Search Results (702)

The indole scaffold represents a privileged structural motif in medicinal chemistry, celebrated for its remarkable chemical versatility, biological ubiquity, and clinical relevance. This review provides a comprehensive analysis of the recent research on the indole nucleus, emphasizing its physicochemical properties, reactivity patterns, and capacity to interact with a wide array of biological targets. Found in key endogenous compounds such as serotonin and melatonin, indole serves as a cornerstone in neurochemical signaling, circadian regulation, and chrono-metabolic homeostasis. Beyond its physiological roles, synthetic indole derivatives have shown extensive therapeutic potential across diverse domains, including oncology, infectious diseases, neurodegenerative disorders, immunomodulation, and metabolic syndromes. The review explores structure–activity relationships (SAR), pharmacokinetics, and the molecular mechanisms by which indole-based compounds exert their tremendous effects, that are ranging from enzyme inhibition to receptor modulation. Special focus is given to current clinical applications and emerging strategies for enhancing drug specificity, bioavailability, and safety through indolic frameworks. Additionally, we highlight the translational potential of indole-containing molecules in personalized medicine, underscoring opportunities for future drug discovery. By integrating insights from medicinal chemistry, biochemistry, pharmacology, and clinical science, this review affirms the indole ring’s enduring value as a central scaffold in therapeutic innovation. Full article

Serotonergic signaling is traditionally conceived as a transient, vesicle-mediated process restricted to the synaptic cleft. Here, we propose an expanded model in which serotonin can also be inserted into the plasma membrane of neurons and glial cells, forming a stable, membrane-associated reservoir that prolongs its availability beyond classical synaptic timescales. In this framework, the synapse emerges not as a simple neurotransmitter–receptor interface but as a dynamic, multiscale medium where membrane order, hydration, and quantum-level processes jointly govern information flow. Two temporal “tunnels” appear to regulate serotonin bioavailability: its aggregation in synaptic vesicles during exocytosis, and its cholesterol-dependent insertion into neuronal and glial membranes at the tripartite synapse. Lipid raft microdomains enriched in cholesterol and gangliosides thus act as active regulators of a continuum between transient and constitutive serotonin signaling. This extended serotonergic persistence prompts a reconsideration of current pharmacological models and the action of antidepressants such as fluoxetine, which not only inhibits the serotonin transporter (SERT) but also accumulates in lipid rafts, perturbs raft organization, and alters serotonin–cholesterol equilibria, contributing to SERT-independent effects. Grounded in the recently established fundamental parameters of biological systems, this model invites a broader, quantum-informed rethinking of synaptic transmission. Full article

Chronic ethanol exposure and genetic factors interact to drive neuroadaptations in alcohol use disorders (AUD). However, the system-level coordination of molecular responses across brain regions remains unclear. The 5-HT system and BDNF are key regulators of neuroplasticity in alcoholism. The 5-HT₇ receptor modulates both behavior and serotonin signaling. We investigated midbrain 5-HT₇ overexpression in C57BL/6 mice given 5-week ethanol access. Our results showed complex, region-specific changes in 5-HT and BDNF signaling, as well as selective behavioral alterations. Ethanol abolished the antidepressant-like effect of 5-HT₇ overexpression and increased anxiety-like behavior, without affecting baseline locomotion or novel object recognition. At the molecular level, ethanol suppressed 5-HT₇-mediated CREB/BDNF signaling and differentially regulated 5-HT_1A and 5-HT_2A expression across regions. To extract general principles, we used integrative systems analysis based on population-averaged generalized estimating equations (GEE), and mapped effects in the (t₁, t₂) plane. We identified two regularities: first, regional specificity of responses, and second, divergence across regulatory levels, with opposing effects more frequent at the mRNA level and concordant effects more common at the protein level. These findings suggest that neuroadaptation to combined 5-HT₇ and ethanol factors follows region- and level-specific rules, rather than a single global program, underscoring the value of integrative analysis. Full article

