bluuebunny/crossref_metadata_2025 huggingface dataset:
Age Associated Downregulation of Glutamate/GABA Transporters Expression in Rostral Ventral Lateral Medulla (RVLM)
Authors: Balivada Sivasai , Pawar Hitesh J , Montgomery Shawnee , Ganta Chanran K , Kenney Michael J
Published: November 2023

Physiological function is altered with advancing age, including changes in sympathetic nervous system regulation. Studies focused on Glutamate/GABA ionotropic receptors using pharmacological agonists and antagonists in the rostral ventral lateral medulla (RVLM) indicates changes in medullary mechanisms regulating sympathetic nerve discharge (SND) in aged Fisher 344 rats. Identifying molecular mechanisms involved in this alteration is necessary to understand the regulation of central sympathetic neural circuits. Based on this rationale, we hypothesized that aging alters the basal regulation of RVLM Glutamate/GABA system‐associated genes. To test this hypothesis, the RVLM containing area was micro‐punched from young, middle‐aged and aged Fisher 344 rats. RNA level expression changes in RVLM GABA/Glutamate system‐associated genes were analyzed using RT2 profiler array and Taqman® real‐time PCR. Genes that showed >2fold differences in expression were analyzed at protein level by using immunoblot analysis. Downregulation of RVLM glutamate (Slc1a6) and GABA (Slc6a13) transporter genes was observed in aged compared with young rats at the RNA level, with a similar trend at the protein level. Slc1a6 and Slc6a13 transporters are known to modulate the amount of Glutamate/GABA in synaptic cleft and extra synaptic space. Down regulation of these transporters suggests there may be an altered Glutamergic/GABAergic balance in the aged RVLM.

Support or Funding Information

Supported by NIH AG‐041948.
Neuronal Nitric Oxide Synthase Colocalizes with N‐methyl‐D‐aspartate (NMDA) and Alpha‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic Acid (AMPA) Receptors in the Dorsolateral Periaqueductal Gray of Rats
Authors: Lin Li‐Hsien , Jones Susan , Dampney Roger A. , Talman William T.
Published: November 2023

The midbrain periaqueductal gray (PAG) plays an important role in cardiovascular regulation, respiratory control, pain modulation, and autonomic responses to stressful stimuli. Among the four columns of the PAG, the dorsolateral PAG (dlPAG) contains the highest density of neurons that express neuronal nitric oxide synthase (nNOS), the enzyme for synthesis of nitric oxide (NO) in neurons. Because inhibition of NO synthesis in the dlPAG produces pressor responses, attenuates fear responses and attenuates stress responses, it has been suggested that NO may modulate cardiovascular regulation and responses to fear and stress. NMDA type and AMPA type glutamate receptors are also expressed in the dlPAG and have been implicated in cardiovascular control and defensive behavior. Physiological studies have suggested that NO and glutamate receptors may interact in the dlPAG in cardiovascular regulation and stress responses. An NO donor injected into the dlPAG has been shown to decrease cardiovascular responses induced by NMDA, while an nNOS inhibitor increased them. NO‐induced flight behavior was prevented by antagonists to NMDA or AMPA receptors in the dlPAG. However, anatomical data to support interactions between NO and glutamate receptors in the dlPAG have been missing. We performed fluorescent immunohistochemistry for nNOS, NMDAR1 (subunit of NMDA receptor) and GluR2 (subunit of AMPA receptor) and examined labeled sections with confocal microscopy to test the hypothesis that nNOS and glutamate receptors colocalize in the rat dlPAG. We found that nNOS and NMDAR1 immunoreactivity (IR) colocalize in dlPAG neurons in rat. We noted 94.9 ± 1.1% nNOS‐IR containing neurons in the dlPAG also contained NMDR1‐IR, while 26.9 ± 4.2% NMDAR1‐IR containing cells also contained nNOS‐IR. Colocalization of nNOS‐IR and GluR2‐IR was also observed in the dlPAG with 91.9 ± 2.3% of nNOS‐IR containing neurons also containing GluR2‐IR and 28.2 ± 5.5% of GluR2‐IR containing cells also containing nNOS‐IR. NMDAR1‐IR and GluR2‐IR also colocalized in the dlPAG. Of the NMDAR1‐IR containing dlPAG cells 78.6 ± 9.1% were positive for GluR2‐IR while 65.7 ± 1.7% of GluR2‐IR containing dlPAG cells were positive for NMDAR1‐IR. Our data support our hypothesis that nNOS colocalizes with NMDA and AMPA receptors in the dlPAG and provide an anatomical basis for interaction between NO and glutamate receptors in regulating cardiovascular function and responses to fear and stress by the dlPAG.

Support or Funding Information

NIH R01HL088090 and VA Merit Review
Synaptic gating of viscerosensory signals in the solitary tract nucleus
Authors: McDougall Stuart , Thek Kimberly , Guo Haoyao , Allen Andrew
Published: November 2023

