Search Results (178)

Introduction: Chronic non-cancer pain represents a major global health challenge because of its high prevalence, functional impact, and limited response to conventional therapies, highlighting the need for alternative approaches. In this context, subanesthetic-dose ketamine has emerged as a promising therapeutic option because of its ability to modulate central sensitization and enhance analgesia through NMDA receptor antagonism. However, current evidence regarding its long-term efficacy and safety remains limited and heterogeneous. Objective: To evaluate the efficacy and safety of subanesthetic ketamine for the management of chronic non-cancer pain in adults, based on randomized controlled trials published between 2005 and 2025. Methods: A systematic review was conducted in accordance with the PRISMA 2020 guidelines. Randomized controlled trials involving adults with chronic non-cancer pain were included, comparing ketamine with placebo or other active agents. The databases searched were PubMed, ScienceDirect, and the Cochrane Library. Risk of bias was assessed using the Cochrane RoB-2 tool, and the certainty of evidence was evaluated using GRADE. Results: Five trials met the inclusion criteria. All included studies evaluated intravenous ketamine at doses ranging from 0.3 to 0.5 mg/kg. Overall, ketamine demonstrated significant short-term pain relief (p < 0.05), particularly in neuropathic conditions; however, the magnitude of this effect decreased progressively after the infusion ended. Reported adverse effects were mild and transient, with no evidence of severe toxicity. Heterogeneity in dosing protocols, pain phenotypes, comparator strategies, and follow-up duration limited cross-study comparability. Conclusions: Current evidence supports the short-term efficacy and safety of subanesthetic-dose ketamine as an analgesic option for chronic non-cancer pain, especially in neuropathic syndromes. However, the transient nature of its effects and the heterogeneity among studies underscore the need for standardized protocols and longer follow-up periods. Despite its generally favorable short-term safety profile, subanesthetic ketamine should be used with caution under strict clinical supervision, as the potential for long-term neurocognitive, urological, and hepatic adverse effects remains insufficiently defined. Full article

Background/Objectives: Schizophrenia is a severe psychiatric disorder frequently characterised by sleep and circadian disturbances, which are closely linked to cognitive dysfunction, symptom exacerbation, and poor functional outcomes. A growing body of evidence implicates the orexin (hypocretin) system—an essential regulator of arousal, sleep–wake stability, metabolic processes, and motivated behaviour—in the pathophysiology and treatment response of psychotic disorders. We aimed to investigate the relationships between the orexinergic system and psychoses. Methods: On 3 March 2026, we searched the PubMed, Scopus, PsycInfo/Articles and Cinahl databases for studies dealing with the orexin system and psychotic disorders and treatment response. Results: We found 20 eligible studies reporting variable and inconsistent alterations in orexin signalling in patients with schizophrenia. Studies were mostly cross-sectional and heterogeneous in design. Antipsychotic medications interfere with orexin-dependent pathways, potentially contributing to both therapeutic effects and adverse outcomes such as sleep disruption and metabolic dysregulation. Conclusions: While evidence from preclinical studies could point to an influence of dopaminergic activity through orexinergic mechanisms, with possible attenuation of antipsychotic-induced motor side effects and improvement of attentional deficits associated with NMDA receptor hypofunction, the utility of dual orexin receptor antagonists (DORAs) in psychoses is unclear. Despite the high prevalence of insomnia in schizophrenia, its pharmacological management remains suboptimal, with current treatments often limited by reduced efficacy or tolerability concerns. DORAs, which are currently approved medications for the treatment of insomnia, represent a novel and mechanistically distinct therapeutic option that may improve sleep while modulating arousal- and cognition-related circuits relevant to psychosis. Full article

