For decades, ischemic neuronal death was understood largely as a story about glutamate. Acid-sensing ion channels (ASICs) have revised that account. When cerebral blood flow stops, the penumbra can develop prolonged extracellular acidosis, and experimental studies implicate ASIC1a in mediating sufficient Ca[2+] entry to injure neurons even when glutamate receptors are blocked, a contribution shaped by channel expression, subunit composition, and the intracellular signaling context. However, sustained acidosis does not necessarily imply sustained channel opening, given ASIC1a desensitization. Besides acidosis, glutamate, polyamines, a paradoxical intracellular alkalization, and oxidative stress can enhance ASIC1a activity or expression, and the channel also signals through a non-conducting route, recruiting RIPK1 to trigger necroptosis independently of ion flux. The relative contributions of these conducting and non-conducting mechanisms in vivo remain incompletely defined. Endogenous mechanisms may constrain injury by internalizing the channel, altering subunit expression, including conditioning-associated ASIC2a upregulation, and degrading ASIC1a through estrogen signaling. We argue that these responses are better understood as constraints on injury than as a genuine survival program, a distinction with mechanistic and therapeutic consequences. Critically, the contribution of these mechanisms may vary over time. The same channel acts as a target of homeostatic regulation before stroke, a driver of death during ischemia, a potential target at reperfusion when acidosis persists but restored flow finally permits drug delivery, and an impediment to repair for weeks afterward. The question in ASIC-targeted neuroprotection is not only whether to inhibit the channel, but also when and for how long.

Type 2 long QT syndrome (LQT2) increases the risk of cardiac arrest and sudden death due to reduced rapid delayed rectifier potassium currents (IKr) in the heart. Caused by loss-of-function genetic variants in the hERG K[+] channel, LQT2 might benefit from variant-targeted therapy approaches. T1019PfsX38 and Q1070X are LQT2-causing variants reported in Oman and Saudi Arabia. Although nonsense-mediated mRNA decay (NMD) has been proposed to contribute to reduced expression of these truncating variants, it remains unclear whether residual mutant hERG channel function can be pharmacologically enhanced. We used the patch-clamp technique and examined the effects of the hERG potentiator NS1643 on wild-type-, T1019PfsX38- and Q1070X-hERG channels expressed in HEK293 cells. We started by assessing the response of these variants under the influence of a ventricular action potential clamp protocol, then used additional protocols to elucidate the drug's mechanism of action. NS1643 [10 µM] enhanced the repolarization currents in wild-type-, T1019PfsX38- and Q1070X-expressing cells. Its effect was associated with accelerated activation rates and a negative shift in the voltage dependence of activation. In addition, NS1643 suppressed fast deactivation transitions. We conclude that the functions of T1019PfsX38- and Q1070X-hERG channels can be augmented by hERG potentiators if NMD is incomplete, which may facilitate the development of a mechanism-based rescue approach.

Circadian rhythms regulate physiological and behavioural processes, with the light-dark cycle acting as the principal environmental cue synchronising the biological clock; disruption of this cue can affect brain function and behaviour. Using zebrafish (Danio rerio) as a translational model, we examined how chronic photoperiod alteration, applied from the larval stage to adulthood, affects exploratory activity, anxiety-like behaviour, aggression, and social preference, and whether these changes are paralleled by shifts in gut microbiota composition and brain transcriptomic profile. Zebrafish were reared under three photoperiod regimes: 14L/10D (control), 20L/4D (extended light), and 4L/20D (extended dark), followed by behavioural, gut metagenomic, and brain transcriptomic analyses. Extended darkness (4L/20D) reduced anxiety-like behaviour, whereas extended light (20L/4D) increased aggression both extended photoperiods altered social behaviour, but with distinct behavioural profiles. Gut microbiota in the 20L/4D group showed phylum-level co-dominance of Actinomycetota and Pseudomonadota, including a greater presence of potentially pathogenic taxa, while the 4L/20D group was dominated by Bacillota. Brain transcriptome profiling, based on a single pooled sample per condition, identified transcripts showing the largest expression differences in each group: in 20L/4D, transcripts linked to phototransduction (gnat1, saga, pde6ga, exorh), ribosomal function (rpl13a, rpl9, knop1), melatonin synthesis (asmt), calcium signalling (plcb4a), and glycolysis (eno1a) were elevated; in 4L/20D, transcripts linked to neuroprotection (nr4a1), DNA repair and chromatin remodelling (fance, uimc1, histh1l), synaptic plasticity (serpina10a), neurodevelopment (six6a), and cell-cycle regulation (btg2) were elevated. These findings indicate that photoperiod shapes zebrafish behaviour, gut microbial composition, and brain gene expression, providing a hypothesis-generating basis for future studies incorporating biological replication.