Inhibitory input at the solitary tract nucleus (NTS) is thought to alter autonomic reflex performance. Somatostatin (SOM) neurons are a class of inhibitory interneuron within the central nervous system and present within the NTS. Here we aimed to quantify the impact inhibition had on vicerosensory signal throughput within the NTS. Using a SOM‐Channel rhodopsin 2‐YFP mouse model, we took whole cell recordings from NTS neurons in horizontal brain stem slices that contained both the NTS and solitary tract (ST). This model allowed the specific activation of the SOM inhibitory network within NTS via ChR2. First we targeted SOM‐ChR2‐YFP positive neurons to characterise LED pulse parameters and assay boundaries. Each LED pulse (465 nm, 10 mW) evoked one action potential regardless of pulse duration (0.5 to 100 ms). We then recorded neurons randomly to determine if they received ST input and/or SOM input. LED pulses evoked consistent action potential dependent IPSCs in recorded neurons. Where all (n=42) exhibited LED‐evoked IPSCs and none exhibited LED‐evoked EPSCs or exhibited ChR2 currents. LED‐evoked IPSC amplitude increased with LED duration indicating converging inhibitory input at these NTS neurons. Combined, these data indicate SOM input to NTS neurons is exclusively inhibitory and that though SOM neurons are relatively sparse, SOM efferents synapse extensively throughout the NTS. Shocks to the solitary tract evoked low jitter EPSCs that identified second order NTS neurons. We demonstrated that almost all randomly sampled neurons were second order. Some SOM‐ChR2‐YFP neurons also received direct ST input and additional inhibitory input from other SOM interneurons. We investigated the neurotransmitters and post synaptic receptors involved and find LED‐evoked IPSCs were both GABA and glycine mediated. This finding was surprising as glycinergic transmission has not been described in the medial NTS previously. In current clamp studies, we determined the impact of SOM input on action potential (AP) generation and throughput. LED‐IPSPs prevented spontaneous AP firing when neurons were depolarized and delayed AP onsets in response to current injections. LED‐IPSPs also prevented ST‐evoked AP firing, effectively dropping throughput from 86.7 to 6.7%. Combined, these data indicate that an extensive inhibitory network exists within the NTS that likely operates to coordinate or alter autonomic reflex function.
Hypoxia‐Inducible Factor (HIF)‐1 Alpha Expression Induced by Proinflammatory Cytokines in NG108‐15 Neuronal Cells
Authors: Haibara Andrea S , Sharma Neeru M , Patel Kaushik P
Published: November 2023

Previous studies have shown that upregulation of proinflammatory cytokines, such as interleukin (IL)‐1β and tumor necrosis factor (TNF)‐α, in the paraventricular nucleus (PVN) has been related to the increased sympathetic outflow seen in heart failure. Recently, we have observed that HIF‐1α, a transcription factor responsible for inducing various genes, is also increased in the PVN of rats with heart failure. In addition, HIF‐1α siRNA administered to the PVN normalizes the increased renal sympathetic nerve activity in rats with HF. However, the specific relationship between proinflammatory cytokines and HIF‐1α expression remains unclear. Therefore, we hypothesized that the increased proinflammatory cytokines would cause augmentation of the HIF‐1α expression. To test this hypothesis, we stimulated NG108‐15 neuronal cell culture with IL‐1β and TNF‐α (10 ng/ml) and evaluated the HIF‐1α protein expression using the Western Blot technique at different time points (4, 8, 16 and 24h). Our results showed a significant increase (1.7 fold) in the expression of HIF‐1α 24h after the treatment of the cells with IL‐1β in comparison with untreated cells. Concomitantly, IL‐1β treatment also induced significant increase in nNOS expression (2.2 fold). In contrast, the treatment of the cells with TNF‐α failed to induce any significant changes in HIF‐1α over this time frame, but induced a significant increase (1.5 fold) in the nNOS expression 16h after treatment. Taken together, these results show that cytokines, particularly IL‐1β, induces enhanced expression of HIF‐1α in NG108‐15 cultured neurons and also suggest that perhaps increased expression of HIF‐1α due to the proinflammatory cytokines is may not be directly involved in the up‐regulation of nNOS in cultured NG108‐15 cells.

Support or Funding Information

CNPq‐Brazil 234520/2014‐0 and NIH grants HL124104 & HL62222
Microinjection of Brain‐Derived Neurotrophic Factor (BDNF) into the Subfornical Organ Decreases Blood Pressure
Authors: Smith Pauline M , Ferguson Alastair V
Published: November 2023

Brain‐derived neurotrophic factor (BDNF) is a peptide known to be involved in several mammalian physiological processes including cardiovascular homeostasis. Intracerebroventricular (icv) BDNF administration and microinjection of BDNF into discrete brainstem nuclei have been shown to increase blood pressure. Expression of BDNF transcripts have been identified in the subfornical organ (SFO), a forebrain circumventricular organ with well‐documented roles in cardiovascular regulation. Whole‐cell patch clamp electrophysiological studies from our laboratory have shown that BDNF influences the activity of the majority of SFO neurons tested. Given the involvement of the SFO in cardiovascular regulation and electrophysiological evidence from our laboratory that BDNF influences the activity of SFO neurons, the present study was undertaken to determine the effects of direct administration of the BDNF into the SFO of urethane anesthetized male Sprague Dawley rats. Microinjection of BDNF (0.5μl, 2nM) into the SFO resulted in rapid, short duration decreases in BP (mean AUC = −134.8 ± 22.2 mmHg*sec, n=4) without effect on HR (mean AUC = 2.4 ± 0.3, n=4). These hypotensive effects were site specific as microinjection into non‐SFO sites were without effect on BP (mean AUC = −13.5 ± 8.4 mmHg*sec, n=5) or HR (mean AUC = 0.8 ± 1.4 beats, n=5). These observations identify the SFO as a possible CNS location at which BDNF may act to influence cardiovascular regulation.

Support or Funding Information

Supported by the Canadian Institutes of Health Research
The Effects of Chronic Treatment with Ivabradine on the Cardiovascular Reflexes Sensitivity in Rats
Authors: Chianca Deoclecio Alves , Paiva Franciny A. , Silva Fernanda C. , Caldeira Henrique M. A. , de Menezes Rodrigo C. , Dias da Silva Valdo J.
Published: November 2023

