bluuebunny/crossref_metadata_2025 huggingface dataset:
Inhibition of Streptococcus pneumoniae colonization with deoxycholic acid, a secondary bile acid metabolite
Authors: Wier Meagan , McDevitt Erin , Vidal Ana , Alibayov Babek , Scasny Anna , McDaniel Larry , Vidal Jorge
Published: May 2023

Streptococcus pneumoniae (pneumococcus) colonizes the upper respiratory tract, including the nasopharynx, of children and the elderly. Despite antibiotics and vaccines readily available, pneumococcus kills millions worldwide yearly. We have found that the secondary bile acid metabolite and endogenous salt deoxycholic acid (DoC) affects the viability of this human pathogen while also playing multiple roles in host physiology. Via in vitro studies, we assessed the anti-microbial activity of DoC and investigated its potential to eradicate S. pneumoniae colonization using a model of human nasopharyngeal colonization and an in vivo mouse model. At a physiological concentration, DoC (0.5 mg/ml; 1.27 mM) killed all tested strains of S. pneumoniae (n=48) 2 hours post-inoculation. Our model of nasopharyngeal colonization showed that DoC eradicated colonization by S. pneumoniae strains as quickly as 10 minutes post-exposure. The mechanism of action did not involve activating autolysis since autolysis-defective double mutant strains (Δ lytAΔ lytC and Δ spxBΔ lctO) were found to be as susceptible to DoC as the wild-type strain (WT). Oral streptococcal species (n=20) were, however, not as susceptible to DoC at 0.5 mg/ml. Unlike trimethoprim, whose spontaneous resistance frequency (srF) for TIGR4 or EF3030 was ≥ 1 x 10-9, no spontaneous resistance was observed with DoC. Finally, the efficacy of DoC to eradicate S. pneumoniae colonization was assessed in vivo using an intranasal topical route (i.n.) and separately as prophylactic treatment. Mice that were challenged with S. pneumoniae EF3030 carried a median of 4.05 x 105 CFU/ml four days post-inoculation compared to 6.67 x 104 CFU/ml for mice treated with DoC. Furthermore, mice in the prophylactic DoC group had approximately a 99% reduction of pneumococcal density illustrating the possibility of deoxycholic acid as a safe, endogenous human bile salt with therapeutic potential against increasingly-resistant S. pneumoniae strains.

This study was in part supported by grants from the National Institutes of Health (NIH; 1R21AI144571-01 and 1R21AI151571-01A1 to J.E.V.). B.A. was supported by a Fulbright scholarship awarded by the U.S. Department of State. The content is solely the responsibility of the authors and does not necessarily represent the official view of the NIH or the U.S. Department of State.

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.
In vivo determination of direction of blood flow in the newly discovered SCN-OVLT vascular portal system in rat
Authors: Roy Ranjan , Yao Yifan , Silver Rae , Stern Javier
Published: May 2023

By transporting products directly from the capillary bed of one region to the capillary bed of another region, vascular portal pathways enable minute amounts of important secretions to reach their specialized targets in high concentrations, without dilution in the systemic circulatory system. For decades there has been only one known portal system in the mammalian brain - that of the pituitary gland, first identified in 1933 (Popa and Fielding, J. Anatomy 1933). This year, we described a second portal pathway in the mouse linking the capillary vessels of the brain's clock suprachiasmatic nucleus (SCN) to those of the organum vasculosum of the lamina terminalis (OVLT), a circumventricular organ (Yao et al., Nat. Comm. 2021). A caveat in this initial work was that the direction of blood flow was unknown. To determine whether the SCN signaled the OVLT or vice-versa, we performed in vivo 2-photon imaging in anesthetized eGFP-vasopressin (VP) rats using a recently developed approach (Roy et al., Cell Report 2021) to study blood flow in this portal system. To delineate the SCN microvasculature in vivo, we intravenously infused fluorescent dextrans in anesthetized rats. The SCN-OVLT portal system was identified as Alexa 633 (an artery/arteriole specific dye)-negative vessels originating from a dense SCN capillary network that run rostrally towards the OVLT. These vessels displayed a mean diameter of ~20 μm. Blood flow in the portal vessels was measured by monitoring red blood cell (RBC) movement after intravenous injections with Rho70 kDa. Using kymographs, we found that in all cases, RBCs flowed rostrally, from the SCN towards the OVLT. Importantly, we found than blood flow was significantly higher at night (ZT17-19) compared to daylight (ZT5-7) (p< 0.001), while directionality remained the same (SCN→OVLT). Taken together, our results support the presence of a functional SCN-OVLT portal system in the rat in which blood flows unidirectionally from the SCN towards the OVLT. Moreover, our studies support the notion that blood flow in this system can be regulated. This clock portal system points to entirely new routes and targets for secreted signals from the SCN, restructuring our understanding of its output pathways.

Support: NIH HLBI R01HL162575 to JES, AHA916907 to RKR and NSF 1749500 to RS.

