bluuebunny/crossref_metadata_2025 huggingface dataset:
Do senescent cells drive the ageing phenotype of skeletal muscle in vivo?
Authors: Shigdar Shahjahan , Staunton Caroline , Vasilaki Aphrodite , McArdle Anne
Published: June 2021

Loss of skeletal muscle mass and function are critical factors in the development of frailty. The number of senescent cells increases with age in rodents (Krishnamurthy et al., 2004) and primates (Kreiling et al., 2011). We hypothesise that these cells trigger a local and/or systemic chronic inflammatory status in old mice with the production of senescence associated secretory phenotype molecules (SASPs) and we further hypothesise that this leads to the activation of NF‐kB mediated inflammatory pathway seen in skeletal muscle of old mice (Vasilaki et al, 2006), potentially by the so‐called bystander effect (Nelson et al, 2017).

Initial studies have investigated whether key senescence associated molecules (such as p16, p21, and p53) are increased in the muscle bulk of old (24 months old) compared with young (3 months old) C57BL6 Wild Type (WT) mice in vivo. Whole quadriceps muscles from young and old mice were subjected to western blot analysis for senescence associated cyclin‐dependent kinase inhibitors, including p16, p21 and p53.

Western blot analysis demonstrated that muscle from old mice showed a significantly increased content of p16, p21, and p53 compared with muscles of young mice (p<0.05) and analyses are underway to characterise the nature of cells expressing these senescent proteins within the muscle bulk. Further studies will determine the potential production of a SASP by these cells and the effect on chronic activation of NF‐kB in muscle fibres of old mice.

Support or Funding Information

Work generously funded by the British Society for Research into Ageing and the Rosetrees Trust.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Novel intravital assessment of muscle cytosol H202 content supports a key role for motor unit remodelling in sarcopenia.
Authors: Staunton Caroline Amy , Vasilaki Aphrodite , Barrett‐Jolley Richard , McArdle Anne , Jackson Malcolm J.
Published: June 2021

Sarcopenia; the age‐related loss of muscle mass and function, significantly affects quality of life in the ageing population and has been linked to remodelling and loss of motor units. Reactive oxygen species (ROS) generation, inflammation and FOXO‐dependant muscle atrophy are three key pathways associated with muscle dysfunction and this study focusses on the role of H202 in skeletal muscle ageing.

The aim was to determine whether increases in H202 concentration occur in skeletal muscle fibres from adult (6–8 months) and old (26 months) mice and whether this was confined to denervated fibres, or additionally to healthy muscle fibres.

The role of hydrogen peroxide (H202) in motor unit remodelling was examined using AAV‐mediated transfection of cyto‐Hyper2 (a highly specific H202 probe), into muscle of a transgenic Thy‐1 CFP mice. AAV6‐Hyper2 (5×1010 vg/ml) was directly injected into the anterior tibialis (TA) muscles of mice at 28 days prior to surgical crush of the common peroneal nerve or sham control mice and the TA muscles of these mice were imaged using intravital fluorescence microscopy at 3, 7 and 21 days post‐crush. Electrophysiological approaches are also being utilised to examine the structure and function of fibres and how this changes with ageing.

Data from the sequential intravital images from adult mice showed that that the TA muscle fibres following nerve crush had an elevated H202 content that was statistically significant (p<0.001) by 3 days post nerve crush which coincided with the time at which neuromuscular junction (NMJ) breakdown occurred at the presynaptic terminus. Complete loss of pre‐synaptic structure of the NMJ was seen by 7 days post‐crush when H202 levels remained elevated and when skeletal muscle fibre atrophy was apparent. At 21 days post‐injury, full reinnervation of the muscle had occurred with both pre and post‐synaptic structures intact although there remained some faint AChR clustering. At this time point the muscle fibre H202 levels had returned to baseline values.

In light of these unique data, current work is examining aged Thy‐1 CFP mice (26 months old) to determine the fibre H202 content following nerve injury and the regenerative capacity of the nerves. Potential therapeutic targets are also being examined using RNA‐seq approaches to identify novel sprouting factors and proteins of interest that could be driving these processes.

Support or Funding Information

This work was funded by the MRC.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Muscle metaboreflex activity after an acute session of exercise under hypoxia
Authors: Crisafulli Antonio , Sainas Gianmarco , Magnani Sara , Roberto Silvana , Mannoni Mauro Ottavio , Pinna Virginia , Tocco Filippo , Doneddu Azzurra , Mulliri Gabriele
Published: June 2021