A low resting heart rate would be of great benefit for patients with cardiovascular disease. In this sense, ivabradine which selectively inhibits the pacemaker If channel with no negative inotropic or proarrhythmic effects, has emerged as promising bradycardic agent. However, little is known about the ivabradine effects on the heart rate (HR) autonomic control. Since the cardiovascular reflexes are components of the autonomic control, in this study we examined the effects of chronic treatment with ivabradine on the Baroreflex and Bezold‐Jarish reflex sensitivity. Rats were divided into 2 groups: receiving intraperitoneal injection of PBS 1mL/Kg (n=4) or ivabradine 2mg/kg (n=4) for 7 consecutive days. The rats were submitted to vessels femoral cannulation and cardiovascular recordings (blood pressure and heart rate) on the fifth and seventh‐day of treatment, respectively. We performed Phenylephrine (PHE; 2μg/kg i.v.) and Sodium Nitroprusside injections (SNP; 8μg/kg i.v.) and ΔHR/ΔMAP index was calculated to assess the Baroreflex sensitivity. We also performed different Phenylbiguanide doses (PBG; 1.25; 2.5 and 5μg/kg i.v.) to evaluate the Bezold‐Jarish reflex sensitivity. The animals treated with ivabradine presented baseline HR 240±19bpm vs. 369±15bpm (p<0.05) in the controls rats. In relation to Baroreflex sensitivity, our results demonstrated an increase in tachycardia gain in the ivabradine‐treated rats (ΔHR/ΔMAP index; PBS: −2.2±0.5 bpm/mmHg vs. ivabradine: −10.7±2.9 bpm/mmHg; p<0.05). About the Bezold‐Jarish reflex, we observed that ivabradine treatment decreases the bradycardic responses evoked by PBG doses (PBG 2.5μg/kg; PBS: −215±38bpm vs. ivabradine: −70±52bpm; p<0.05), (PBG 5μg/kg; PBS: −194±51bpm vs. Ivabradine: −79±28 bpm; p<0.05). Our results suggest an increase in the Baroreflex gain and a decrease in the Cardiopulmonary reflex in ivabradine treated animals.

Support or Funding Information

CAPES, CNPq, FAPEMIG and UFOP.
Benzamil Attenuates Osmosensitive OVLT Neuron Excitation by Hyperosmotic NaCl
Authors: Kinsman Brian J , Browning Kirsteen N. , Stocker Sean D.
Published: November 2023

Central hypertonic NaCl infusion increases sympathetic nerve activity, vasopressin secretion, and blood pressure. These responses are eliminated by lesion of osmosensitive sites in the lamina terminalis, including the organum vasculosum of the lamina terminalis (OVLT). Intriguingly, intracerebroventricular pretreatment with benzamil (a non‐voltage dependent sodium channel blocker) also attenuates those responses to central NaCl. Taken together, this suggests benzamil may act on those osmosensitive neurons to attenuate physiologic responses to central NaCl. Therefore, I hypothesized that a benzamil‐sensitive channel/transporter mediates OVLT neuron osmosensitivity to NaCl. I evaluated the effect of benzamil on OVLT neuron excitation in response to hyperosmotic (+15mOsm) or isosmotic (+0mOsm) elevations in bath NaCl using whole‐cell recordings of adult rat OVLT neurons in slices. Initially, I measured changes in action potential (AP) discharge frequency with 295mOsm isosmotic, 310mOsm hyperosmotic and 310mOsm + 50μM benzamil bath perfusates. Osmosensitive OVLT neuron (n=14) peak AP discharge increased significantly from a 295mOsm baseline (0.41±0.08 Hz) to 310mOsm (0.94±0.11 Hz; p<0.05), but decreased significantly in response to sequential addition of 50μM benzamil to the 310mOsm perfusate (0.50±0.09 Hz; p<0.05). To assess the effects of benzamil on basal activity, I tested isosmotic 50μM benzamil on a separate set of osmosensitive OVLT neurons (n=9). Isosmotic 50μM benzamil biphasically increased AP discharge from 0.41±0.23 Hz to 0.77±0.34 Hz (p<0.05 compared to baseline), and then decreased AP discharge to 0.18±0.07 Hz (p>0.05 compared to baseline). Concomitantly, isosmotic 50μM benzamil depolarized neuron membrane potentials from −51.3±0.77 mV to −46.6±1.4 mV (p<0.05), and decreased the magnitude of neuron AP after hyperpolarizations from 6.85±0.42 mV to 2.67±0.44 mV (p<0.05). Injection of hyperpolarizing current pulses revealed that isosmotic 50μM benzamil also increases osmosensitive OVLT neuron input resistance (n=6) from 1228±148 MΩ to 1443±157 MΩ (p<0.05). These data demonstrate that high‐dose (50μM) benzamil in isosmotic NaCl exerts complex effects on OVLT neuron basal electrophysiology due to its multiple sodium channel/transporter targets. Still, 50μM benzamil does attenuate excitation of OVLT neurons by hyperosmotic NaCl. This data indicates that a benzamil‐sensitive protein contributes to the sodium‐/osmo‐ sensory function of OVLT neurons.
Defect Mitochondrial Biogenesis at Rostral Ventrolateral Medulla in Neurogenic Hypertension under Peripheral Inflammation
Authors: Chan Julie YH , Wu Kay LH
Published: November 2023

Neuroinflammation‐associated oxidative stress in rostral ventrolateral medulla (RVLM), where sympathetic premotor neurons reside, is involved in neurogenic hypertension developed under peripheral inflammation. In this study, we investigated whether this neurogenic hypertension is attributable to defect mitochondrial biogenesis. In normotensive Sprague‐Dawley rats, intraperitoneal infusion of a low dose of E. coli lipopolysaccharide (LPS) for 7 days promoted a pressor response, alongside a decrease in mitochondrial DNA (mtDNA) copy number, reductions in protein expression of nuclear DNA‐encoded transcription factors for mitochondrial biogenesis, including mitochondrial transcription factor A (TFAM) and nuclear factor erythroid‐derived 2‐like 2 (Nrf2), and suppression of nuclear translocation of the phosphorylated Nrf2 (p‐Nrf2) in RVLM neurons; all of which were abrogated by treatment with intracisternal infusion of an interleukin‐1β (IL‐1β) blocker, IL‐1Rα, or a mitochondrial electron carrier, coenzyme Q. Microinjection into RVLM of IL‐1β suppressed the expressions of p‐Nrf2 and TFAM, and evoked a pressor response; conversely, the Nrf2 inducer, tert‐butylhydroquinone, lessened the LPS‐induced suppression TFAM expression and pressor response. At cellular level, exposure of N2a cells to IL‐1β decreased mtDNA copy number, increased protein interaction of Nrf2 to its negative regulator, kelch‐like ECH‐associated protein 1 (Keap1), and reduced DNA binding activity of p‐Nrf2 to Tfam gene. Together these results indicate that defect mitochondrial biogenesis in RVLM neurons entailing a redox‐sensitive and IL‐1β‐dependent suppression of TFAM because of the increase in the formation of Keap1/Nrf2 complex, reductions in nuclear translocation of the activated Nrf2 and its binding to the Tfam gene promoter may underlie neurogenic hypertension developed under the peripheral inflammation.