Alzheimer’s disease (AD), the leading cause of global dementia, is a multifactorial process that goes beyond the accumulation of β-amyloid (Aβ) plaques and tau protein tangles, including glia cell-mediated neuroinflammation, vascular dysfunction, metabolic alterations, and synaptic loss. Its complex etiology also involves oxidative stress and mitochondrial dysfunction. Multiple neurotransmitter systems involved in the pathogenesis and the various cognitive and non-cognitive symptoms of AD are thus altered. The cholinergic system, historically the first to be associated with AD, suffers early degeneration and loss of neurons/receptors, correlating with cognitive impairment. The glutamatergic system, the main excitatory system, exhibits excitotoxicity due to increased extracellular glutamate and alterations in NMDA/AMPA receptor distribution, exacerbating neuronal damage. The GABAergic system, the main inhibitor, shows alterations in parvalbumin-positive interneurons, leading to hyperexcitability and dysfunction of neuronal networks. Monoaminergic systems (serotonergic, dopaminergic and noradrenergic) undergo early degeneration in key nuclei such as the raphe and locus coeruleus, contributing to the apathy, depression and sleep disturbances characteristic of AD. Other less explored systems, such as histaminergic and purinergic, are also crucial in cognitive modulation and neuroinflammation. The endocannabinoid system acts as a master modulator with neuroprotective and anti-inflammatory effects. These systems do not operate in isolation; their complex interactions generate pathological circuits that amplify neuronal dysfunction. The limited efficacy of current therapies, which are primarily symptomatic, highlights the need for multimodal approaches that may transform AD treatment toward personalized and more effective interventions. Full article

The clinical renaissance of psychedelic medicine has highlighted the therapeutic potential of rapid-acting neuroplastogens, or “psychoplastogens,” for psychiatric disorders. However, the widespread application of classical psychedelics—such as psilocybin and LSD—and the atypical dissociative ibogaine is severely limited by their hallucinogenic properties and, particularly in the case of ibogaine, life-threatening cardiotoxicity. Addressing these limitations, Tabernanthalog (TBG) has emerged as a frontrunner in the field. This non-hallucinogenic analog of ibogaine was rationally designed to eliminate interactions with the human ether-à-go-go-related gene (hERG, KCNH2) potassium channel, thereby mitigating cardiotoxic risks. While initially characterized for its anti-addictive and antidepressant-like properties, recent data from 2024–2025 have significantly expanded its therapeutic horizon. TBG demonstrates robust efficacy in preclinical models of neuropathic and visceral pain, as well as in the rescue of cognitive deficits associated with cancer-related cognitive impairment (CRCI). TBG has shown efficacy in reversing cognitive impairments induced directly by the presence of a tumor in preclinical models, rather than by chemotherapy-specific neurotoxicity. Crucially, emerging evidence suggests that TBG’s mechanism extends beyond simple 5-HT2A receptor agonism. New findings point to a multi-target profile involving the inhibition of nicotinic acetylcholine receptors (nAChRs), positive modulation of NMDA receptors, and functional crosstalk with mGlu2 receptors. Furthermore, TBG appears to induce structural neuroplasticity without the widespread induction of immediate early genes (IEGs) seen with classical hallucinogens, suggesting a decoupling of therapeutic rewiring from the subjective psychedelic experience. This review synthesizes current preclinical evidence to discuss TBG as a promising chemical scaffold for next-generation neurotherapeutics targeting the intersection of psychiatry and neurology. Full article

Background: Neuropsychiatric disorders such as Alzheimer’s disease (AD), bipolar disorder (BD), and depression exhibit shared glutamatergic abnormalities, although their upstream molecular mechanisms remain poorly defined. Magnesium (Mg²⁺) serves as a key regulator of N-methyl-D-aspartate (NMDA) receptor function; however, the role of Mg²⁺ transporters, particularly SLC41A1, has not been systematically investigated. As NMDA receptor dysregulation contributes to emotional and cognitive impairments, elucidating Mg²⁺-NMDA signaling may enable the development of novel therapeutic strategies. Methods: We integrated Mendelian randomization, locus colocalization, human brain transcriptomics, functional enrichment, and co-expression analyses to determine whether SLC41A1 functions as a cross-disorder molecular driver. In addition, in vitro electrophysiological experiments using field potential recordings in hippocampal Schaffer-CA1 synapses were conducted to validate its functional role in NMDA receptor-mediated synaptic transmission. Results: Genetically elevated SLC41A1 expression increased the risk of AD, BD, depression, and alcohol dependence, with strong colocalization analyses supporting shared causal variants. Transcriptomic profiling revealed SLC41A1 upregulation in AD and BD, with enrichment in magnesium transport, mitochondrial function, and synaptic signaling pathways. Co-expression networks across GTEx brain regions demonstrated strong correlations with NMDA-related genes (e.g., GRINA, CAMK2G, GRIN2C). Under NMDAR-selective recording conditions, both imipramine treatment and SLC41A1 knockdown significantly reduced NMDAR-mediated fEPSP amplitudes, supporting a role for SLC41A1 in regulating NMDA receptor-dependent synaptic responses. Conclusions: This study identifies SLC41A1 as a magnesium-centered, transdiagnostic therapeutic target that links Mg²⁺ homeostasis to NMDA-dependent synaptic dysfunction. These findings provide a mechanistic foundation for developing SLC41A1-modulating or magnesium-based therapeutic approaches for mood and cognitive disorders. Full article

