both DM groups. In both species, after weight loss, the OB groups retained a higher acute insulin response compared to the DM groups, however, the differences between the OB and DM groups were significant (p-value of 0.032 for monkeys and 0.03 in humans). Insulin sensitivity in humans increased in both DM and OB groups (p <0.001 and 0.003, respectively). However, there was a larger change in the OB group. Conclusion: These results demonstrate a significant improvement in glycemic control (temporarily) from both long-term very low-calorie diets and gastric bypass. Pancreatic ß-cell function, however, cannot be restored to normal, even after significant weight loss (and sustained weight loss maintenance) in the diabetic groups. These results strongly support much earlier intervention to reduce obesity long before T2DM develops, as the reversibility of ß-cell defects disappears with overt T2DM, despite some limited improvement in glycemia.

NIH grants NO1AG3 1012, NIA, and NIDDK

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.
Redistribution of blood flow during exercise is impaired in heart failure with preserved ejection fraction
Authors: Ramchandra Rohit , Hamilton Charlotte , Shanks Julia , Pachen Mridula , Chang Joshua , Chen Siyi
Published: May 2023

Exercise intolerance is a cardinal symptom in heart failure with preserved ejection fraction (HFpEF). The underlying pathophysiological mechanisms of HFpEF and their influence on exercise intolerance remains poorly understood. This study investigated the role of re-distribution of blood flow in modulating the increase in hindlimb muscle blood flow during HFpEF.We proposed that exercise intolerance is partially contributed by an impaired ability to divert blood flow from peripheral organs such as the kidney during exercise. We utilised an ovine model of HFpEF in which hypertension was established in aged female sheep. We then examined the mean arterial pressure, heart rate, cardiac output, renal blood flow and hindlimb blood flow response to treadmill exercise in both groups of conscious animals.Animals with HFpEF had elevated left ventricular end diastolic pressures (13 ± 6 vs. 0 ± 1 mmHg, p<0.05) as well as enlarged cardiomyocytes compared to normotensive controls. Exercise in the control animals led to increases in cardiac output and heart rate. These responses were significantly attenuated in HFpEF (increase of 4.5 ± 1 vs. 8 ± 1 L/min, p<0.05) and heart rate (increase of 32 ± 3 vs. 41 ± 4 bpm, p<0.05). In a separate group of instrumented animals, the increase in blood flow to the hindlimb vasculature was attenuated in the HFpEF animals compared to control animals (increase of 2 ± 1 vs. 4 ± 2 L/min, p<0.05). There was a reduction in renal blood flow in the control animals (-150 ± 50 ml/min) and this change was reversed to an increase in the HFpEF animals (+50 ± 20 ml/min).Our results suggest that the exercise intolerance observed in our ovine model of HFpEF may in part be due to an impaired ability to regulate blood flow to the kidney and hindlimb muscles during exercise.

RR gratefully acknowledges granting support from the Health Research Council of New Zealand, the University of Auckland Faculty Research Development Fund and the National Heart Foundation of New Zealand.

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.
ChREBP/ ChREBP-beta expression mediates the paradoxical effect of fructose on body weight of fructose-fed rats by brown adipose tissue activation
Authors: Leibowitz Avshalom , Khashab Rawan
Published: May 2023

Introduction: Western diet fructose content is a neglected nutrition component, with significant devastating metabolic effects like metabolic syndrome (MeS) and obesity. The data suggest that Food-induced thermogenesis is a contributing factor for regulating body weight. Carbohydrate Responsive Element Binding Protein-beta (ChREBPβ) is recognized now as the regulator of fructose metabolism. Brown adipose tissue (AT) which plays essential role as a thermoregulatory organ, is recognized now also as an endocrine tissue that participates in glucose and lipids metabolism. ChREBP expression is associated with activating of BAT and improve metabolic status. On the other hand, increased ChREBPβ seems to have a deleterious metabolic effect on brown AT. Methods: Sprague-Dawley male rats, 8 weeks old were fed High Fructose Diet (HFRD) or match regular chow for 6 weeks (n=8). Body weight (BW) and precise food intake were measured weekly. Brown (peri-aortic and interscapular, PA and IS respectively) and white (mesenteric) AT were collected for further molecular studies. Results: HFrD fed rats gain significantly less weight than the control group (from 236±2 to 397±8 vs. 233±2 to 430±9 gr. P<0.05) despite eating an equal food amount (28±1vs.29±1.5 g/rat/week). The expression of uncoupling 1 (UCP1) mRNA, a BAT activation marker, was significantly higher in BAT than in WAT. Fructose consumption increased UCP1 BAT expression compared to regular chow. However, the expression of ChREBP and ChREBPβ in BAT was significantly lower in HFrD fed rats. Conclusions: In the HFrD rat model of MeS, fructose consumption leads to lesser weight gain for the same caloric intake. This BW difference is accompanied by the activation of BAT in the HFrD group. This paradoxical effect may be regulated by decreased ChREBP/ChREBPβ expression in response to fructose.

