bluuebunny/crossref_metadata_2025_split huggingface dataset:
Acute Stress Diminishes M‐Current in Corticotrophin‐Releasing Hormone Neurons through AMPK Activation
Authors: Li De pei , Zhou Jing‐Jing , Gao Yonggang , Li De‐Pei 
Published: November 2023

Acute stress activate hypothalamus‐pituitary‐adrenal gland axis and corticotrophin‐releasing hormone (CRH) neurons in the paraventricular nucleus (PVN) of hypothalamus. However, the molecular and cellular mechanisms underlying hyperactivity of PVN‐CRH neurons in acute stress are not clear. M‐channel is regulated by AMPK activity and plays important role in the regulation of neuron activity. We hypothesized that M‐channel function is impaired in PVN‐CRH neurons during acute stress. Whole‐cell patch‐clamp recording were performed on PVN‐CRH neurons identified by specific expression of eGFP driven by the rat crh premotor. Acute stress (2‐hr restraint) profoundly increased firing rate of PVN‐CRH neurons while decreased M‐current in these neurons. M‐channel blocker XE991 induced lesser increased in firing activity of PVN‐CRH neurons in acutely stressed rats compared with unstressed rats. Microinjection of XE991 into the PVN produced significantly lesser increases in plasma corticosterone concentration in acute stress rats than in unstressed rats. Furthermore, acute stress decreased KV7.3 subunit membrane‐fraction protein expression levels while increased phosphorylated AMPK level in the PVN tissues compared with unstressed rats. However, the Kv7.3 cytoplasma‐fraction protein level and Kv7.2 subunit expression level in the PVN tissue. Treatment with AMPK inhibitor compound C not only recovered the Kv7.3 membrance‐fraction expression level but also reinstalled the reduced M‐current and XE991‐induced excitatory effect on PVN‐CRH neruons in acute stressed rats. Finally, microinjection of compound C into the PVN reinstalled XE991‐induced increase in plasma corticosterone levels. Collectively, these results suggested that acute stress diminishes M‐current in PVN‐CRH neurons, which is related to AMPK activation.Support or Funding InformationThis study was supported by NIMH grants MH096086.
Angiotensin type 1A receptor expressing neurons in the NTS receive direct solitary tract excitatory neurotransmission
Authors: Carter David A , Guo Haoyao , Allen Andrew M , McDougall Stuart J 
Published: November 2023

Second order neurons in the nucleus of the solitary tract (NTS) receive direct viscero‐sensory afferents from internal organs via the solitary tract (ST) to coordinate autonomic reflexes. Approximately 90% ST vagal afferents from the heart and lungs are unmyelinated c‐fibres and express transient receptor potential vallinoid type 1 (TRPV1). Activation of the angiotensin type 1A receptor (AT1AR) in the NTS modulates cardiorespiratory reflexes and is thought to potentiate ST excitatory input. Here we aimed to characterise ST input to AT1AR expressing NTS neurons, and determine what proportion of the monosynaptic afferents express TPRV1. Second, we determined the impact of angiotensin II (AngII) on ST neurotransmission to AT1AR expressing NTS neurons. We employed in vitro slice electrophysiology and whole cell recordings. Twenty‐two transgenic mice expressing green fluorescent protein in AT1AR neurons were sacrificed and 250 μm horizontal brain stem slices were prepared and superfused with artificial cerebrospinal fluid. Electrical stimulation of the ST evoked low jitter excitatory post‐synaptic currents (ST‐EPSCs) in 28 of 41 GFP positive neurons, identifying them as second order. The normalised amplitude (eEPSC/eEPSCMAX) and paired pulse ration (PPR) of ST‐EPSCs (50 Hz, 200 μs) and frequency of spontaneous (F‐sEPSCs) and asynchronous EPSCs (F‐aEPSCs) were analysed before and during the addition of 100 nM capsaicin (CAP) or 2 μM AngII to the superfusate. CAP decreased F‐aEPSCs (CSF: 13.9 ± 2.3 Hz, CAP: 0.3 ± 2.7 Hz, n = 5), however only inhibited ST‐EPSCs in 1/5 second order neurons tested. AngII had no effect on ST‐EPSC amplitude (CSF: 0.84 ± 0.03, AngII: 0.85 ± 0.05), PPR (CSF: 0.34 ± 0.05, AngII: 0.34 ± 0.04, n = 8) or F‐sEPSC. Combined, this data indicates that NTS AT1AR neurons receive direct viscerosensory signals mostly via TRPV1‐ve pathways. Further, that AT1AR is not likely to be expressed on the excitatory ST axons/terminals contacting these AT1AR expressing NTS neurons. This suggests AT1AR neurons in the NTS receive predominately Aδ‐fibre input which relay high fidelity, low threshold signals from the viscera through the central nervous system.Support or Funding InformationThis work is supported by a National heart foundation post‐graduate research scholarship.
Heparanase contributes to sepsis‐associated encephalopathy and neurovascular glycocalyx degradation
Authors: Ford Joshay , Orfila James , Perez Mario , Yang Yimu , Haeger Sarah , Herson Paco , Schmidt Eric 
Published: November 2023