Support or Funding Information

This study was supported by grant (CMRPG8C0051) from Kaohsiung Chang Gung Memorial Hospital.
Methionine Sulfoxide Reductase‐A Deficient Mice Exhibit Sympathetic Activity‐Dependent Oxidative Stress: Implications for End‐Organ Damage
Authors: Sabharwal Rasna , Abboud Francois M. , Chapleau Mark W.
Published: November 2023

Methionine sulfoxide reductase A (MsrA) selectively reverses oxidation of protein methionine and protects against oxidative damage. We recently reported that MsrA deficient (−/−) mice exhibit increased sympathetic tone under basal conditions, and augmented angiotensin II (Ang II) hypertension associated with left ventricular (LV) dysfunction and dilatation of ascending aorta; with the Ang II‐related pathologies abrogated by treatment with the sympathoinhibitory drug rilmenidine (RIL) [FASEB J, 2015; Auton Neurosci, 2015]. The aims of this study were to determine if MsrA−/− mice exhibit oxidative stress in LV and ascending aorta, and if basal and Ang II‐induced oxidative stress are dependent on sympathetic activity. Superoxide (O2•−) was measured in tissue sections from LV and ascending aorta (dihydroethidium staining) from untreated control C57BL6 and MsrA−/− mice (12–16 wks of age), and mice infused with Ang II (1000 ng/kg/min, SC) with or without ICV infusion of RIL over the last two weeks of Ang II infusion. O2•− levels in LV and aorta were significantly higher in MsrA−/− (n=8) vs. C57BL6 (n=7) mice, both under basal conditions (untreated) and after 4 weeks of Ang II infusion (Table). Ang II‐induced increases in O2•− were much greater in MsrA−/− mice (Table). Treatment of Ang II‐infused mice with RIL normalized O2•− levels in both genotypes (Table). Furthermore, O2•− levels in Ang II‐infused mice (n=7) were positively correlated with sympathetic tone measured in the same mice (r2 = 0.76 for LV, r2 = 0.88 for ascending aorta, P<0.05). In summary: (1) oxidative stress is evident in LV and ascending aorta of MsrA−/− mice under basal condition, (2) MsrA−/− and Ang II infusion synergistically increase oxidative stress, and (3) oxidative stress during chronic Ang II infusion is entirely dependent on sympathetic activity. Taken together, our results suggest that sympathetic activity‐dependent oxidative stress contributes to LV dysfunction/remodeling and aortic dilatation in MsrA−/− mice.

Support or Funding Information

HL14388, VA
Knockdown of Bradykinin B1 Receptor Reduces Neuro‐inflammation and Prevents the Development of Salt‐Sensitive Hypertension
Authors: Sriramula Srinivas , Lazartigues Eric
Published: November 2023

We previously reported that DOCA‐salt hypertension is associated with increased bradykinin B1 receptor (B1R) expression in the brain. In the present study, we tested the hypothesis that B1R knockdown prevents the development of hypertension. To test this hypothesis, wild‐type (WT) and B1R knockout (KO) mice were implanted with telemetry probes for conscious blood pressure (BP) monitoring. DOCA (1 mg/g, sc) was implanted following baseline BP recording and drinking water was replaced by 1% NaCl solution. Autonomic function was analyzed using a pharmacological method involving ip injection of propranolol (4 mg/kg) and atropine (1 mg/kg). Changes in heart rate (ΔHR) were used as index of sympathetic and parasympathetic tones. Baseline mean arterial pressure (MAP) was not different between WT and B1R KO mice (102±2 vs. 104±5 mmHg), nor were ΔHR following assessment of sympathetic (−73±6 vs. −75±15 beats/minute) or parasympathetic tone (+166±7 vs. +153±12 beats/minute). Three weeks after DOCA‐salt treatment, MAP was significantly increased in WT mice (138±3 mmHg, P<0.01 vs. baseline). However, this increase was blunted in B1R KO mice (121±2 mmHg, P<0.05 vs. WT+DOCA). In addition, DOCA‐salt mediated enhancement of cardiac sympathetic drive (increased bradycardia to propranolol, −145±21 beats/minutes, P<0.01 vs. baseline) and reduction of parasympathetic tone (reduced tachycardia to atropine, +111±8 beats/minute, P<0.01 vs. baseline) were normalized in B1R KO mice (−72±13 and +165±6 beats/minute, respectively, P<0.05 vs. WT+DOCA). DOCA‐salt treatment resulted in sympathoexcitation in WT mice, as indicated by increased urinary norepinephrine levels (299±23 ng/ml, P<0.05 vs. control), but this increase was blunted in B1R KO mice with DOCA (172±30 ng/ml, P<0.05 vs. WT+DOCA). Moreover, pro‐inflammatory high‐mobility group box 1 (HMGB1) and cyclooxygenase 2 protein levels were significantly upregulated in the hypothalamus following DOCA treatment in WT mice (2.5 and 2 fold, respectively, P<0.05 vs. control) but not in B1R KO mice. WT mice treated with DOCA‐salt showed increased inflammation as indicated by increased gene expression of TNF (3 fold, n=9, p<0.001 vs. WT), IL‐1beta (8 fold, n=9, p<0.001 vs. WT) and IL‐6 (5 fold, n=9, p<0.01 vs. WT) in the hypothalamic paraventricular nucleus (PVN) which was attenuated in B1R KO mice. Taken together, these data suggest that B1R knockdown prevents the development of hypertension, possibly through decreased sympathetic activity, reducing HMGB1 expression, and diminishing its downstream neuroinflammatory cascade.