No disclosure

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.
Greater renal interstitial expansion and inflammation in older male versus older female rats following a four-day simulated heatwave
Authors: Monroe Jacob , Schlader Zachary , Basile David
Published: May 2023

Acute kidney injury (AKI) is an emerging cause of morbidity during heatwaves worldwide and is associated with negative health outcomes. Older age increases the likelihood of AKI, which is a top cause of hospitalization during heatwaves in older adults. Further, biological sex likely affects the severity of, and prognosis following, AKI. Moreover, recent observations suggest that older women are at greater risk of AKI during heatwaves compared to older men. Whether this observation can be directly attributed to biological sex is unclear. Therefore, we tested the hypothesis that older female rats experience more severe kidney injury during a four-day simulated heatwave, compared to older male rats.To test this hypothesis, older (18-22 month old) male (M) and female (F) Wistar rats were exposed to a 36°C (M: n=5; F: n=8) or a 21°C (M: n=2; F: n=2) environment for three hours over four consecutive days. During, and for five hours following heat exposure, the rats did not have access to food or water, but otherwise were housed in standard housing conditions with free access to food and water. Core temperature (Tc) was continuously monitored and rats were removed from the heat if Tc reached 40.5℃, a safeguard put in place to prevent heatstroke. Data are presented as mean±SD.Male and females did not differ in the amount of time exposed to heat during each day (average duration - M: 39.3±4.0, F: 42.3±5.2 minutes, P=0.86) or body weight loss during heat exposure (average body weight loss - M: -2.0±0.1, F: -2.5±0.1% P=0.93). Serum creatinine concentration did not differ between heat exposed males and females on Day 1 (pre- M: 0.4±0.2, F: 0.4±0.1; post- M: 0.5±0.2, F: 0.4±0.2 mg/dL) or Day 4 (post- M: 0.4±0.1, F:0.3±0.1 mg/dL; P=0.86) Heat exposure resulted in cortical interstitial expansion and immune cell infiltration in aged male, but not female rats (M Heat: 77.2±36.1, F Heat: 12.1±16.5, M Control: 18.2±17.5, F Control: 13.4±19.0 dots per image, P=0.002). Only older male rats displayed greater interstitial immune cell infiltration than older controls in response to heating (P=0.04). Immunohistochemistry demonstrated distinct populations of CD3e+ T cells, CD20+ B cells and CD68+ macrophages within the interstitial immune cell infiltration in the older male rats. Kidney expression of kidney injury molecule 1 (KIM1, P=0.41) and neutrophil gelatinase associated lipocalin (NGAL, P=0.12) did not differ between older male and female rats exposed to heat or control conditions. Compared to older female rats, older male rats display increased cortical interstitial expansion and inflammation following a four-day simulated heatwave.

UL1TR002529, T32DK120524

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.
Physiological responses of adults with coronary artery disease during extreme heat exposure
Authors: Bartlett Audrey-Ann
Published: May 2023

Introduction: Extreme heat is becoming more frequent due to climate change. Different regions experience different forms of heat, such humid or dry heat, a greater risk of morbidity and mortality becomes apparent with higher temperatures. Adults with heart disease are especially vulnerable to the health risks of extreme heat. One possible reason for this greater risk is that adults with heart disease might experience greater physiological heat strain during extreme heat exposure. The objective of this study was to determine if adults with coronary artery disease (CAD) experience greater physiological strain relative to adults without CAD during hot/humid and very hot/dry heat exposures.Methods: 28 adults with stable CAD (2 females/26 males, 66±7 y, 1.96±0.17 m2) and 26 adults without CAD (non-CAD; 13 females/12 males, 69±4 y, 1.86±0.21 m2) rested for 3 hours in hot/humid (HH; 38°C/60% relative humidity; n= 22 CAD and 26 non-CAD) and very hot/dry (VHD; 45°C/15% relative humidity; n=24 CAD and 13 non-CAD) environments on separate days. Participants consumed 3 mL/kg/h of water during each exposure. Core (rectal) and skin temperatures, heart rate, and whole-body sweat loss were measured. Results: During exposure to HH, adults with CAD experienced a greater increase in core (0.58±0.28°C vs. 0.37±0.23°C, p=0.009) and mean skin (5.08±1.11°C vs. 4.06±0.76°C, p=0.0005) temperatures and sweat more (832±252 g vs. 471±244 g, p<0.0001). The increase in heart rate (CAD: 9±7 bpm vs. non-CAD: 9±6 bpm, p=0.914) and percent change in body weight (CAD: +0.12±0.32% vs. non-CAD: +0.25±0.22%, p=0.106) did not differ between groups. During exposure to VHD, adults with CAD experienced a greater increase in mean skin temperature (5.79±1.06°C vs. 4.92±1.23°C, p=0.029), greater sweat loss (1239±171 g vs. 794±159 g, p<0.0001), and greater percent change in body weight (-0.41±0.29% vs. -0.11±0.16%, p=0.001). The change in core temperature (CAD: 0.62±0.37°C vs. healthy: 0.48±0.21°C, p=0.092) and heart rate (CAD: 9±7 bpm vs. healthy: 13±6 bpm, p=0.196) did not differ between groups. Conclusion: During hot/humid heat exposure, adults with CAD experience greater thermal strain and fluid loss, whereas they experience greater fluid loss and dehydration during a very hot/dry heat exposure. The greater physiological heat strain experienced by adults with CAD may reflect the impact of altered cardiovascular function and/or medications on internal distribution and ultimately contribute to a greater risk of heat-related mortality.