In healthy subjects, when the muscle metaboreflex (MM) is activated, mean blood pressure (MBP) increases because of a sympathetic‐induced increase in both systemic vascular resistance (SVR) and cardiac output (CO)1. Acute hypoxia vasodilation has been often reported despite the increased sympathetic tone2. We hypothesized that a single session of exercise under normobaric hypoxia (ENH) resulted in an attenuation of the MBP increment during the muscle metaboreflex activated immediately after the ENH session. 10 well trained healthy male subjects (age 34.2±11.7 yrs) participated in this study. In separate days they underwent, randomly assigned, three exercise sessions consisting of 10 min pedaling at a workload corresponding to 80% of anaerobic threshold previously assessed. In one session (TEST21%) subjects breathed normoxic air (O2 21%), in the other two tests they breathed hypoxic air with O2 concentration of 16% (TEST16%) or 13% (TEST13%) respectively. Immediately after each exercise session they underwent randomly assigned the following protocol: 1) muscle metaboreflex activation obtained by the post‐exercise muscle ischemia (PEMI) method, and 2) control exercise recovery (CER) test. Response to the metaboreflex for each cardiovascular parameter was assessed as PEMI minus CER level. Hemodynamic parameters were evaluated by impedance cardiography. Results show that SVR response was reduced during the MM after the TST13% with respect to the other two tests (−46.5±394.2 vs. +108.9±256.3 and +213.6±228.8 dynes•s‐1•cm‐5 respectively, p<0.05). However, the MBP response was similar between conditions. This because of an increased CO response which occurred during TEST13% in comparison with TEST21% and TEST16% (+421.3±545 vs. +63.2±322.9 and +128.3±238.6 ml respectively, p<0.05). It was concluded that an acute session of exercise under hypoxia is able to reduce the capacity to vasoconstrict the vascular bed during the metaboreflex activation obtained by PEMI. However, mechanisms controlling cardiovascular responses successfully defended MBP response by increasing CO which compensated for the reduced SVR increment.

Support or Funding Information

This study was supported by the University of Cagliari and the Italian Ministry of Scientific Research.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Virtual Unreality – Promise vs. Performance of Technology in Anatomy Education
Authors: Wainman Bruce , Pukas Giancarlo , Wolak Liliana , Zheng Eric , Norman Geoffrey
Published: June 2021

A number of studies have shown that computer generated, interactive, 3D projections (a type of virtual reality or VR) of human anatomy have serious handicaps when compared to ordinary physical models. The mechanism underlying the deficiency is not clear. In the present study we replicated the finding of a large benefit for physical models over equivalent VR; amounting to an effect size of 1.38. We then showed, with a series of experiments, that the advantage is not a consequence of haptic (touch) feedback, or “transfer appropriate processing” (Learning in 3D is more effective when tested in 3D). Instead, it appears that the advantage of the physical model is entirely a result of binocular vision; restricting viewing to one eye extinguishes the advantage. Additional testing with the Microsoft HoloLens, using an exact duplicate of the physical model rendered as a mixed reality (MR) object, showed performance equal to the 3D projection and equal to the physical model when learned and tested with monocular vision and much worse than the physical model. The 10–20 fold cost of using VR and MR learning objects over the physical models does not appear to be justified given the cost and inferior performance in increasing anatomic knowledge.

Support or Funding Information

Paul R. MacPherson Institute for Leadership, Innovation and Excellence in Teaching and the Faculty of Health Sciences, McMaster University.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Time course of changes in arterial and venous function during normal and hypertensive pregnancies in humans
Authors: Yoo Jeung‐Ki , Badrov Mark B. , Syed Owais , Parker Rosemary S. , Stickford Abigail S. , Okada Yoshiyuki , Best Stuart A. , Levine Benjamin D. , Fu Qi
Published: June 2021

Gestational hypertensive disorders (GHD) affect about 10% of pregnant women in the United States, and the most severe form (pre)eclampsia is the leading cause of maternal and fetal death and morbidity. The underlying mechanisms remain uncertain; however, impaired adaptation in maternal vascular function may be one contributing factor. We evaluated the time course of change in arterial and venous function before, early, late, and after pregnancy in women without a history of GHD (controls; n=26), women with a history of GHD (GHD history group; n=16), and women who developed GHD during the study (developed GHD group; n=7). Vascular and hemodynamic measurements were longitudinally performed prior to pregnancy (mid‐luteal phase), during early pregnancy (4–8 weeks of gestation), late pregnancy (32–36 weeks), and postpartum (6–10 weeks after delivery). A repeated‐measures analysis using linear mixed models was used for data analysis. At pre‐pregnancy, there was no difference in age, supine blood pressure, and heart rate among groups. Brachial artery endothelium‐dependent flow‐mediated dilation (FMD) showed significant differences among groups (group time interaction; P=0.03, Time; P=0.03, Group; P=0.01). Specifically, women who developed GHD in the study had lower FMD during early and late pregnancy (mean±SE; pre: 4.60±1.11%, early: 4.96±0.98%, late: 4.69±1.04%, and post: 5.64±0.97%) compared to controls (4.85±0.62%, 7.40±0.51%, 9.44±0.52%, and 6.91±0.53%) and the GHD history group (4.88±0.83%, 6.69±0.69%, 7.09±0.71%, and 5.25±0.79%). There were no significant interactions in forearm vascular resistance (FVR) or calf venous compliance (plethysmography; group time interaction P=0.9 and 0.6, respectively) among groups, while FVR decreased during pregnancy in all subjects. Our findings suggest that impaired endothelial functional adaptation during pregnancy, rather than regional (limb) vascular resistance and venous compliance is associated with the occurance of GHD in humans.

