Search Results (197)

Background: The red nucleus (RN) is a phylogenetically conserved structure within the midbrain that is traditionally associated with general motor coordination; however, its specific role in controlling directional movement remains poorly understood. Methods: This study systematically investigates the function and mechanism of RN neurons in directional movement by combining stereotactic brain injections, fiber photometry recordings, multi-unit in vivo electrophysiological recordings, optogenetic manipulation, and anterograde trans-synaptic tracing. Results: We analyzed mice performing standardized T-maze turning tasks and revealed that anatomically distinct RN neuronal ensembles exhibit direction-selective activity patterns. These neurons demonstrate preferential activation during ipsilateral turning movements, with activity onset consistently occurring after movement initiation. We establish a causal relationship between RN neuronal activity and directional motor control: selective activation of RN glutamatergic neurons facilitates ipsilateral turning, whereas temporally precise inhibition significantly impairs the execution of these movements. Anterograde trans-synaptic tracing using H129 reveals that RN neurons selectively project to spinal interneuron populations responsible for ipsilateral flexion and coordinated limb movements. Conclusions: These findings offer a framework for understanding asymmetric motor control in the brain. This work redefines the RN as a specialized hub within midbrain networks that mediate lateralized movements and offers new avenues for neuromodulatory treatments for neurodegenerative and post-injury motor disorders. Full article

Background: We recently reported sex-dependent impairment in cognitive functions in male and female mice exposed for 24 h, 48 h or 15 days to 2G hypergravity (HG). Methods: In the present study, we investigated brain functional correlates by analyzing synaptic activity and plasticity in the CA1 area of the hippocampus in both genders of mice previously exposed to 2G for the same duration. This was assessed by electrophysiological extracellular recordings in ex vivo slice preparations. Results: Basal synaptic transmission and glutamate release were unchanged regardless of HG duration. However, plasticity was altered in a sex- and time-specific manner. In males, long-term potentiation (LTP) induced by strong high-frequency stimulation and NMDA receptor (NMDAr) activation was reduced by 26% after 24 h of exposure but recovered at later timepoints. This deficit was reversed by D-serine or glycine, suggesting decreased activation at the NMDAr co-agonist site. In females, LTP deficits (23%) were found only after 15 days following mild theta burst stimulation and were not reversed by D-serine. Long-term depression (LTD) was unaffected in both sexes. Conclusions: This study highlights, for the first time, sex-dependent divergence in the CA1 hippocampal plasticity timeline following 2G exposure. The synaptic changes depend on exposure duration and the stimulation protocol and could underlie the previously observed cognitive deficits. Full article

Brain ischemia is a severe condition caused by reduced cerebral blood flow, leading to the disruption of ion gradients in brain tissue. This imbalance triggers spreading depolarizations, which are waves of neuronal and glial depolarization propagating through the gray matter. Microelectrode arrays (MEAs) are essential for real-time monitoring of these electrophysiological processes both in vivo and in vitro, but their sensitivity and signal quality are critical for accurate detection of extracellular brain activity. In this study, we evaluate the performance of a flexible microelectrode array based on gold-coated zinc oxide nanorods (ZnO NRs), referred to as nano-fMEA, specifically for high-fidelity electrophysiological recording under pathological conditions. Acute mouse brain slices were tested under two ischemic models: oxygen–glucose deprivation (OGD) and hyperkalemia. The nano-fMEA demonstrated significant improvements in event detection rates and in capturing subtle fluctuations in neural signals compared to flat fMEAs. This enhanced performance is primarily attributed to an optimized electrode–tissue interface that reduces impedance and improves charge transfer. These features enabled the nano-fMEA to detect weak or transient electrophysiological events more effectively, making it a valuable platform for investigating neural dynamics during metabolic stress. Overall, the results underscore the promise of ZnO NRs in advancing electrophysiological tools for neuroscience research. Full article