National Health and Medical Research Council

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.
Click chemistry, FRET-FCS, and expansion microscopy reveal that Na, K-ATPase forms complexes in the plasma membrane
Authors: Brismar Hjalmar , Edwards Steven , Bauer Sebastian , Meineke Birthe , Elsässer Simon , Wennmalm Stefan
Published: May 2023

In order to study the spatial distribution of Na, K-ATPase alpha and beta subunits in the plasma membrane of epithelial cells we have developed sample preparation protocols based on genetic code expansion, click chemistry and expansion microscopy. HEK 293T cells were transiently transfected with constructs containing the coding sequence for Na, K-ATPase subunits (alpha1 and beta1) carrying a premature amber or ochre stop codon. Two bioorthogonal tRNA and tRNA synthetase pairs were also transfected for stop codon suppression and site-specific insertion of two unnatural amino acids. The unnatural amino acids were then labelled with small organic dyes using CuAAC and SPIEDAC click reactions. Care was taken to keep the transfection and expression levels low.In living cells, we used Fluorescence Correlation Spectroscopy (FCS) and FRET to assess the density of click-labeled and endogenous [SE1] Na, K-ATPase in the plasma membrane. The dyes Alexa488 and Alexa647 were used as a FRET sensor for homo- and heterodimer analysis and, using FRET-FCS, we could detect the oligomerization of alpha and beta in a complex containing two alpha and two beta subunits in a heterodimer.FCS measurements in cells where both the alpha and beta subunits were labeled was used to calculate the absolute density of endogenous and exogenous Na, K-ATPase in the plasma membrane. To detect oligomerization, we used cells where the beta subunit was labeled with a 50/50 mix of Alexa488 and Alexa647. We successfully detected FRET signals and an analysis of the FRET-FCS data revealed a high density of oligomers. FRET-FCS is, compared to conventional cross-correlation FCCS, one to two orders of magnitude more sensitive for the detection of oligomers. FRET-FCS is also inherently insensitive to heterogenous labeling efficiencies, which is a great advantage during live cell measurementsExpansion microscopy was performed using a modified MAP protocol, reaching an isotropic expansion of approximately 4.5-fold. Confocal airyscan microscopy of the expanded cells with <50nm resolution revealed local variations in Na, K-ATPase density and enabled detailed cluster analysis.In conclusion we demonstrate that the density of Na, K-ATPase has large local variations and that the Na, K-ATPase oligomerizes in the plasma membrane. We propose that this oligomerization can have a regulatory function for the net efficiency of Na, K-ATPase in the cell.

VR 2020-05347, VR 2019-00217 (Swedish Research Council)

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.
Diesel exhaust particles alter adipose mitochondria bioenergetics
Authors: Warren Cali , Curtiss Katrina , Saito Erin , Reynolds Paul , Bikman Benjamin
Published: May 2023

Diesel exhaust particles (DEP) constitute a significant quantity of air pollution that infiltrate the bloodstream to drive systemic pathologies. While some pathologies are obvious, such as COPD and heart failure, others are less apparent, such as insulin resistance, diabetes, and even obesity. In every case, a role for the receptor of advanced glycation end-products (RAGE) has been implicated. RAGE are cell surface receptors that are implicated in pathological processes, such as inflammation and diabetic complications. Despite the known connection between DEP and metabolic disorders, the effects of DEP exposure on adipose tissue mitochondrial function is unknown. To understand the potential role of RAGE signaling in the context of adipose tissue DEP exposure, mice were nasally exposed to either room air, nebulized diesel exhaust particles, or nebulized diesel exhaust particles + semi-synthetic glycosaminoglycan ethers (SAGEs, RAGE signaling inhibitors) every weekday for three weeks. Inguinal adipose tissue samples were obtained following exposure, and mitochondrial respiration rates were measured. In mice exposed to DEP or DEP + SAGE, mitochondrial respiration of inguinal adipose tissue was not significantly different compared to the room air control mice with the addition of glutamate and malate or ADP. However, respiration was significantly increased with the addition of succinate and FCCP in the inguinal adipose tissue from mice exposed to DEP. The results of this work indicate that DEP exposure elicits a negative effect on adipose mitochondrial respiration.

This work was supported in part by funding from Levels Health (BTB) and the National Institutes of Health (NIH 1R15-HL152257, PRR and BTB).

