Search Results (132)

Background/Objectives: This prospective observational cohort study aimed to evaluate the influence of heated tobacco (HT) and electronic cigarettes (ECs) on bone remodeling markers such as receptor activator of nuclear factor kappa-B ligand (RANKL) and osteoprotegerin (OPG), and periodontal status, at baseline and at 3 months after initial periodontal therapy. Methods: The sample comprised 236 participants (130 women, 106 men; mean age 38.96 ± 7.69 years), distributed across non-smokers (n = 72), heated tobacco/HT product users (n = 83), and electronic cigarette/EC users (n = 81). For each patient, the periodontal charting included periodontal probing depth (PPD), bleeding on probing (BOP), and clinical attachment loss (CAL). Unstimulated saliva samples were analyzed for RANKL and OPG levels. All patients underwent nonsurgical periodontal therapy (scaling and root planing). Between-group comparisons were performed using the Kruskal–Wallis test followed by Bonferroni-adjusted pairwise comparisons, while within-group changes over time were assessed using the Wilcoxon signed-rank test. To complement the primary nonparametric analyses, two-way mixed-design ANOVA and ANCOVA models adjusted for baseline values and periodontitis stage were performed as sensitivity analyses. Statistical significance was set at p < 0.05. Results: At baseline, both product user groups exhibited significantly higher PPD (p = 0.005) and CAL (p = 0.001) compared with non-smokers, with no differences between HT and EC users. Salivary RANKL levels were significantly higher in HT and EC users than in non-smokers, and OPG levels did not differ significantly. Following non-surgical periodontal therapy, all parameters improved significantly across groups (p < 0.001). At the 3-month follow-up, both product user groups maintained higher PPD (p = 0.008), CAL (p = 0.001), and salivary RANKL levels, compared with non-smoking individuals (p < 0.001). The RANKL/OPG ratio remained significantly different only for EC users compared with non-smokers (p < 0.001). Conclusions: HT and EC use were associated with differences in periodontal parameters and higher RANKL levels, while differences in the RANKL/OPG ratio were observed in EC users compared with non-smokers. Non-surgical periodontal therapy improved clinical parameters and reduced the RANKL/OPG ratio, highlighting the importance of biofilm control. Full article

New psychoactive substances (NPS) are a heterogeneous group of recreational drugs that mimic the actions and psychoactive effects of existing pharmaceutical products or recreational drugs. As NPS can be highly potent, even exceeding their template compound’s potency, there are frequent reports of non-fatal and fatal intoxications. One principal target for hallucinogenic and psychedelic drugs, including NPS, is the 5-hydroxytryptamine receptor 2A (5-HT_2A). Since NPS are designed to evade legal restrictions, this drug market is quickly evolving, and researchers are playing catch-up, investigating these novel compounds for their toxicological and pharmacological properties. Receptor binding affinity (Ki) is an important property describing ligand–receptor interactions and is a prerequisite for receptor activation. Competitive in vitro assays can be used to assess Ki; this is a resource-intensive process. We used publicly available Ki data for the 5-HT_2A, calculated molecular descriptors and fingerprints, and trained five classification machine learning models. The predictive performance of the models had precisions and recalls up to 93% and 92%, respectively. We used explainable artificial intelligence, i.e., SHAP values and similarity maps, for model interpretation. The results are in line with previous experiments and support its suitability to predict the binding affinities of possible 5-HT_2A ligands. Full article

