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Expert Opinion on Pharmacotherapy Jun 2024Developmental epileptic encephalopathies (DEEs) pose significant challenges due to their refractory nature and limited treatment options. Despite advancements in genetic... (Review)
Review
INTRODUCTION
Developmental epileptic encephalopathies (DEEs) pose significant challenges due to their refractory nature and limited treatment options. Despite advancements in genetic understanding, effective therapies targeting underlying pathophysiology are lacking. Serotoninergic dysfunction has been implicated in epilepsy, sparking interest in serotonin as a therapeutic target.
AREA COVERED
This article explores the potential of bexicaserin, a selective 5-HT2C receptor agonist, as an adjunctive antiseizure medication in DEEs. Bexicaserin is thought to modulate GABAergic neurotransmission, suppressing central hyperexcitability. Preclinical studies demonstrate its efficacy across various seizure models. Clinical trials, including the Pacific Study, reveal promising results in reducing motor seizures. However, challenges such as adverse effects and treatment discontinuation underscore the need for further investigation.
EXPERT OPINION
The efficacy of 5-HT2C serotoninergic agonists, validated in preclinical and clinical studies, highlights serotonin's role in DEEs. Bexicaserin offers new therapeutic possibilities, potentially synergizing with existing antiseizure medications. Polypharmacotherapy, targeting distinct pathways, may enhance therapeutic outcomes. Monitoring pharmacological interactions and addressing central nervous system comorbidities are crucial for optimizing treatment strategies. Further research is needed to elucidate bexicaserin's mechanisms and potential antiepileptogenic effects.
PubMed: 38916481
DOI: 10.1080/14656566.2024.2373350 -
American Journal of Physiology.... Jun 2024The intestinal barrier plays a crucial role in homeostasis, both by facilitating absorption of nutrients and fluids, and providing a tight shield to prevent the invasion...
The intestinal barrier plays a crucial role in homeostasis, both by facilitating absorption of nutrients and fluids, and providing a tight shield to prevent the invasion by either pathogen or commensal microorganisms. Intestinal barrier malfunction is associated with systemic inflammation, oxidative stress, and decreased insulin sensitivity, which may lead to the dysregulation of other tissues. Therefore, a deeper understanding of physiological aspects related to an enhanced barrier function is of significant scientific and clinical relevance. The naked mole-rat has many unusual biological features, including attenuated colonic neuron sensitivity to acid and bradykinin, and resistance to chemical-induced intestinal damage. However, insight into their intestinal barrier physiology is scarce. Here, we observed notable macroscopic and microscopic differences in intestinal tissue structure between naked mole-rats and mice. Moreover, naked mole-rats showed increased number of larger goblet cells and elevated mucus content. In measuring gut permeability, naked mole-rats showed reduced permeability compared to mice, measured as transepithelial electrical resistance, especially in ileum. Furthermore, intestinal ion secretion induced by serotonin, bradykinin, histamine, and capsaicin was significantly reduced in naked mole-rats compared to mice, despite the expression of receptors for all these agonists. In addition, naked mole-rats exhibited reduced pro-secretory responses to the non-selective adenylate cyclase activator forskolin. Collectively, these findings indicate that naked mole-rats possess a robust and hard-to-penetrate gastrointestinal barrier, that is resistant to environmental and endogenous irritants. Naked mole-rats may therefore provide valuable insights into the physiology of the intestinal barrier and set the stage for the development of innovative and effective therapies.
PubMed: 38915279
DOI: 10.1152/ajpgi.00080.2024 -
ELife Jun 2024The serotonin-gated ion channel (5-HTR) mediates excitatory neuronal communication in the gut and the brain. It is the target for setrons, a class of competitive...
The serotonin-gated ion channel (5-HTR) mediates excitatory neuronal communication in the gut and the brain. It is the target for setrons, a class of competitive antagonists widely used as antiemetics, and is involved in several neurological diseases. Cryo-electron microscopy (cryo-EM) of the 5-HTR in complex with serotonin or setrons revealed that the protein has access to a wide conformational landscape. However, assigning known high-resolution structures to actual states contributing to the physiological response remains a challenge. In the present study, we used voltage-clamp fluorometry (VCF) to measure simultaneously, for 5-HTR expressed at a cell membrane, conformational changes by fluorescence and channel opening by electrophysiology. Four positions identified by mutational screening report motions around and outside the serotonin-binding site through incorporation of cysteine-tethered rhodamine dyes with or without a nearby quenching tryptophan. VCF recordings show that the 5-HTR has access to four families of conformations endowed with distinct fluorescence signatures: 'resting-like' without ligand, 'inhibited-like' with setrons, 'pre-active-like' with partial agonists, and 'active-like' (open channel) with partial and strong agonists. Data are remarkably consistent with cryo-EM structures, the fluorescence partners matching respectively apo, setron-bound, 5-HT bound-closed, and 5-HT-bound-open conformations. Data show that strong agonists promote a concerted motion of all fluorescently labeled sensors during activation, while partial agonists, especially when loss-of-function mutations are engineered, stabilize both active and pre-active conformations. In conclusion, VCF, though the monitoring of electrophysiologically silent conformational changes, illuminates allosteric mechanisms contributing to signal transduction and their differential regulation by important classes of physiological and clinical effectors.