Alzheimer’s disease is a progressive neurodegenerative disorder marked by cognitive decline, and its global prevalence is expected to increase substantially in the coming decades. This review examines current therapeutic approaches and explores the potential role of medicinal plants and natural products in the treatment and prevention of Alzheimer’s disease. This review examines the pathophysiology of Alzheimer’s disease, with particular emphasis on the cholinergic, amyloid, and tau hypotheses. It evaluates currently approved therapeutic approaches, including cholinesterase inhibitors and NMDA receptor antagonists, as well as emerging immunotherapies. In addition, this review provides a comprehensive analysis of the pharmacological properties of various medicinal plants and explores innovative drug delivery systems. Research reveals that while conventional drugs like donepezil and memantine provide symptomatic relief, they do not halt disease progression. Recent immunotherapies, including lecanemab and donanemab, show potential to reduce amyloid-beta accumulation and slow cognitive decline; however, they face safety concerns, such as amyloid-related imaging abnormalities, and high costs. By comparison, several natural products—including huperzine A, curcumin, resveratrol, and epigallocatechin-3-gallate—demonstrate multi-target therapeutic potential through anti-inflammatory, antioxidant, and cholinergic-modulating mechanisms. This review offers a comprehensive contrast between natural products and traditional drugs as well as the safety and economic limitations of immunotherapies. Given the multifactorial nature of AD, therapeutic strategies that address multiple pathological pathways appear necessary. In this regard, plant-derived compounds, due to their broad pharmacological activity and generally favorable safety profiles, emerge as promising candidates for long-term management and may contribute meaningfully to the development of future therapeutic approaches for AD. Full article

Recently, complementary and alternative medicine (CAM) has been actively employed for patients experiencing symptoms unresponsive to Western medical treatments like drug therapy. The natural compounds carotenoids and astaxanthin (AST) have demonstrated various beneficial biological actions for human health in several studies. Given their broad pharmacological activities and reduced toxicity, ASTs possess significant potential as resources for the development of natural analgesic drugs. Given recent studies showing that AST can modulate neuronal excitability, including nociceptive sensory transmission through voltage-gated Ca²⁺ channels and the n-methyl-D-aspartate (NMDA) glutamate receptor, and inhibit the cyclooxygenase-2 cascade, AST holds promise as a CAM, particularly as a therapeutic agent for nociceptive and pathological pain. Based on the in vivo research findings from our laboratory presented in this review, we have confirmed that carotenoid ASTs possess: (i) an intravenous anesthetic effect on both nociceptive and inflammatory pain comparable to existing analgesics such as ketamine; and (ii) an anti-inflammatory effect on chronic pain with an efficacy almost equivalent to that of the commonly used non-steroidal anti-inflammatory drug (NSAID) celecoxib. Therefore, these findings suggest that, as natural compounds, ASTs contribute to the relief of nociceptive and inflammatory pain, implying their potential for clinical application. Full article

Locus coeruleus (LC) noradrenergic neurons project their axons to the cerebellar cortex and modulate cerebellar circuit function via distinct adrenergic receptor (AR) subtypes. The present study investigated the mechanism by which optogenetic activation of LC noradrenergic neurons modulates facial stimulation-evoked long-term synaptic plasticity at cerebellar mossy fiber-granule cell (MF-GrC) synapses in urethane-anesthetized DBH-Cre mice. Blockade of GABA_A receptors, 20 Hz facial stimulation induced MF-GrC long-term potentiation (LTP) in the control group, and this LTP was impaired by optogenetic activation of LC noradrenergic neurons via α2-ARs. Meanwhile, facial stimulation induced LTP of glutamate sensor fluorescence in the granular layer, which was abolished by chemogenetic activation of LC noradrenergic neurons. Following NMDA receptor blockade, optogenetic activation of LC noradrenergic neurons triggered facial stimulation-induced MF-GrC long-term depression (LTD) via α2A-ARs. Optogenetically activated LC noradrenergic neuron-induced MF-GrC LTD was abolished by protein kinase A (PKA) inhibition but not by protein kinase C inhibition. Immunofluorescence results revealed abundant α2A-AR expression in the granular layer, with particularly high levels in glomeruli, and no colocalization with the glutamate sensor. These results indicate that optogenetic activation of LC noradrenergic neurons impairs facial stimulation-induced MF-GrC LTP by triggering presynaptic LTD via the α2A-AR/PKA signaling cascade. Full article