Support or Funding Information

15SDG25720021 (SS), NIH/NHLBI (HL093178) (EL), and P30GM106392
The renin angiotensin system (RAS) in the heart: Effects of aerobic training
Authors: Silva Sebastiao Donato , Jara Zaira Palomino , Moreira Roseli , Montezano Augusto , Casarini Dulce , Touyz Rhian , Michelini Lisete Compagno
Published: November 2023

Goals

To investigating the sequential effects of aerobic training on cardiac Ang II/Ang (1–7) ratio and its relationship with cardiac hypertrophy and inflammatory markers.

Methods

Male SHR were trained (T) or kept sedentary (S) for 2 months. After measurement of resting arterial pressure (AP) and heart rate (HR) at weeks 0 (S0), 1 (T1), 2 (T2), 4 (T4) e 8 (S8 and T8) rats were euthanized for heart harvesting. Ang II and Ang (1–7) (HPLC), oxidative stress (DHE staining) and genic expression of hypertrophy and inflammatory markers were measured in the left ventricle (LV). WKY rats were used as time‐control

Results

SHR‐S0 vs. WKY‐S0 had higher AP and HR (169±1 mmHg; 358±7 bpm), LV hypertrophy (corresponding to increases of +27% in LV/BW and 2.4‐, 3.9‐ and 4.0‐fold in α‐MHC, β‐MHC and α‐actin, respectively), increased ROS density (+19%) and elevated TNFα expression (2.8‐fold) in LV, but similar Ang II and Ang‐(1–7) content (87±3 and 54±3 pmol/g tissue, respectively). In the SHR, T promptly reduced LV Ang II (−71%, T1), increased Ang‐(1–7) (+30%, T2) and reduced and normalized DHE density (T2), with a transitory increase of IL‐1b and TNFα (T1‐T2) and a transitory decrease of β‐MHC (T1) and α‐MHC (T2). LV Ang II/Ang (1–7) ratio reduction (−73%) and normalization of ROS content were maintained up to T8, while β‐MHC (T8), IL‐1b and TNFα (T4‐T8) were reduced below S levels. In the SHR‐T, α‐MHC and α‐actin were still higher and LV/BW similar to that of SHR‐S at the end of protocols. T effects were accompanied by HR (−15%, T4‐T8) and AP (−10%, T8) reductions.

Conclusion

Although not reducing LV hypertrophy of the SHR, training reduces RAS vasoconstrictor, proliferative and trophic axis, improves oxidative stress (early normalization) and reduces the pro‐inflammatory profile and β‐MHC expression (late effects) in the heart.

Support or Funding Information

Fapesp; Capes; Cnpq
Resveratrol Consumption and RIP140 Knockout Mice Demonstrate a Novel Relationship between Increased Mitochondrial Content and Compromised Bone Mineral Mass, Microarchitecture, and Strength
Authors: Miotto Paula M , Frendo‐Cumbo Scott , Sacco Sandra M , Wright David C , Ward Wendy E , Holloway Graham P
Published: November 2023

The polyphenol resveratrol (RSV) is associated with many health benefits, including the prevention of high fat (HF) diet induced glucose‐intolerance. However, the off‐target effects of resveratrol on bone health, specifically within the context of diet induced glucose‐intolerance, is unknown. The purpose of this study was to evaluate, in tibias, the effect of RSV on bone microarchitecture, mineral mass, and strength. Moreover, we aimed to elucidate molecular adaptations within bone that could provide insight regarding the impact of RSV on bone health. Male C57BL6 mice (8 weeks old) were randomized to 1 of 3 diets: control, CON (10% fat), HF (60% fat), or HF‐RSV (100mg/kg/day) for 12 weeks. Glucose‐tolerance tests verified that the HF diet induced glucose‐intolerance and that RSV prevented this effect. Combined HF‐RSV consumption led to compromised trabecular microarchitecture, lower bone mineral mass, and lower bone strength. This corresponded with elevated markers of osteoclast activation (decreased ratio of osteoprotegerin to receptor activator of nuclear factor kappa‐B ligand), bone resorption (cathepsin K), and increased mitochondrial content (electron transport chain complex subunits I–V). Further, we demonstrated proof‐of‐principle that elevated bone mitochondrial content is inversely related to bone health. Specifically, we utilized RIP140 knockout (KO) mice, a molecular model of elevated mitochondrial content. Similar to HF‐RSV mice, RIP140 KO mice displayed elevated mitochondrial content and compromised bone microarchitecture, bone mineral, and bone strength. This corresponded with higher markers of osteoclast activation and bone resorption, similar to HF‐RSV mice. Together, these findings suggest that although RSV successfully mitigates HF diet induced glucose‐intolerance, there can be negative consequences on bone health. Further, insulin sensitizing agents that are known to increase mitochondrial biogenesis should be considered for off‐target effects on bone health, as these data demonstrate that elevations in bone mitochondrial content are associated with decrements in bone health.