Topics: Receptors, Serotonin, 5-HT3; Fluorometry; Humans; Patch-Clamp Techniques; Protein Conformation; Serotonin; Cryoelectron Microscopy; HEK293 Cells; Binding Sites; Ion Channel Gating
PubMed: 38913422
DOI: 10.7554/eLife.93174 -
Mini Reviews in Medicinal Chemistry Jun 2024Depression is a debilitating mental illness that has a significant impact on an individual's psychological, social, and physical life. Multiple factors, such as genetic...
Depression is a debilitating mental illness that has a significant impact on an individual's psychological, social, and physical life. Multiple factors, such as genetic factors and abnormalities in neurotransmitter levels, contribute to the development of depression. Monoamine oxidase inhibitors, tricyclic antidepressants, serotonin reuptake inhibitors (SSRIs), serotonin-noradrenaline reuptake inhibitors, and atypical and new-generation antidepressants are well-known drug classes. SSRIs are the commonly prescribed antidepressant medications in the clinic. Genetic variations impacting serotonergic activity in people can influence susceptibility to diseases and response to antidepressant therapy. Gene polymorphisms related to 5-hydroxytryptamine (5-HT) signaling and subtypes of 5-HT receptors may play a role in the development of depression and the response to antidepressants. SSRIs binding to 5-HT reuptake transporters help relieve depression symptoms. Research has been conducted to identify a biomarker for detecting depressive disorders to identify new treatment targets and maybe offer novel therapy approaches. The pharmacological potentials of the piperazine-based compounds led researchers to design new piperazine derivatives and to examine their pharmacological activities. Structure-activity relationships indicated that the first aspect is the flexibility in the molecules, where a linker of typically a 2-4 carbon chain joins two aromatic sides, one of which is attached to a piperazine/phenylpiperazine/benzyl piperazine moiety. Newly investigated compounds having a piperazine core show a superior antidepressant effect compared to SSRIs in vitro/in vivo.
PubMed: 38910275
DOI: 10.2174/0113895575319878240612070850 -
Cerebral Cortex (New York, N.Y. : 1991) Jun 2024Serotonin (5-HT) regulates working memory within the prefrontal cortex network, which is crucial for understanding obsessive-compulsive disorder. However, the mechanisms...
Serotonin (5-HT) regulates working memory within the prefrontal cortex network, which is crucial for understanding obsessive-compulsive disorder. However, the mechanisms how network dynamics and serotonin interact in obsessive-compulsive disorder remain elusive. Here, we incorporate 5-HT receptors (5-HT1A, 5-HT2A) and dopamine receptors into a multistable prefrontal cortex network model, replicating the experimentally observed inverted U-curve phenomenon. We show how the two 5-HT receptors antagonize neuronal activity and modulate network multistability. Reduced binding of 5-HT1A receptors increases global firing, while reduced binding of 5-HT2A receptors deepens attractors. The obtained results suggest reward-dependent synaptic plasticity mechanisms may attenuate 5-HT related network impairments. Integrating serotonin-mediated dopamine release into circuit, we observe that decreased serotonin concentration triggers the network into a deep attractor state, expanding the domain of attraction of stable nodes with high firing rate, potentially causing aberrant reverse learning. This suggests a hypothesis wherein elevated dopamine concentrations in obsessive-compulsive disorder might result from primary deficits in serotonin levels. Findings of this work underscore the pivotal role of serotonergic dysregulation in modulating synaptic plasticity through dopamine pathways, potentially contributing to learned obsessions. Interestingly, serotonin reuptake inhibitors and antidopaminergic potentiators can counteract the over-stable state of high-firing stable points, providing new insights into obsessive-compulsive disorder treatment.