While there has been increasing recognition of long‐term neurocognitive dysfunction in survivors of sepsis (termed sepsis‐associated encephalopathy, SAE), little is known about its underlying pathogenesis. We developed a mouse model of septic neurocognitive dysfunction by investigating the effects of sepsis on synaptic plasticity in the hippocampus (an area important in learning and memory). As heparan sulfate (HS) is known to contribute to the regulation of hippocampal synaptic plasticity, we sought to determine the role of SAE with heparanase, a HS‐specific glucuronidase that contributes to the pathogenesis of septic lung and kidney injury. In wild‐type mice, cecal ligation and puncture (CLP) induced physical signs (piloerection, lethargy, and weight loss) of sepsis that peaked by 24–48 h; these signs abated before 7 days. Despite this apparent resolution of septicemia, CLP significantly impaired hippocampal long‐term potentiation 7 days after injury, indicative of SAE. Similar findings were noted with intraperitoneal lipopolysaccharide (LPS, 20 μg/g), a non‐infectious model of sepsis. Consistent with our previous observations in septic lung and kidney injury, CLP increased brain heparanase expression at 48 h, with induction of both proheparanase and active heparanase. Pharmacologically blocking heparanase expression attenuated the loss of hippocampal long‐term potentiation 7 days after CLP or LPS administration. Interestingly, in vivo brain microscopy revealed that endotoxemia was associated with heparanase‐mediated loss of neurovascular glycocalyx thickness, suggesting a potential vascular‐specific mechanism by which septic heparanase induction may induce SAE. In conclusion, CLP induces neurocognitive dysfunction that persists after overt sepsis resolution; this dysfunction was attenuated by heparanase inhibition. These findings identify a potential animal model of SAE as well as possible pathophysiologic mechanisms underlying its development.Support or Funding InformationK08 HL105538
Reduction of Astrocyte and Microglial Activation in Insulin/Saline‐treated Diabetic Ketoacidosis by the KCa3.1 Blocker TRAM‐34
Authors: Glaser Nicole S , Little Christopher J , Cohen Michael D. , Tancredi Daniel J. , Wulff Heike , O'Donnell Martha E. 
Published: November 2023

Previous studies have provided evidence that diabetic ketoacidosis (DKA) and/or its treatment with insulin and saline (I/S) causes brain injury in children. However, mechanisms underlying DKA‐related brain injury have been poorly understood. In recent studies using immunohistochemistry (IHC) in a streptozotocin (STZ)‐induced DKA juvenile rat model, we examined expression of glial fibrillary acidic protein (GFAP) and CD‐11b protein (OX42) in hippocampus, cortex and striatum at 4, 24 and 72 hr after I/S treatment. We found increased GFAP in hippocampus as well as increased OX42 in both hippocampus and cortex, suggesting that reactive gliosis and microglial activation occur during DKA‐related brain injury. Other studies have shown that TRAM‐34, a KCa3.1 channel blocker, reduces microglial activation in the rat middle cerebral artery occlusion model of cerebral ischemia. The present study was conducted to determine whether TRAM‐34 could also reduce DKA‐related inflammatory changes in the brain. We used IHC to investigate the effects of TRAM‐34 on GFAP and OX‐42 expression in brain sections from juvenile rats with STZ‐induced DKA before, during and after treatment with insulin and saline. As in previous studies, OX42 staining intensity was increased in the hippocampus and cortex during DKA and increased further 4 hours after I/S treatment in a manner sustained through 24 and 72 hours after recovery from DKA. GFAP staining intensity was also increased over the same time course in hippocampus but not cortex. However, in rats administered TRAM‐34 (IP, 40 mg/kg) at the start of I/S treatment, staining intensities of both OX42 and GFAP were significantly reduced at all time points after DKA. OX42 staining intensity was also decreased during DKA prior to I/S treatment in TRAM‐34 treated rats. We conclude that DKA causes inflammatory changes in the brain including reactive gliosis and activation of microglia. Treatment with TRAM‐34 not only decreases microglial activation but also reduces reactive gliosis, suggesting an overall decrease in the brain's inflammatory response to DKA.Support or Funding InformationSupported by ADA
Inhibition of sodium bicarbonate cotransporter exaggerates ischemic penumbral cell death
Authors: Yao Hang , Azad Priti , Zhao Huiwen , Poulsen Orit , Haddad Gabriel G 
Published: November 2023