The serotonergic system, originating in the raphe nuclei, differentially modulates the dorsal and ventral hippocampus, which are implicated in cognition and emotion, respectively. Emerging evidence from rodent models (e.g., neonatal ventral hippocampal lesion, pharmacological NMDA receptor antagonist exposure) and human postmortem studies indicates dorsoventral serotonergic alterations in schizophrenia. These data include elevated 5-HT1A receptor expression in the dorsal hippocampus, linking serotonergic hypofunction to cognitive deficits, and hyperactive 5-HT2A/3 receptor signaling and denser serotonergic innervation in the ventral hippocampus driving local hyperexcitability associated with psychosis and stress responsivity. These dorsoventral serotonergic alterations are shown to disrupt the excitation–inhibition balance, impair synaptic plasticity, and disturb network oscillations, as established by in vivo electrophysiology and functional imaging. Synthesizing these multi-level findings, we propose a novel “dorsoventral serotonin imbalance” model of schizophrenia, in which ventral hyperactivation predominantly contributes to psychotic symptoms and dorsal hypoactivity underlies cognitive deficits. We further highlight promising preclinical evidence that selective targeting of region- and receptor-specific targeting, using both pharmacological agents and emerging delivery technologies, may offer novel therapeutic opportunities enabling symptom-specific strategies in schizophrenia. Full article

Neuroactive steroids (NAS) have long been recognized for their hypnotic and anesthetic properties in both clinical and preclinical settings. While sex differences in NAS sensitivity are acknowledged, the underlying mechanisms remain poorly understood. Here, we examined sex-specific responses to an endogenous NAS epipregnanolone (EpiP) in wild-type mice using behavioral assessment of hypnosis (loss of righting reflex, LORR) and in vivo electrophysiological recordings. Specifically, local field potentials (LFPs) were recorded from the central medial thalamus (CMT) and electroencephalogram (EEG) signals were recorded from the barrel cortex. We found that EpiP-induced LORR exhibited clear sex differences, with females showing increased sensitivity. Spectral power analysis and thalamocortical (TC) and corticocortical (CC) phase synchronization further supported enhanced hypnotic susceptibility in female mice. Our findings reveal characteristic sex-dependent effects of EpiP on the synchronized electrical activity in both thalamus and cortex. These results support renewed exploration of endogenous NAS as clinically relevant anesthetic agents. Full article

Background/Objectives: Chronic pain is a significant global health challenge and is associated with diverse conditions, such as diabetic neuropathic pain and spinal stenosis. Understanding the mechanisms of pain transmission is crucial, for both the peripheral and central pathways. However, there are limitations in spinal electrophysiological techniques in terms of the injection method. Traditional methods such as spinal injections may differ in the distributions and concentrations of drugs compared with intrathecal administration during the behavior test. So, we developed a new intrathecal administration method for electrophysiological recordings. Methods: Sprague–Dawley rats were injected with lidocaine intrathecally, and the analgesic effect was evaluated by the von Frey test. In vivo extracellular single-unit recordings of the superficial dorsal horn neurons were performed following a newly developed technique. Lidocaine was intrathecally injected into the arachnoid membrane after laminectomy. After that, the neural responses in the superficial dorsal horn were measured. Results: Newly developed intrathecally administered dye reached the spinal cord and the cauda equina. Intrathecally administrated lidocaine increased the paw withdrawal threshold and suppressed spinal neuronal firing. This suppression correlated with increases in paw withdrawal thresholds. Conclusions: This innovative method provides insights into the central effects of analgesics, which will help the development of therapies for chronic pain. Full article