Support or Funding Information

This study was funded by the National Institutes of Health grant (R21HL088184), the American Heart Association Grant‐in‐Aid (13GRNT16990064), the Harry S. Moss Heart Trust, and the Texas Health Resources Research & Education Institute Award

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
ELP‐VEGF Treatment Improves the Maternal Syndrome of Preeclampsia in the Dahl Salt Sensitive (S) Rat
Authors: Ross Courtney A. , Maeda Kenji J. , Logue Omar C. , Bidwell Gene L. , Garrett Michael R. , Sasser Jennifer
Published: June 2021

Preeclampsia, a hypertensive disorder of pregnancy, is detrimental to both mother and fetus; however, there is currently no effective treatment for preeclampsia. The anti‐angiogenic protein sFlt‐1 has been implicated in the pathogenesis of preeclampsia through both clinical and experimental studies, leading us and others to propose that antagonism of sFlt‐1 via administration of vascular endothelial growth factor (VEGF) will reduce the maternal symptoms of hypertension and proteinuria in preeclamptic pregnancy. In this study, we tested the hypothesis that VEGF fused to the synthetic carrier elastin like polypeptide (ELP) will improve the maternal syndrome in the Dahl S rat model of superimposed preeclampsia. Female Dahl S rats (16–18 weeks of age) were placed in metabolic cages for 24‐hour urine collection, mated with Dahl S male rats, and randomly divided into control and ELP‐VEGF treated groups. ELP‐VEGF was administered via osmotic pump (5 mg/kg/day, Alzet 2ML1) beginning on day 10 of pregnancy, and pumps were replaced on day 17 of pregnancy. Urine was collected again on day 19, and blood and tissues were harvested on day 20. Urinary protein excretion (Bradford assay) did not differ between groups at baseline (87±11 vs 99±21 mg/d), but was significantly lower during late pregnancy in the ELP‐VEGF treated rats (* p=0.004, table). A subset of ELP‐VEGF‐treated rats (n=4) was implanted with telemetry transmitters (DSI) before mating. While previous studies have shown that blood pressure increases during pregnancy in the Dahl S rat, ELP‐VEGF treatment resulted in a fall in mean arterial pressure of 27±5 mmHg from day 9 to day 18 of pregnancy. No significant differences in fetal growth or litter size were observed following treatment. These data suggest that ELP‐VEGF treatment improves the maternal syndrome of preeclampsia without impairing fetal outcomes.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Vascular Permeability is increased in Cerebral Arteries from the Dahl S Model of Superimposed Preeclampsia
Authors: McClung Daniel , Maeda Kenji , Garrett Michael , Ryan Michael , Sasser Jennifer
Published: June 2021

Preeclampsia is clinically defined as elevated blood pressure after 20 weeks gestation along with other major organ involvement, such as brain, renal, or liver. It impacts 3–8 % of pregnancies, and there is currently no cure other than delivery of the placenta. The mechanisms leading to preeclampsia are not fully understood; however, recent work by our laboratory showed that the pregnant Dahl S rat closely mimics women with preexisting hypertension that develop preeclampsia. Therefore, pregnant Dahl S rats can be utilized to better understand the pathophysiological mechanisms and consequences of superimposed preeclampsia. Impaired cerebral vascular function has been implicated as a potential mechanism contributing to the increased risk of neurological complications associated with preeclampsia. In this study, we tested the hypothesis that pregnancy induces vascular permeability in cerebral arteries in Dahl S rats. Female Dahl S rats were mated at 16–18 weeks of age, while age‐matched virgin littermates were used as controls (n=5 per group). Middle cerebral arteries were isolated on gestational day 19–21, cannulated with glass pipettes, and pressurized to assess arterial permeability by measuring the change in intravascular pressure over time. Starling's Law states that fluid flux across a vessel wall is the result of hydraulic pressures and oncotic pressures due to differences in osmolality. In our model, the oncotic pressure gradient across the vessel wall was 0 mmHg, leaving only hydraulic pressures to determine fluid flux; therefore, the rate in pressure drop measured inside an isolated vessel is an indirect assessment of vascular permeability. Isolated vessels were equilibrated at 37°C for 30 minutes in physiological salt solution and pressurized to 75 mmHg. The diameter of isolated arteries after equilibration was 162±11 μm and 157±11 μm in virgin and pregnant rats, respectively (p=0.51). Intraluminal pressure was recorded every 5 minutes for one hour. As shown in the figure, the drop in intravascular pressure is greater in vessels isolated from pregnant rats compared to the pressure drop in vessels from virgin rats (*p< 0.01 vs virgin, n=5). Over the 60 minute experimental period, there was a significant difference in the drop in pressure permeability between the virgin and pregnant Dahl S rats (24.4±5.0 mmHg vs. 50.2±3.7 mmHg, respectively, P<0.01, n=5). These data indicate that pregnancy increases cerebral arterial permeability in Dahl S rats.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Effect of hypercapnia on the swallow‐breathing relationship in cats
Authors: Reed Mitchell , Huff Alyssa , Poliacek Ivan , Bolser Donald C. , Pitts Teresa
Published: June 2021