Sodium bicarbonate co‐transporter (NBC) is the major bicarbonate‐dependent acid‐base transporter in mammalian astrocytes and has been implicated in ischemic brain injury. Nevertheless, the role of NBC in the ischemic penumbral cell death has not been well understood. In this work, we obtained skin biopsies from a healthy human subject and reprogrammed skin cells into induced pluripotent stem cells (iPSCs). These iPSCs were further differentiated into neuroprogenitor cells (NPCs) and then into astrocytes. These astrocytes express GFAP, S100β and Aquaporin 4 and readily propagate calcium waves. Using pH sensitive dye BCECF and PCR technique, we have confirmed that these astrocytes express functional electrogenic sodium bicarbonate cotransporter (NBCe). Using an ischemic solution (IS) that mimics the ischemic penumbral environment and a NBC blocker S0859, we have studied the involvement of NBCe1 in IS‐induced human astrocytes death. q‐PCR result shows a significant increase in NBCe1 gene expression following a 24 hour IS treatment while this does not occur in NBCn1. Cell viability was analyzed by propidium iodide stained cell counting which was normalized by the Hoechst stained cell counting and presented as the percentage of injured cell number over the entire cell counting. A 24 hr incubation of S0859 at concentration range from 0.1 to 100 μM did not induce any cell injuries in astrocytes in the normal condition. A 24 hr IS treatment resulted in a 43.6±4.5% cell death in these astrocytes (n=10). While a 24 hr IS + 30 μM S0859 elicited a 97.5±1.6% cell death (n=10), which is significantly different from that seen in IS treatment group (p<0.001). In summary, a NBC blocker exaggerates IS‐induced cell death which suggests that the activities of NBC (possibly NBCe1) are essential for astrocytes to survive the ischemic penumbral environment.Support or Funding InformationThis project was supported by NIH 5P01HL098053
Direct pathway from ventral medial prefrontal cortex to dorsomedial hypothalamus drives psychological stress‐induced hyperthermia
Authors: Kataoka Naoya , Nakamura Kazuhiro 
Published: November 2023

Psychological stress‐induced hyperthermia is a basic autonomic stress response observed in many mammals including humans. We have reported that stress induces thermogenesis in brown adipose tissue (BAT), hyperthermia and tachycardia by activating a direct neural pathway from the dorsomedial hypothalamus (DMH) to the rostral medullary raphe (rMR) (Kataoka et al. Cell Metabolism, 2014). However, the mechanism by which stress signals activate the DMH neurons driving the sympathetic stress responses remains unknown. In this study, we sought for the upper neurons that provide the DMH with such psychological stress inputs. Retrograde tracing with the retrograde neural tracer, cholera toxin b‐subunit (CTb) revealed numerous projections from the medial prefrontal cortex (mPFC) to the DMH. Stimulation of mPFC neurons with a nanoinjection of bicuculline, a GABAA receptor antagonist, in anesthetized rats increased BAT sympathetic nerve activity, BAT temperature and heart rate. These bicuculline‐evoked sympathetic responses were eliminated by bilateral inhibition of DMH neurons with muscimol nanoinjections. Importantly, rats exposed to social defeat stress, a sociopsychological stress model, exhibited expression of Fos, a marker for neuronal activation, in DMH‐projecting neurons in the ventral part of the mPFC (vmPFC), and inhibition of vmPFC neurons with muscimol nanoinjections strongly reduced BAT thermogenesis and hyperthermia evoked by social defeat stress in free‐moving rats. In contrast, inhibition of neurons in the infralimbic cortex, a dorsal part of the mPFC, exhibited a weaker inhibitory effect on these stress responses. Furthermore, selective stimulation of vmPFC–DMH monosynaptic transmission using an in vivo optogenetic technique elicited BAT thermogenesis and heart rate. These results indicate that the vmPFC–DMH monosynaptic pathway provides the DMH with stress signals to activate the DMH–rMR sympathoexcitatory pathway driving BAT thermogenesis for the development of stress‐induced hyperthermia.Support or Funding InformationNEXT Program (LS070), KAKENHI (21890114, 22689007, 24790233, 26118508, 26713009), Nakajima Foundation, Takeda Science Foundation, and Kowa Life Science Foundation
Blockade of Acid‐Sensing Ion Channels Attenuates the Skeletal Muscle Metaboreflex in Humans
Authors: Fernandes Igor Alexandre , Campos Monique Opuszcka , Mansur Daniel Elias , Mattos João Dario , Rocha Marcos Paulo , Rocha Natalia Galito , Nóbrega Antonio Claudio Lucas 
Published: November 2023