This study aimed to identify candidate molecular pathways mediating dopaminergic dysfunction induced by PFAS mixture exposure, with a focus on the TM/5-HT signaling axis and calcium-linked lipid metabolites, and to explore potential gut-brain axis involvement. Adult mice were exposed to a PFAS mixture. Behavioral tests assessed spatial memory, spontaneous activity, and motor coordination. Histopathological and ultrastructural analyses examined neuronal atrophy, mitochondrial damage, α-synuclein (α-syn), and tyrosine hydroxylase (TH). Transcriptomics, metabolomics, and gut microbiota profiling (16S rRNA sequencing) were performed, followed by integrated multi-omics and correlation analyses. PFAS exposure was associated with PD-relevant motor and cognitive impairments, including impaired spatial memory, reduced spontaneous activity, and motor coordination deficits. Neuronal atrophy, mitochondrial structural damage, upregulation of α-syn, and downregulation of TH were observed. Transcriptomics identified 315 differentially expressed genes (DEGs) enriched in ciliary movement, neuroactive ligand-receptor interactions, and serotonergic synapses. Metabolomics identified 130 differentially abundant metabolites involved in arachidonic acid metabolism and serotonergic synapses. Integrated analysis highlighted correlative changes in the TM/5-HT signaling pathway. Phosphatidylinositol PI(16:0/20:2(11Z,14Z)) showed a strong positive correlation with Dbh gene expression, suggesting a candidate association between Dbh expression and phosphatidylinositol alterations. Gut microbiota analysis revealed compositional alterations (e.g., Muribaculaceae, Ileibacterium) and predicted functional shifts (e.g., tryptophan metabolism–related modules) were observed; these findings are exploratory. This study identifies multi-omics signatures associated with PFAS mixture-induced dopaminergic dysfunction in mice. The TM/5-HT pathway emerges as a candidate molecular axis requiring further investigation. Gut microbiota alterations suggest a potential peripheral component, but causality and gut-brain axis involvement remain hypothetical and need direct experimental validation. Full article

Neurodegenerative diseases such as Alzheimer’s (AD) and Huntington’s (HD) remain major therapeutic challenges due to limited treatment efficacy. Imidazoline I2 receptor (I2-IR) ligands have recently emerged as promising neuroprotective agents, with reported roles in modulating oxidative stress, neuroinflammation, and protein aggregation. This study evaluates the therapeutic potential of several I2-IR ligands, including Idazoxan, CR4056, and novel compounds, using Caenorhabditis elegans (C. elegans) models of AD and HD. Transgenic strains CL2006 (expressing human Aβ1-42) and EAK103 (expressing Ht513) were employed to assess locomotor activity, oxidative stress tolerance, Aβ and Ht aggregation, and sod-1 gene expression. Several ligands significantly improved movement, reduced Aβ and Ht aggregates, and enhanced antioxidant gene expression, particularly Idazoxan, LSL42, and PIP01. Notably, some compounds exhibited prooxidant effects, highlighting the utility of C. elegans for early in vivo toxicity screening. Importantly, this study provides the first in vivo evidence of the efficacy of I2-IR ligands in HD models and reinforces their potential as therapeutic candidates for HD. Overall, these findings suggest a potential role for modulation of I2-IR-related pathways in neurodegeneration and support the utility of C. elegans as a rapid, cost-effective platform for preclinical drug evaluation. Full article

As freshwater resources become increasingly limited, exploiting brackish and marine waters for aquaculture is viewed as a promising alternative. Nile tilapia (Oreochromis niloticus), although considered euryhaline, shows relatively restricted tolerance to salinity compared with other tilapia species, making it an ideal model to study adaptive responses to osmotic stress. Serotonin (5-HT) and dopamine (DA) are key modulators of stress responses through their activation of metabotropic G protein-coupled receptors (GPCRs). In this study, we investigated the transcriptional profiles of metabotropic serotonin and dopamine receptors across the brain, intestine, and liver of Nile tilapia reared in different salinity conditions (0 ppt, 16 ppt, 30 ppt). The results showed both dopamine and serotonin metabotropic receptors were duplicated with potential neofunctionalization, contributing to osmoregulatory capacity. Nile tilapia showed altered brain drd1, htr1 and htr7 subtypes in response to salt change. Meanwhile, the drd3 subtype showed pronounced alterations in the intestine and liver under elevated salinity. Notable transcriptional alterations in htr4 subtypes were observed in both brain and liver, suggesting their potential involvement in modulating energy balance and stress adaptation. Correlation network analyses further demonstrated coordinated regulation among receptor paralogues in the brain. These findings provide potential targets, such as ligand analog additives or genetic enhancement, for future functional validation and for improving salinity tolerance in Nile tilapia culture. Full article