Swallow‐breathing coordination is critical for maintaining a clear airway during the act of swallowing. Swallows can occur during all phases of breathing, however, they are primarily initiated during expiration. The interaction between central pattern generators for swallowing and breathing contribute to this phase preference. While hypercapnia has known effects on the breathing central pattern generator, the effects of elevated CO2 on swallow‐breathing coordination are unknown. We examined the influence of hypercapnia on swallow‐breathing phase preference in the cat. Swallowing was induced in anesthetized spontaneously breathing cats by injection of water into the oropharynx and experiments were conducted under conditions of room air, 5% CO2, or 10% CO2. Electromyogram activity was measured using bipolar electrodes inserted into laryngeal and pharyngeal muscles (mylohyoid, geniohyoid, thyrohyoid, and thyropharyngeus), parasternal muscles and costal diaphragm. In cats breathing room air, 71% of swallows occurred during expiration (E), 12% during inspiration (I), 10% during the transition from inspiration to expiration (I to E), and 7% during the transition from expiration to inspiration (E to I). Under hypercapnic conditions swallows occurred more frequently during inspiration with 80% (5% CO2) and 68% (10% CO2) occurring during either the I or the E to I phases of breathing, and 16% (5% CO2) and 25% (10% CO2) occurring during expiration. These preliminary results suggest hypercapnia may affect swallow‐breathing coordination by causing the initiation of swallow to occur in more inspiratory phases (I and E to I).

Support or Funding Information

Supported by R00‐HL 111215, NIH HL 103415, and 1OT20D001983.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
A new method for automated and unbiased classification of respiratory‐related electromyogram (EMG) and pressure waveforms
Authors: Sunshine Michael Daniel , Fuller David Dwight
Published: June 2021

Respiratory muscle EMG activity recorded with intramuscular electrodes and pressure waveforms recorded using whole body plethysmography are common outcome measures in pre‐clinical studies of respiratory control in awake‐behaving animals. These methodologies produce complicated waveforms which are dynamically changing on short time scales. Indeed, it is rare for an awake rodent to breathe with the regular and “metronomic” pattern that often typifies breathing in anesthetized rodents and respiratory motor patterns observed in vitro. However, many studies in rodent models ignore the complex behavioral influences on respiratory waveforms, and only limited periods of “stable breathing” are chosen for detailed analyses. In ongoing studies, we are developing an unbiased, automated classification system to compare the features (e.g., amplitude, duration), frequency (number of occurrences), and patterning (presentation order) of respiratory‐related EMG and pressure waveforms. The detection algorithm weights specific features of each waveform including: peak‐to‐peak amplitude, time to peak amplitude, area under the curve, and total duration of the event. K‐means clustering is then used to separate the different waveforms into distinct groups. The algorithm was validated using pressure waveforms collected via whole body plethysmography or intramuscular diaphragm EMG in awake adult male rats. For both EMG and pressure data, the algorithm was able to detect and quantify the occurrence of distinct waveforms likely associated with sniffing and tidal breathing. The waveforms were automatically stratified based on waveform characteristics such as amplitude and rate of change (e.g., incrementing or decrementing patterns). This analysis revealed at least six distinct waveforms for both the pressure and EMG data. We conclude that the method can rapidly stratify and quantitate respiratory‐related waveform data in a completely unbiased manner.

Support or Funding Information

T32‐HD043730 (MDS). SPARC OT2 OD023854 (DDF). 1 R01 NS080180‐01A1 (DDF)

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Characterization of alterations in basal inspiratory motor output and chemical control of breathing in two Parkinson's Disease rat models
Authors: Solomon Irene C. , Tuchinsky Jacob J. , Brogan Anna , Wadolowski Robert M.
Published: June 2021

Respiratory dysfunction in Parkinson's Disease (PD) patients manifests as a variety of altered breathing patterns that are suggested to result from impairment of central respiratory control. Experimental rodent (rat) PD models have been developed and studied in order to gain insight into both the motor and non‐motor symptoms that underlie PD; however, very few studies have focused on central respiratory deficits in any of these models. Ongoing work in our laboratory has begun to address this issue by characterizing the alterations in basal inspiratory motor output (tongue and/or diaphragm EMG activity) and chemical control of breathing in the 6‐hydroxydopamine (6‐OHDA) neurotoxin‐induced unilateral substantia nigra (SN)‐ and medial forebrain bundle (MFB)‐lesioned rat PD models. For these studies, experiments were conducted in spontaneously breathing urethane‐anesthetized adult female rats 2‐weeks after SN (n=6) or MFB (n=8) 6‐OHDA injections; control rats received vehicle injections (SN, n=5; MFB, n=5). Following recording of basal inspiratory‐related activity, rats were exposed to either hypoxic (12% O2 for 90s; HVR) or hypercapnic (7% CO2 for 5 min; HCVR) gas. Our preliminary data indicate that both SN‐ and MFB‐lesioned rats exhibited alterations in respiratory activity but the respiratory behaviors noted were not identical. Compared to control rats, SN‐lesioned rats exhibited (1) slightly higher basal breathing frequency; (2) similar HVR frequency increase; (3) attenuated HVR amplitude increase; and (4) similar HCVR frequency and amplitude increases. In contrast, MFB‐lesioned rats (compared to control rats) exhibited (1) similar basal breathing frequency; (2) slightly enhanced HVR frequency increase; (3) no change or a decrease in HVR amplitude; (4) markedly reduced or absent HCVR frequency increase; and (5) similar HCVR amplitude increase. While these 6‐OHDA site‐targeted PD models appear to exhibit differences in basal respiratory behaviors and chemical control of breathing deficits, our preliminary observations indicate that both SN‐ and MFB‐lesioned rats are viable models for studying respiratory abnormalities in PD. However, we suggest that it may be necessary to study multiple PD models to fully capture the ventilatory abnormalities seen in PD patients and identify the mechanisms that underlie these respiratory abnormalities.

