Search Results (652)

Nicotinic acetylcholine receptors (nAChRs) are membrane-bound proteins that mediate fast synaptic transmission throughout the nervous system. A functional nAChR subtype is formed by the combination of multiple subunits arranged as homomeric or heteromeric pentamers, each with a distinct pharmacological profile. Disruption of their neurotransmission contributes to various neuropathologies, emphasizing the need for detailed knowledge of receptor structure, function, subunit composition, dynamics, and potential ligand-binding sites. However, their structural complexity as integral membrane proteins has hindered expression in mammalian cell lines and proven even more challenging to crystallize, limiting insights into ligand interactions. Understanding the molecular determinants governing nAChRs function is essential for the rational design of selective therapeutics targeting neurological disorders. The emergence of a chimeric receptor approach has dramatically improved the ability to study these important proteins and opened new avenues for high-throughput screening in drug discovery efforts. This review explains how the design of chimera constructs using soluble homologs, such as AChBP, provides researchers with an immense opportunity to investigate receptor structure–function relationships and subtype-specific properties, thereby facilitating the development of more effective treatments. Full article

Numerous research works have tried to evaluate the correlation between inflammation and the onset of prostate cancer. Given the in vitro antioxidant power and the anti-proliferative effects on human prostate cancer cells shown by a Juglans regia L. fresh fruit extract, the aim of this work was the evaluation of its potential in the acute and chronic inflammatory states in vivo, revealing a strong anti-inflammatory activity. In the zymosan-induced edema formation assay, a light and non-significant edema reduction was shown. On the contrary, in the zymosan-induced thermal hyperalgesia assay, the reversion of hyperalgesia after the extract administration was determined. Moreover, in the formalin test, the extract caused a significant decrease in the licking time caused by the aldehyde, especially in the late phase. In silico, quercetin showed the best fit into the enzymatic pocket of AChE (docking score: −11.306 Kcal/mol). Neochlorogenic acid and ellagic acid gave the best docking scores on BChE (−10.292 Kcal/mol and −10.054 Kcal/mol, respectively). Abscisic acid showed a high binding affinity for the glucocorticoid receptor. Finally, quercetin and abscisic acid were quantified to complete the data by HPLC-DAD, giving 0.246 ± 0.003 mg/g of dried extract and 0.036 ± 0.004 mg/g of dried extract, respectively. Full article

Nicotine is the main substance responsible for the development of tobacco addiction. The α3β4 nicotinic acetylcholine receptors (nAChRs) are a potential key target for mitigating nicotine reward. Preliminary studies in our laboratory suggest that α-conotoxin [S9K]TxID serves as a selective and potent antagonist targeting α3β4 nAChRs, which may be beneficial in addressing nicotine addiction. However, the mechanisms of [S9K]TxID treatment in nicotine addiction are still to be determined. This study aimed to identify the differential metabolic profiles of [S9K]TxID treatment in nicotine addiction using an untargeted metabolomic profiling method. As demonstrated by behavioral experiments, [S9K]TxID effectively attenuated nicotine-induced conditioned place preference (CPP) expression without exerting inhibitory effects on the central nervous system (CNS). The results of untargeted metabolomics revealed that eight metabolites were significantly altered after [S9K]TxID treatment, particularly phenylalanine. [S9K]TxID also attenuated nicotine-induced metabolic disorders by regulating phenylalanine, tyrosine and tryptophan biosynthesis. In conclusion, our findings suggest that [S9K]TxID could be a potential therapeutic compound for nicotine addiction. 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

Glioblastoma (GBM) is the most common malignant primary brain tumor in adults. Since numerous studies highlight the significance of cholinergic system components in tumor development, acetylcholine (ACh) and the differential activation of its receptors could play a crucial role in GBM progression. The aim of this study was to test this hypothesis by assessing the relevance of the cholinergic system in GBM cells and their microenvironment. We analyzed bulk RNA-seq expression data using the TIMER2.0 web server, focusing on the impact of patient survival in relation to muscarinic receptors (CHRM) and neutrophil infiltration in low-grade glioma (LGG) and GBM. Our analysis revealed a marked decrease in survival associated with all CHRMs, particularly in LGG. Moreover, GBM showed higher neutrophil infiltration and reduced survival, especially in relation to CHRM3. These findings were validated in the U251 cell line and in human GBM tumor biopsies (GBM-b), which also displayed CHRM3 expression. Additionally, we show that GBM cells exposed to cholinergic stimulation exhibited increased vascular endothelial growth factor (VEGF), IL-8 production, and PD-L1 expression, while the VEGF increase was blocked by tiotropium (Tio), a CHRM3 antagonist. Similarly, polymorphonuclear cells from GBM patients (PMN-p) displayed increased PD-L1 expression and IL-8 production upon cholinergic stimulation. Finally, as we previously reported on the relevance of thymic stromal lymphopoietin (TSLP) in GBM pathophysiology, here, we found that TSLP upregulated CHRM3 expression. Our findings highlight the importance of the cholinergic system in the tumor microenvironment, where it may act directly on tumor cells or influence neutrophil physiology, thereby modulating tumor progression. Full article