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.
Zinc Deficiency Drives Renal NFkB Activation
Authors: Wenegieme Tara-Yesomi , Waite Aston , McMichael Kelia , Naraine Meagan , Ume Adaku , Williams Clintoria
Published: May 2023

Background: Zinc deficiency (ZnD) is comorbid with life-threatening diseases such as diabetes and kidney disease. In these populations, the prevalence of hypertension is elevated. In our published studies, we demonstrated that ZnD alone was sufficient in promoting hypertension in hypertensive-resistant mice. Specifically, our findings revealed that hypertension was a consequence of renal sodium retention. However, the underlying molecular mechanisms driving these effects were undefined. Hypothesis: Since the transcription factor nuclear factor-κB (NFκB) is implicated in the pathogenesis of hypertension, we tested the hypothesis that ZnD drives renal NFκB activation. Experimental Design: To examine the impact of ZnD on renal NFκB, adult male C57Bl/6 mice were fed a zinc deficient or zinc adequate diet for 10 weeks. Both NFκB expression and nuclear translocation were examined by immunofluorescence and Western blot. To directly investigate the role of zinc in NFκB regulation, mouse tubule epithelial cells were exposed to medium containing a zinc chelator (N, N, N', N'-tetrakis(2-pyridylmethyl)ethane-1,2-diamine, TPEN) or vehicle for 24 hours. To examine whether ZnD-induced effects on NFκB were reversible, the medium of TPEN-exposed cells were supplemented with zinc. Results: While NFκB expression was undetectable in zinc adequate mice, its expression and nuclear localization were enhanced in zinc deficient mice, as assessed by both immunofluorescence and Western blot. Interestingly, immunofluorescence revealed increased NFκB expression and nuclear localization exclusively in selected tubules. Consistently, our in vitro model demonstrated that TPEN-induced ZnD also promoted NFκB expression and nuclear translocation. Notably, zinc repletion reversed TPEN-induced NFκB upregulation. Conclusions: Collectively, both in vivo and in vitro findings reveal that 1) renal NFκB is a zinc-regulated nuclear transcription factor and 2) ZnD drives NFκB upregulation in selected tubular epithelial cells. Significance: Importantly, this study identifies NFκB as a potential mediator of ZnD-induced renal sodium retention and subsequently hypertension.

Funding Source: AHA-16SDG27080009

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.
Electrical stimulation-induced muscle contraction does not reduce intramuscular accumulation of Doxorubicin 24 hours following administration
Authors: McCue Meghan , Rebalka Irena , Hawke Thomas , MacLean David
Published: May 2023

Background: Doxorubicin (Dox) is a commonly used chemotherapeutic drug. Although an effective anti-cancer agent, it can be profoundly toxic to skeletal muscle (SM). Dox has been demonstrated to accumulate rapidly in SM, leading to tissue damage and cellular dysfunction. Exercise prior to Dox treatment may reduce drug accumulation. However, little is known about the effects of exercise on intramuscular accumulation following Dox administration. Electrical stimulation (stim) could be a low-effort way to exercise SM following Dox administration; however, it has yet to be investigated in this context. Aim: This study aimed to determine if various stim protocols could reduce Dox accumulation in rodent hindlimb muscles 24 hours following drug administration. Hypothesis: Stim-induced muscle contraction will reduce intramuscular accumulation of Dox in a time- and intensity-dependent manner when compared to unstimulated muscles. Methods: Male Sprague-Dawley rats (n=42) were randomly assigned to one of six stim protocols (1 Hz or 3 Hz, for 5, 15, or 30 minutes) or a true control group. Stim groups received a single intraperitoneal dose of Dox (4.5 mg/kg). Twenty-four hours following Dox administration, the assigned stim protocol was carried out on the left sciatic nerve while the right leg served as an intra-individual control. Tissues and plasma were immediately harvested following the stim protocol to determine the acute effects of SM contraction. Drug and metabolite concentrations were assessed in both tissue and plasma using high-performance liquid chromatography. Results: None of the stim protocols investigated led to a reduction in intramuscular accumulation of Dox in the white gastrocnemius [summed data: 3.09±0.76 (stimulated leg) vs. 2.49±0.16 nmol/kg (unstimulated leg), p>0.05] or the soleus [summed data: 1.8±0.27 (stimulated leg) vs.1.5±0.23 nmol/kg (unstimulated leg), p>0.05]. These data are supported by plasma Dox concentrations which were similar in all groups (p>0.05), suggesting minimal uptake or release of Dox by SM. The concentration of Doxorubicinol, a highly toxic metabolite of Dox, also remained unchanged in both muscles and plasma (p>0.05). Conclusion: Electrical stimulation-induced muscle contraction did not reduce intramuscular accumulation of Dox 24 hours following drug administration. While unable to reduce accumulation, stim may still be a valuable tool for maintaining muscle mass and function during Dox treatment. Further investigation is required to characterize and optimize the role of stim during chemotherapy.

Funding: This study was funded by a Rene Guilbeault Research Award.