Support or Funding Information

NIH NS101737; Thomas Hartman Center for Parkinson's Disease Research at Stony Brook University

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Maternal High Fat Diet Causes Changes in Pulmonary Function and Persistent Deficits in Pulmonary Vascularization
Authors: Heyob Kathryn M. , Mieth Saya , Lee Robert J. , Rogers Lynette K.
Published: June 2021

Background

Maternal obesity has been associated with multiple complications for both the mother and the child including hypertensive disorders and gestational diabetes for the mother and macrosomia and congenital abnormalities for the child. Previously, we demonstrated increases in inflammation, deficits in alveolarization, and decreases in angiogenic pathways in the offspring (PN21) of mice maintained on high fat diets during pregnancy and lactation. For the current studies we tested the hypothesis that maternal obesity would impair lung function in the offspring and that angiogenic pathways would continue to be depressed into adulthood (3 mon).

Methods

Female mice were fed high fat diets (HFD) or control diets (CD) for 8 weeks prior to mating and through weaning. At weaning the pups were placed on either CD or HFD until 3 months of age. Pulmonary function was assessed using a Scireq Flexivent. Expressions of angiogenic pathway proteins were measured by western blot in lung tissues.

Results

At 3 months, pulmonary function tests indicated decreased inspiratory capacity, resistance (Rrs), elastance (Ers) and airway resistance (Rn) in the offspring that were fed HFD after weaning. These finding were exacerbated in pups having been born to and nursed by mothers fed HFD. Protein expression of PTP1B was also suppressed at 3 months.

Conclusions

Maternal and adult HFD results in altered pulmonary function at 3 months of age. Changes in pulmonary function may contribute to increased morbidities associated with obesity.

Support or Funding Information

The authors gratefully acknowledge funding from the NIH/NICHD, R01HD0880833.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
The role of Corticotrophin Releasing Hormone in Paraventricular Nucleus in Elevated Sympathetic Outflow in Spontaneous Hypertension Rat
Authors: Zhou Jingjing , Ma Hui‐Jie , Li De‐Pei
Published: June 2021

Corticotrophin releasing hormone (CRH) is one of the critical neuropeptides that regulate neuroendocrine and autonomic function. CRH expression level is significantly increased in the hypothalamic in patients with essential hypertension. However, the roles of CRH in the regulation of blood pressure and sympathetic outflow is unknown. We hypothesized that CRH and its receptors in the paraventricular nucleus (PVN) in the hypothalamus are involved elevated sympathetic vasomotor tone in essential hypertension. Arterial blood pressure basal (ABP), heart rate (HR), and renal sympathetic activity (RSNA) were recorded in anesthetized male adult spontaneous hypertension rats (SHR) and its normotensive control Wistar‐Kyoto (WKY) rats. Bilateral microinjection of CRH into the PVN dose‐dependently increased the ABP, HR, and RSNA in both SHRs and WKY rats. CRH‐induced sympathoexcitatory effect was significantly greater in SHR than in WKY rats and this effect was eliminated by microinjection of the CRH receptor 1 (CRHR1) specific antagonist NBI 35965 but not antisauvagine‐30, the specific antagonist for CRH receptor 2 (CRHR2). Bilateral microinjection of NBI 35965 into PVN significantly reduced the basal ABP, HR, and RSNA in SHR but in WKY rats. However, microinjection the antagonist antisauvagine‐30 into the PVN did not significantly alter ABP, HR, and RSNA in either SHR or WKY rats. Furthermore, the CRHR1 immunoreactivity was positive in retrogradely labeled PVN‐RVLM neurons. In addition, western blotting analysis revealed that CRHR1 expression levels in the PVN was significantly higher in SHR than in WKY rats. These data suggest that the enhanced CRH and its receptor function in the PVN is involved in elevated sympathetic drive in essential hypertension.

Support or Funding Information

This work was supported by the National Institutes of Health (Grants MH096086 to D.‐P. L.).

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Effect of Graded Sympathetic Activation on Regional Cerebral Vascular Conductance
Authors: Kaur Jasdeep , Barbosa Thales C. , Young Benjamin E. , Stephens Brandi Y. , Vranish Jennifer R. , Brothers R. Matthew , Fadel Paul J.
Published: June 2021