The epithelial sodium channel (ENaC) is a key regulator of electrolyte homeostasis and blood pressure. A characteristic ENaC feature is sodium self-inhibition (SSI), a rapid autoregulatory mechanism in which extracellular Na+ ions allosterically bind ENaC and facilitate transition into a low open probability state. Although SSI is an important functional parameter for assessing ENaC activity and gating, its quantification has traditionally relied on manual two-electrode voltage-clamp (TEVC) recordings with limited scalability and throughput. Here, we improved and evaluated experimental strategies and analytical methods for robust quantification of ENaC SSI in manual and automated TEVC systems: (1) The determination of SSI from extrapolation of transient current recordings in response to a jump in the extracellular Na+ concentration; (2) the estimation of SSI by comparison of steady-state currents before and after chemical modification of a βS520C-ENaC mutant with MTSET; and (3) quantification of SSI from the analysis of steady-state current-voltage relationships recorded at different extracellular Na+ concentrations. The latter procedure is the most reliable for SSI quantification in perfusion rate-limited automated TEVC systems. These methods can expand the capabilities of automated electrophysiology and support medium- to high-throughput investigation of autoregulatory mechanisms in ENaC variants and the discovery of novel ENaC modulators.

Excessive dietary salt intake is a global health concern, affecting cardiovascular, renal, and bone health. While the renin-angiotensin-aldosterone system (RAAS) is a known regulator of dietary salt-induced hormonal responses, the impact of adrenal cortisol remains unclear. Here, we performed a retrospective analysis in individuals (n = 321) consuming a random diet. Dietary salt intake positively correlated with urinary cortisol and inversely correlated with plasma fibroblast growth factor 23 (FGF23), a bone-derived hormone regulating phosphate and vitamin D homeostasis. Controlled salt diets in healthy individuals confirmed a dose-dependent increase in urinary cortisol and suppression of plasma FGF23. In mice, oral corticosterone, a cortisol analogue, reduced circulating FGF23 levels. RNA-seq analysis of corticosterone-treated MC3T3 osteoblasts identified suppression of FGF23 via glucocorticoid receptor activation, anti-inflammatory pathways, and reduced osteoblast activity. Our findings provide evidence for an endocrine cascade in which high salt intake elevates cortisol signaling and suppresses FGF23.

Heart rate variability (HRV) is widely used as a non-invasive marker of cardiac autonomic regulation in human and experimental animal research. Its accessibility, repeatability, and applicability across clinical, psychophysiological, wearable, and preclinical settings make HRV a valuable translational tool. However, HRV indices are highly sensitive to physiological and methodological context, including recording duration, signal quality, respiratory pattern, posture, behavioral state, circadian timing, medication use, anesthesia, temperature, species, strain, artefact correction, frequency-band selection, and analytical method. Human HRV standards provide a strong methodological foundation, but they cannot be directly transferred to animal models without considering species-specific differences in basal heart rate, respiratory frequency, autonomic regulation, recording conditions, and experimental constraints. In animal studies, additional sources of heterogeneity include telemetry versus surface ECG recordings, conscious versus anesthetized states, handling and restraint, surgical recovery, body temperature control, and inconsistent frequency-domain definitions. This review synthesizes current methodological knowledge on HRV measurement in human and experimental animal studies and highlights major challenges that limit reproducibility and translational interpretation. Attention is given to common methodological pitfalls, and the risk of overinterpreting single indices such as LF/HF as direct measures of sympathovagal balance. We also propose a minimum reporting framework for human and experimental animal HRV studies, with shared translational items intended to support authors, reviewers, and editors. Transparent reporting of acquisition, preprocessing, analysis, and physiological context may improve comparability across studies and strengthen the role of HRV as a bridge between mechanistic animal research and human autonomic assessment.Clinical trial number: not applicable.