Background/Objectives: Combination therapy for schizophrenia may exacerbate side effects mediated by multiple brain receptors. This study aimed to elucidate the pharmacodynamic and pharmacokinetic interactions between chlorpromazine and risperidone. We investigated dopamine 2 (D₂), serotonin 2A (5-HT_2A), histamine 1 (H₁), and muscarinic acetylcholine (mACh) receptor occupancy in the brain as well as pharmacokinetic interactions after oral administration of chlorpromazine and risperidone in rats. Methods: Rats were orally administered chlorpromazine, risperidone, or their combination. A tracer cocktail solution was injected intravenously to measure multiple receptor occupancies simultaneously. Tracer and drug concentrations in the brain tissue and plasma were quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Results: Receptor occupancy increased in a dose-dependent manner. The doses required for 70% D₂ receptor occupancy were 4.5 mg/kg for chlorpromazine and 1.5 mg/kg for risperidone. Co-administration of chlorpromazine (4.5 mg/kg) and risperidone (1.5 mg/kg) resulted in an increase in D₂ and 5-HT_2A receptor occupancy to approximately 90%. Risperidone alone caused a transient increase in H₁ receptor occupancy to 80%, while co-administration increased mACh receptor occupancy to 60%. Co-administration with chlorpromazine significantly increased the plasma concentrations of risperidone and its metabolite, paliperidone, and decreased the oral clearance of risperidone by 5.9-fold. Conclusions: Co-administration of chlorpromazine and risperidone increases the occupancy of D₂, 5-HT_2A, and mACh receptors in the rat brain and increases the plasma concentrations of risperidone and paliperidone, suggesting a potential risk of enhanced adverse effects due to both pharmacokinetic and pharmacodynamic interactions involving target and non-target brain receptors. Full article

Background: Neuroblastoma is the most common extracranial solid malignancy in infants and children. High-risk neuroblastoma patients are commonly treated with temozolomide (TMZ), which typically exhibits a poor therapeutic response. Serotonin, also known as 5-hydroxytryptamine (5-HT), plays various essential functions in the human body. In the central nervous system, it serves as a neurotransmitter. Beyond its physiological roles, 5-HT has recently been identified as a potential growth factor for several human tumors, including gliomas and carcinoid tumors. Recent literature has demonstrated that 5-HT receptor antagonists can inhibit the growth of cancer cells. Furthermore, both 5-HT receptors and their antagonists have been identified as potential anticancer agents, suggesting their significance in the development of new treatment strategies. Objectives: The primary aim of this study was to examine the effects of 5-HT and 5-HT antagonists on tumor (neuroblastoma (SH-SY5Y)) and healthy cells (microglia (HMC3)) and determine the impact of their interaction with the anticancer agent TMZ on cell proliferation/viability and migration. Methods: The study explored the interaction between 5-HT, the 5-HT antagonist granisetron (GRN), the anticancer agent TMZ, and their combinations, specifically assessing their influence on cell proliferation, viability, and migration. Results: As a result, the single and combined applications of 5-HT, TMZ, and GRN, a 5-HT antagonist, inhibited cell growth and proliferation in SH-SY5Y, causing decreased cell viability. Additionally, the combination of 5-HT and GRN increased the efficacy of TMZ. Conclusions: The study findings revealed that 5-HT and 5-HT antagonists may have therapeutic effects by exhibiting antiproliferative effects in SH-SY5Y cells at high concentrations. Full article

Growing evidence suggests that psychiatric disorders are characterized by a prolonged inflammatory state, which may influence the efficacy of compounds targeting serotonin. Serotonin is a key signaling molecule in neuroplasticity of the adult hippocampus and involved in antidepressant action. Recent in vitro studies indicate the neurotransmitter may also facilitate the response to inflammation and potentially modulate microglial function towards neuroprotection. Using Tph2^−/− rats depleted of brain serotonin, we examined microglial expression of various serotonin receptors (5-HTRs) in vivo in both the hippocampus and prefrontal cortex and assessed mRNA levels of cytokines and brain-derived neurotrophic factor (BDNF). We observed age-dependent and region-specific gene expression of 5-HTRs on sorted microglia, paralleling changes in BDNF signaling, especially with 5-HT2b. Notably, both 5-HT2b and BDNF expression in the hippocampus was significantly upregulated in the absence of brain serotonin. Our data indicate distinct roles of 5-HTR subtypes in early network formation (5-HT1b, 5-HT5b) and in the response to endogenous changes (5-HT2b, 5-HT5a). Understanding serotonin–microglia interplay could offer therapeutic insights into the maintenance of mood via brain–immune cell interactions. Full article