The role of sympathetic nervous system in cerebral blood flow regulation remains poorly characterized. Previous studies have shown heterogeneity in regional cerebral circulation in response to various stimuli such as exercise, hypoxia, hypocapnia, etc. Recently, Ogoh et al. demonstrated that a moderate level (−50 Torr) of lower body negative pressure (LBNP) caused a significant reduction in internal carotid artery (ICA) blood flow, whereas vertebral artery (VA) blood flow remained unchanged, albeit trending towards a lower blood flow. Although a moderate increase in sympathetic nerve activity (SNA) occurs at −50 LBNP, it has been shown that SNA increases progressively with higher levels of LBNP. Whether VA blood flow is protected at higher levels of LBNP remains unknown. In this study, we tested the hypothesis that greater reflex‐mediated sympathetic activation via a higher level of LBNP will reduce conductance and blood flow to both the ICA and VA. In 9 young, healthy men, heart rate (ECG), arterial blood pressure (brachial sphygmomanometer), VA, ICA, and brachial artery blood flow (duplex Doppler ultrasound), middle cerebral artery (MCA) blood velocity (transcranial Doppler) and end‐tidal CO2 (ETCO2; capnograph) were measured at rest, and during 3–5 min of low, moderate and high LBNP (−30, −50, and −70 Torr, respectively). Conductance was calculated as blood flow of the respective artery/mean arterial pressure. Brachial artery blood flow and conductance were significantly reduced during all LBNP trials, indicating reflex‐mediated sympathetic vasoconstriction. Neither ETCO2 (Δ −1.9 ± 1.3 mmHg relative to baseline, p=0.18) nor any of the cerebral blood vessel measures were affected during −30 Torr LBNP. At −50 Torr LBNP, a reduction in ETCO2 (Δ −5.3 ± 1.6 mmHg relative to baseline, p=0.01) was accompanied by a reduction in ICA conductance (Δ −17.0 ± 8.4% baseline, p=0.057) whereas VA conductance remained unchanged (Δ −8.6 ± 5.6% baseline, p=0.24). Interestingly, with a similar reduction in ETCO2 at −70 Torr LBNP (Δ −4.3 ± 1.3 mmHg relative to baseline, p=0.04), there was a significant reduction in both ICA (Δ −13.1 ± 3.1% baseline, p=0.017) and VA conductance (Δ −20.4 ± 5.3% baseline, p=0.019). Thus, VA conductance was unaffected during low and moderate levels of LBNP however, high levels of LBNP induced a significant reduction in VA conductance and blood flow and this reduction appeared to be independent of the decrease in ETCO2. Collectively, these preliminary findings suggest that large increases in reflex‐mediated sympathetic activation via high levels of LBNP causes significant reductions in both ICA and VA conductance and blood flow.

Support or Funding Information

1 RO1 HL 127071

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
A novel non‐invasive method to measure sympathetic activity and autoregulation in humans
Authors: Wilson Richard JA. , Jendzjowsky Nicholas , Steinback Craig , Tsai Willis H. , Herman Robert J.
Published: June 2021

Current methods to assess sympathetic nervous system activity are associated with technical difficulty, invasiveness (microneurography) and poor temporal resolution ([plasma norepinephrine]). Use of heart rate variability overcomes most of these issues but is controversial because of limited accuracy. We have developed a quick, easy and non‐invasive approach based on spectral domain optical coherence tomography (OCT) that also allows investigation of arterial autoregulation. Here, we compare OCT and heart rate variability to microneurography, the gold standard of sympathetic assessment. We recruited 6 healthy males (26±3y) and 5 healthy females (23±1y), instrumented them for ECG and muscle sympathetic nerve microneurography and exposed them to respiratory and sympathetic provocations.

Choroid vascular perfusion density (VPD) decreases with cold pressor test, inhaled hypoxia and breath‐hold, and increases with hyperoxia and hyperventilation suggesting that sympathetic activity dominates choroid responses. In contrast, retinal pigment epithelium VPD was unaffected by the cold pressor test, increased with hypoxia and breath hold and decreases with hyperoxia and hyperventilation, suggesting autoregulation dominates the retinal pigment epithelium. With regards to integrated muscle sympathetic nerve activity, heart rate variability had low predictive power whereas OCT was strongly (inversely) correlated (R= −0.91; p<0.01).

These data suggest OCT may provide a novel approach to assessing autoregulation and sympathetic activity with superior predictability compared to heart rate variability. Given that sympathetic nervous system activity is a main determinant of autonomic function, sympathetic excitation is associated with serious cardiorespiratory/metabolic diseases and autoregulation is critical for brain health, we suggest that this new OCT technique will be of broad use to clinicians and researchers alike.

Support or Funding Information

This study was supported by Canadian Institute for Health Research (RJAW & WT). RJAW is an Alberta Innovates Health Solutions Senior Scholar. NGJ received postdoctoral salary support for this project from Alberta Innovates Health Solutions and the T Chen Fong Foundation.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Acute preoperative anti‐inflammatory treatment in a rat model for postoperative cognitive dysfunction; a role for the gut‐brain axis?
Authors: Schoemaker Regien G. , Hovens Iris B. , Falcao Salles Joana G. , de Haan Jacco J. , van Leeuwen Barbara L.
Published: June 2021

Background

Inflammation is considered a key factor in the development of post‐operative cognitive dysfunction (POCD). We hypothesize that acute preoperative anti‐inflammatory treatment with ibuprofen improves postoperative cognitive performance involving the gut‐brain axis in a rat‐model of POCD.

Methods

Male Wistar rats of 3 and 23 months old were fasted and received one preoperative bolus of ibuprofen (15 mg/kg i.p.) or handling without intervention as control, 30 minutes before being subjected to major abdominal surgery. Before and 7 days after intervention, fecal samples were collected to analyse the gut microbiome. Subsequently, rats were tested in the open field, novel object‐ and novel location recognition test and Morris water maze. Microglial morphology (IBA‐1) and neurogenesis (Double cortin) were assessed by immunohistochemistry after sacrifice at day 14.