The neuropharmacology of psychedelics has traditionally focused on serotonergic mechanisms, particularly 5-HT2A receptor activation. However, this paradigm incompletely explains the diversity of neurobiological and therapeutic effects observed across psychedelic compounds. Non-classical psychedelics such as salvinorin A, the primary active constituent of Salvia divinorum, challenge this framework through direct kappa opioid receptor (KOR) agonism, representing a serotonin-independent pathway to altered consciousness. This review systematically examines the role of the endogenous opioid system in mediating psychedelic effects, with emphasis on salvinorin A’s unique KOR-dependent mechanisms. We synthesized preclinical and clinical evidence from in vitro studies, genetically modified animal models, optogenetic circuit dissection, and human neuroimaging trials. Salvinorin A’s selective KOR activation is characterized by pronounced β-arrestin-biased signaling, distinguishing it from endogenous dynorphins and classical KOR agonists. This produces rapid receptor desensitization, transient functional plasticity, and profound dissociative effects mediated through thalamocortical disruption, mesolimbic dopaminergic suppression, and fragmentation of large-scale brain networks. Classical serotonergic psychedelics indirectly engage opioid systems through downstream 5-HT2A signaling, contributing to analgesic and mood-regulatory effects via secondary MOR/DOR modulation. Despite being a potent opioid agonist, salvinorin A exhibits low abuse potential due to aversive phenomenology, dopaminergic suppression, and absence of positive reinforcement in animal models. Incorporating opioid receptor pharmacology into psychedelic neuroscience expands mechanistic understanding beyond serotonin-centric models, revealing multiple neurochemical pathways capable of inducing therapeutically relevant altered states. This framework enables rational development of biased KOR ligands and establishes salvinorin A as a paradigmatic model for non-serotonergic psychedelia with applications in treatment-resistant depression, addiction, and chronic pain. Full article

Modern advances in artificial intelligence have accelerated the development of computational tools for protein–ligand structure prediction, yet their real-world performance remains uneven across receptor classes and ligand chemotypes. Recently published cryo-EM structures of several different psychedelics bound to the serotonin 5HT_2A receptor provide a unique opportunity to explore how modern AI-based modeling performs in a pharmacologically important GPCR system. Here, we compare three major approaches: AI-based protein–ligand cofolding (Boltz-2), a leading AI-driven docking module (Uni-Mol Docking v2), and a widely used classical physics-based docking pipeline (AutoDock Vina) across a series of tryptamine and phenethylamine psychedelics. Predicted binding poses were comparatively assessed through structural alignment with these newly available cryo-EM complexes. Additionally, calcium-mobilization assays were performed to provide a coarse functional readout for comparison with computationally predicted binding affinities. This study integrates methodological review with exploratory benchmarking to illustrate how different modeling paradigms behave on a shared receptor–ligand test set. Our results highlight substantial variation between modeling strategies, with AI-based cofolding often producing global binding orientations more closely resembling experimental structures, and classical docking showing greater variability across ligands, while still outperforming AI-driven docking on average. These observations underscore both the growing utility and current limitations of AI-assisted structure prediction in serotonergic drug discovery, and emphasize the importance of careful, experimentally anchored evaluation as such tools continue to advance. 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