Support or Funding Information

Supported by NSERC, OMAFRA, and CFI, Canada.
Treadmill exercise with robotic resistance improves stepping and enhances synaptic plasticity in spinal cord injured rats
Authors: Ruiz Emanuel , Villanueva Silvia , Estrada Christina , Hinahon Erika , Traughber Terence , Sirot Steve , Robles Madely , Martinez Richard , de Leon Ray
Published: November 2023

It has been shown that robotic‐assisted treadmill training with body weight support improves the recovery of stepping patterns after a spinal cord injury (SCI). We examined the effects of robotic‐applied resistive forces in a rodent model of SCI. Thirty‐three female Sprague Dawley rats received a severe mid‐thoracic spinal cord contusion injury. A baseline test was performed two weeks later, after which treadmill training using a robotic device to apply viscous forces that opposed horizontal or vertical movements of the hind limbs. One group rats (n=10) was trained with a robotic horizontal force (HF) and another group (n=7) was trained with a vertical force (VF), another group Trained (T) without force (n=8) and one group was untrained (UT) (n=8). Training was performed for 15 minutes/day, 5 days/week. After 6 weeks of training with robotic resistive forces, improvements in step cycle kinematics were observed based on data collected by the robotic device. Specifically, training with the HF significantly increased step length and forward displacement by 24% and 16% respectively relative to untrained controls. Training with VF did not affect step length parameters but instead impacted vertical velocity. Specifically, training with VF significantly increased peak vertical velocity during lift and peak vertical velocity prior to paw contact by 49% and 40% respectively. These findings suggested that treadmill training with HF and VF was effective in shaping hind limb movements in SCI rats. We next performed immunohistochemical analyses of biochemical markers for synaptic plasticity in the ventral horn of the lumbar spinal cord. The expression of synaptophysin was significantly greater after HF training compared to VF and T training (p<0.05). This finding suggested that HF training increased synapses in the lumbar spinal cord more so than other forms of training. Interestingly, a high level of synaptophysin expression was also observed in UT rats and was similar to the expression associated with HF training. On‐going experiments with VGLUT and GLYT2 labeling around motor neurons will provide greater insight into the nature of these synapses. These findings have implications for the use of treadmill exercise therapies following SCI.

Support or Funding Information

NIH grant R15NS082711 to R. de Leon
Effects in young men of isometric handgrip training (IHG) on endothelium‐dependent vasodilator responses in the contralateral arm: changes in the contribution of cyclooxygenase (COX) products
Authors: Tsitoglou Kyriakos , Martin Una , Marshall Janice
Published: November 2023

Previous studies have shown that IHG and rhythmic handgrip training can reduce arterial blood pressure (ABP), especially in hypertensive subjects. The mechanisms underlying these effects are unclear, but it has been proposed that IHG training achieves its effects mainly by decreasing sympathetic activity. However, in hypertensive patients, IHG decreases plasma markers of oxidative stress. Thus, we tested the hypothesis in young normotensive men, that IHG improves endothelial function remotely, in the non‐trained arm. In 10 recreationally‐active men (18–25 years), we used laser Doppler fluximetry on the non‐dominant forearm to record changes in cutaneous red cell flux (RCF) evoked by iontophoresis of acetylcholine (ACh, 8 × 20s pulses: 7 at 100 μA, 8th at 200 μA, at 60s intervals), and following release of arterial occlusion for 3 min (reactive hyperaemia) before and after IHG training of the dominant forearm. IHG training comprised 4×3 min contractions at 30% Maximum voluntary contraction (MVC) at 5 min intervals, 4 days/week for 4 weeks. Before and after IHG training, we tested the contribution of COX products to dilator responses. IHG training did not affect resting ABP: 124±1.8/70±1.7 vs 125±1.8/72±1.6 mmHg. As expected, MVC was increased in the trained arm (29.0±1.3 vs 33.5±1.5Kg: P<0.05, paired t‐test), but not in the contralateral arm (26±0.9 vs 27.1±2.6Kg). Before training, ACh‐induced dilator responses were unaltered by COX inhibition with aspirin (600mg p.o.): maximum RCF 192.2±5.5 vs 182.6±4.7 PU respectively), suggesting any contribution of COX dilator and constrictor products was balanced. By contrast, aspirin attenuated peak reactive hyperaemia from 92.9±2.5 to 75.07± 2.58PU (P<0.05 : RMANOVA) indicating a contribution of COX dilator products. After IHG training, neither the magnitude of ACh‐induced dilatation, nor reactive hyperaemia was changed, but aspirin now augmented the ACh response: maximum RCF 192.6±4.1 increased to 227.5±5.2PU (P<0.001), but had no effect on reactive hyperaemia (92.1±2.3 vs 91.8±3.6PU). These results suggest that in young normotensive men, IHG training of one arm has no effect on ABP and no net effect on the magnitude of endothelial‐dependent dilatation remotely, but does change the balance of influence of vasoconstrictor and dilator COX products. We propose that during IHG training, the contribution of COX dilator products to endothelium‐dependent, agonist‐evoked dilatation and reactive hyperaemia is attenuated and replaced with the influence of another dilator such as nitric oxide, leaving vasoconstrictor COX products limiting even greater agonist‐induced dilatation.

Support or Funding Information

Alexander S. Onassis Public Benefit Foundation
Effects of isometric handgrip (IHG) training of one forearm on reactive and exercise hyperaemia in the ipsilateral and contralateral arm of White European Young Men
Authors: Tsitoglou Kyriakos , Martin Una , Marshall Janice
Published: November 2023