Calcium- and voltage-gated potassium channels of large conductance (BK channels) in smooth muscle (SM) act as part of a negative feedback mechanism on SM contraction and associated decrease in cerebral artery diameter. Functional BK channels result from tetrameric association of α subunits encoded by KCNMA1 (Slo1). Ionic current from slo1 channels is inhibited by cholesterol in artificial lipid bilayers, an effect significantly reduced by the slo1 Y450F substitution. Whether such substitution affects cholesterol action on cerebral artery SM BK channel function and diameter remains unknown. Using the KCNMA1Y450F knock-in (K/I) mouse, we determined the effect of cholesterol enrichment on BK currents in native SM cells from middle cerebral artery using patch-clamp electrophysiology and the artery diameter ex vivo response to cholesterol. Results show that the KCNMA1Y450F K/I mutation modifies both basal function and the channel’s response to cholesterol enrichment. Such modifications are detectable solely in SM cells from males, demonstrating sexual dimorphism. Unexpectedly, the modifications introduced by the Y450F substitution do not translate into observable changes in middle cerebral artery diameter ex vivo, suggesting that mechanisms at the SM level compensate for changes driven by the KCNMA1 point mutation under study. Full article

Background: Peripheral nerves have a certain regenerative ability, but their repair and regeneration after injury is a complex process, usually involving a large number of genes and proteins. In a previous study, we analyzed the gene expression profile in rats after sciatic nerve injury and found significant changes in transforming growth factor-beta 1 (TGF-β1) expression, suggesting that TGF-β1 may be involved in the process of nerve regeneration after injury. Methods: In this study, we first detected the time-course expression and localization of TGF-β1 in dorsal root ganglion (DRG) tissues in a rat sciatic nerve transection model via RT-qPCR. Secondly, we investigated the bioactive roles of TGF-β1 in primary cultured DRG neuron cells through a CCK8 assay, TUNEL assay, and immunofluorescence staining. Thirdly, we explored the neuroprotective roles of TGF-β1 in an in vivo model of sciatic nerve regeneration through morphological observation, behavioral, and electrophysiological tests, and a molecular biological measure. Results: We found that TGF-β1 expression was increased after injury and mainly located in the cytoplasm and nuclei of neuron cells in the DRG. TGF-β1 may regulate the viability, apoptosis, and neurite outgrowth of primary DRG neuron cells. In our in vivo model of sciatic nerve regeneration, TGF-β1 improved nerve regeneration and neuronal function recovery after sciatic nerve injury, alleviated the inflammatory response, and relieved neuropathic pain via the TGF-β1/smad2 pathway. Conclusions: This study provides an experimental and theoretical basis for using TGF-β1 as a neuroprotective agent after peripheral nerve injury in clinical practice in the future. Full article

Agmatine is a naturally occurring biogenic amine that acts primarily as an inhibitor of neuronal nitric oxide synthase (nNOS). Previous studies have shown that both acute and chronic agmatine administration induced anxiolytic and antidepressant-like effects in rodents. In the dorsal raphe nucleus (DRN), nitric oxide (NO) donors inhibit serotonergic (5-HT) neuronal activity, with the nNOS-expressing 5-HT neurons showing lower baseline firing rates than the non-nNOS expressing neurons. Our study aimed to test the hypothesis that the psychoactive effects of agmatine are mediated, at least in part, via a mechanism involving the stimulation of the DRN 5-HT neurons, as well as to assess the molecular pathway allowing agmatine to modulate the excitability of 5-HT neurons. Using extracellular in vivo electrophysiology, we demonstrated that both acute (1–3 mg/kg, i.v.) and chronic (40 mg/kg/day, i.p., 14 days) agmatine administration significantly increased the firing rate of DRN 5-HT neurons. Quantitative PCR (qPCR) analysis revealed that chronic agmatine treatment selectively upregulated the expression of serotonin-1B (5-HT_1B) and serotonin-2A (5-HT_2A) receptor mRNA in the DRN. Previous studies have shown that DRN 5-HT_2A receptor activation stimulates 5-HT neurons and produces antidepressant-like effects; our findings suggest that agmatine’s excitatory effect on DRN 5-HT neurons may be partially 5-HT_2A receptor-dependent. Given that modulation of the 5-HT neuronal firing activity is critical for the proper antidepressant efficacy, nNOS inhibitors can be potential antidepressants by their own and/or effective adjuncts to other antidepressant drugs. Full article