The gut microbiota, a complex community of bacteria, fungi, viruses, and other microorganisms, plays a critical role in regulating host physiology through the gut-brain axis. The gut microbiota interacts with the central nervous system through a range of interconnected pathways. These include humoral signaling, immune-related mechanisms, sensory afferent pathways, and the modulation of enteric neural circuits. Recent research has uncovered specialized epithelial sensory cells, like neuropod cells, that can directly detect microbial molecules and send signals via vagal afferents. This discovery highlights a previously unknown aspect of communication between the gut and brain. The review investigates the structural and functional diversity of the ENS, highlighting components like mechanosensory and chemosensory neurons, enteroendocrine cells, and neuropods that interact with vagal afferents. Specific focus is placed on pattern recognition receptors such as TLR5, which allow gut epithelial neuropod cells to sense bacterial flagellin and dynamically regulate appetite via PYY release and vagal signaling. Further examination addresses the impact of microbial metabolites including short-chain fatty acids, bile acids, tryptophan derivatives on neuronal excitability, neurotransmitter synthesis, and neuroimmune interactions. These insights underscore the gut as a sensory organ equipped with neural circuits specialized for detecting microbial cues, reimagining traditional concepts of host-microbe communication. By redefining microbial detection as a distinct sense comparable to vision or taste, the neurobiotic sense offers a transformative perspective on how gut microbes influence behavior, feeding patterns, and brain function. This emerging framework holds the potential to drive novel therapeutic strategies for treating metabolic, inflammatory, and neuropsychiatric disorders.

Acid Sensing Ion Channels (ASICs) are widely expressed in the nervous system and involved in an increasing number of functions such as nociception, mechanoreception, and taste transduction, to name a few. In the CNS, ASICs are involved in synaptic plasticity, learning/memory, and in acidosis-mediated neuronal injury. In retina, ASICs are expressed in rodent, rabbit and monkey retina and pharmacological and gene knockdown studies have indicated changes in the earliest phases of electroretinogram that point to effects on phototransduction. This finding led us to investigate the electrophysiological/pharmacological properties of ASICs in cultured primate rod and cone cells. Patch-clamp recordings showed transient ASIC currents with a threshold pH of ~ 7.0 and pH0.5 of 6.15 ± 0.03 and 6.33 ± 0.03 for cultured rod and cone cells, respectively. The currents were almost completely blocked by amiloride and highly sensitive to PcTx-1. Our results for the first time demonstrate the expression of functional ASICs on primate photoreceptors and suggest that ASIC currents in these cells are mediated predominantly by homomeric ASIC1a channels.

Strenuous exercise induces microstructural muscle damage, leading to delayed onset muscle soreness and reduced performance. Although structural changes are well documented, subsequent inflammatory responses are not fully understood. Research has mainly examined leukocyte infiltration and cytokine expression, while low-abundance bioactive lipid mediators remain understudied. Nutritional strategies, such as palmitoylethanolamide (PEA) supplementation, can modulate these mediators and promote anti-inflammatory, pro-resolving conditions, which may improve recovery. Therefore, the present study evaluated the effect of PEA on the abundance of bioactive lipid mediators in skeletal muscle tissue of healthy males following muscle damaging exercise (MDE). 10 participants were included in a double-blind crossover study where they received PEA (2 × 350 mg/d, Levagen+) or placebo (PLA, maltodextrin), in a randomized order. In each experimental condition participants performed an MDE bout (24 × 10 eccentric contractions of the knee extensors on an isokinetic dynamometer). Muscle biopsies were collected at baseline and 48 h following MDE and analysed for lipid mediator profile via LC-MS/MS-based lipidomics. Many lipid mediators decreased 48 h post-exercise in PLA, whereas they remained unchanged or increased in PEA. This pattern was observed for mediators derived from AA (12-HHTrE, 11-HETE, 12-HETE, 15-HETE, 15-epi-LXA4, 14,15-EpETrE, 5,6-DiHETrE), DHA (4-HDoHE), LA (9-HODE, 13-HODE) and ALA (9-HOTrE, 13-HOTrE). MCTR3 levels were consistently higher in PEA compared to PLA, whereas concentrations of LXB4 and AT-RvD3 were consistently lower in PEA compared to PLA, independent of exercise. In conclusion, PEA supplementation attenuated or counteracted the decline in lipid mediators following exercise, indicating that PEA partially enhances bioactive lipid tone in response to strenuous exercise.