Serotonin (5-HT) is a vital intercellular messenger with diverse signaling functions throughout the human body. We have characterized and implemented a novel, in vitro fluorescence-based method of measuring 5-HT binding to gain a fuller understanding of the interactions between 5-HT and its receptors. This method involves expression of 5-HT receptor proteins in cultured cells with the fluorescent, non-canonical amino acid l-3-(6-acetylnaphthalen-2-ylamino)-2-aminopropanoic acid (ANAP) incorporated into the ligand binding site. ANAP fluorescence was quenched in solution by both 5-HT and dopamine. Time-resolved photoluminescence and transient absorption spectroscopy confirmed that ANAP quenching by 5-HT occurs via a charge-transfer process that recovers through back-electron transfer on the nanosecond timescale. Supported by density functional theory calculations, this process likely involved an ANAP reduction by 5-HT. To test this method on intact receptors in a cellular context, we expressed 5-HT_3A receptors (5-HT-gated ion channels) in HEK293T cells with ANAP inserted co-translationally into the transmitter binding site. Fluorescently labeled 5-HT_3A receptors were functional and activated by 5-HT, as assessed by whole-cell patch clamp. Addition of 5-HT caused a concentration-dependent quenching of fluorescence from ANAP-tagged channels in intact cells and unroofed plasma membranes, demonstrating the utility of this method for measuring 5-HT binding to its receptors. Collectively, these results delineate a technique for measuring transmitter binding that can be widely adopted to explore 5-HT binding not only to 5-HT₃ receptors, but to any 5-HT receptor, transporter, or binding protein in heterologous expression systems. Full article

Background/Objectives: The study aimed to pharmacologically evaluate dually acting ligands, 5-HT₇ antagonists and sodium channel inhibitors, as potential therapeutic agents for the treatment of depression, anxiety, and neuropathic pain. The designed dual ligands combined structural fragments of LP-12 (a 5-HT₇ receptor ligand) and phenytoin (a sodium channel blocker). Methods: A series of 1-(2-biphenyl)piperazine derivatives with a hydantoin core was synthesized and evaluated for 5-HT₇ receptor affinity and sodium channel inhibition. The most potent ligands were further analyzed using molecular docking, cytotoxicity assays (MTT, LDH), and in vitro metabolism studies, including microsomal stability and CYP450 inhibition. In vivo pharmacological effects were assessed in behavioral models: forced swim test, four-plate test, and a streptozotocin (STZ)-induced diabetic neuropathy model in mice. Results: Compounds 10 and 20 exhibited high 5-HT₇ receptor affinity (K_i < 10 nM) and potent sodium channel inhibition (>80% at 1 µM). Docking studies revealed binding modes consistent with established 5-HT₇ ligands. Compound 10 showed lower cytotoxicity than compound 20 in both HepG2 and SH-SY5Y cells and was therefore selected for further evaluation. Metabolic profiling indicated improved microsomal stability relative to verapamil and a low risk of CYP-mediated drug–drug interactions. In vivo, compound 10 produced significant antidepressant- and anxiolytic-like effects, though it failed to reduce neuropathic pain symptoms in the STZ-induced model. Conclusions: Compound 10 shows potential for mood disorder treatment, but further refinement may be needed to improve analgesic efficacy. Full article

Autism spectrum disorder (ASD) is a neurodevelopmental condition marked by social/communication deficits and behavioral abnormalities, with neuronal apoptosis and immune-inflammatory dysregulation implicated in its pathogenesis. Marine-derived polysaccharides, particularly those from Enteromorpha prolifera (PEPs), exhibit neuroprotective and anti-inflammatory properties—yet their therapeutic potential for ASD remains unexplored. Major monosaccharide components of PEPs were identified as rhamnose, xylose, glucose, glucuronic acid, galactose, and ribose through ion chromatography analysis. Infrared spectroscopy confirmed PEPs as pyranose-type polysaccharides with α-glycosidic bonds and uronic acids, while gel permeation chromatography showed a predominant molecular weight of 3.813 kDa (83.919%). To explore the therapeutic potential of PEPs in ASD, a comprehensive method combining network pharmacology, molecular docking, and in vitro validation was conducted. A total of 235 ASD-related target proteins were predicted, with enrichment analyses indicating significant involvement in pathways such as neuroactive ligand–receptor interaction and the MAPK signaling pathway. In vitro assays using valproic acid (VPA)-induced HT22 neuronal cells showed that PEPs significantly attenuated apoptosis. Western blot analysis further confirmed the downregulation of HSP90AA1, cleaved CASP3/pro-CASP3, p-NF-κB1/NF-κB1, p-AKT1/AKT, and p-mTOR/mTOR, as well as the upregulation of IκBα after PEPs treatment. These findings suggest that PEPs exert neuroprotective effects through the modulation of apoptosis and inflammation-related signaling pathways, supporting their potential as a promising candidate for further study in ASD. Full article