Recently, we found that Lystar5 protein from coelomic cells of A. rubens starfish interacts with nicotinic acetylcholine receptors (nAChRs) and integrin α8-like protein. We hypothesized that Lystar5 mediates detachment of coelomic cells from the matrix and their migration. Skin wound healing in humans is based on keratinocytes migration and is regulated by nAChRs and integrins. Here, we revealed that Lystar5 stimulates migration of human skin HaCaT keratinocytes and peripheral blood monocytes. Using ELISA, we found that Lystar5 binds to the membrane fraction of coelomic cells with its loops I and II, which form an active site of Lystar5 and resemble its pro-migratory activity. In keratinocytes and monocytes, Lystar5 and the peptides mimicking its loops I and II bound with α3, α4, and β2 nAChR and α5, αV, and β1 integrin subunits, which form molecular complexes. In keratinocytes, Lystar5 and its mimetics promoted short-term E/N cadherin switch and upregulated expression of α5 and αV integrins, EGFR, and ICAM-1. In keratinocytes and monocytes, Lystar5 and its mimetics upregulated E-selectin secretion. The ability of Lystar5 and its mimetics to stimulate skin keratinocyte migration and immune cell infiltration may be considered promising for the development of new wound-healing agents. Full article

Magnesium ions regulate synaptic and nonsynaptic neuronal excitability from intracellular (Mg²⁺_i) and extracellular (Mg²⁺_o) domains, modulating voltage- and ligand-gated ion channels. K+ inward rectifier (Kir) channel inward rectification arises from Mg²⁺_i blocking the pore and outward K⁺ current, while Mg²⁺_o targets external sites. Mg²⁺_i causes voltage-dependent Ca²⁺ voltage-gated (Ca_V) and Na⁺ voltage-gated (Na_V) channel block while phosphorylation modulates channel activity. Mg²⁺_o elicits direct voltage-dependent Ca_V channel block, and screens surface charge, and in Na_V channels reduces conduction and may cause depolarization by quantum tunneling across closed channels. Mg²⁺_i is an allosteric large conductance Ca²⁺-activated K⁺ (BK) channel activator, binding to low-affinity sites to alter Ca²⁺ and voltage sensitivity but reduces small conductance Ca²⁺-activated K⁺ (SK) channels’ outward K⁺ current and induces inward rectification. N-Methyl-D-aspartate receptor (NMDAR) channels are inhibited by Mg²⁺_i binding within the pore, while Mg²⁺_o stabilizes excitability through voltage-dependent block, Mg²⁺_o forms Mg-ATP complex modifying purinergic P2X receptor (P2XR) channel affinity and gating and directly blocks the pore. Mg²⁺_o reduces gamma-aminobutyric acid type A receptor (GABA_AR) channel Cl⁻ current amplitude and augments susceptibility to blockers. Mg²⁺_o and Mg²⁺_i block nicotinic acetylcholine receptor (nAChR) channels through voltage-dependent pore binding and surface charge screening, impeding current flow and altering gating. Full article

White-matter development during fetal life represents one of the most vulnerable processes to environmental disruption, as it relies on the precisely timed proliferation, migration, and differentiation of oligodendrocyte lineage cells. Among environmental threats, exposure to toxic compounds contained in tobacco smoke and vaping aerosols represents a major yet preventable risk during pregnancy. Despite growing awareness, tobacco smoking remains widespread, and a substantial proportion of the population—including pregnant women—continues to perceive electronic nicotine delivery systems (ENDS) as less harmful, a misconception that contributes to persistent prenatal exposure. These products expose the fetus to numerous substances that readily cross the placenta and reach the developing brain, including compounds with endocrine-disrupting activity, where they interfere with white-matter development. Epidemiological and neuroimaging studies consistently reveal microstructural alterations in white matter that correlate with long-term cognitive and behavioral impairments in offspring exposed in utero. These alterations may arise from both nicotine-specific pathways and the actions of other toxicants in cigarette smoke and ENDS aerosols that cross the placenta and disrupt white-matter emergence and maturation. Preclinical research provides mechanistic insight: nicotine acts directly on nicotinic acetylcholine receptors (nAChRs) in oligodendrocyte precursor cells, disrupting calcium signaling and differentiation, while additional constituents of smoke and vaping aerosols also affect astrocyte and microglial function and disturb the extracellular milieu required for proper myelination. Full article