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.
LRRC8A Anion Channel Knockout Stimulates the Nrf2 Antioxidant Response
Authors: Panja Sourav , Choi Hyehun , Nguyen Hong-Ngan , Lamb Fred
Published: May 2023

Leucine Rich Repeat Containing 8A (LRRC8A) is an essential component of volume‐regulated anion channels (VRACs), which regulate cell volume. These anion channels are activated by pro-inflammatory mediators such as angiotensin II and tumor necrosis factor-α (TNFα). We previously demonstrated that VRAC inhibition or LRRC8A knockdown reduced Nox1 activation and impaired the inflammatory response to TNFα in cultured vascular smooth muscle cells. We hypothesized that loss of LRRC8A would also modify the antioxidant status of VSMCs. Vascular smooth muscle-specific (Sm22alpha-Cre) LRRC8A KO mice were created. Primary VSMC cultures were prepared from aortae and mesenteric arteries from male mice. Western blotting of protein from WT and LRRC8A KO mesenteric artery VSMCs revealed significant upregulation of proteins that are known to be under the control of the Nrf-2 antioxidant response; heme oxygenase 1 (2.1 fold), thioredoxin 1 (1.8 fold), and superoxide dismutase 1 (1.3 fold) superoxide dismutase 3 (1.8 fold). There was no change in the abundance of catalase.To further explore the role of LRRC8A in intracellular signaling, LRRC8A was immunoprecipitated from cultured WT and LRRC8A KO VSMCs and proteins were analyzed by Mass Spectrometry (MS). Reads were sorted for proteins identified in wild type but not in KO cells. This approach identified the Trim21 E3 ubiquitin ligase, a known regulator of the antioxidant response, as an LRRC8A-associated protein. Trim21 ubiquitinates and thereby promotes degradation of p62 (Sequestosome-1, SQSTM1). p62 sequesters Kelch-like ECH-associated protein 1 (Keap1), preventing it from promoting ubiquitination and destruction of Nrf-2 by the proteosome. Consistent with this, TRIM21 KO mice have an augmented antioxidant status and are protected from myocardial inflammation in response to doxorubicin or ligation of the left coronary artery. We considered the possibility that association of TRIM21 with LRRC8A (directly or indirectly) regulates its activity. Co-immunoprecipitation and western blotting confirmed association of LRRC8A with TRIM21. Pulldown of ubiquitinated proteins from WT and KO VSMCs failed to provide evidence that LRRC8A is ubiquitinated, however, p62 ubiquitination was markedly reduced in KO VSMCs. Thus, reduced p62 turnover in LRRC8A KO cells may enhance Keap1 sequestration and increase Nrf2 activity. The ability of LRRC8A knockdown to both impair the inflammatory response to TNFα and to enhance the antioxidant status of VSMCs identify this protein as an appealing target for the treatment of vascular inflammation.

This work was supported by our both grant from NIDDK (1R01DK132948) and NIH (1 R01 HL160975-01A1).

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.
Does cardio-hepatic communication contribute to pregnancy-induced cardiac growth and its reversal?
Authors: Schulman Emily , Collins Helen
Published: May 2023

Introduction: During pregnancy, the maternal heart undergoes physiological cardiac growth, which reverses following parturition; however, the underlying processes that contribute are largely unknown. Changes in both systemic and cardiac metabolism appear to be associated with cardiac growth, which could also contribute during pregnancy. We have shown that several cardiac metabolic transcripts and proteins and liver-derived metabolites are elevated during pregnancy and postpartum and are associated with cardiac growth. Therefore, the goal of this study was to examine the extent to which the cardio-hepatic signaling axis contributes to pregnancy-induced cardiac growth and reversal. Methods and Results: Timed pregnancy studies in 12-week-old FVB/NJ mice revealed that both heart weight (HW:TL; p < 0.0001) and liver weight (LIV:TL; p <0.0001) were highest in lactating 1-week post-birth (PB) mice versus mid-pregnant (8 d), late-pregnant (LP; 16 d), and non-pregnant (NP) mice. Interestingly, we also found that HW:TL ( p < 0.01) and LIV:TL ( p < 0.0001) were significantly reduced in non-lactating 1-week post-birth mice (PBNL) compared with PB mice. Hearts and livers both remained significantly larger, irrespective of lactation status, following parturition through 6 weeks post birth (PB) versus NP. Plasma proteomics revealed significant increases in prolactin at LP in addition to increases in liver-derived proteins including hepatocyte growth factors; however, these levels returned to NP levels by PB. Examination of the liver proteome from the same mice revealed significant increases in fatty acid and ketone body metabolism proteins. Cardiac and liver immunoblot analysis revealed significant reductions in Pdk4 between 1- and 3-week PB and PBNL groups that was reversed by 6-weeks postpartum and a significant increase in Pdk4 expression at 6 weeks postpartum, respectively. Interestingly, we see a sustained increase in cardiac Bdh1 expression that persisted at 6-weeks postpartum which could contribute to the sustained increases in HW:TL versus NP. Conclusion: Changes in both lactation status and metabolism are likely contributing to similar patterns of growth seen in the heart and liver during and following pregnancy.

NIGMS COBRE Pilot project grant P30 GM127607; NIH R01 HL147844 (Hill/ Jones); Jewish Heritage Fund for Excellence Faculty Support; Jewish Heritage Fund for Excellence Research Enhancement Award; UofL School of Medicine Basic Science award; NIGMS IDeA state funded proteomics voucher.