Results

Ibuprofen treatment improved postoperative spatial memory but not spatial learning, and increased microglial activity and neurogenesis in the hippocampus. A principle coordinate analysis of the gut microbiome revealed a significant effect of age (p=0.001), no effect of Ibuprofen, but a significant interaction between these parameters (p =0.045). Microbiome richness appeared positively correlated to spatial learning, and negatively correlated to neurogenesis.

Conclusion

Our data indicate that preoperative ibuprofen treatment can selectively improve spatial memory. As this effect coincides with microglia activation and increased neurogenesis in the Dentate Gyrus of the hippocampus, we conclude that Ibuprofen may improve POCD by selectively interfering with hippocampal Dentate Gyrus function. Although gut microbiome parameters showed age‐, but not Ibuprofen‐related differences, associations with behavior and neurogenesis may support involvement of gut‐brain interactions in POCD.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
N‐Cadherin Juxtacrine Signaling Maintains Blood Brain Barrier and Cognitive Function
Authors: Lee Quinn S. , Kruse Kevin N. , Marottoli Felecia M. , Thomas Riya , Sun Ying , Tai Leon M. , Komarova Yulia A.
Published: June 2021

The blood brain barrier (BBB) consists of a specialized microvasculature with highly restricted permeability to both low and high molecular weight proteins. The BBB plays a critical role in maintaining tissue‐fluid homeostasis and preventing blood‐to‐brain paracellular diffusion of plasma components that can cause neuronal dysfunction. The BBB is composed of brain endothelial cells (BEC), which physically interact with pericytes at the basement membrane. BECs and pericytes express N‐cadherin, which forms homophilic adhesions to establish cross‐communications between these cell types. The role of N‐cadherin in the BBB is not well understood. We have demonstrated that an endothelial specific deletion of N‐cadherin gene (Cdh2) in mice resulted in increased permeability of the BBB in a size dependent manner, suggesting that N‐cadherin juxtacrine signaling in endothelial cells restricts BBB permeability. These changes in the BBB permeability were not associated with pericyte loss since we observed an increase in capillary coverage by pericytes in the cerebral cortex in these mice. To gain a holistic picture of N‐cadherin juxtacrine signaling in maintenance of the BBB, we utilized N‐cadherin biomimetic surfaces to induce signaling in a cell culture model. We found that Trio, a Rho guanine nucleotide exchange factor consisting of two GEFs, is recruited to N‐cadherin adhesions to induce Rac1 signaling through activation of GEF1. Genetic studies in humans provide a causal link between a deficiency of Trio GEF1 activity and neurodevelopmental diseases such as intellectual disability, suggesting that increased vascular leakage and associated neurotoxicity impairs cognitive function. Therefore, we tested whether N‐cadherin deficient mice exhibited cognitive deficit. Using the Morris water navigation task, we demonstrated that loss of N‐cadherin in endothelial cells results in a deficit in spatial learning and memory. This difference to control mice became indistinguishable with age, suggesting that deficiency of N‐cadherin juxtacrine signaling may be an underlying cause for cognitive dysfunction in the elderly population. Hence, mice lacking Cdh2 gene in endothelial cells may serve as an animal model to study vascular leakage and cognitive function in aging.

Support or Funding Information

NIH T32 HL027829, NIH R01 HL103922

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Mutations in the PH Domain of SH2B1 Result in Energy Imbalance and/or Impaired Glucose Metabolism
Authors: Flores Anabel , DeSantis Lauren C. , Malaga Alvaro , Clutter Erik S. , Argetsinger Lawrence S. , Myers Martin G. , Carter‐Su Christin
Published: June 2021

Mutations in the scaffold protein SH2B1 have been identified in individuals with severe early‐onset childhood obesity, insulin resistance, and hyperphagia. This phenotype is mirrored in mice lacking SH2B1 (SH2B1‐KO mice). Three of these mutations, including the P322S mutation, are located in the pleckstrin homology (PH) domain of SH2B1, suggesting that the PH domain is important for the overall function of SH2B1. To gain insight into how SH2B1 regulates energy balance and the function of the PH domain in SH2B1, we used CRISPR‐Cas9 to make a mouse model containing the human P322S obesity‐associated mutation. We also obtained a mouse with an indel that produced a two‐amino acid deletion (ΔP317, R318) in the PH domain. Body weight, food intake, glucose tolerance and insulin tolerance do not appear to be substantially altered by the P322S mutation when mice are fed normal chow (9% fat). However, when the mice were challenged by a high fat (60%) diet, the P322S mutation decreased glucose tolerance. No effect on insulin tolerance was noted. The results with the P322S mouse suggest that the P322S mutation does not have as profound an effect on energy balance as the P322S mutation in humans. However, the decreased glucose tolerance in the absence of insulin sensitivity seen in the P322S mice versus WT control littermates challenged with a high fat diet raises the possibility that the P322S mutation impairs the function of SH2B1 in beta cells and/or liver. While the P322S mutation does not have a profound effect on energy balance, the P322S mutation negatively impacts the survival of SH2B1 P322S homozygote mice. Homozygotes are born at half the expected Mendelian ratio, suggesting that SH2B1 may play a role in the implantation of the fetus and/or development of the pups in the womb. Similar to the SH2B1‐KO mice, the ΔP317, R318 mice show increased body weight, decreased glucose tolerance, decreased insulin sensitivity, and increased adiposity. Surprisingly, the ΔP317, R318 mice do not show increased food intake, suggesting that their increased body weight is due to decreased energy expenditure. These two mouse models emphasize the importance of SH2B1, and in particular, the PH domain of SH2B1, in regulating energy balance and glucose homeostasis.