γ-Aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the central nervous system. However, GABA receptors, notably at the neuromuscular junction (NMJ), have also been identified in the peripheral nervous system. Here, we studied GABA_B receptor (GABA_B–R)-mediated regulation of acetylcholine (ACh) release in mouse NMJs during early postnatal development. The results revealed that, depending on the age of the mice, the activation of GABA_B–R had the opposite effect on ACh release. At the NMJ in mice on the second postnatal (P2) day, the GABA_B–R blocker CGP 55845 (5 μM) significantly increased the level of ACh release, whereas the GABA_B–R agonist baclofen (10 μM) decreased ACh release. In P14-aged mice, CGP 55845 decreased ACh release, while the application of baclofen significantly increased the release. At the NMJ of P14 mice, the mechanism of the ACh release-potentiating effect of GABA_B–R activation involves N-type calcium ion channels and small-conductance calcium ion-activated potassium ion channels. Full article

Parkinson’s disease (PD) involves motor and cognitive impairment that nicotinic acetylcholine receptors (nAChRs) such as the α7 subtype are responsible for regulating. The hippocampus, abundant in α7 nAChRs, was quantitatively evaluated for [¹²⁵I]α-bungarotoxin ([¹²⁵I]α-Bgtx) binding to α7 nAChRs in postmortem human PD (n = 26; 12 male, 14 female) and cognitively normal (CN) (n = 29; 14 male, 15 female) brain slices. Anti-ubiquitin and anti-α-synuclein immunostained adjacent slices were analyzed using QuPath. Autoradiographs of [¹²⁵I]α-Bgtx radioligand binding were analyzed in OptiQuant. Ubiquitin and α-synuclein distribution generally aligned with the distribution of α7 nAChRs detected by [¹²⁵I]α-Bgtx. Binding of [¹²⁵I]α-Bgtx in PD cases was significantly greater than CN with a 32% increase in gray matter binding. A weak positive correlation between age and [¹²⁵I]α-Bgtx binding was found in both PD and CN. In comparison to Alzheimer’s disease hippocampus, [¹²⁵I]α-Bgtx binding in PD gray matter was higher by 41%. Differences in nAChR expression imply unique roles depending on the neurodegenerative pathology. PD may experience an increase in α7 nAChRs as a compensatory mechanism to the loss in neurons, highlighting its neuroprotective capabilities. [¹²⁵I]α-Bgtx shows potential as a radioligand for α7 nAChRs to elucidate the complexities of PD pathology. Full article

Artificial neural networks in drug discovery have shown remarkable potential in various areas, including molecular similarity assessment and virtual screening. This study presents a novel multimodal Siamese neural network architecture. The aim was to join molecular electrostatic potential (MEP) images with the texture features derived from reduced density gradient (RDG) diagrams for enhanced molecular similarity prediction. On one side, the proposed model is combined with a convolutional neural network (CNN) for processing MEP visual information. This data is added to the multilayer perceptron (MLP) that extracts texture features from gray-level co-occurrence matrices (GLCM) computed from RDG diagrams. Both representations converge through a multimodal projector into a shared embedding space, which was trained using triplet loss to learn similarity and dissimilarity patterns. Limitations associated with the use of purely structural descriptors were overcome by incorporating non-covalent interaction information through RDG profiles, which enables the identification of bioisosteric relationships needed for rational drug design. Three datasets were used to evaluate the performance of the developed model: tyrosine kinase inhibitors (TKIs) targeting the mutant T315I BCR-ABL receptor for the treatment of chronic myeloid leukemia, acetylcholinesterase inhibitors (AChEIs) for Alzheimer’s disease therapy, and heterodimeric AChEI candidates for cross-validation. The visual and texture features of the Siamese architecture help in the capture of molecular similarities based on electrostatic and non-covalent interaction profiles. Therefore, the developed protocol offers a suitable approach in computational drug discovery, being a promising framework for virtual screening, drug repositioning, and the identification of novel therapeutic candidates. Full article

Teleost fish are the first evolutionary group to exhibit an innate and adaptive immune system. Within the mechanisms of adaptive immunity, fish possess, among others, T-helper cells (CD4-like) and their differentiation machinery, regulated by the master transcription factors T-bet, GATA3, Foxp3, and RORγ. Many studies support the existence of a non-neuronal cholinergic system involved in the immune response, named after the ability of leukocytes to synthesize de novo acetylcholine (ACh). Organophosphorus pesticides (OPs), such as diazoxon (DXN), are examples of compounds that act as cholinergic disruptors with immunotoxic effects. The present study aimed to evaluate the expression of transcription factors in leukocytes (spleen mononuclear cells, SMNCs) of Nile tilapia by modulating cholinergic pathways in immune cells using agonists, antagonists, and diazoxon (DXN), an anticholinesterase substance. The obtained data showed a significant increase in RORγ mRNA expression upon stimulation with the nicotinic agonist, whereas activation of the muscarinic receptor with its agonist increased T-bet mRNA expression. An alteration in RORγ expression levels induced by DXN exposure was also observed. The results suggest a probable directing of the immune response towards a pro-inflammatory profile orchestrated mainly by RORγ and T-bet transcription factors in response to cholinergic stimuli. Full article