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.
Folate malnutrition as metabolic stressor to promote advanced type 2 diabetes mellitus by switching bioenergetic fluxes and metabolic flexibility
Authors: Chen Wan-Jing , Huang Chih-Yang
Published: May 2023

Type 2 diabetes mellitus (T2DM) is a group of metabolic disorder disease, including abnormal bioenergetic fluxes and glucose-related genetic regulation, eventually leads to severe diabetes complications. Clinical studies have shown that folate malnutrition positively correlated with the progression of T2DM, but the causal relationship and mechanism are still unclear. Aims of the study were to investigate whether the molecular mechanisms by which metabolic folate stress may promote diabetic memory metabolism switched bioenergetic fluxes and metabolic flexibility to mediate advanced T2DM. Primary Human Skeletal Muscle Cells (HSkMC) were cultured with high glucose for 4, 8, 12, and 16 days as the experiment models to test the hypothesis. As compared with the controls, cultivation of HSkMC cells with clinically low serum folate levels (LF) for 4-16 days gradually and significantly promoted (1) morphological alteration, (2) insulin resistance, (3) expressions of bioenergetic markers (NADP/NADPH, Lactate), and (4) mRNA expressions of late on-set T2DM molecules (INS, INSR, SLC2A2, SLC30A8, ABCC8). Energetic metabolic switch in the LF- HSkMC cells, but not the controls, was evident by reduced lactate release, pyruvate dehydrogenase E1 alpha (PDHA) expression and altered NADP/NADPH, NAD+/NADH ratios from 3.4 to1.8 and 2.0 to 1.2, respectively. Blockage of mTOR pathways, epigenetic acetylation (Sirt1) abolished LF-promoted metabolic disorder, regulated mRNA expressions of glucose and insulin related molecules (INSR, SLC2A2 and ABCC8). Collectively, metabolic folate stress promotes metabolic memory switched bioenergetic fluxes and metabolic flexibility to mediate advanced type 2 diabetes.

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 Effects of Dietary Salt on Blood Pressure Variability, Cerebral Perfusion and Cognitive Function in Young-Adult Male Rats
Authors: Sun Fen , Zhao Lu-Ping , Zhang Jin-Yang , Jin Chao , Jin Qi
Published: May 2023

Background: There is controversy about the relationship between dietary salt intake and cognitive function. Experimental studies showed that extremely high salt diets increased blood pressure (BP) levels, leading to cognitive impairment. However, extremely high salt diets are not clinically relevant. The present study examined how high dietary salt could affect cognitive function and whether these effects are via BP stability and cerebral hypoperfusion. Methods: SD rats (male, young adult) were on the control diet (0.4% NaCl), low salt diet (0.1% NaCl), or high salt diets (with three does at 1%, 2%, or 4% NaCl) for 12 weeks. BP levels, heart rate (HR), and BP variability (SD and CV) were measured repeatedly at baseline, 1, 2, 3, 4, 6, 8, and 12 weeks after the onset of the diet. Anxiety and cognitive function (open field, novel object recognition, and T-maze) were measured repeatedly at baseline, 4, 8, and 12 weeks after the onset of the diet. Blood Na+ and cerebral blood flow (CBF) were measured at the endpoint. Results: Rats with the low salt diet showed significantly reduced systolic BP (SBP) and diastolic BP (DBP) levels compared to those with the control diet and high salt diets at 8 weeks after the onset of the diet. Notably, rats with the low salt diet had the highest SBP variability (SBPV) and DBPV, while those with the control diet showed the lowest SBPV and DBPV. In high salt diet groups, SBPV and DBPV increased in a dose-dependent manner. There is no significant difference in HR between groups. Rats only with a 4% NaCl diet showed worse cognitive function compared to rats with low salt and control diet 8 weeks after the onset. Blood Na+ was similar between groups. Interestingly, the high salt diet increased the CBF in a dose-dependent manner. The CBF of the low salt diet was similar to those with 2% salt die, and the CBF of the control group was the lowest. Conclusions: This study suggests that a moderate-high salt diet would not affect cognitive function in young-adult male SD rats. Only consumption of an extremely high salt diet impaired cognitive function, and this harmful effect was not via cerebral hypoperfusion. Moreover, both low and high salt diets increased BPV.

This research was funded by the START-UP FUNDING OF HANGZHOU NORMAL UNIVERSITY, grant number 4255C50221204123 (Dr. Fen Sun).

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.
Myoglobin-driven ET-1 production and downstream activation of TRPC3- but not TRPC6-dependent vasoconstriction contributes to rhabdomyolysis-induced AKI
Authors: Afolabi Jeremiah , Kanthakumar Praghalathan , Williams Jada , Kumar Ravi , Adebiyi Adebowale
Published: May 2023