Background/Objectives: Neurotensin receptors (NTSRs), members of the G protein-coupled receptor (GPCR) family, have been found to be overexpressed in several types of human cancers, including breast, colon, lung, liver, prostate, and pancreatic cancer. In particular, NTSR1 is overexpressed in at least 75% of pancreatic ductal adenocarcinomas. The aim of the present study was the development and evaluation of new ^99mTc-labeled nonpeptide NTSR1-antagonists for SPECT imaging of NTSR-positive tumors. Methods: Multistep syntheses of NTSR1 antagonist derivatives were performed following our previously described procedure. Two different chelating strategies were applied for ^99mTc radiolabeling to provide the [^99mTc]Tc-HYNIC complex [^99mTc]1 and the [^99mTc]Tc-tricarbonyl complex [^99mTc]2. Receptor binding assays were performed using hNTSR1-expressing CHO cells. Radiochemical yields (RCYs) were determined by radio-HPLC. For [^99mTc]1 and [^99mTc]2, log D_7.4, plasma protein binding, stability in human plasma and serum, and cellular uptake in HT-29 cells were determined. Biodistribution studies and small animal SPECT studies were performed in HT-29 tumor-bearing nude mice. Results: The radiosynthesis of [^99mTc]1 (log D_7.4 = −0.27) and [^99mTc]2 (log D_7.4 = 1.00) was successfully performed with RCYs of 94–96% (decay-corrected). Both radioligands were stable in human serum and plasma, showed plasma protein binding of 72% ([^99mTc]1) and 82% ([^99mTc]2), and exhibited high and specific uptake in HT-29 cells. Biodistribution studies in HT-29 tumor-bearing mice showed a higher tumor accumulation of [^99mTc]1 compared to [^99mTc]2 (8.8 ± 3.4 %ID/g vs. 2.7 ± 0.2 %ID/g at 2 h p.i.). [^99mTc]2 showed exceptionally high intestinal accumulation (49 ± 22 %ID/g at 1 h p.i.) and was therefore considered unfavorable. In the SPECT/CT imaging of HT-29 tumor xenografts, [^99mTc]1 showed a higher NTSR1-specific tumor uptake than [^99mTc]2 at all time points after tracer injection, with 12 ± 2.8 %ID/g for [^99mTc]1 vs. 3.1 ± 1.1 %ID/g for [^99mTc]2 at 4 h p.i. and adequate tumor-to-background ratios. Conclusions: In particular, the [^99mTc]Tc-HYNIC ligand ([^99mTc]1) showed promising preclinical results, being a potential candidate for SPECT imaging and, therefore, appropriate for translation into the clinic. Full article

Many drug discovery efforts have identified potentially promising molecules; however, a common limitation of these reports is the lack of further experimental confirmation of pharmacokinetic properties and behavioral effects of discovered compounds. In this study, we aim to address this limitation. Therefore, we build on our previous virtual screening campaign by synthesizing, analyzing in silico, and evaluating experimentally the SERAAK1 compound, which was initially identified as a ligand for 5-HT_1A, 5-HT_2A, and D₂ receptors. Through these investigations, we discovered that SERAAK1 binds to the orthosteric pocket of the 5-HT_2A receptor in a similar mechanism to that known for marketed antipsychotic medications. Molecular dynamics simulations revealed that the SERAAK1 compound remains stable in the orthosteric binding pocket of the 5-HT_2A receptor. The determination of the ADMET parameters indicated the directions for further optimization of the compounds. In vivo studies demonstrated the anxiolytic and antidepressant properties of the SERAAK1 compound. Full article