Depression is a common, debilitating, and potentially life-threatening mental disorder affecting individuals across all age groups and populations. It represents one of the major challenges of contemporary medicine. It is estimated that more than 300 million people worldwide are affected, and patients with major depressive disorder (MDD) exhibit a significantly increased risk of suicide, underscoring the urgent need for effective and long-lasting therapeutic strategies. Growing evidence indicates that the pathophysiology of depression involves a complex interplay of genetic vulnerability, chronic stress, dysregulation of the hypothalamic–pituitary–adrenal (HPA) axis, neuroinflammation, oxidative stress, mitochondrial dysfunction, and impaired synaptic plasticity, collectively contributing to symptom heterogeneity and treatment resistance. In this review, we synthesize data derived from PubMed, Google Scholar, and ClinicalTrials.gov databases concerning pharmacological and non-pharmacological treatment strategies, with particular emphasis on their cellular and molecular mechanisms of action. We present currently used classes of antidepressant drugs, including selective serotonin reuptake inhibitors (SSRIs), serotonin–norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants (TCAs), and monoamine oxidase inhibitors (MAOIs), discussing their limitations in the context of contemporary pathophysiological models of depression. We then focus on emerging therapies targeting the glutamatergic, GABAergic, and dopaminergic systems, including ketamine, esketamine, (R)-ketamine, the dextromethorphan–bupropion combination (DMX–BUP), neurosteroids (zuranolone, brexanolone), as well as selective serotonin receptor modulators (gepirone ER) and dopaminergic modulators (cariprazine). The review is complemented by a discussion of non-pharmacological neuromodulatory approaches, such as transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), and photobiomodulation. Rather than providing another summary of clinical response indicators, this article integrates the molecular underpinnings of novel antidepressant agents and neuromodulation techniques with current concepts of depression pathophysiology, highlighting their relevance for the development of precise, mechanistically targeted, and multimodal treatment strategies. Full article

Major depressive disorder is increasingly recognized as a metabolic–immune disorder in which chronic inflammation diverts tryptophan (Trp) metabolism toward the kynurenine pathway (KP), reducing serotonin synthesis and producing neurotoxic metabolites such as quinolinic acid (QA). Elevated kynurenine (KYN)/Trp ratios and an altered QA/kynurenic acid (KYNA) balance have been consistently reported in depressed individuals, implicating the KP as a key therapeutic target. Exercise provides a unique, translationally relevant intervention: unlike pharmacological agents acting directly on neurotransmission, contracting skeletal muscle acts as a “kynurenine sink” by inducing kynurenine aminotransferases that convert circulating KYN into neuroprotective KYNA, thereby reducing brain KYN uptake and mitigating excitotoxicity. Clinical studies and meta-analyses confirm that aerobic, resistance, and high-intensity training produce antidepressant effects comparable to pharmacotherapy, while also improving cognition, fatigue tolerance, and cardiometabolic function. Beyond KP remodeling, exercise-induced myokines (irisin, IL-6, BDNF, apelin, FGF21) and adipokines (adiponectin, leptin modulators) coordinate systemic anti-inflammatory and neurotrophic adaptations that enhance resilience and brain plasticity. Furthermore, pharmacological “exercise mimetics” and metabolic modulators, such as PPAR agonists, AMPK activators, NAD⁺ boosters, meldonium, trimetazidine, and adiponectin receptor agonists, may be promising adjuncts for patients with low exercise capacity or metabolic comorbidities. This review provides a novel concept, positioning exercise as a systemic antidepressant that breaks the kynurenine lock of depression. Through proper interpretation of skeletal muscle as an endocrine organ of resilience, we integrate molecular, clinical, and translational findings to show how exercise remodels Trp–KYN metabolism and inflammatory signaling and how pharmacological mimetics may extend these benefits. This perspective consolidates scattered mechanistic and clinical data and outlines a forward-looking therapeutic framework that links exercise and lifestyle, metabolism, and drug discovery. We highlight that re-consideration of our understanding of depression, as a whole-body disorder, should provide new opportunities for precision interventions. Full article

Migraine is characterized by severe pain and somatic symptoms like allodynia and photophobia, driven by neuroinflammation that sensitizes the trigeminal vascular system (TVS). This study investigated how neuroinflammation induced by systemic lipopolysaccharide (LPS) affects migraine-related nociceptive signaling. Using a chronic migraine model in rats with nitroglycerin (NTG), we compared prenatal and acute postnatal LPS administration. Rats with prenatal LPS exhibited lower mechanical thresholds and enhanced allodynia and photophobia after NTG. Acute LPS also increased allodynia, but not photophobia. Both LPS groups showed increased mast cell degranulation in the dura mater. Plasma CGRP after NTG administration was elevated in the acute LPS group. Electrophysiology revealed enhanced trigeminal afferent responses to serotonin in both acutely and prenatally LPS-treated rats. Calcium imaging demonstrated increased neuronal responses to serotonin and capsaicin, suggesting an upregulation of serotonin and TRPV1 receptors. Our findings show that LPS-induced neuroinflammation, whether prenatal or acute, promotes sensitization of peripheral and central nociceptive pathways, involving serotoninergic mechanisms. Full article