Acute kidney injury (AKI) is the most severe and life-threatening complication of rhabdomyolysis, with 10-40% of patients developing some form of kidney insufficiency within days. Experimental evidence indicates that renal vasoconstriction plays a significant role in the pathophysiology of rhabdomyolysis-induced AKI. Rodents subjected to glycerol-induced rhabdomyolysis exhibited increased plasma concentrations of endothelin-1 (ET-1). Treating glomerular mesangial cells with myoglobin has also been shown to increase the cellular production of ET-1. The downstream effectors of ET-1-induced vasoconstriction are smooth muscle Ca2+ permeable transient receptor potential canonical (TRPC) channels. There are seven members of the TRPC gene family (TRPC1-7). Whereas TRPC2 and 7 are absent, TRPC1, 3, 4, 5, and 6 are expressed in renal vessels, with TRPC3 predominant. TRPC3, TRPC6, and TRPC7 are highly homologous. Although the ET system is known to be associated with rhabdomyolysis-induced AKI, the function of renal vascular ion channels in the disease is unclear. Here, we investigated the involvement of TRPC3 and TRPC6 in glycerol-induced rhabdomyolysis in rats. ET-1 production is increased in myoglobin-treated epithelial cells, the primary source of renal ET. Rhabdomyolysis also increased renal ET-1 production, decreased renal blood flow (RBF), and increased renal vascular resistance, effects attenuated by ET receptor and TRPC channel blocker Pyr3. Furthermore, we used TRPC3 and TRPC6 knockout (KO) rats to support the pharmacological approaches. Basal day and night arterial pressure, heart rate, GFR, plasma creatinine, and BUN were unchanged in WT vs. KO rats. Twenty-four h rhabdomyolysis led to comparable increases in urinary ET-1 production in WT and KO rats. However, rhabdomyolysis-induced decreases in GFR, elevations in BUN, and plasma creatinine were all attenuated in the TRPC3 but not TRPC6 KO rats. Similarly, morphological kidney damage (tubular necrosis, casts, and dilatation) was mitigated in the TRPC3 KO with no protection offered by the KO of TRPC6 channels. Together, our data suggest that myoglobin-driven ET-1 production and downstream activation of TRPC3- but not TRPC6-dependent vasoconstriction contributes to rhabdomyolysis-induced AKI.

American Heart Association Predoctoral Fellowship

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.
Gravid grasshoppers produce more energy but jump shorter distances
Authors: Truini Dana , Kirkton Scott
Published: May 2023

The negative effects of gravidity on locomotion have been well documented in terrestrial vertebrates but are relatively unknown in insects. During gravidity, the egg mass of Schistocerca americana grasshoppers can be up to 40% of their body mass. However, jumping muscle mass remains relatively unchanged during gravidity. Using female grasshoppers that ranged in body size from 1.6 g to 3.3 g (n=25), we investigated how gravidity affects maximal jump performance. Each grasshopper’s maximal jump was captured using eight Qualisys infrared high-speed cameras filming at 1121 fps. Biomechanical data were generated using Qualisys Track Manager and the effects of body size/gravity were analyzed using regression in JMP. Larger grasshoppers have significantly more eggs, a larger egg mass, and a greater portion of their body dedicated to eggs (egg mass: y=0.52x-0.82; r2=0.76; p<0.0001). We found that the take off angle, take off acceleration, force, and time spent in the air during a jump was similar regardless of body size or gravidity. However, larger, more gravid grasshoppers had significantly lower take off velocities (y=-0.40x+4.36; r2=0.22; p<0.02) and did not jump as far (y=-0.18x+1.44; r2=0.18; p<0.05). When we compared the actual jump distance to the predicted jump range, we found that more gravid grasshoppers were significantly closer to the expected range than smaller, less gravid grasshoppers (y=6.23x+77.31; r2=0.16; p<0.05). In addition, more gravid grasshoppers produced significantly more energy during a jump than less gravid animals (y=2.94x+5.77; r2=0.19; p<0.05). The increased jump energy of more gravid grasshoppers may be due to an increased reliance on anaerobic ATP production. This supports previous work that gravid grasshoppers have more problems with oxygen delivery. For example, gravidity reduces the total tracheal respiratory volume by 10%, reduces tidal volumes, and increases respiratory rates. Future work will measure phospho-arginine and lactate to determine, if due to oxygen delivery problems, gravid grasshoppers rely more on anaerobic ATP to produce powerful escape jumps.

This research was supported by the National Science Foundation (Award 1827495 to SDK) and Union College Biology Department.

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.
Angiotensin-(1-7) improves blood pressure and cardiovascular autonomic function in human aging
Authors: Miller Amanda , Arnold Amy
Published: May 2023