Frmpd3 (FERM and PDZ Domain Containing 3), a scaffold protein potentially involved in excitatory synaptic function, has not been thoroughly characterized in terms of its expression and functional role in vivo. Here, we investigated the distribution of Frmpd3 in the central nervous system and its potential regulatory role in epilepsy, a neurological disorder characterized by disrupted excitatory–inhibitory balance. The distribution of Frmpd3 throughout the mouse brain was investigated by immunofluorescence. Western blotting was conducted to examine potential alterations in Frmpd3 protein expression in the hippocampus of a pentylenetetrazol (PTZ)-induced chronic epilepsy model. Using stereotaxic techniques, we delivered Frmpd3 siRNA-AAV9 into the hippocampal CA1 region to achieve targeted protein knockdown. Then, the functional consequences of Frmpd3 depletion were assessed through behavioral observations and electrophysiological recordings in PTZ-treated mice. Finally, protein–protein interactions were investigated using immunoprecipitation and Western blot analysis. Immunofluorescence analysis revealed Frmpd3 expression in cortical, hypothalamic, cerebellar, and hippocampal neurons of adult mice. Subcellular localization studies demonstrated predominant distribution of Frmpd3 in the excitatory postsynaptic density (PSD) of hippocampal CA1 neurons, with additional expression in inhibitory neurons. Quantitative analysis showed significantly elevated Frmpd3 protein levels in the hippocampus of PTZ-induced epileptic mice compared to controls. Frmpd3 knockdown in the CA1 region resulted in the following: (1) reduced seizure frequency, (2) prolonged seizure latency, and (3) decreased incidence of PTZ-induced generalized seizures. Local field potential (LFP) recordings demonstrated that seizure amplitude tended to be reduced, and epileptic discharge durations tended to be shorter in Frmpd3-depleted mice compared to controls. Furthermore, we observed decreased membrane expression of the AMPA receptor GluA2 subunit in the hippocampus of Frmpd3 knockdown mice. Molecular interaction studies revealed that Frmpd3 forms complexes with glutamate receptor-interacting protein (GRIP) and GluA2. Our findings identify Frmpd3 as a novel regulatory scaffold protein that modulates epileptic susceptibility through molecular interactions with GRIP and GluA2. The underlying mechanism appears to involve Frmpd3-mediated regulation of GluA2 trafficking from the cytoplasm to the membrane, ultimately enhancing neuronal excitability through increased membrane expression of GluA2-containing AMPA receptors. Full article

Background/Objectives: Lactate, classically considered a metabolic byproduct of anaerobic glycolysis, is implicated in ischemic acidosis and neuronal injury. The recent evidence highlights its potential role in sustaining metabolic networks and neuroprotection. This study investigates lactate’s compensatory mechanisms in ischemic brain injury by analyzing post-ischemic metabolic enrichments and inter-regional metabolite correlations. Methods: Dynamic metabolic profiling was conducted using ¹³C-labeled glucose combined with ¹H-¹³C NMR spectroscopy to quantify the metabolite enrichment changes in a murine cerebral ischemia model (n = 8). In vivo validation included intracerebroventricular pH-neutral lactate infusion in ischemic mice to assess the behavioral, electrophysiological, and mitochondrial outcomes. In vitro, HT22 hippocampal neurons underwent oxygen–glucose deprivation (OGD) with pH-controlled lactate supplementation (1 mM), followed by the evaluation of neuronal survival, mitochondrial membrane potential, and glycolytic enzyme expression. Results: NMR spectroscopy revealed a 30–50% reduction in most cerebral metabolites post-ischemia (p < 0.05), while the quantities of lactate and the related three-carbon intermediates remained stable or increased. Correlation analyses demonstrated significantly diminished inter-metabolite coordination post-ischemia, yet lactate and glutamate maintained high metabolic activity levels (r > 0.80, p < 0.01). Lactate exhibited superior cross-regional metabolic mobility compared to those of the other three-carbon intermediates. In vivo, lactate infusion improved the behavioral/electrophysiological outcomes and reduced mitochondrial damage. In the OGD-treated neurons, pH-neutral lactate (7.4) reduced mortality (p < 0.05), preserved the mitochondrial membrane potential (p < 0.05), and downregulated the glycolytic enzymes (HK, PFK, and PKM; p < 0.01), thereby attenuating H⁺ production. Conclusions: Under ischemic metabolic crisis, lactate and the three-carbon intermediates stabilize as critical substrates, compensating for global metabolite depletion. pH-neutral lactate restores energy flux, modulates the glycolytic pathways, and provides neuroprotection by mitigating acidotoxicity. Full article