It has been demonstrated that prolonged exposure to stress engenders a plethora of neuropsychiatric, immune and metabolic disorders. However, its pathophysiology transcends the conventional hypothalamic–pituitary–adrenal (HPA) axis. This review addresses the central question of how integrated neural and microbial pathways regulate stress responses and resilience. We present a model in which the parasympathetic nervous system (particularly the vagus nerve) and the gut microbiota interact to form a bidirectional neuroimmune network that modulates the HPA axis, immune function, neurotransmitter balance, and metabolic adaptation. Key molecular pathways include nitric oxide synthesis via the classical nitric oxide synthase (NOS)-dependent and microbiota-mediated nitrate–nitrite routes, inducible nitric oxide synthase (iNOS) regulation, nuclear factor erythroid 2-related factor 2 (Nrf2) signalling, lysosomal function, autophagy and the cholinergic anti-inflammatory reflex. Other pathways include the gamma-aminobutyric acid (GABA) and serotonin (5-HT) systems, NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) signalling, polyamine metabolism and peroxisome proliferator-activated receptor gamma (PPARγ). Intermittent hypoxia training (IHT) enhances mitochondrial function, oxidative stress responses, autonomic balance and gut microbiota composition. This promotes parasympathetic activity and stress resilience that is tailored to the individual. These adaptations support the concept of personalised stress response profiles based on hypoxic adaptability. Clinical implications include combining IHT with vagus nerve stimulation, probiotics, dietary strategies, and stress reduction techniques. Monitoring vagal tone and microbiota composition could also serve as predictive biomarkers for personalised interventions in stress-related disorders. This integrative framework highlights the therapeutic potential of targeting the parasympathetic system and the gut microbiota to modulate stress. Full article

Serotonin receptors, in particular 5-HT_1A and 5-HT_2A receptors, are important molecular targets for the central nervous system (CNS) disorders, such as schizophrenia, depression, anxiety disorders, memory deficits, and many others. Here, we present structural and pharmacological evaluation of a serotonin receptor ligand, SERAAK2, identified in a structure-based virtual screening campaign. Molecular docking studies revealed that SERAAK2 binds with its molecular targets via Asp3.32 as the main anchoring point, which is typical for orthosteric ligands of aminergic GPCRs. Molecular dynamics simulations confirmed the stability of the ligand binding poses in the studied receptors. MMGBSA calculations were in accordance with the receptor in vitro binding affinity studies, which indicated that SERAAK2 is a potent ligand of 5-HT_1A and 5-HT_2A receptors. It was also found that SERAAK2 displays favorable ADMET parameters. The demonstrated anxiolytic- and antidepressant-like effects of SERAAK2 in animal models, which may involve its interaction with 5-HT_1A receptors, warrant further studies to confirm these activities and elucidate the underlying mechanisms. Full article

The resin extract of Garcinia nigrolineata (GNR-E), a tropical plant used in Southeast Asian traditional medicine, was evaluated for its antidepressant-like effects in a chronic mild stress (CMS) mouse model, with imipramine as a reference drug. GNR-E dose-dependently alleviated CMS-induced anhedonia (sucrose preference test) and behavioral despair (forced swimming and tail suspension tests). Neurochemical analyses revealed that GNR-E increased serotonin (5-HT) and norepinephrine (NE) levels, reduced expression of their transporters (SERT, NET) and receptors (5-HT1A, 1B, 2A, 2C, 7; α2A, 2C) in the frontal cortex and hippocampus, and normalized HPA-axis hyperactivity by lowering serum corticosterone and modulating glucocorticoid receptor (GR) and SGK-1 mRNA expression. In vitro, GNR-E inhibited monoamine oxidase (MAO)-A and -B (Ki = 2.33 and 1.55 µg/mL, respectively). Phytochemical analysis identified xanthones, particularly cowanin, as key constituents. These findings highlight GNR-E’s potential as a novel plant-based antidepressant, warranting further investigation into its active compounds and clinical applications. Full article