Background: Aging is the largest independent risk factor for developing hypertension and cardiovascular disease (CVD); however, the molecular mechanisms underlying age-related CVD remain poorly understood. Our laboratory recent published that levels of angiotensin (Ang)-(1-7), a protective hormone of the renin-angiotensin system, are reduced in healthy aged mice and that chronic restoration of Ang-(1-7) levels lowers blood pressure and sympathetic tone in aged mice. In this translational study, we hypothesized that, aging in humans is associated with low Ang-(1-7) and that restoring levels of Ang-(1-7) can decrease blood pressure via modulation of the autonomic nervous system. Methods: To test this hypothesis, plasma Ang-(1-7) levels and blood pressure were measured in older (>60 yrs n=8) and younger (<40 yrs, n=10) healthy humans. In a separate double-blind, randomized, crossover study, we performed acute intravenous (IV) infusion of Ang-(1-7) and saline in older adults (n=3). Ang-(1-7) was infused at escalating doses (2ng/kg, 6ng/kg, 8ng/kg; 10 minutes per dose), with the highest dose held for an additional 70 minutes. Blood pressure, heart rate, and muscle sympathetic nerve activity (MSNA) were measured continuously before and during Ang-(1-7) and saline treatments. Heart rate variability (HRV) and low frequency systolic blood pressure variability (LFSBP) were calculated via spectral analysis methods. Results: Plasma Ang-(1-7) levels were lower in older versus younger adults (9.4±1.5 vs. 28.0±4.9 pg/mL, respectively; p = 0.005), with no differences in plasma Ang II levels. Ang-(1-7) was inversely correlated to systolic blood pressure in older adults (r2=0.497, p=0.034), but not in younger adults (r2=0.110, p=0.384). In older adults, acute IV Ang-(1-7) infusion lowered blood pressure [Δ from baseline: -12±10 Ang-(1-7) vs. 4±2 mmHg saline, p < 0.050]. This depressor effect of Ang-(1-7) was associated with decreased measures of sympathetic tone [LFSBP (Δ from baseline: 0.35±0.08 Ang-(1-7) vs. 1.94±0.79 mmHg2 saline; p=0.0372) and MSNA burst incidence (Δ from baseline: -9 Ang-(1-7) vs. 8 A.U. saline)] as well as increased vagal tone (high frequency HRV, Δ from baseline: 295±117 Ang-(1-7) vs. 7±96 s2 saline, p = 0.050). Conclusions: These findings suggest that Ang-(1-7) is lower in healthy aged humans and associated with systolic hypertension. Additionally, acute infusion of Ang-(1-7) decreases blood pressure and sympathetic tone and increase vagal tone in this population. Overall, these data provide further rationale for targeting Ang-(1-7) to improve cardiovascular autonomic control in aging.

NIH: K99HL159272, American Heart Association: 18POST33960087

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.
Regulation of endothelial cell mitochondrial phenotype by mechanosensitive ion channel TRPV4
Authors: Dalal Kesha , Katari Venkatesh , Paruchuri Sailaja , Thodeti Charles
Published: May 2023

Transient receptor potential vanilloid type 4 (TRPV4) is a mechanosensor that regulates endothelial cell (EC) proliferation, migration, and angiogenesis. However, the molecular mechanisms by which TRPV4 regulates EC functions are not well understood. In this study, we investigated if TRPV4 regulates EC function via modulation of mitochondria by employing three types of EC expressing different levels of TRPV4, normal (NEC), TRPV4-deficienct (TEC), and TRPV4 knockout (KOEC). First, we confirmed the functional expression of TRPV4 in these EC using qPCR and calcium imaging. Confocal images upon MitoTracker staining revealed spherical and/or round shaped mitochondria with a perinuclear localization in NEC while in TEC and KOEC the mitochondrial network was elongated and rod shaped with a whole cell distribution. Furthermore, Transmission Electron Microscopy confirmed the presence of clear round mitochondria in NEC compared to elongated mitochondria with distinct cristae in TEC and KOEC. These results indicate increased fusion in TRPV4 deficiency or deletion. When cultured on ECM gels of varying stiffness that mimic stiffness of matrix in pathophysiological conditions such as tumor or heart failure (0.2, 8, and 50 kPa), we found increased distribution of mitochondria in EC with increasing stiffness. Moreover, western blot analysis showed increased expression of a fusion/fission protein ratio (Optic Atrophy 1 (OPA1)/mitochondrial fission factor (MFF)), in TEC and KOEC. Further, uncoupling mitochondrial function by mitochondrial stressors (Oligomycin, FCCP, and Rot/AA) significantly increased basal oxygen consumption rate (OCR), maximal OCR, ATP-linked OCR, and spare capacity in TEC and KOEC than NEC. Finally, a small molecule inhibitor of OPA1, MYLS22, attenuated/normalized the mitochondrial energy metabolism to that of NEC but did not affect NEC. These findings suggest that mechanosensitive TRPV4 channels regulate EC mitochondrial morphology and function through increased OPA1.

National Institutes of Health (R15CA202847, R01HL119705, and R01HL148585) to CKT

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Sex-specific and immune-cell-specific contributions of beta2 integrins in myocardial ischemia-reperfusion injury
Authors: Fan Zhichao , Liu Wei , Cronin Chunxia , Wen Lai , Ley Klaus , Liang Bruce
Published: May 2023

Leukocyte recruitment and their mediated inflammatory responses are critical for cardiovascular diseases, including myocardial ischemia-reperfusion (I/R) injury, which accounts for 9% mortality and 10% morbidity rates in ischemic heart disease patients. Blocking leukocyte recruitment in mouse knockouts (KO) of beta2 integrin (CD18) or blocking beta2 integrin with anitibodies in multiple animals significantly reduced infarct size after myocardial I/R injury. However, the cell-specific contribution of leukocyte beta2 integrin to I/R injury is unknown. In this study, we used the newly established CD18flox/flox (hITGB2 KI) mouse strain to address this knowledge gap. We crossed them to CSF1R-cre (CD115) and MRP8-cre (S100A8) and tested the KO of beta2 integrins in different leukocyte populations. Interestingly, CSF1R-cre CD18flox/flox unexpectedly deleted beta2 integrins in all peripheral blood leukocyte populations, including blood neutrophils, monocytes, CD4 T cells, CD8 T cells, B cells, and NK cells. It also elevated the cell number of these leukocyte populations in peripheral blood. In MRP8-cre CD18flox/flox mice, beta2 integrins were only knocked out in neutrophils but not other peripheral blood leukocytes. And only neutrophil number was elevated in peripheral blood. After 35 minutes of myocardial ischemia and 24 hours of reperfusion, we found both CSF1R-cre CD18flox/flox and MRP8-cre CD18flox/flox mice have significantly reduced infarct size compared to cre- controls. However, if we distinguish the sex in analysis, we only found a significant alleviation in female but not male CSF1R-cre CD18flox/flox mice. In contrast, we observed a significant alleviation only in male but not female MRP8-cre CD18flox/flox mice. These results suggested sex-specific and immune-cell-specific contributions of beta2 integrins in myocardial ischemia-reperfusion injury and provided new insights into beta2 integrin targeting therapies.