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.
Chronic Intermittent Hypoxia Facilitates Action Potential Firing in PVN-projecting MnPO Neurons
Authors: Jia Shuping , Farmer George , Little Joel , Paundralingga Obed , Cunningham Joseph
Published: May 2023

Our previous results indicate that Chronic intermittent hypoxia (CIH) enhances glutamatergic neurotransmitter release in PVN-projecting MnPO neurons. Very little information exists regarding how CIH affects the excitability of PVN-projecting MnPO neurons. MnPO neurons exhibit a wide diversity of spontaneous and evoked firing patterns. Initial studies indicate CIH modulates resting membrane properties and AP firing patterns which may be associated with alterations in hyperpolarization-activated cyclic nucleotide-gated currents (Ih). The Ih current is an inward current activated by hyperpolarization from the resting potential and is an important modulator of action potential firing frequency. Data were collected in PVN-projecting MnPO neurons which play an important role in CIH-induced hypertension. Adult male Sprague Dawley rats (250-350g) received bilateral PVN injections of 200 nL retrograde adeno-associated virus pAAV-CAG-tdTomato. Three weeks following injections, rats were either exposed to a 7-day intermittent hypoxia protocol consisting of 6 min cycles (3 min 21% O2, 3 min 10% O2) repeated 10x/hr for 8 hours (during the normal inactive/sleep phase) or room air (Norm). Following CIH/Norm treatment, rats were deeply anesthetized and sagittal brain slices of MnPO were prepared using standard slice procedures. Spontaneous activity and responses to current injections were recorded from PVN projecting MnPO neurons using whole cell current-clamp. Data was analyzed off-line using Clampfit. There was a trend for spontaneous activity to be higher in PVN-projecting MnPO neurons from rats exposed to 7 days CIH when compared to normoxic controls (Norm: 2.29 ± 0.51 vs CIH: 3.3 ± 0.84) that was not due to a change in resting membrane potential. The threshold to evoke AP potentials was significantly lower in CIH neurons (5 pA injecting current, 17/19 CIH neurons vs 9/13 Norm neurons, CIH 8.6 ± 0.79 mv vs Norm 13.06±1.53 mv, p<0.01; 10 pA injecting current, 19 CIH neurons vs 12/13 Norm neurons CIH 14.74±0.92 mv vs Norm 19.72 ±1.64 mv, p<0.01). However, evoked action potentials were less sensitive to increasing current injection amplitudes in CIH vs Norm treated rats. Following bath application of the specific Ih blocker ZD7288 (ZD, 30 μm) spontaneous action potential activity was reduced by 24% in Norm neurons and 47% in CIH neurons (p=0.0313). These data demonstrate that CIH facilitates action potential generation in PVN projecting MnPO neurons and changes in Ih currents may contribute to this increase in excitability.

R01 HL155977

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.
The HIF-prolyl hydroxylases have distinct and non-redundant biological roles in the pathogenesis of colitis-associated cancer
Authors: Harnoss Jonathan , Kennel Kilian , Burmeister Julius , Radhakrishnan Praveen , Giese Nathalia , Giese Thomas , Salfenmoser Martin , Gebhardt Jasper , Strowitzki Moritz , Taylor Cormac , Wielockx Ben , Schneider Martin
Published: May 2023

Colitis-associated colorectal cancer (CAC) is a severe complication of inflammatory bowel disease (IBD). HIF-prolyl hydroxylases (PHD1, PHD2, and PHD3) control cellular adaption to hypoxia and are considered promising therapeutic targets in IBD. However, their relevance in the pathogenesis of CAC remains elusive. We induced CAC in Phd1-/-, Phd2+/-, Phd3-/-, and WT mice with azoxymethane (AOM) and dextran sodium sulfate (DSS). Phd1-/- mice were protected against chronic colitis and displayed diminished CAC growth compared to WT mice. In Phd3 -/- mice, colitis activity and CAC growth remained unaltered. In Phd2+/- mice, colitis activity was unaffected, but CAC growth was aggravated. Mechanistically, Phd2 deficiency (i) increased the number of tumor-associated macrophages (TAMs) in AOM/DSS-induced tumors, (ii) promoted the expression of EGFR ligand epiregulin ( Ereg) in macrophages, and (iii) augmented signal transducer and activator of transcription 3 (STAT3) and extracellular signal-regulated kinase 1/2 (ERK1/2) signaling which at least in part contributed to aggravated tumor cell proliferation in colitis-associated tumors. Consistently, Phd2 deficiency in hematopoietic ( Vav:Cre-Phd2f/f) but not in intestinal epithelial cells ( Villin:Cre-Phd2f/f) increased CAC growth. In conclusion, the three different PHD isoenzymes have distinct and non-redundant, either promoting (PHD1), diminishing (PHD2), or neutral effects (PHD3) on CAC growth.

KBK received funding from the German Cancer Aid. MJS. received funding from the German Research Foundation (DFG; STR 1570/1-1) and the Braun Foundation (Braun®; BBST-D-18-00018). MSch received funding from the German Federal Ministry of Education and Research (BMBF; 031L0084). JMH received funding from the Heidelberg Stiftung Chirurgie.