Recent animal studies indicate that acid‐sensing ion channels (ASICs) play a role in evoking the metabolic component of the exercise pressor reflex. Nonetheless, it is still unclear whether these findings can be translated to humans. Our purpose was then to investigate the contribution of ASICs in mediating the metaboreflex‐induced increase in blood pressure and muscle sympathetic nerve activity in a human model. Five healthy subjects (32 ± 5 yrs) underwent two experimental conditions: (1) Control (C) and (2) Amiloride (AMD, 3 hours after oral administration of 5 mg of amiloride + 50 mg of hydrochlorothiazide), a non‐selective antagonist of ASICs. In each condition, beat‐by‐beat mean blood pressure (MBP, Finometer), muscle sympathetic nerve activity (MSNA, peroneal nerve microneurography) and femoral artery blood flow (FBF, Doppler ultrasound) were recorded during rest, static handgrip exercise (SHE, 2 min at 30% of the maximal voluntary contraction) and post‐exercise muscle ischemia (PEMI, 2 min). Blood samples were taken from the antecubital vein of the exercising arm during the last 30 s of PEMI and changes on lactate concentration were determined. MBP responses were slightly but significantly attenuated during SHE in the AMD condition (AMD +29.6 ± 7.0 vs. C +35.3 ± 8.4 mmHg, p = 0.05). A smaller increase in MSNA (N = 4) was also observed as a consequence of ASICs blockade (AMD +6.1 ± 3.5 vs. C +12.5 ± 4.2 bursts/min, p = 0.013). Similarly, AMD attenuated the PEMI‐induced increases in both MBP (AMD +18.9 ± 2.0 vs. C +31.35 ± 4.3 mmHg, p = 0.02) and MSNA (AMD +10.0 ± 4.3 vs. C +21.6 ± 1.4 bursts/min, p = 0.04). Increases in lactate concentration (AMD +1.00 ± 1.5 vs. C + 1.85 ± 0.15 mmol/l, p > 0.05) were similar between the experimental conditions. Femoral blood flow and conductance did not present substantial changes (p > 0.05). Although AMD antagonizes ASICs when administered in small doses, its influence on epithelial or voltage‐gated sodium channels and a related impairment in the impulse conduction in sensory nerves must not be discarded. To test the hypothesis that the attenuation of the skeletal muscle metaboreflex was only a consequence of non‐selective blockade of ASICs, MBP (N = 4) and MSNA (N = 2) responses were also recorded during rest and a cold pressor test (CPT, 20 min after PEMI). AMD had no impact on MBP (AMD +23.6 ± 3.7 vs. C +20.5 ± 4.2 mmHg; P > 0.05) and MSNA (AMD +22.9 ± 3.0 vs. C +23.6 ± 6.3 bursts/min, P > 0.05) responses during CPT, indicating that there was no impairment on sensory nerves ability to generate and conduct action potentials. Therefore, our findings suggest that ASICs also play a role in evoking the skeletal muscle metaboreflex in humans.Support or Funding InformationGrant Funding Source: CNPq, FAPERJ, CAPES e FINEP
Mechanisms involved in sodium depletion‐induced facilitation of respiratory responses to baroreceptor activation
Authors: de Paula Patricia Maria , Borsari Karine Cristina , Zoccal Daniel Breseghello , Menani Jose Vanderlei 
Published: November 2023