Alpha7 nicotinic receptors (α7-nAChRs) are implicated in many neurological disorders, but how they fold and assemble is not well understood. Unlike native α7-nAChRs, α7-5HT3 chimeras fold efficiently in HEK cells and do not require chaperones RIC3 or TMEM35A (NACHO) for proper assembly. We investigated the effects of swapping 5HT3 and α7-receptor protein sequences on α7-5HT3R chimera surface expression in mammalian HEK293 or Bosc23 cells, or chimeric receptor function using Xenopus laevis oocytes with or without chaperones. α7-5HT3Rs, consisting of human α7-nAChRs with mouse 5HT3 transmembrane domains (TMs) express without chaperones as measured by cell surface alpha-bungarotoxin binding. However, when subunit TMs from α7-nAChRs and 5HT3Rs were mixed, chaperones were required. Substituting the SAP motif prior to the α7-nAChR “Latch” tail sequence for the 5HT3 C-terminal decreased expression relative to α7-nAChRs with chaperones. Chaperone effects on L264 and G265 mutations in M2 were also investigated. Some constructs that express well in HEK293 or Bosc23 cells are nonfunctional in oocytes with or without NACHO. Our data do not support direct binding of RIC3 or NACHO to the α7-nAChR TM4 (M4) region; instead, they emphasize the functional importance of the conserved SAP motif. Full article

Background: Inflammatory bowel disease (IBD) is a chronic relapsing inflammatory disorder with limited treatment options. Emerging evidence reveals bidirectional crosstalk between gut and brain through inflammatory signaling, leading us to hypothesize that anti-neuroinflammatory agents may concurrently ameliorate intestinal inflammation. The scorpion venom-derived heat-resistant synthetic peptide (SVHRSP), a bioactive peptide initially identified in scorpion venom and subsequently synthesized by our laboratory, possesses neuroprotective, anti-inflammatory, and antioxidative activities. Its properties make SVHRSP a promising candidate for investigating the therapeutic potential of anti-neuroinflammatory strategies in mitigating intestinal inflammation. Methods: Using a chronic dextran sodium sulfate (DSS)-induced colitis model in wild-type and α7 nicotinic acetylcholine receptor (α7nAChR) knockout mice, along with lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages, we assessed SVHRSP’s effects on inflammation, histopathology, gut permeability, oxidative stress markers, and α7nAChR-Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signaling. Results: SVHRSP treatment significantly ameliorated colitis symptoms in wild-type mice by reducing inflammation, repairing histological damage, restoring gut barrier function, and attenuating oxidative stress, with these effects abolished in α7nAChR knockout mice. Mechanistically, SVHRSP activated JAK2/STAT3 signaling through α7nAChR engagement, suppressing proinflammatory cytokine production in macrophages. Conclusion: These results demonstrated that SVHRSP alleviated intestinal inflammation via α7nAChR-dependent JAK2/STAT3 activation. Combined with its known neuroprotective properties, our findings support the repurposing of this neuroactive peptide, SVHRSP, for treating intestinal inflammatory disorders. Full article

This study investigates the neuroprotective and anxiolytic effects of Solanum macrocarpon L. leaf n-butanol extract (SMB) in a zebrafish model of scopolamine (SCOP; 100 μM)-induced cognitive and behavioral impairments. SCOP, a muscarinic receptor antagonist, is commonly used to mimic memory deficits and anxiety-like behaviors associated with neurodegenerative conditions. Zebrafish were chronically exposed to SMB at concentrations of 1, 3, and 6 mg/L. Behavioral assessments included anxiety-related paradigms, such as novel tank diving (NTT), novel approach (NA), and light–dark transition (LD) tests, as well as cognitive assays, including the Y-maze and novel object recognition (NOR) tests. SMB significantly mitigated SCOP-induced anxiety-like behaviors and cognitive deficits in a dose-dependent manner. Biochemical analyses demonstrated that SMB inhibited acetylcholinesterase (AChE) overactivity, indicating restoration of cholinergic function. Furthermore, SMB enhanced the activity of endogenous antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) and significantly reduced oxidative stress biomarkers, including malondialdehyde (MDA) and protein carbonyls. These findings suggest that SMB may exert neuroprotective effects through modulation of cholinergic signaling and oxidative stress. Overall, SMB represents a promising phytotherapeutic candidate for mitigating cognitive and anxiety-related symptoms linked to oxidative damage. Further investigations are warranted to characterize its active constituents and assess long-term efficacy and safety in models of neurodegeneration. Full article