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.
Impact of heart failure with preserved ejection fraction on large conducting airways in humans
Authors: Johnston Jessica , Borlaug Barry , Johnson Bruce , Smith Joshua
Published: May 2023

Background: Heart failure patients with preserved ejection fraction (HFpEF) exhibit exercise intolerance and exertional dyspnea. The underlying pathophysiology is complex and involves multiple physiological systems. To this point, HFpEF patients exhibit pulmonary abnormalities at rest and during exercise. For example, HFpEF patients have higher work of breathing during exercise due to greater inspiratory and expiratory resistive work of breathing. Importantly, this greater resistive work of breathing is not associated with higher inspiratory and expiratory flow rates suggesting pulmonary resistance is elevated in HFpEF patients. One potential explanation for the increase in resistive work of breathing during exercise in HFpEF patients is smaller luminal area of the airways. Purpose: The purpose of this study was to determine if differences exist in the luminal area of the large conducting airways in HFpEF patients compared to controls. We hypothesized that HFpEF patients will exhibit smaller luminal areas of the large conducting airways compared to controls. Methods: HFpEF patients (n=9; 67±7 yrs; 30±3 kg/m2) and controls (n=8; 62±9 yrs; 24±3 kg/m2) were enrolled. All participants performed pulmonary function testing and a thoracic computerized tomographic (CT) scan (assessed at total lung capacity). The airway luminal area was quantified from three-dimensional reconstructions from the high-resolution CT scans. The luminal areas of the large conducting airways were measured at three discreet points (corresponding to the beginning, middle, and end of the airway), averaged, and indexed to height. Results: The luminal area of the trachea was not different between groups (p=0.95). HFpEF patients had smaller luminal area of the right main bronchus (control: 1.38±0.21 vs. HFpEF: 1.18±0.13 mm2/cm) and left main bronchus (control: 0.98±0.20 vs. HFpEF: 0.79±0.15 mm2/cm) (both, p<0.04) than controls. HFpEF patients also had smaller luminal area of the bronchus intermedius (control: 0.82±0.14 vs. HFpEF: 0.67±0.15 mm2/cm) and left lower lobe bronchus (control: 0.48±0.13 vs. HFpEF: 0.36±0.07 mm2/cm) compared to controls (both, p<0.04). No differences were present between groups in the right and left upper lobe bronchi (both, p>0.40). Conclusion: HFpEF patients have smaller luminal areas of some, but not all large conducting airways compared to controls. These findings provide support for smaller large conducting airways in HFpEF contributing to the pulmonary abnormalities during exercise in these patients.

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.
Compartment-specific calcium dynamics and their role in somatodendritic exocytosis and autoregulation of vasopressin neurons
Authors: Kirchner Matthew , Althammer Ferdinand , Shook Erin , Montanez Juliana , Stern Javier
Published: May 2023

Vasopressin (VP) neurons exhibit somatodendritic release (SDR) of their neuropeptide cargo, in addition to axonal release. The phasic firing of these neurons dictates the volume and pattern of this exocytosis. This phasic patterning and SDR are dependent on intracellular changes in Ca2+ (Δ[Ca2+]i). When SDR occurs, VP acts in an autocrine manner to inhibit VP firing activity via activation of V1aR-mediated increases in [Ca2+]i. Because SDR and subsequent autoinhibition are dictated by Δ[Ca2+]i, we investigated whether this Ca2+-dependent inhibition involved afterhyperpolarizations (AHPs) and how compartment-specific Ca2+ dynamics affected neuronal properties. Using a combination of patch clamp electrophysiology, simultaneous Ca2+ imaging, and targeted photolytic uncaging, we investigated the properties of Ca2+ spread in soma and dendrites of VP magnocellular neurons of supraoptic nucleus (SON). We found that whereas Ca2+ uncaging in soma efficiently invades dendrites, dendritic Ca2+ uncaging fails to propagate into the soma, supporting unidirectional Ca2+ movement between cellular compartments. Moreover, we found that Ca2+ uncaging in the soma but not dendrites evoked AHPs, indicating compartmental localization of AHP mechanisms and/or channels. Blockade of mitochondrial Ca2+ reuptake (Ru360 in the pipette) prolongs Δ[Ca2+]i elevations and AHPs triggered by Ca2+ uncaging, indicating that mitochondria in VP neurons plays an important role in shaping Ca2+ dynamics and AHP properties in these neurons. Consistent with previous reports, we found that bath application of VP (1 μM) inhibits VP neuronal activity. Moreover, we found that VP enhances the apamin-insensitive slow AHP by prolonging its duration but not its amplitude, whereas a V1aR antagonist SR49059 (1 μM) per se inhibits slow AHPs in these neurons. These results expose vital aspects of the mechanisms that dictate phasic firing, SDR, and the autoinhibitory nature of VP in SON.