Support or Funding Information

Howard Hughes Medical Institute Gilliam Fellowship, NIH T32‐GM008322, NIH RO1‐DK54222, NIH RO1‐DK107730, Univ of Michigan Rackham Merit Fellowship

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
A comparison of liquid vinegar and commercial vinegar pills for managing insulin resistance and postprandial glucose concentrations
Authors: Johnston Carol S. , Feise Natasha
Published: June 2021

A recent meta‐analysis concluded that vinegar consumption could be considered effective adjunct therapy for improving glycemic control. However, liquid vinegar consumption is often poorly tolerated and ingestion can invoke nausea. These investigations examined the effect of liquid vinegar versus commercial vinegar pills on insulin resistance and postprandial glycemia in healthy adults. These trials were approved by the university IRB, and all participants provided written consent. All participants were healthy (fasting glucose concentrations averaging 91–94 mg/dl). An 8‐week, parallel arm, randomized controlled trial examined the efficacy of liquid vinegar ingestion (2 Tbsp. red wine vinegar twice daily with meals [3.6 g acetic acid]) versus vinegar pill ingestion (2 vinegar tablets daily with meals [0.045 g acetic acid]) on HOMA‐IR. Eleven participants (28.6±7.0 y; 29.3±4.4 kg/m2) and twelve participants (28.0±7.7 y; 28.2±5.9 kg/m2) completed the trial in the liquid and pill groups respectively. After 8 weeks, insulin resistance was reduced 12% in the liquid vinegar group as compared to a 7% rise the pill group (change in HOMA‐IR scores: −0.66±1.3 vs. +0.31±1.1; p=0.079). A crossover trial (n=12) examined the efficacy of liquid vinegar ingestion (25 g apple cider vinegar [1.25 g acetic acid]) versus vinegar pill ingestion (4 vinegar tablets [0.70 g acetic acid] either consumed whole or crushed and dissolved in water) on postprandial glycemia. At 30 minutes following meal ingestion (buttered bagel + juice; 106 g carbohydrate), blood glucose concentrations at 30 minutes post‐meal were reduced 12% in comparison to the pill group or to a no vinegar control (135.6±15.8, 154.3±22.2, 152.7±30.6, and 157.7±22.8 mg/dl for the liquid vinegar, whole pill, crushed pill, and control groups respectively; p=0.023). These data suggest that in healthy adults, commercial vinegar pills with acetic acid content ranging from 45–700 mg acetic acid per serving are not effective for improving glycemic control.

Support or Funding Information

This work was supported by the Barrett Honors College, Arizona State University.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Exogenous ketones lower blood glucose level
Authors: Ari Csilla , Kovacs Zsolt , Murdun Cem , Koutnik Andrew P. , Goldhagen Craig R. , Rogers Christopher , Park Collin , Bharwani Sahil , Diamond David M. , D'Agostino Dominic P.
Published: June 2021

Certain disease conditions, involving inflammation and oxidative stress, are accelerated by high blood glucose levels. The safe reduction of blood glucose levels is difficult due to their regulation by powerful homeostatic mechanisms. The ketogenic diet (KD) induces a metabolic shift towards fatty acid oxidation and hepatic ketogenesis, elevating the ketone bodies acetoacetate (AcAc), β‐hydroxybutyrate (βHB), and acetone in the blood, which serve as alternative metabolic substrates to glucose. However, patient compliance to KD can be low; therefore, exogenous ketones provide an alternative method to establish and maintain elevated blood ketone levels. In this study, we tested the changes in blood glucose and ketone (βHB) levels in response to acute, sub‐chronic and chronic administration of one or more ketogenic compounds in either a post‐exercise or rested state. Rodent models with (WAG/Rij rats, WR and GLUT1Deficiency Syndrome mice, GLUT1D) and without (Sprague Dawley rats, SPD) pathology were tested. Experimental groups included either KD, standard diet with water (control, C) or in combination with the following ketogenic compounds: 1,3 butanediol (BD), beta hydroxybutyrate ketone mineral salt (KS), KS with medium chain triglyceride (KSMCT), BD acetoacetate diester (KE), KE with MCT (KEMCT), and KE with KS (KEKS).

In SPD rats without exercise, KD, KS, KE and KSMCT significantly reduced blood glucose levels, compared to control. After exercise blood glucose was significantly lower in the KEMCT group, compared to control. In WR rats KE, KS, KSMCT, KEKS and KEMCT groups had lower blood glucose than control, in both a rested or post‐exercise state. In GLUT1D mice without exercise, KD and KS resulted in significantly lower glucose levels. These results indicate that ketogenic compounds were efficacious in reducing blood glucose levels in and outside the context of exercise.

Support or Funding Information

University of South Florida Foundation, GLUT1 Deficiency Syndrome Foundation, National Development Agency of Hungary

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.