Background: Cognitive disorders are a class of neurological diseases characterized by declines in cognitive function, imposing a heavy physical and mental burden on middle-aged and elderly individuals. Since the underlying mechanisms of cognitive disorders are not yet fully understood, and different types of cognitive disorders may involve distinct mechanisms, the development of drugs with multi-target therapeutic and preventive effects is of great significance. Currently approved drugs for Alzheimer’s disease, such as acetylcholinesterase inhibitors and NMDA receptor antagonists, show limited efficacy and poor prognosis, highlighting the urgent need for safe and effective alternative treatments. Methods: Plant-derived polysaccharides (PDPs) possess antioxidant, anti-inflammatory, neuroprotective, and immunomodulatory activities, and polysaccharides derived from traditional Chinese medicine, in particular, show great potential for treating cognitive disorders. In recent years, interventions with plant polysaccharides that modulate the gut microbiota to affect the “gut–brain axis” and improve cognitive function have become an emerging research focus. Clinical evidence has also increasingly supported the beneficial effects of polysaccharides on cognitive disorders. Therefore, this study focuses on plant polysaccharides in the intervention of cognitive disorder-related diseases, including both in vivo and in vitro experiments, and summarizes existing findings according to different mechanisms of action. Results and Conclusions: Relevant clinical reports are incorporated to provide a theoretical basis and strong support for the development of polysaccharide-based interventions and new drug development for cognitive disorders. Full article

Background: Ketamine and magnesium sulfate are commonly used perioperatively to prevent shivering, a frequent and clinically relevant complication of spinal and general anesthesia. Although their hypothermic effects are well documented, the neurotransmitter mechanisms underlying these effects remain insufficiently understood. This study examines whether serotonergic, adrenergic (α₂), and GABAergic (GABA_A) systems contribute to hypothermia induced by ketamine and a ketamine–magnesium sulfate combination. Methods: Body temperature was measured in Wistar rats after administration of ketamine (10 mg/kg) or the ketamine (5 mg/kg)–magnesium sulfate (5 mg/kg) combination. To assess neurotransmitter involvement, animals received yohimbine (α₂ antagonist), methysergide (non-selective 5-HT antagonist), or bicuculline (GABA_A antagonist) prior to ketamine or the drug combination. Data were analyzed using two-way repeated measures ANOVA followed by Tukey’s post hoc test. Results: Yohimbine at 0.5 and 1 mg/kg significantly potentiated ketamine-induced hypothermia, while only 3 mg/kg enhanced the effect of the ketamine–magnesium sulfate combination. Methysergide had a bidirectional influence: 1 mg/kg methysergide deepened ketamine-induced hypothermia, whereas 0.5 mg/kg methysergide attenuated the hypothermic effect of the ketamine–magnesium sulfate combination. Bicuculline (1–2 mg/kg) did not alter the hypothermic responses to ketamine or the combination. Conclusions: These findings indicate that ketamine- and ketamine–magnesium sulfate-induced hypothermia is primarily modulated by serotonergic and adrenergic mechanisms, whereas GABA_A receptor-dependent pathways do not appear to play a major role under the experimental conditions used. These results provide new mechanistic insights into NMDA antagonist–related thermoregulation and may help inform anesthetic strategies for shivering prevention and maintenance of perioperative thermal stability. Full article