The precise regulation of synaptic function by targeted protein degradation is fundamental to learning and memory, yet the roles of many brain-enriched E3 ubiquitin ligases in this process remain elusive. Here, we uncover a critical and previously unappreciated role for the E3 ubiquitin ligase PRAJA1 in orchestrating synaptic plasticity and hippocampus-dependent memory. Utilizing C57BL/6 and 5xFAD male mice and employing a multi-faceted approach including protein biochemistry, molecular biology, in vitro electrophysiology, and behavioral assays, we demonstrate that long-term potentiation (LTP) induction triggers a rapid, proteasome-dependent downregulation of PRAJA1 within the CA1 region of the hippocampus. Critically, selective knockdown of PRAJA1 in vivo profoundly enhanced both object recognition and spatial memory, while disrupting normal exploratory behavior. Mechanistically, we reveal that PRAJA1 acts as a key regulator of synaptic architecture and transmission: its downregulation leads to a reduction in key synaptic proteins and spine density, influencing the excitatory/inhibitory balance and facilitating synaptic plasticity. Conversely, increased PRAJA1 expression potentiates GABAergic transmission. Furthermore, we identify spinophilin as a novel substrate of PRAJA1, suggesting a direct molecular link between PRAJA1 and synaptic remodeling. Strikingly, our findings implicate dysregulation of PRAJA1 in the pathogenesis of Alzheimer’s disease, positioning PRAJA1 as a potential therapeutic target for cognitive enhancement in neurodegenerative conditions. These results unveil PRAJA1 as a critical molecular brake on synaptic plasticity and memory formation, offering a promising new avenue for understanding and potentially treating memory impairment. Full article

25I-NBOMe (4-Iodo-2,5-dimethoxy-N-(2-methoxybenzyl) phenethylamine) is a synthetic psychedelic compound abused for its ambiguous legal state as a counterfeit lysergic acid diethylamide (LSD). 25I-NBOMe acts as a selective agonist of 5HT_2A receptors leading to hallucinations, intoxications, and fatalities. Here, we assessed the rewarding properties of 25I-NBOMe and its behavioral and neurotoxic acute effects on the central nervous system of C57BL/6J mice. We evaluated the dopamine (DA) levels using in vivo microdialysis in the nucleus accumbens (NAc) shell after 25I-NBOMe (0.1–1 mg/kg i.p.) injection. We also investigated the effects of 25I-NBOMe (0.1–1 mg/kg i.p.) on locomotor activity, reaction time, and prepulse inhibition. Moreover, we assessed the acute 25I-NBOMe (1 µM) effects on synaptic transmission and plasticity in the medial prefrontal cortex (mPFC) by using ex vivo electrophysiology. Our findings suggest that 25I-NBOMe affects the DA transmission in NAc shell at the highest dose tested, increases the reaction time within 30 min after the administration, and disrupts the PPI. In slices, it prevents long-term synaptic potentiation (LTP) in the mPFC, an effect that could not be reverted by the co-administration of the selective 5HT_2A antagonist (MDL100907). Overall, these findings provide valuable new insights into the effects of 25I-NBOMe and the associated risks of its use. Full article