Topics: Prefrontal Cortex; Obsessive-Compulsive Disorder; Serotonin; Humans; Dopamine; Models, Neurological; Receptors, Dopamine; Nerve Net; Computer Simulation; Receptor, Serotonin, 5-HT2A; Receptors, Serotonin; Neuronal Plasticity; Receptor, Serotonin, 5-HT1A
PubMed: 38904079
DOI: 10.1093/cercor/bhae258 -
Expert Opinion on Pharmacotherapy Jun 2024Adrenergic neurotransmitter reuptake inhibitors are gaining attention in treatment for attention-deficit hyperactivity disorder (ADHD). Due to their effects on... (Review)
Review
INTRODUCTION
Adrenergic neurotransmitter reuptake inhibitors are gaining attention in treatment for attention-deficit hyperactivity disorder (ADHD). Due to their effects on norepinephrine, dopamine, and serotonin neurotransmission, they benefit both ADHD and comorbid disorders and have some other advantages including longer duration of action and fewer adverse effects compared to stimulants. There is continued interest in these agents with novel mechanisms of action in treatment of ADHD.
AREAS COVERED
The authors conducted a PubMed literature search using the following key words: 'ADHD' AND 'adrenergic reuptake inhibitors' OR 'nonstimulants' OR 'atomoxetine' OR 'Viloxazine' OR 'Dasotraline' OR 'Centanafadine' OR 'PDC-1421' OR 'Reboxetine' OR 'Edivoxetine' OR 'Bupropion' OR 'Venlafaxine' OR 'Duloxetine.' They reviewed FDA fact sheets of available medications for safety/tolerability studies and reviewed published clinical studies of these medications for treatment of ADHD.
EXPERT OPINION
Adrenergic neurotransmitter reuptake inhibitors fit the diverse needs of children and adolescents with ADHD with 1) poor tolerability to stimulants (e.g. due to growth suppression, insomnia, rebound irritability, co-morbid depression, anxiety and tic disorders, substance abuse or diversion concerns), 2) cardiac risks, and/or 3) need for extended duration of action. Their differences in receptor affinities and modulating effects support the unique benefits of individual agents.
Topics: Humans; Attention Deficit Disorder with Hyperactivity; Child; Adolescent; Adrenergic Uptake Inhibitors; Central Nervous System Stimulants; Animals; Neurotransmitter Uptake Inhibitors
PubMed: 38900676
DOI: 10.1080/14656566.2024.2369197 -
Cranio : the Journal of... Jun 2024To investigate the relationship between T102C (rs6313) polymorphism in the 5-hydroxytryptamine receptor-2A (5HTR2A) gene and temporomandibular disorder (TMD) and anxiety.
OBJECTIVE
To investigate the relationship between T102C (rs6313) polymorphism in the 5-hydroxytryptamine receptor-2A (5HTR2A) gene and temporomandibular disorder (TMD) and anxiety.
METHODS
This observational case-control study included 80 patients and 70 healthy controls. TMD was diagnosed using the criteria for TMD (DC/TMD). Anxiety was assessed with the Beck anxiety scale. A genotyping study of HTRR2A T102C (rs6313) gene polymorphism was performed from genomic DNA isolated from blood.
RESULTS
The TMD group had higher anxiety scores than the control group ( < .05). The TMD group was similar to the control group regarding genotype and allele frequencies. However, the polymorphic CC genotype was more common in those with high anxiety ( < .05).
CONCLUSION
There was no clear evidence of an association between TMD and the T102C polymorphism in HTR2A and TMD. However, anxiety is closely related to the T102C polymorphism in HTR2A.
PubMed: 38899594
DOI: 10.1080/08869634.2024.2369729 -
ACS Pharmacology & Translational Science Jun 20241-(2,5-Dimethoxy-4-iodophenyl)-2-aminopropane (DOI, or DOX where X = -I) was first synthesized in 1973 in a structure-activity study to explore the effect of various... (Review)
Review
1-(2,5-Dimethoxy-4-iodophenyl)-2-aminopropane (DOI, or DOX where X = -I) was first synthesized in 1973 in a structure-activity study to explore the effect of various aryl substituents on the then newly identified, and subsequently controlled, hallucinogenic agent 1-(2,5-dimethoxy-4-methylphenyl)-2-aminopropane (DOM, or DOX where X = -CH). Over time, DOI was found to be a serotonin (5-HT) receptor agonist using various peripheral 5-HT receptor tissue assays and later, following the identification of multiple families of central 5-HT receptors, an agonist at 5-HT serotonin receptors in rat and, then, human brain. Today, , currently referred to as , are receiving considerable attention for their potential therapeutic application in various neuropsychiatric disorders including treatment-resistant depression. Here, we review, for the first time, the historical and current developments that led to DOI becoming a unique, perhaps a landmark, agent in 5-HT receptor research.