A series of 2- and 3-methoxyphenylpiperazine derivatives in combination with a 2-hydroxypropoxy linker and coumarins containing various substituents was synthesized and evaluated for antidepressant-like activity. Microwave-assisted synthesis was used, and the structures of all compounds were confirmed by ¹H, ¹³C NMR, and HRMS spectrometry. The affinity toward the 5-HT_1A and 5-HT_2A receptors was determined using radioligand binding assays and analyzed by molecular docking studies. Among the compounds evaluated, four demonstrated high affinity for the 5-HT_1A receptor with the following Ki values: 5-(2-hydroxy-3-(4-(2-methoxyphenyl)piperazin-1-yl)propoxy)-4,7-dimethyl-2H-chromen-2-one (5) (90 nM), 6-acetyl-5-(2-hydroxy-3-(4-(2-methoxyphenyl)piperazin-1-yl)propoxy)-4,7-dimethyl-2H-chromen-2-one (7) (90 nM), 7-(2-hydroxy-3-(4-(3-methoxyphenyl)piperazin-1-yl) propoxy)-4-methyl-2H-chromen-2-one (10) (87 nM), and 8-acetyl-7-(2-hydroxy-3-(4-(2-methoxy phenyl)piperazin-1-yl)propoxy)-4-methyl-2H-chromen-2-one (11) (96 nM), and four demonstrated high affinity for the 5-HT_2A receptor with the following Ki values: 6-acetyl-7-(2-hydroxy-3-(4-(3-methoxyphenyl)piperazin-1-yl)propoxy)-4-methyl-2H-chromen-2-one (2) (83 nM), 8-acetyl-7-(2-hydroxy-3-(4-(3-methoxyphenyl)piperazin-1-yl)propoxy)-4-methyl-2H-chromen-2-one (12) (67 nM), 7-(2-hydroxy-3-(4-(2-methoxyphenyl)piperazin-1-yl) propoxy)-2H-chromen-2-one (13) (18 nM), and 7-(2-hydroxy-3-(4-(3-methoxyphenyl)piperazin-1-yl)propoxy)-2H-chromen-2-one (14) (68 nM). In functional assays, 8-acetyl-7-(2-hydroxy-3-(4-(2-methoxyphenyl) piperazin-1-yl)propoxy)-4-methyl-2H-chromen-2-one (compound 11) exhibited a significant 5-HT_1A antagonistic profile. Computational studies revealed the structural details responsible for the high affinity of selected derivatives, which were compared to known 5HT_1A partial agonists. Full article

The structures of glycans, specifically their terminal positions, play an important role as ligands for receptors in regulating the adhesion ability of platelets. Recent advances in our understanding of free/unbound serotonin (5-HT) in blood plasma at supraphysiological levels implicate it as one of the most profound influencers in remodeling the platelet’s surface N-glycans. Proteomic analysis of the membrane vesicles identified enzymes, specifically glycosyltransferases, only on the surface of the platelets isolated from the supraphysiological level of 5-HT-containing blood plasma. However, these enzymes can only be effective on the cell surface under certain biological conditions, such as the level of their substrates, temperature, and pH of the environment. We hypothesize that exosomes released from various cells coordinate the required criteria for the enzymatic reaction on the platelet surface. The elevated plasma 5-HT level also accelerates the release of exosomes from various cells, as reported. This review summarizes the findings from a wide range of literature and proposes mechanisms to coordinate the exosomes and plasma 5-HT in remodeling the structures of N-glycans to make platelets more prone to aggregation. Full article