The integrity of esophageal epithelial cells in patients with gastroesophageal reflux disease (GERD) or GERD-like symptoms is the first mechanism of protection to decrease the sensitivity to gastric reflux and heartburn symptoms. We investigated the protective effects of Poliprotect^® (PPRO), a CE-marked medical device, on esophageal epithelial integrity using in vitro and ex vivo models. In vitro, the protective effects of PPRO were tested on Caco-2 cells. PPRO demonstrated safety and protection against oxidative damage induced by hydrogen peroxide. It also preserved epithelial integrity by maintaining transepithelial electrical resistance (TEER) against damage from calcium removal or bile acid exposure (taurodeoxycholic acid, TDCA). Ex vivo, esophageal biopsies from patients subjected to endoscopy were mounted in Ussing chambers and exposed to damaging agents (HCl or HCl + TDCA). Untreated biopsies (control) showed significant loss of epithelial resistance (up to −33%). In contrast, low concentrations of PPRO (50–100 µg/mL) provided strong protection against these damages (p < 0.001), even after 60 min of washing. Histological analysis confirmed the barrier-enhancing effect of PPRO. Overall, PPRO effectively protected the esophageal epithelium from damage in both models, suggesting its potential role in alleviating GERD or GERD-like symptoms by strengthening mucosal barriers and reducing epithelial sensitivity to reflux. Full article

We previously reported that membrane-type 5-matrix metalloproteinase (MT5-MMP) deficiency not only reduces pathological hallmarks of Alzheimer’s disease (AD) in 5xFAD (Tg) mice in vivo but also impairs interleukin-1 beta (IL-1β)-mediated neuroinflammation and Aβ production in primary Tg immature neural cell cultures after 11 days in vitro. We now investigate the effect of MT5-MMP on incipient pathogenic pathways that are activated in cortical primary cultures at 21–24 days in vitro (DIV), during which time neurons are organized into a functional mature network. Using wild-type (WT), MT5-MMP^−/− (MT5^−/−), 5xFAD (Tg), and 5xFADxMT5-MMP^−/− (TgMT5^−/−) mice, we generated primary neuronal cultures that were exposed to IL-1β and/or different proteolytic system inhibitors. We assessed neuroinflammation, APP metabolism, synaptic integrity, and electrophysiological properties using biochemical, imaging and whole-cell patch-clamp approaches. The absence of MT5-MMP impaired the IL-1β-mediated induction of inflammatory genes in TgMT5^−/− cells compared to Tg cells. Furthermore, the reduced density of dendritic spines in Tg neurons was also prevented in TgMT5^−/− neurons. IL-1β caused a strong decrease in the dendritic spine density of WT neurons, which was prevented in MT5^−/− neurons. However, the latter exhibited fewer spines than the WT under untreated conditions. The spontaneous rhythmic firing frequency of the network was increased in MT5^−/− neurons, but not in TgMT5^−/− neurons, and IL-1β increased this parameter only in Tg neurons. In terms of induced somatic excitability, Tg and TgMT5^−/− neurons exhibited lower excitability than WT and MT5^−/−, while IL-1β impaired excitability only in non-AD backgrounds. The synaptic strength of miniature global synaptic currents was equivalent in all genotypes but increased dramatically in WT and MT5^−/− neurons after IL-1β. MT5-MMP deficiency decreased endogenous and overexpressed C83 and C99 levels but did not affect Aβ levels. C99 appears to be cleared by several pathways, including γ-secretase, the autophagolysosomal system, and also α-secretase, via its conversion to C83. In summary, this study confirms that MT5-MMP is a pivotal factor affecting not only neuroinflammation and APP metabolism but also synaptogenesis and synaptic activity at early stages of the pathology, and reinforces the relevance of targeting MT5-MMP to fight AD. Full article