NHLBI F32HL158172 (MKK), NHLBI HL090948 (JES), NINDS NS094640 (JES)

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 in mice leads to impaired colonic corticosterone production and prolonged inflammation following induction of colitis
Authors: Muir Rachel , Klocke Barbara , Jennings Melissa , Molina Patrick , Hsu Jung-Shan , Kellum Cailin , Alexander Katie , Lee Goo , Foote Jeremy , Lorenz Robin , Pollock Jennifer , Maynard Craig
Published: May 2023

Early life stress (ELS) is an environmental trigger linked to increased risk of inflammatory bowel disease (IBD). Our goal was to identify mechanisms whereby ELS in mice affects susceptibility to, and/or severity of, intestinal inflammation. We hypothesized that ELS alters the delicate balance of typical homeostatic mediators in the intestinal microenvironment, predisposing ELS-exposed individuals to IBD onset or worsened disease upon a pro-inflammatory triggering event within the gut. We utilized 2 published animal models of ELS. In the first model, newborn mice were separated from the dam daily for 4-8 hours beginning on postnatal day 2, then weaned early on postnatal day 17. Normally reared (NR) control mice were left undisturbed with the dams until standard weaning on postnatal day 21. In the second model, dams were fed the synthetic glucocorticoid – dexamethasone, or vehicle ad libitum in drinking water (3 μg/mL) on post-partum days 1-14. Colitis was induced in 4-week-old mice via intraperitoneal injection of IL-10 receptor blocking antibody (100 μg) every 5 days for 15 days. Five or 15 days later, histological colitis scores and colonic transcripts for Tnf, glucocorticoid receptors, and steroidogenic enzymes were measured. ELS-exposed mice displayed altered mucosa-associated immune cell balances, with an initial deficit in anti-inflammatory IL-10-producing CD4 T cells at 4-wks of age (n≥11, p<0.05), followed by an increase in IFNγ-producing CD4 T cells at 8-wks of age (n≥7, p<0.05). ELS-exposed mice also displayed reduced levels of the glucocorticoid, corticosterone in the plasma (n≥10, p<0.01) as well as locally within the colon (n≥7, p<0.05). Upon colitis induction, NR control animals showed improvements in indices of inflammation following cessation of IL-10 receptor blockade, whereas ELS-exposed animals maintained high levels of intestinal Tnf (n≥7, p<0.01) and histological signs of colitis (n≥7, p<0.05). In colitic animals, prior exposure to ELS was associated with significantly lower expression of genes associated with corticosterone synthesis ( Cyp11a1; n≥5, p<0.05) and responsiveness ( Nr3c1, Nr5a2; n≥5, p<0.01). Finally, ex-vivo TNF stimulation of colonic crypt cells from ELS mice led to increased inhibition of corticosterone synthesis, relative to NR control mice (n≥4, p<0.05). Our study identifies impaired local colonic glucocorticoid production and responsiveness as a potential mechanism whereby ELS predisposes to chronic colitis in susceptible hosts.

Crohn's and Colitis Foundation Research Initiatives Award

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.
T cell pro-inflammatory cytokine production in young adults with major depressive disorder
Authors: Joseph Blessy , Darling Ashley , Sharma Sunita , Grotle Ann-Katrin , Saunders Erika , Greaney Jody , Trott Daniel
Published: May 2023

Background: Major Depressive Disorder (MDD) is increasingly prevalent in young adults and is a significant contributor to disease burden worldwide. Previously we have shown that young adults with MDD produce greater T cell mitochondrial ROS compared to their heathy non-depressed counterparts. Because evidence from rodent models of stress-related mood disorders demonstrates that increased T cell mitoROS drives excessive proinflammatory cytokine production, we next sought to determine if either CD4+ (Helper) or CD8+ (cytotoxic) T cells likewise produce increased proinflammatory cytokines in young adults with MDD. We hypothesized that there will be elevated proinflammatory cytokine production in young adults with MDD compared to their healthy non-depressed counterparts. Methods: Peripheral blood mononuclear cells were isolated by density centrifugation from 5 young adults with MDD having mild to moderate symptom severity and 9 non-depressed young healthy adults. Interleukin 2 (IL-2), Interleukin 6 (IL-6), Interferon Gamma (IFN-γ), and Tumor Necrosis Factor alpha (TNF-) production were assessed by flow cytometry. All data are expressed as mean SE and group differences were assessed by unpaired T test. Results: We found that adults with MDD exhibited a greater proportion of CD8+ Interleukin 6 (IL-6) (n= 8; 5 HA, 3 MDD) (HA = 22 3.5%, MDD = 255.6%; P= 0.004) producing cells compared to healthy. There were no significant differences in the proportions of CD8+ cells producing IFN-γ (HA = 14 1.2%, MDD = 3.1%; P= 0.31), IL-2 (HA =76 3.9%, MDD = 69 6.6%; P= 0.17), and TNF- (HA = 21 2.3%, MDD = 23.5%; P= 0.11) in those with MDD compared to controls. Additionally, there were no differences in CD4+ production of these same cytokines. We also assessed phenotype of the T cells using CD27 (central vs effector) and CD45 RA (Naïve vs TEMRA). Interestingly, a greater proportion of TNF- producing CD8+ and CD4+ cells exhibited an effector memory phenotype in adults with MDD compared to controls (CD8: HA = 25.8 2.4%, MDD = 46.8 3.3%; P= 0.0001; CD4+: HA=31 2.9%, MDD = 394.3%; P= 0.05). These data provide insight into the T cell subtypes that may be driving the inflammation associated with MDD. Conclusion: These preliminary findings suggest that young adults with MDD may exhibit a proinflammatory T cell phenotype characterized by greater IL-6 and TNF- production.