While under physiological conditions, extracellular pH in the brain is reasonably constant, several mechanisms induce transient and localized pH fluctuations. Multiple pathologies involve prolonged changes in pH. Therefore, detecting and monitoring pH changes is crucial for the proper functioning of the nervous system. Acid-Sensing Ion Channels (ASICs) are Na+-permeable ion channels, predominantly expressed in the nervous tissue and activated by protons. Thus, ASICs act as pH sensors, leading to neuronal excitation when the pH drops. ASICs belong to the epithelial sodium channel/degenerin (ENaC/DEG) family of amiloride-sensitive transmembrane ion channel proteins. There are at least eight different ASIC subunits encoded by five genes. Functional ASICs assembled in the plasma membrane are homo- or heteromeric trimers. Trimers containing ASIC1a are of particular interest as, in addition to sodium ions, they also conduct calcium ions and thus can regulate multiple cellular processes. ASICs are involved in numerous physiological functions and pathological states. Biophysical properties of ASICs, their evolutionary origins, regulation and pharmacology, their roles in the peripheral nervous system and in the regulation of synaptic transmission have been recently reviewed in many details. Here we shall focus on brain ASICs in the context of the following issues. (i) The role of ASICs in the homeostasis of extracellular рН in the brain; (ii) interactions of ASICs with major neurotransmitters and (iii) ASICs as emerging key factors and drug targets in brain pathology with focus on stroke, neurological consequences of neonatal hyperbilirubinemia, and Alzheimer's disease.

Pharmacological inhibition of the chloride-bicarbonate exchanger pendrin with PDSinh-C01 potentiates the diuretic action of furosemide in healthy mice. Because pendrin contributes to acid-base regulation and blood pressure control, it may represent an attractive therapeutic target in chronic kidney disease (CKD). We investigated whether this pendrin inhibitor improves metabolic acidosis and salt-sensitive hypertension in the 5/6 nephrectomy (5/6Nx) model of CKD. Seven-week-old female Sprague Dawley rats underwent 5/6Nx and implantation of telemetry devices for blood pressure monitoring. All animals received a high-salt (2% NaCl) diet and were randomized (n = 7-9/group) to daily subcutaneous injections for three days of vehicle, PDSinh-C01 (10 mg/kg), furosemide (6 mg/kg), or their combination. The 5/6Nx model recapitulated key features of CKD, including reduced eGFR, hypertension, proteinuria, and hyperchloremic metabolic acidosis. Combination therapy produced the greatest reduction in mean arterial pressure (-11 ± 2 mmHg) compared with vehicle (-3 ± 2 mmHg), furosemide (-6 ± 1 mmHg), or pendrin inhibitor alone (-6 ± 2 mmHg). Furosemide and combination therapy increased urine volume at 6h, whereas only combination therapy increased urine volume at 24h. After three days, the pendrin inhibitor alone and combination therapy increased venous bicarbonate concentrations compared with vehicle (24.5 ± 2.1 and 24.3 ± 1.4 vs. 21.4 ± 1.4 mmol/l). In conclusion, PDSinh-C01 combined with furosemide improves salt-sensitive hypertension in CKD, while PDSinh-C01 alone and in combination with furosemide ameliorates metabolic acidosis. These findings support pendrin as a regulator of electrolyte and acid-base balance and as a potential therapeutic target in CKD.

Linking the distinctive structural and functional properties of lipids belonging to different signaling classes is a frontier of physiology. The present minireview focuses on the endocannabinoidome phospholipase NAPE-PLD, which has bile acids (BAs) as structural cofactors at membrane interface and generates bioactive N-acylethanolamines (NAEs) that promote pleiotropic effects. NAPE-PLD is thus at the crossroads of both their physiological functions, an area of ongoing research. The wide internal channel of NAPE-PLD facilitates the transmembrane transport of pyridoxal 5'-phosphate (PLP) and can support the activity of PLP-dependent enzymes in mitochondria, peroxisome and other subcellular compartments. Recent insights demonstrate that drugs and agents that stabilize NAPE-PLD can control blood pressure, vascular resistance and cardiovascular morbidity in clinics, offering new perspectives on the interaction between NAEs and BAs in cardiometabolic and neurological disorders.