Substance Use Disorder (SUD) constitutes a major and persistent global public health burden, accounting for approximately 600,000 deaths annually, largely driven by opioid use. Despite substantial advances in addiction neuroscience, currently approved therapeutic strategies remain limited in efficacy, as they predominantly target isolated neurobiological processes and fail to concurrently address core mechanisms such as glutamatergic hyperactivity, mesolimbic hypodopaminergic, and dysfunction of cortical and executive control networks. This mechanistic fragmentation contributes to persistently high relapse rates and underscores the need for integrative and multitarget therapeutic approaches. Within this context, ibogaine has re-emerged as a clinical candidate due to its distinctive multimodal neuropharmacological profile and its reported capacity to modulate multiple pathways implicated in addictive behaviours. However, the clinical translation of ibogaine remains substantially constrained by fragmented and heterogeneous evidence, the absence of regulatory frameworks in several jurisdictions, limited phytochemical validation and standardization of available formulations, and unresolved concerns regarding cardiac safety. This scoping review critically synthesizes the available preclinical and clinical literature on ibogaine in the treatment of SUD, with particular emphasis on reported effects on withdrawal symptoms and craving, dose–response relationships, and the occurrence of cardiac adverse events. By clarifying the current state of the evidence and delineating key translational constraints, this review defines the conditions under which ibogaine, an indole alkaloid isolated from Tabernanthe iboga Baill. (Apocynaceae), may warrant continued investigation. The hypothesis of a neurobiological “reset”, supported by emerging preclinical and clinical data, positions ibogaine as a compound of relevance in addiction research and highlights the need for rigorous pharmacological, toxicological, and regulatory evaluation to inform safer and more standardized clinical pathways. Full article

Growing evidence has revealed that gut dysbiosis is associated with the development of anxio-depressive disorders through mechanisms that involve neuroimmune signaling, neurotransmitter changes, and neuroplasticity in the brain. This study investigated the effects of gingerol-enriched ginger (GEG) on specifically anxiety-related neuroinflammation-, neuroimmunity-, neuroplasticity-, neurotransmission-, and neurotoxicity-associated genes in different brain regions, as well as on alterations linked to colonic microflora-driven dysbiosis, in the spinal nerve ligation (SNL) rat model of neuropathic pain (NP). Twenty-seven male rats were assigned to 3 groups: sham, SNL, and SNL-treated with GEG at 200 mg/kg body weight (SNL+200GEG) via oral gavage for 5 weeks. Anxiety-like behavior was assessed on the elevated plus maze (EPM). mRNA expression was assessed by qRT-PCR using respective primers. Correlation between behavioral parameters and colonic microbiome composition was analyzed using the Spearman rank correlation. The SNL+200GEG group demonstrated decreased anxiety-like behavior in the SNL model. Compared to the SNL group, the SNL+200GEG group had increased mRNA expression of NRF2 (amygdala: left), LXRα (amygdala: both sides), and CX3CR1 (amygdala: both sides, hippocampus: right). GEG modulated neuroplasticity as shown by increased gene expression of PGK1 (amygdala: right, hippocampus: both sides), MEK1 (frontal cortex: both sides), LDHA (frontal cortex: both sides), GPM6A (frontal cortex: both sides, amygdala: right, hippocampus: right, and hypothalamus), and GLUT1 (amygdala: right) as well by decreased gene expression of HIF1α (in all brain regions except for the hypothalamus). GEG modulated neurotransmission via clearance of excessive glutamate release as suggested by increased gene expression of SLC1A3 (frontal cortex: both sides, hippocampus: right) and via augmenting mGluR5 signaling as shown by increased gene expression of GRM5 (hippocampus: both sides, hypothalamus) as well as downregulation of KMO, HAAO, GRIN2B, and GRIN2C influencing downstream serotonergic neurotransmission and NMDA receptor-mediated glutamatergic pathways in different brain regions. GEG further alleviated neurotoxicity through downregulated gene expression of SIRT1, KMO, IDO1, and HAAO in different brain regions. Moreover, the increased relative abundance of Bilophila spp., accompanied by decreased time spent in the EPM open arms, suggests that increased Bilophila abundance increases anxiety-like behavior. GEG supplementation mitigated anxiety-like behavior in male rats with NP, at least in part, by reducing SNL-induced inflammatory sequelae-related mRNA gene expression in different brain regions. In addition, there is a positive correlation between the abundance of Bilophila wadsworthia and the degree of anxiety-like behavior. Full article