This research was supported by grants from the National Institutes of Health, National Heart, Lung, and Blood Institute, USA (R01HL145454, R41HL156322, and R44HL152710) and a startup fund from UConn Health.

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.
Nitric oxide-mediated vasodilation in tibial bone in young healthy individuals
Authors: Draghici Adina , Ely Matthew , Taylor J. Andrew
Published: May 2023

Despite the critical importance of sufficient and well-regulated blood flow supply for bone health, regulation of bone blood flow in humans remains poorly understood. We have recently shown that sympathetic and myogenic control have active roles in regulating blood flow to tibial bone in humans. Responses are smaller and delayed in the tibia compared to the whole leg, underscoring the importance of directly interrogating mechanisms underlying bone blood flow control. Nitric oxide (NO) mediated vasodilation is another important regulatory mechanism and studies to date have been confined to assessment of whole limb blood flow responses that primarily reflect muscle. In young healthy individuals (N=8), we characterized NO-mediated vasodilation in tibial blood flow and contrasted it to whole leg blood flow. We employed sublingual nitroglycerin (0.4 mg) as an NO donor. We obtained a 5 min resting baseline, followed by the responses to sublingual nitroglycerin for 10 min in supine subjects. Tibial blood flow was measured continuously via near infrared spectroscopy as total hemoglobin (Hb) and whole leg blood flow as popliteal Doppler flow velocity in the same leg. NO-mediated vasodilation was characterized by peak response, time to peak response, and time to return to baseline over the 10 min response. Tibial blood flow (total Hb) increased rapidly in response to nitroglycerin reaching a maximum of 1.61 ± 0.69 μM after 3.5 min. Afterwards, total Hb steadily declined, returning to baseline values by 10 min. Whole leg blood flow increased at a slower rate reaching a maximum of 7.12 ± 2.72 cm/s after 4.5 min. However, whole leg blood flow remained elevated throughout the entire 10 min measurement. Our results indicate that similar to other vascular beds, bone vasculature has a robust NO-mediated vasodilation, but appears to be faster and shorter lasting compared to the whole leg vasculature. This is not dissimilar from our previous findings indicating different time characteristic time-courses of response to other vascular controllers in tibial bone compared with whole leg vasculature.

Paralyzed Veterans of America Research Foundation (AED), NIH NIAMS R21 AR074054 (JAT)

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.
Elucidating the role of renal olfactory receptor 1393 in female Type 1 diabetic mice
Authors: Shaw Britney , Jordan Ali , Shepard Blythe
Published: May 2023

Diabetes mellitus is a condition arising from the inability to sufficiently produce or respond to insulin, thus manifesting glucose intolerance. We previously identified an olfactory receptor (Olfr1393), which is localized in the renal proximal tubule where glucose is reabsorbed by Sglt1 and Sglt2. Inhibition of these transporters have therapeutic value by decreasing glucose reabsorption and promoting glycosuria to enable improved glucose homeostasis in patients with diabetes. On a normal chow diet, whole-animal Olfr1393 knockout (KO) mice are euglycemic yet present with glycosuria and improved glucose tolerance (Shepard et al 2016). While this phenotype was observed in both male and female mice, the female KOs presented with more robust glycosuria (p=0.03) and a significant reduction in SGLT1 total cellular membrane expression (p=0.04). Recently, we found that when administered low-dose models of Streptozotocin (STZ)—an alkylating agent that depletes pancreatic β cells thereby mimicking Type 1 diabetes—male Olfr1393 KO mice exhibit an improved diabetic phenotype. However, in keeping with other published reports, we found that the wildtype (WT) and KO female mice were unaffected by STZ treatment. This resistance to STZ has been explained by the anti-apoptotic activity of estrogen receptor signaling that protects pancreatic beta islet cells from chemical-induced damage. To overcome this, slow-release pellets containing 4-hydroxytamoxifen (4OH)—an estrogen receptor modulator in pancreatic beta islet cells—were implanted in both male and female C57BL/6J mice three days prior to STZ challenge (55 mg/kg body weight for 5 consecutive days). Using this method, we were able to successfully induce diabetes in the female mice (female fasting blood glucose - 4OH vehicle: 178 ± 3.50 mg/dL; placebo STZ: 330 ± 8.22 mg/dL; 4OH STZ: 436 ± 4.65 mg/dL). We also noted that 4OH-treated male mice exhibited a more robust diabetic phenotype (male fasting blood glucose - 4OH vehicle: 185 ± 4.95 mg/dL; placebo STZ: 450 ± 11.6 mg/dl; 4OH STZ: 575 ± 4.95 mg/dl). With the successful induction of diabetes in female mice, we have used the same method to test the hypothesis that Olfr1393 female KO mice are protected from the development of diabetes and kidney damage. Female Olfr1393 WT and KO mice were administered 4OH pellet implantations followed by STZ-treatment. Preliminary data suggests that loss of Olfr1393 does indeed attenuate, but does not eliminate, the development of hyperglycemia (2-hour fasting blood glucose values - female WT: 368 mg/dL; female KO: 247.5 mg/dL). Future study will determine if the loss of Olfr1393 also protects against diabetes-induced glomerular hyperfiltration and altered renal blood flow.