NIH R21 MH123928 and R00133414 (JLG), NIH K01AG061271 and R01AG060395 (DWT).

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 Differences in renal ischemia-reperfusion injury following deletion of Netrin-1 in the kidney
Authors: McLarnon Sarah , Honeycutt Samuel , O'Brien Lori
Published: May 2023

Netrin-1, an angiogenic guidance cue, is heavily expressed in the kidney. Our lab has previously reported that deletion of Netrin-1 in Foxd1-positive stromal progenitors ( Foxd1GC/+Netrin1fl/fl ) results in abnormal vascular patterning during kidney development, including a reduction in interlobar branching. It remains unknown how these changes in vascular patterning affect kidney function and physiology. In the current study, we hypothesized that changes in developmental patterning of the kidney vasculature would protect from renal ischemia-reperfusion injury in a sex-specific manner due to ischemic preconditioning to the kidney tubular cells. To test this hypothesis, we performed warm, bilateral ischemia-reperfusion by clamping the renal pedicles for 26-minutes in wild-type ( Netrin1fl/fl or Netrin1fl/+ )(3M, 3F), heterozygous ( Foxd1GC/+Netrin1fl/+ ) (2M, 4F), and mutant ( Foxd1GC/+Netrin1fl/fl ) (3M, 1F) male (M) and female (F) mice. Following 24-hours of reperfusion, blood and kidneys were collected for analysis of kidney injury markers. We found that plasma creatinine (p2-wayANOVA=0.021) and blood urea nitrogen (p2-wayANOVA=0.009) were decreased in female mice compared to male mice regardless of genotype. In both male and female mutant mice, there was a decrease in these markers of injury compared to heterozygous and wild-type control mice, although this did not reach statistical significance. In agreement, immunofluorescent staining of kidney injury marker 1 (KIM-1) indicated less tubular injury in female mice compared to males. These data suggest that female mice are less susceptible to ischemic injury than male mice despite both sexes having similar alterations in vascular patterning following deletion of Netrin-1. Further, our results indicate a protective effect of these developmental patterning changes due to Netrin-1 deletion. We suspect that changes in the vasculature in our mutant mice provide a preconditioning-like environment to mediate this effect. Future studies will investigate the underlying mechanisms which drive this injury phenotype between sexes. Understanding how renal vascular development impacts kidney injury is critical to the development of new therapeutic strategies to prevent the sustained injury following periods of ischemia.

NIH R01DK121014 to LO

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.
The endoplasmic reticulum acetyl-CoA transporter AT-1 plays a role in the protective unfolded protein response in the exocrine pancreas
Authors: Cooley Michelle , Thomas Diana , Deans-Fielder Kali , Peng Yajing , Lugea Aurelia , Waldron Richard , Pandol Stephen , Puglielli Luigi , Groblewski Guy
Published: May 2023

Pancreatic acinar cells are responsible for the synthesis and secretion of digestive enzymes. In order to sustain high rates of secretory protein production, acinar cells rely on adaptive mechanisms to mitigate endoplasmic reticulum (ER) stress and maintain secretory homeostasis. The adaptive unfolded protein response (UPR), mediated by the IRE1-XBP1s axis, is essential for acinar function and protects against cellular injury. Recent work has demonstrated that the ER acetyl-CoA transporter, AT-1, is necessary for nascent secretory protein acetylation and export out of the ER and is regulated by IRE1-XBP1s. Furthermore, AT-1 is rapidly downregulated during experimental pancreatitis. To investigate the role of AT-1 in exocrine pancreas function, we generated inducible, acinar-specific AT-1 knockout mice (Ela-Cre AT-1-/-). Loss of AT-1 produced a chronic pancreatitis phenotype characterized by inflammation, immune cell infiltration, tissue fibrosis, and aberrant intracellular activation of the proteolytic digestive enzyme trypsin. Despite the histological and biochemical dysfunction observed, Ela-Cre AT-1-/- mice grow normally, have typical lifespans, and do not lose pancreatic mass. Interestingly, XBP1s expression is significantly upregulated in Ela-Cre AT-1-/- and may confer a protective effect with loss of AT-1. Our data suggests a role for AT-1 in the IRE1-XBP1s axis and highlights the previously undescribed role of protein acetylation in exocrine pancreas physiology. Given the numerous potential downstream effects of dysregulated acetyl-CoA transport, this model will advance our understanding of pancreatic function and disease.

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.