Disorders in blood volume may cause behavioral, hormonal and autonomic responses in order to restore homeostasis. The model of sodium depletion elicited by furosemide promotes neuroendocrine responses, reductions in vascular reactivity and blood volume, with no changes in blood pressure and heart rate (HR) due to the activation of the renin‐angiotensin system. It was demonstrated that changes in the sodium balance modifies the cardiorespiratory responses to peripheral baroreceptor activation in anesthetized conditions. In the present study, we explored the cardiorespiratory baroreflex responses in normovolemic and 24‐h sodium depleted conscious rats and evaluated the contribution the angiotensinergic mechanisms in the reflex responses of both groups. Male Holtzman rats (290–320 g, n=19/group) that received catheter implants into the femoral artery and vein were used. Baroreceptor activation was performed by intravenous (iv) phenylephrine (phenyl) infusions (5 μg/kg/ml) and ventilation (VE) was measured by whole body plethysmograph. Subcutaneous furosemide injections (20 mg/kg) followed by 24 h of sodium‐deficient diet was used to induce sodium depletion. Sodium‐depleted animals (n=19) showed similar baseline mean arterial pressure (102±2 vs 107±2 mmHg), HR (382±9 vs 385±7 bpm) and VE (468±27 vs 447±26 ml/min/kg) compared to normovolemic control animals (n=19). Phenyl infusions in normovolemic and sodium‐depleted rats produced similar pressor (Δ = 58±2 and 59±2 mmHg) and bradicardic (Δ = −97±10 and −120±11 bpm) responses. However, a larger increase in VE during baroreflex activation was observed in sodium‐depleted animals in comparison to controls (Δ = 152±40 vs 53±26 ml/min/kg, p<0.05). This increased VE response of sodium‐depleted rats was attenuated (Δ = 77±33 ml/min/kg) after the systemic antagonism of angiotensin II type 1 receptor with losartan (10 mg/kg). The results suggest that neuroendocrine changes produced by sodium depletion, mainly the increase in angiotensin II levels, facilitate the respiratory response to baroreceptor activation in conscious sodium‐depleted rats.Support or Funding InformationFAPESP, FAPESP/Pronex, CNPq, Prope UNESP
Repeated moderate heat exposure decreases resting sympathetic activity in humans
Authors: Cui Jian , Blaha Cheryl , Sinoway Lawrence I. 
Published: November 2023

Acute whole‐body heat stress evokes sympathetic activation. However, the chronic effects of repeated moderate heat exposure (RMHE) on muscle sympathetic nerve activity (MSNA) remains unclear. We performed the RMHE with 4 weeks (5 days/week) of warm baths (39–42 °C for 30 min) in 6 elder volunteers (5 M and 1 F, 59 ± 3 yrs, 177 ± 4 cm, 88 ± 10 kg, BMI 27.6 ± 2.3). Subjects were in the recumbent position in the bathtub with water up to their mid chest. Blood pressure (BP) and heart rate (HR) were monitored with an automated sphygmomanometer throughout each bath. The internal temperature (Tcore) was measured via an ingestible pill telemetry system during the 1st, 11th (i.e. day 15th), and last bath in each subject. Hemodynamic variables and MSNA were examined prior, 1 day post 4 weeks of RMHE and 1 week after end of RMHE in a laboratory at ~23 °C. During the baths, the maximal increase in Tcore was Δ0.9 ± 0.1 °C, the maximal increase in HR was Δ12 ± 2 beats/min, and the maximal drop in mean BP was Δ15 ± 2 mmHg. Under normothermic condition, the resting MSNA significantly decreased after RMHE (prior, post, post 1‐wk: 32.6 ± 2.5, 27.4 ± 2.4, 27.6 ± 2.2 bursts/min; P<0.001; one‐way repeated measures ANOVA). The MSNA burst incidence (i.e. bursts/100 heart beats) also decreased significantly (P=0.002). The resting HR decreased in all subjects after RMHE (60.2 ± 1.6, 56.5 ± 2.1, 56.8 ± 1.8 beats/min, P<0.05), while supine BP was not significantly altered (P>0.05). These data suggest that the RMHE evoked by warm bath is a simple and safe approach to decrease baseline sympathetic activity and HR. The mechanism(s) should be examined in future studies.Support or Funding InformationAHA 15GRNT24480051 (JC) and P01 HL096570‐05 (LIS)
Molecular insights into the regulation of expression of snake venom toxin genes in Pseudonaja textilis
Authors: Han Xia , Acerbi Enzo , Ye Quan‐zhi , Kini R. Manjunatha 
Published: November 2023

Snake venom toxin genes are specifically expressed in the venom gland when it is empty (e.g. after milking). Tissue‐ and time‐specific expression of toxin genes is regulated at transcriptional level by cis‐elements and transcription factors. Recently, we have identified that multiple AG‐rich motifs in intron 1 of trocarin D, a gene encoding venom prothrombin activator in Tropidechis carinatus, silence gene expression in both mammalian and unmilked venom gland cells. Several transcription factors were identified to bound AG‐rich motifs and repress gene expression. However, the complete regulatory mechanisms of specific expression of toxin genes are still unknown. To understand this, we have sequenced the transcriptomes of both milked and unmilked venom gland tissues from a common snake P. textilis (which possesses similar AG‐rich motifs). We have compared the expression levels of different genes and performed gene ontology enrichment analysis. We also analyzed the microRNAs for their expression levels and targets of regulation in these tissues. Here I will present our findings, which will contribute to the understanding of roles of transcription factors and microRNAs in the regulation of specific expression of toxin genes.Support or Funding InformationSource of research support: Academic Research Grants from NUS