NIDDK, Yale O'Brien Center

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.
ZFP24 drives SOX9 upregulation and protects tubular epithelial cells during acute kidney injury
Authors: Kim Ji Young , Pabla Navjot
Published: May 2023

SOX9 is a transcription factor that controls cell-fate determination during embryonic development and adult tissue homeostasis in multiple organs including the kidneys. SOX9 expression is low in the adult kidneys, however, stress conditions can trigger its transcriptional upregulation in tubular epithelial cells. Functionally, SOX9 plays a protective role during the early phase of acute kidney injury (AKI) and facilitates repair during the recovery phase. To identify the upstream transcriptional regulators that drive SOX9 upregulation in tubular epithelial cells, here we have used an unbiased transcription factor screening approach. Our preliminary screening and validation studies show that Zinc finger protein 24 (ZFP24) controls injury induced SOX9 upregulation in tubular epithelial cells. ZFP24, a Cys2-His2 (C2H2) zinc finger protein is essential for oligodendrocyte maturation and myelination, however its role in the kidneys or in SOX9 regulation remains unknown. We find that tubular epithelial ZFP24 gene ablation exacerbates ischemia, rhabdomyolysis, and cisplatin-associated AKI. Importantly, ZFP24 gene deletion results in suppression of SOX9 upregulation in injured tubular epithelial cells. Chromatin immunoprecipitation and promoter luciferase assays confirmed that ZFP24 binds to a specific site in both murine and human SOX9 promoter. Importantly, CRISPR/Cas9 mediated introduction of mutations in the ZFP24 binding site in the SOX9 promoter in vivo led to suppression of SOX9 upregulation during AKI. These findings identify ZFP24 as a critical stress-responsive transcription factor that protects tubular epithelial cells during AKI in part through SOX9 upregulation.

The current study was supported by NIDDK 1R01DK132230 grant to N.P.

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.
Can you stomach it? Comparative transcriptomics and biochemistry of the stomachs of prickleback fishes (Stichaeidae) consuming different diets
Authors: German Donovan , Herrera Michelle , Heras Joseph
Published: May 2023

Despite obvious whole animal, tissue level, and biochemical differences among species with different diets, dietary specialization has molecular underpinnings that are not well understood. In this project, we used comparative transcriptomics of stomach tissues to observe how prickleback fishes (Stichaeidae) achieve dietary-driven differences in stomach function. Xiphister mucosus (herbivore), X. atropurpureus (omnivore), Phytichthys chirus (omnivore) and the carnivorous Anoplarchus purpurescens were harvested from the wild, and fed omnivore and/or carnivore diets in the laboratory. Transcriptomes were sequenced for stomach tissues from two individuals per species and diet treatment. The number of shared orthologs varied with phylogenetic relatedness of the species (i.e., sister-taxa X. mucosus and X. atropurpureus shared the most expressed genes among the species), and differential expression and selection analyses are underway, although hydrogen-potassium ATPase appears to be under positive selection in some species. All four fish species strongly expressed pepsinogen and chitinase genes in their stomachs, yet biochemical activity levels (N ≥ 6 per species and diet treatment) of these two digestive enzymes matched natural diet, with the species consuming the most protein ( A. purpurescens) and chitin ( P. chirus) having the highest pepsin and chitinase activities, respectively. These activities were relatively unaltered by the laboratory diets, suggesting that activity level cannot be changed significantly through a dietary shift. Although intestinal carbohydrases typically show support for the Adaptive Modulation Hypothesis—a match among digestive enzyme activities with concentrations of ingested substrate—this may be one of the first investigations to observe such support for gastric enzymes. Thus, beyond being an important vertebrate innovation, the stomach may also provide digestive benefit depending on natural diet.

NSF Grant IOS-1355224 and NSF DBI-1852096

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 gut-microbiome and anxiety in male and female zebrafish
Authors: Lapoint Phoebe , LaPoint Phoebe , Uno Jennifer
Published: May 2023

Recent research from the CDC indicates that 41.5% of adults in the US classify themselves as anxious or depressed. Interestingly, anxiety disorders are disproportionately more prevalent in women than men. It is well established that the microbiome greatly influences stress responses, mood states, and other aspects of brain health including anxiety disorders. It is also known that the microbial composition differs in males and females. This study aims to determine the similarities and differences between the male and female zebrafish microbiome and identify if these differences impact anxiety. Zebrafish were treated with amoxicillin to decrease the total intestinal bacterial abundance. The zebrafish were then subjected to an acute stress protocol or a chronic stress protocol. For acute stress, fish were net stressed for three minutes, followed by 3 minutes of acclimation. Chronic stress was induced over 8 days with fish being stressed daily prior to the three minute net stress. Fish behavior and anxiety were assessed using the EthoVision tracking system and software. We observed a 48% and 67% decrease in bacterial abundance in males and females respectively treated with amoxicillin (p<0.05, n= 5). Interestingly both males and females treated with antibiotics showed significantly fewer right and left crosses following acute stress exposure- no significant differences were observed between male and female fish (p<0.05, n=10). In chronically stressed fish, no differences were seen in anxiety-like behavior in control or antibiotic-treated fish regardless of sex. These results support current research indicating the overall role of the microbiome in anxiety and depression however, the differences between intestinal bacteria in males and females behavior remains unclear.