PubMed: 38898956
DOI: 10.1021/acsptsci.4c00157 -
ACS Pharmacology & Translational Science Jun 2024The 5-hydroxytryptamine-3 receptor (5-HTR), a subtype of serotonin receptor, is a ligand-gated ion channel crucial in mediating fast synaptic transmission in the central... (Review)
Review
The 5-hydroxytryptamine-3 receptor (5-HTR), a subtype of serotonin receptor, is a ligand-gated ion channel crucial in mediating fast synaptic transmission in the central and peripheral nervous systems. This receptor significantly influences various neurological activities, encompassing neurotransmission, mood regulation, and cognitive processing; hence, it may serve as an innovative target for neurological disorders. Multiple studies have revealed promising results regarding the beneficial effects of these phytoconstituents and extracts on conditions such as nausea, vomiting, neuropathic pain depression, anxiety, Alzheimer's disease, cognition, epilepsy, sleep, and dyskinesia via modulation of 5-HTR in the pathophysiology of neurological disorder. The review delves into a detailed exploration of , , and studies and clinical studies that discussed phytoconstituents acting on 5-HTR and attenuates difficulties in neurological diseases. The diverse mechanisms by which plant-derived phytoconstituents influence 5-HTR activity offer exciting avenues for developing innovative therapeutic interventions. Besides producing an agonistic or antagonistic effect, some phytoconstituents exert modulatory effects on 5-HTR activity through multifaceted mechanisms. These include γ-aminobutyric acid and cholinergic neuronal pathways, interactions with neurokinin (NK)-1, NK2, serotonergic, and γ-aminobutyric acid(GABA)ergic systems, dopaminergic influences, and mediation of calcium ions release and inflammatory cascades. Notably, the phytoconstituent's capacity to reduce oxidative stress has also emerged as a significant factor contributing to their modulatory role. Despite the promising implications, there is currently a dearth of exploration needed to understand the effect of phytochemicals on the 5-HTR. Comprehensive preclinical and clinical research is of the utmost importance to broaden our knowledge of the potential therapeutic benefits associated with these substances.
PubMed: 38898946
DOI: 10.1021/acsptsci.4c00084 -
Journal of Neurochemistry Jun 20243,4-Methylenedioxymethamphetamine (MDMA, 'ecstasy') is re-emerging in clinical settings as a candidate for the treatment of specific neuropsychiatric disorders (e.g....
3,4-Methylenedioxymethamphetamine (MDMA, 'ecstasy') is re-emerging in clinical settings as a candidate for the treatment of specific neuropsychiatric disorders (e.g. post-traumatic stress disorder) in combination with psychotherapy. MDMA is a psychoactive drug, typically regarded as an empathogen or entactogen, which leads to transporter-mediated monoamine release. Despite its therapeutic potential, MDMA can induce dose-, individual-, and context-dependent untoward effects outside safe settings. In this study, we investigated whether three new methylenedioxy bioisosteres of MDMA improve its off-target profile. In vitro methods included radiotracer assays, transporter electrophysiology, bioluminescence resonance energy transfer and fluorescence-based assays, pooled human liver microsome/S9 fraction incubations, metabolic stability studies, isozyme mapping, and liquid chromatography coupled to high-resolution mass spectrometry. In silico methods included molecular docking. Compared with MDMA, all three MDMA bioisosteres (ODMA, TDMA, and SeDMA) showed similar pharmacological activity at human serotonin, dopamine, and norepinephrine transporters (hSERT, hDAT, and hNET, respectively) but decreased agonist activity at 5-HT receptors. Regarding their hepatic metabolism, they differed from MDMA, with N-demethylation being the only metabolic route shared, and without forming phase II metabolites. In addition, TDMA showed an enhanced intrinsic clearance in comparison to its congeners. Additional screening for their interaction with human organic cation transporters (hOCTs) and plasma membrane monoamine transporter (hPMAT) revealed a weaker interaction of the MDMA analogs with hOCT1, hOCT2, and hPMAT. Our findings suggest that these new MDMA bioisosteres might constitute appealing therapeutic alternatives to MDMA, sparing the primary pharmacological activity at hSERT, hDAT, and hNET, but displaying a reduced activity at 5-HT receptors and alternative hepatic metabolism. Whether these MDMA bioisosteres may pose lower risk alternatives to the clinically re-emerging MDMA warrants further studies.
PubMed: 38898705
DOI: 10.1111/jnc.16149