Regular physical activity elicits coordinated molecular adaptations across skeletal muscle, the cardiovascular system, metabolic organs and the brain, underpinning improvements in performance and cardiometabolic health. While classical signaling pathways such as AMPK-PGC‑1α, Ca[2+]/calcineurin, and mTORC1 have been extensively characterized, long non-coding RNAs (lncRNAs) have recently emerged as key regulators of exercise-induced remodeling. Here, we synthesize current evidence on lncRNAs as molecular mediators of exercise adaptations, drawing on mechanistic studies and systems-level transcriptomics. In skeletal muscle, the exercise-induced lncRNAs CYTOR and TUG1 modulate fast-twitch myogenesis, mitochondrial function and fiber-type specification. In the heart, CPhar, lncExACT1 and Mhrt779 discriminate physiological from pathological hypertrophy and encode antihypertrophic "memory," whereas endothelial NEAT1 integrates aerobic training with m[6]A-modulated pyroptosis and atheroprotection. MALAT1 mediates neuroprotection after exercise preconditioning in ischemia/reperfusion models. Omics and network analyses reveal highly modality-, tissue- and cell-type-specific lncRNA programs during human training and across multiple organs. Emerging clinical data support circulating lncRNAs such as MALAT1 and HOTTIP as candidate biomarkers of vascular function and training adaptation. Collectively, lncRNAs constitute a hidden regulatory layer that shapes the quality, magnitude and persistence of exercise-induced adaptations. However, mechanistic evidence is currently limited to a small number of "flagships" lncRNAs, and non-muscle tissues and inter-organ communication remain underexplored. Priorities include functional validation of atlas-derived candidates, dissection of exerkine lncRNAs, and integration of lncRNA biology into precision exercise medicine.

Acid-sensing ion channels (ASICs) are widely recognized as proton (H[+])-gated cation channels that respond to extracellular acidification associated with pathological states such as ischemia, inflammation, and epilepsy. However, an emerging body of evidence compels a broader conceptual reframing: ASICs function as dynamic sensors of metabolic state, integrating real-time signals of neural activity, including CO2-derived H[+], lactate, and nano-domain pH transients, to regulate neuronal excitability and intercellular communication. Here, we review the mechanisms by which activity-dependent pH shifts arise in the brain, how lactate potentiates ASIC gating through divalent-cation chelation and direct channel modulation, and how the tripartite neuron-astrocyte-vascular unit functions as a spatially organized pH-sensing system. We discuss how astrocytes simultaneously buffer extracellular pH and express ASICs, placing them at the center of a bidirectional metabolic feedback loop, and how ASICs in cerebrovascular cells may link neural metabolic load to vascular tone. Finally, we identify key open questions, including the spatial scale of physiologically relevant pH nano-domains, the role of ASIC tachyphylaxis as a "use-history" sensor, and whether ASIC-dependent metabolic signaling shapes circuit-level dynamics during sleep-wake transitions and high-demand cognitive states. This perspective reframes ASICs not merely as damage sensors but as constitutive physiological transducers of brain metabolic activity.

Mucociliary transport (MCT) is the dominant mechanical host defense system in human airways. Although the importance of the peripheral airway in the pathophysiology of bronchial asthma has recently attracted attention, the characteristics of MCT in the peripheral airway during asthma remain unclear. This study aimed to investigate MCT velocity in the central and peripheral airways and the effects of thymic stromal lymphopoietin (TSLP) on MCT. Central and peripheral airways were isolated from freshly obtained porcine airways immediately after slaughter. The airway specimens were mounted in a custom-built fluorescence microscopy-based measurement system. MCT velocity and ciliary beat frequency (CBF) were measured under the following conditions: without stimulation, in the presence of a low concentration of acetylcholine (ACh), and after stimulation TSLP, which reflects the pathophysiological condition of bronchial asthma. MCT velocity in the peripheral airways was slower than that in the central airways at less than one tenth (median: 75.40 μm/sec vs. 2.63 μm/sec). Under physiologically low ACh concentrations, MCT velocity was increased in the peripheral airway but not in the central airway. TSLP addition partially inhibited MCT velocity in both the central and peripheral airways by approximately two-thirds to one-half. TSLP also partially inhibited the CBF in both the central and peripheral airways from approximately two-thirds to one-third. Furthermore, TSLP receptor (TSLPR) expression was confirmed in airway tissues by immunohistochemical staining. The inhibitory effects of TSLP on MCT velocity were completely abolished by pre-incubation with a Janus kinase (JAK) inhibitor. In conclusion, TSLP has the potential to reduce MCT velocity, especially in the peripheral airways, by inhibiting TSLPR signaling pathways, resulting in impaired CBF. The characteristics of MCT differ between the central and peripheral airways. Importantly, TSLP-induced MCT impairment may aggravate mucus plug formation in the peripheral airways in patients with bronchial asthma.