Background: Thunbergia alata is employed in traditional medicine to treat culture-bound syndromes such as “susto” (fright) or “espanto” (fearfulness). These conditions may correlate with depressive disorders. However, there is no evidence that this species has antidepressant properties. Aims: To characterize the antidepressant-like effect of an aqueous extract of T. alata in different paradigms and to analyze the role of brain monoamines in such actions. Methods: Independent groups of mice were treated with saline or the extract (1, 5, 10, 50, and 100 mg/kg; p.o.) and evaluated in the tail suspension (TST) and forced swimming tests (FST). Biochemical mechanisms were analyzed using inhibitors of monoamine synthesis, ligands of serotonergic receptors, and in vitro assays of MAO-A and MAO-B activity. Acute and sub-acute toxicity was evaluated. Results: The extract significantly reduced the immobility time of mice in both the TST and the FST, without affecting locomotor activity, as did the prototypical antidepressant desipramine. PCPA, AMPT, and NAN-190 abolished the extract’s effects on despair, while serotonergic ligands (8-OH-DPAT, fluoxetine, and pindolol) facilitated their antidepressant action. T. alata inhibited MAO-A and B activity. High doses of the extract produced no change in organ morphology; LD₅₀ was >2000 mg/kg. Conclusions: This is the first study to demonstrate that an aqueous extract of T. alata produces antidepressant effects mediated by the monoamine brain levels, especially serotonin. In addition to its use in culture-bounded syndromes, the present findings of safety and efficacy give support to the proposal that T. alata may be used in the treatment of depression. Full article

Citalopram, a common selective serotonin reuptake inhibitor (SSRI), has been increasingly detected in aquatic environments due to ineffective removal and improper disposal. Although developmental exposure to SSRIs is linked to neurotoxicity, little is known about the persistence of gene expression alterations following limited exposure periods. Zebrafish embryos were exposed from 2 to 24 h post-fertilization (hpf) at concentrations of citalopram hydrobromide spanning surface water to therapeutic serum levels (0.03, 0.9, 50, and 250 μg/L), followed by removal of the citalopram and development until 48 hpf. Whole-embryo RNA sequencing at 48 hpf revealed a non-linear dose–response wherein the lowest dose resulted in the induction of the highest number of differentially expressed genes (DEGs). Gene set enrichment analyses (GSEA) and overrepresentation analyses (ORAs) showed that 0.03 μg/L citalopram caused upregulation of metabolic and developmental pathway genes, but suppressed synaptic membrane genes, whereas 0.9 μg/L resulted in strong downregulation of key neurotransmitter receptors. At 50 μg/L, genes linked to oxidative stress (glutathione metabolism and ferroptosis) were upregulated, and at 250 μg/L, stress and apoptotic processes were increased, while glutamate receptor genes were repressed. All four citalopram doses suggested synaptic and neurotransmitter alterations, implying that persistent neurodevelopmental impacts resulted from a limited early window of exposure. These data highlight that transient, low-level SSRI exposures shape long-term embryonic gene expression. Full article

Radical drug therapy for schizophrenia is usually hard to achieve with one currently available antipsychotic agent. Indeed, it is the negative symptoms of this morbidity that are a dilemma to neutralize. Most of the first-generation agents can deal with the positive symptoms of the disease to a convincing degree, but not with its negative symptoms. The creation of so-called second-generation agents aimed to treat the negative symptoms, as these invisible barriers are the real reasons that isolate psychotic individuals and hinder their integration into society. Unfortunately, these newly designed drugs, including OLZ, turned out to induce different categories of undesired effects; the most embarrassing among them are the metabolic drawbacks, such as insulin resistance, weight gain, and other subcategories of metabolic consequences. Antagonism induced at certain receptors, particularly 5-HT2C and histamine H1 receptors, is implicated particularly in these metabolic adverse effects. The choice of antipsychotics (APCs) should be tailored separately for each case, as each patient responds variably to each neuroleptic. This possibility exists due to the abundant alternatives within the currently available APC medications. This work aims to discuss the reasons behind these undesired metabolic effects, how to deal with them, how to choose the appropriate agent for each psychotic case, and how to manage intoxication using olanzapine. To address these inquiries, we carefully selected 154 relevant studies, including robust meta-analyses, from the past 20 years and analyzed them in this work. Full article