Background/Objectives: The neurotransmitter glycine is involved in several physiological and pathological conditions in the Central Nervous System. Different biological structures, including glycine receptors and transporters, are under study as targets for potential drugs acting against serious neurological and psychiatric disorders. The regulation of glycine release from nerve terminals is only partially understood. We report here preliminary evidence of the modulation of glycine release through presynaptic metabotropic glutamate receptors 1 (mGlu1) from glycinergic nerve terminals in mouse hippocampi. Methods: Purified mouse hippocampal synaptosomes labeled with [³H]glycine were used to study glycine release under superfusion conditions. Results: The group I metabotropic glutamate receptor agonist 3,5-DHPG potentiated depolarization-evoked [³H]glycine release from hippocampal synaptosomes, an effect strongly counteracted by the selective mGlu1 antagonist LY 367385. 3,5-DHPG failed to increase [³H]glycine release in Grm1^crv4/crv4 mice, a mouse model lacking mGlu1. Although further research is needed to clarify these mechanisms, data suggest that glycine-releasing hippocampal nerve terminals are endowed with presynaptic mGlu1 receptors whose activation potentiates glycine release. Conclusions: Considering that in the hippocampus, glycine is relevant as a co-agonist of glutamate at NMDA receptors and that mGlu1 receptor ligands are under study as potential drugs, we propose that the possible effects of these agents on the release of glycine should be considered when studying these compounds. Full article

The cells in the central nervous system (CNS) can adapt to injury and inflammation through structural and functional changes, many of which are mediated by the kynurenine pathway (KP). Studies using glia–neuron co-cultures showed that the biflavonoid agathisflavone (FAB), purified from the leaves of Cenostigma pyramidale Tul., a plant native to the Brazilian caatinga, exerts strong neuroprotective effects. This study evaluated whether agathisflavone (1 µM) modulates these responses in human and murine astrocytes and microglia exposed to inflammatory activation with lipopolysaccharide (LPS, 1 µg/mL), excitotoxic activation of NMDA receptors with quinolinic acid (QUIN, 500 µM), or inhibition of the KP rate-limiting enzyme indoleamine 2,3-dioxygenase 1 (IDO1) with 1-methyl tryptophan (1-MT, 1.5 μM). Co-treatment with FAB increased astrocyte viability relative to LPS, QUIN, or 1-MT alone, by up to 35% (p < 0.05), while reducing GFAP overexpression and other features of reactive astrogliosis. FAB decreased the proportion of Iba-1⁺ microglia, indicating anti-inflammatory effects. When combined with QUIN or 1-MT, FAB reversed the elevation of iNOS (p < 0.0001) and reduced IL1β upregulation. FAB also modulated KP activity in a cell type-specific manner. In astrocytes, FAB with QUIN or with 1-MT increased IDO activity, whereas in microglia, FAB alone reduced it. In microglia, kynurenine-3-monooxygenase (KMO) expression was significantly increased under FAB+QUIN or FAB+1-MT (p < 0.0001). Finally, astrocyte-conditioned medium from FAB-treated cells increased the viability of neuron-like PC12 cells by up to 40%. Collectively, these findings show that FAB confers cytoprotective and anti-inflammatory actions on glial cells, modulates KP signalling in a context-dependent manner, and supports neuronal survival under neuroinflammatory conditions. Full article

Since the introduction of the NMDA receptor antagonist (S)-ketamine for depression therapy, it has become evident that the glutamatergic hypothesis of depression, proposed over 20 years ago, was justified and based on solid foundations. A significant breakthrough with this drug is its ability to produce a rapid and relatively long-lasting antidepressant effect in patients who are resistant to traditional depression treatments, both pharmacological and non-pharmacological. However, alongside its beneficial effects, (S)-ketamine can cause several side effects that make it a less safe option. As a result, strategies are being explored to mitigate the risks associated with its use. These strategies include leveraging the shared mechanism of action between ketamine and various modulators of the glutamatergic system. Preclinical studies have shown that low doses of mGlu₂ and mGlu₅ receptor antagonists can enhance the therapeutic effects of ketamine or its enantiomers without producing the typical side effects associated with ketamine. This review discusses the research on this synergistic effect, the underlying mechanisms, and the role of mGlu₂ and mGlu₅ receptors in the antidepressant action of ketamine. Full article