There is evidence that IHG training reduces arterial blood pressure (ABP), particularly in hypertensive subjects and that it may also enhance reactive hyperaemia in the trained arm. We have tested in normotensive, young men, whether IHG improves reactive and exercise hyperaemia in the contralateral, untrained arm, which would be evidence of remote effects on dilator function. The study was performed on 10 recreationally active, White European men (18–25 years). IHG training comprised 4×3 min contractions at 30% Maximum voluntary contraction (MVC) at 5 min intervals, 4 days/week for 4 weeks, undertaken with the dominant arm. Before and after IHG training, forearm blood flow (FBF) was recorded by venous occlusion plethysmography in the trained arm and non‐trained contralateral arm, at rest and at intervals after 3‐mins arterial occlusion (reactive hyperemia), or 3‐min rhythmic handgrip contractions at 60% Maximum voluntary contraction (MVC; exercise hyperemia). As expected, MVC was increased after IHG training in the trained arm (29.0±1.3, vs 33.5±1.5*Kg, *: P< 0.01, paired t‐test), but not in the untrained arm (27.0±0.9 vs 27.1±0.9Kg). IHG training did not affect resting ABP: 124±1.8/70±1.7 vs 125±1.8/72±1.6 mmHg, or resting FBF: 4–9±0.9 vs 5.1±0.8 ml.min−1.100ml−1 in dominant arm before vs after IHG training. However, reactive hyperaemia was increased in both the trained arm and non‐trained arm by IHG training: peak FBF increased from 41.4±1.9 to 50.8±2.0* ml.min−1. 100ml−1 (*: P< 0.01 RMANOVA) in the trained arm, and from 41.3±4.8 to 52.8 ± 1.7* ml.min−1. 100ml−1 in the non‐trained arm. Further, exercise hyperaemia was increased in both arms by IHG training, peak FBF was increased from 75.6±2.5 to 110.2±2.6* ml.min−1. 100ml−1 in the trained arm and from 77.8±9.4 to 101.1±2.9* ml.min−1. 100ml−1. These results indicate that in healthy young men, IHG training of one arm for 4 weeks improves peak muscle power and induces a parallel increase in exercise hyperaemia associated with submaximal isometric contraction in the trained arm. In addition, our results indicate for the first time, that not only is there a concomitant increase in reactive hyperaemia in the trained arm, but also a substantial increase in reactive hyperaemia and in exercise hyperaemia to submaximal contraction in the contralateral, non‐trained arm, in the absence of a change in muscle power. The mechanisms underlying these changes remain to be determined but we propose that they reflect a generalised beneficial effect of IHG training on endothelial dilator function.

Support or Funding Information

Alexander S. Onassis Public Benefit Foundation
An Eight‐Week Exercise Program Increased Exhaled Nitric Oxide (FENO) Levels in Adolescents
Authors: Shin Hye‐Won , Cooper Dan , Haddad Fadia , Lu Kim , Aizik Shlomit
Published: November 2023

RATIONALE

Exhaled NO (FENO) measurement is a non‐invasive tool to assess airways inflammation. However, little is known about how exercise training affects nitric oxide (NO) levels in human airways. We hypothesized that aerobic training program will increase FENO due to inflammation from repeated bouts of exercise.

METHODS

17 healthy and 5 asthmatic (4 are on ICS) adolescents (14–17 y/o) completed an eight‐week exercise program (1 hour/session, 3 days/week). FENO and lung functions were collected before and after ten two‐min bouts of cycle ergometer exercise (~72% peak VO2 max) prior and at the end of the training program. FENO50 was obtained according to the ATS guideline using a chemiluminescence analyzer (NIOX, Aerocrine AB, Sweden). FENO were also measured utilizing multiple constant flow rate maneuvers at 100, 150, and 200 ml/s to estimate maximum airway wall flux (JawNO) and alveoli NO (CANO). Lung function was assessed using spirometry. Blood IgE levels were obtained prior and at the end of the training program.

RESULTS

Mean (SD) FENO50 levels at baseline were 17 (6) for controls and 17 (7) for asthmatics. Following training we observed substantial variability in FENO levels in both healthy and asthmatic adolescents (Figure 1). The JawNO was increased for those who with increased FENO50 following exercise training (658 (358) pl/s at pre‐training vs. 1149 (884) pl/s at post‐training). CANO did not changed following training (2.7 (2.7) ppb at pre‐training vs. 4.5 (5.1) ppb at post‐training). After a brief exercise, the mean (SD) change of FENO50 regardless of training status was −11.1 (23.9) in healthy controls and −12 (15.8) in asthmatics. In contrast to FENO, the lung function indices (i.e., FEV1/FVC, FEF25‐75) were not changed following exercise challenge nor following exercise training. In addition, there is no relationship between blood IgE levels and the changes in FENO levels following exercise training.

CONCLUSIONS

This study demonstrates that exercise training generates substantial changes in FENO levels in certain individuals. This result may suggest, in part, that increased levels of inflammatory mediators with repeated bouts of exercise following training may stimulate NO production in the human airways.

Support or Funding Information

This work was supported by NIH Program Project Grant P01 HD048721.
Influence of High Intensity Power Training on Central Arterial Stiffness in Young Healthy Subjects
Authors: Ellis Brian , Wells Andrew , Smith Michael
Published: November 2023

PURPOSE

It is currently understood that aerobic exercise training can decrease central arterial stiffness, whereas resistance training may increase central arterial stiffness. Recently, high intensity power training (HIPT) has grown in popularity, and the effect of this novel training on central arterial stiffness remains unknown. Therefore, our goal was to investigate the effect of HIPT on central pulse wave velocity (cPWV) in healthy young men and women.

METHOD

Subjects were randomized to a control group (N=2) or training group (N=5). The training group participated in HIPT training three times a week for 8 weeks. Each session consisted of a combination of multi‐joint exercises such as the squat, deadlift, and bench press, along with olympic movements such as the clean, jerk, and snatch, as well as other functional exercises that were completed for time, or as many repetitions as possible (AMRAP). PWV was measured using applanation tonometry at the carotid and femoral arteries at the outset of the training, and again eight weeks later. A 30‐second recording of each site was simultaneously obtained for later analysis. The foot of each arterial pulse wave was marked, a time difference was calculated, and finally averaged into a mean time value. The cPWV was calculated using eighty percent of the distance between measurement sites divided by the mean time value.

RESULTS

In the control group, cPWV did not change from pre‐ to post‐training (8.0 m/s vs. 7.9 m/s; P=0.94), whereas cPWV increased in the training group, but was not statistically significant (8.2 m/s vs. 9.2 m/s; P=0.08).