Elon University

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Differential Expression of miRNAs by Anti-Obesity Treatment Sulforaphane in Skeletal Muscle of Diet-Induced Obesity in Mice
Authors: Rizk Nasser , Mohamed Omnia , Alasmar Dima
Published: May 2023

Background: Skeletal muscles comprise 40–60% of the body's total weight and 30% of the metabolic rate at rest. As the primary site for glucose uptake into tissues by insulin induction, it is crucial for metabolic homeostasis in the body. The natural isothiocyanate compound sulforaphane primarily functions as an antioxidant, but numerous studies have revealed that it also has anti-obesity properties. Recent studies have demonstrated that miRNAs are essential in controlling skeletal muscle dysfunction. The objective is to investigate the miRNA expression profile in the skeletal muscles of DIO mice given SFN and to ascertain their function by identifying the metabolic pathways and gene ontologies involved. Methods: Male mice of CD1 strain were randomized at age four weeks and fed a high fat diet to induce diet-induced obesity (DIO) followed by SFN and vehicle treatment for four weeks. Total RNA was extracted from the skeletal muscles of DIO mice, and small RNA sequencing was utilized to identify the microRNA expression profiles. In addition, pathway mapping and gene ontology (GO) tools were used to evaluate the biological processes and signaling pathways affected by the differentially expressed microRNAs. Results: Body weight, food intake, plasma glucose, and leptin levels were all significantly lower in the SFN-treated group compared to the control group. Furthermore, in SFN-treated DIO mice, eight differentially expressed miRNAs were detected, five upregulated (mmu-miR-150-5p, mmu-miR-486a-3p, mmu-miR-126b-5p, mmu-miR-140-3p, mmu-miR-92a-3p) and three of which were downregulated (mmu-miR-101a-3p, mmu-miR-29c-3p, mmu-miR-3074-5p). Furthermore, SFN treatment alters miRNAs that regulate genes involved in insulin signaling, MAPK, and PI3K/Akt signaling pathways, all essential regulators of skeletal muscle metabolism, including insulin resistance and obesity. Conclusion: SFN induced a change in the expression profiles of microRNAs in the skeletal muscle of DIO mice, which regulate gene targets of miRNAs involved in a variety of biological processes that combat obesity.

This study was supported by the Qatar National Research Foundation grant (NPRP9-351-3-075)

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.
Cardiac Adaptions to Exercise Training in Mice Lacking Adiponectin
Authors: Asher Andy , Medarev Steven , Faal Madikay , Smith Cole , Qasim Muhammad , Belenko Jasen , Mitchell Logan , Ojah-Maharaj Jayden , Hendrickson Dylan , Faynberg Victor , Morales Paula , Garcia Michelle , Pinto Jose , Muller-Delp Judy
Published: May 2023

Hypoadiponectinemia is associated with development of cardiovascular disease. We have previously reported that exercise-induced adaptations of the heart are impaired in mice with germline deletion of adiponectin. To determine a direct role for acute deletion of adiponectin in cardiac adaptations to exercise training, we exercise trained young adult mice with normal circulating adiponectin (wild type, WT) and mice in which adiponectin was acutely deleted (Cre-Lox conditional knockout system induced with Tamoxifen chow, AdipoKO) before undergoing 8 weeks of exercise training. Sedentary WT and AdipoKO mice were housed under similar cage conditions for 8 weeks. Lean mass and fat mass were assessed bi-weekly with Echo-MRI during the training and sedentary periods. Exercise tolerance, and cardiac function were assessed before and after completion of the 8 weeks training/sedentary period. Exercise training reduced fat mass and increased lean muscle mass in both WT mice and AdipoKO mice. Exercise training increased exercise tolerance in both WT mice and AdipoKO mice. Fractional shortening increased in WT mice, both sedentary and exercise trained, over the 8-week period, whereas fractional shortening tended to decrease in both sedentary and exercise trained AdipoKO mice. At the end of the 8-week exercise training/sedentary period, fractional shortening was significantly higher in WT mice compared to AdipoKO mice. At the end of the 8-week exercise training/sedentary period, ejection fraction was significantly higher in WT mice as compared to AdipoKO. Eight weeks of exercise training increased cardiac output in WT mice and cardiac output was higher in WT mice as compared to AdipoKO mice at the end of the 8-week exercise training/sedentary period. These data suggest that central cardiovascular adaptation is an important contributor to the increase in exercise tolerance that occurs in response to exercise training in WT mice. In contrast, in mice lacking adiponection, peripheral changes in metabolism and oxygen utilization are more likely contributors to the increase in exercise tolerance that occurs in response to exercise training.

NIH R56AG068156

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.