CONCLUSIONS

Our results suggest that there may be unfavorable cardiovascular adaptations associated with participation in HIPT absent a traditional aerobic training component. Further research using a more robust sample size is indicated to find a significant conclusion.
Effects of Interval and Continuous Exercise Regimens on Platelet Mitochondrial Bioenergetics under Hypoxic Stress
Authors: Wu Li‐Hua , Wang Jong‐Shyan
Published: November 2023

Mitochondrial bioenergetics is an important in the regulation of platelet function. The purpose of this study was to investigate the effects of aerobic interval (AIT) and moderate continuous training (MCT) on mitochondrial oxidative phosphorylation and thrombin generation (TG) of platelets during hypoxic stress. Twenty‐four sedentary males were randomized to perform either aerobic interval training (AIT; 3‐minute intervals at 40% and 80% VO2max, n=12) or moderate continuous training (MCT; sustained 60% VO2max, n=12) for 30 minutes/day, 5 days/week for 6 weeks. At rest and immediately after hypoxic exercise test (HE, 100W under 12%O2 for 30 min), mitochondrial oxidative phosphorylation and dynamic TG were measured by a high resolution respirometer (Oxygraph‐2k) and a calibrated automated thrombinography, respectively. The results demonstrated that AIT rather than MCT regimen significantly increased ATP‐linked O2 consumption rate (OCR), Complex II‐mediated OCR, and reserve capacity of OCR, which were accompanied by lowered dynamic TG in platelet‐rich plasma. Moreover, AIT significantly diminished the extents of mitochondrial dysfunction and TG elevation caused by HE, compared to MCT did. Hence, we conclude that AIT is superior to MCT for improving platelet mitochondrial bioenergetics and suppressing thrombus formation at a hypoxic environment.
Aerobic Interval Training Improves Hemodynamic Response to Exercise by Enhancing Production and Function of Monocyte‐derived Endothelial Progenitor Cells
Authors: Wang Jong‐Shyan
Published: November 2023

Monocyte‐derived endothelial progenitor cells (monocyte‐derived EPCs) potentially incorporate into the injured vessels and subsequently trans differentiate into vascular endothelial cells. This study explicates the manner in which interval and continuous exercise regimens affect central/peripheral hemodynamic responses to exercise by modulating various monocyte‐derived EPC subsets. Sixty healthy sedentary males were randomized to engage either aerobic exercise training (AIT, 3‐minute intervals at 40% and 80% VO2max, n=20) or moderate continuous training (MCT, sustained 60% VO2max, n=20) for 30 minutes/day, 5 days/week for 6 weeks, or to a control group that did not received exercise intervention (n=20). Monocyte‐derived EPC characteristics and angiogenic factor production were measured at rest and following hypoxic exercise test (HE, 100W under 12%O2). The results demonstrated that AIT exhibited larger improvements in VO2max, peak cardiac output (QH) and peak perfusions of frontal cerebral lobe (QFC) and vastus lateralis (QVL), and flow‐mediated vasodilation (FMD) of brachial artery than the MCT group. Furthermore, AIT (i) increased circulating Mono‐1 and Mono‐2 EPC counts; (ii) diminished the shedding of endothelial cells; and (iii) promoted the migration and tube formation of EPCs at rest or following HE, compared to those of MCT. Additionally, Mono‐1 and ‐2 EPC counts were directly related to VO2max, peak QH/QFC/QVL levels, and FDM. Therefore, we conclude that AIT is superior to MCT for enhancing aerobic capacity and hemodynamic responses to exercise, possibly by promoting the mobilization/functionality of monocyte‐derived EPCs.

Support or Funding Information

National Science Council of Taiwan (grant number NSC 100‐2314‐B‐182‐004‐MY3), Chang Gung Medical Research Program (grant number CMRPD3D0131), and Healthy Aging Research Center, Chang Gung University (grant number EMRPD1A0841)
Endurance Training Alters Expression of Over 3000 Isoforms and 34 Novel Transcripts in Human Skeletal Muscle
Authors: Lindholm Malene , Giacomello Stefania , Solnestam Beata Werne , Fischer Helene , Kjellqvist Sanela , Huss Mikael , Sundberg Carl Johan
Published: November 2023

Background and objective

Long‐term endurance training has many beneficial effects on both skeletal muscle function and health and prevents many common diseases e.g., cardiovascular disease, type II diabetes and obesity. The mechanisms of molecular adaptation regulating these effects are not fully understood. To date, global transcriptome changes in skeletal muscles have been studied at gene level. However, global isoform expression changes following exercise training in humans are hitherto unknown. The objective of the present study was thus to investigate endurance‐induced global isoform expression changes, as well as potential transcriptional effects on previously unannotated parts of the genome with training.

Methods and results

23 healthy volunteers trained only one leg for a three‐month period (45 min, 4 times per week). Before and after the training period, skeletal muscle biopsies were obtained from m. vastus lateralis of both legs. One‐legged performance and citrate synthase activity significantly increased with training and there were significant differences between the trained and untrained legs. Global isoform expression analysis (from 2×100 base pairs paired‐end RNA sequencing) of all biopsies showed a highly training‐specific response. Using multivariate statistics, we found 3404 differentially expressed isoforms, mainly associated with energy production through oxidative phosphorylation. Several genes had many isoforms that changed significantly, for example 5 isoforms of CAPN3 (a protease), 4 different isoforms of MDH1 (citric acid cycle), 8 isoforms of NEB (within sarcomeres) and 6 isoforms of PDHA1 (pyruvate dehydrogenase complex). 54 genes had isoforms that were differentially expressed in opposite directions. In addition, 34 novel transcripts, several showing protein‐coding potential, significantly changed with training.

Conclusion

This human training study induced consistent differential expression of isoforms and novel transcripts that were concordant with the phenotypic adaptation. It is likely that the observed differential isoform expression to a large degree reflect adaptation mechanisms and processes that contribute to the functional and health benefits that are known to follow regular physical activity.

Support or Funding Information

This work was supported by the Swedish National Centre for Research in Sports, Karolinska Institutet PhD funding (KID) and the Wallenberg Advanced Bioinformatics Infrastructure