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Brain Sciences Aug 2023Fear is characterized by distinct behavioral and physiological responses that are essential for the survival of the human species. Fear conditioning (FC) serves as a... (Review)
Review
Fear is characterized by distinct behavioral and physiological responses that are essential for the survival of the human species. Fear conditioning (FC) serves as a valuable model for studying the acquisition, extinction, and expression of fear. The serotonin (5-hydroxytryptamine, 5-HT) system is known to play a significant role in emotional and motivational aspects of human behavior, including fear learning and expression. Accumulating evidence from both animal and human studies suggests that brain regions involved in FC, such as the amygdala, hippocampus, and prefrontal cortex, possess a high density of 5-HT receptors, implicating the crucial involvement of serotonin in aversive learning. Additionally, studies exploring serotonin gene polymorphisms have indicated their potential influence on FC. Therefore, the objective of this work was to review the existing evidence linking 5-HT with fear learning and memory in humans. Through a comprehensive screening of the PubMed and Web of Science databases, 29 relevant studies were included in the final review. These studies investigated the relationship between serotonin and fear learning using drug manipulations or by studying 5-HT-related gene polymorphisms. The results suggest that elevated levels of 5-HT enhance aversive learning, indicating that the modulation of serotonin 5-HT2A receptors regulates the expression of fear responses in humans. Understanding the role of this neurochemical messenger in associative aversive learning can provide insights into psychiatric disorders such as anxiety and post-traumatic stress disorder (PTSD), among others.
PubMed: 37626553
DOI: 10.3390/brainsci13081197 -
Herbal medicines for insomnia through regulating 5-hydroxytryptamine receptors: a systematic review.Chinese Journal of Natural Medicines Jul 2023Insomnia is a common sleep disorder without effective therapy and can affect a person's life. The mechanism of the disease is not completely understood. Hence, there is... (Review)
Review
Insomnia is a common sleep disorder without effective therapy and can affect a person's life. The mechanism of the disease is not completely understood. Hence, there is a need to understand the targets related to insomnia, in order to develop innovative therapies and new compounds. Recently, increasing interest has been focused on complementary and alternative medicines for treating or preventing insomnia. Research into their molecular components has revealed that their sedative and sleep-promoting properties rely on the interactions with various neurotransmitter systems in the brain. In this review, the role of 5-hydroxytryptamine (5-HT) in insomnia development is summarized, while a systematic analysis of studies is conducted to assess the mechanisms of herbal medicines on different 5-HT receptors subtypes, in order to provide reference for subsequent research.
Topics: Sleep Initiation and Maintenance Disorders; Plants, Medicinal; Receptors, Serotonin; Serotonin; Sleep; Humans; Animals
PubMed: 37517817
DOI: 10.1016/S1875-5364(23)60405-4 -
Nutrients Jun 2023Evidence is emerging for the role of intestinal tryptophan metabolism in the development of inflammatory bowel disease (IBD). In order to identify the role of altered... (Meta-Analysis)
Meta-Analysis Review
The Involvement of Intestinal Tryptophan Metabolism in Inflammatory Bowel Disease Identified by a Meta-Analysis of the Transcriptome and a Systematic Review of the Metabolome.
Evidence is emerging for the role of intestinal tryptophan metabolism in the development of inflammatory bowel disease (IBD). In order to identify the role of altered intestinal tryptophan metabolism in IBD pathogenesis, a meta-analysis of the transcriptome was performed to identify differentially expressed genes involved in the tryptophan metabolism pathways in intestinal biopsies of IBD as compared to non-IBD controls. Moreover, a systematic review of the metabolome was performed to identify the concurrent changes in tryptophan metabolites. Integration of the transcriptome and metabolome identified various alterations in intestinal tryptophan metabolism during active disease in IBD patients, including decreased intestinal tryptophan absorption, enhanced kynurenine pathway, increased interstitial serotonin availability, changed indole pathway, and activated aryl hydrocarbon receptor signaling. Therefore, a network of intestinal tryptophan metabolism pathways in IBD could be established, helping to assess the potential of genes and metabolites involved in these pathways as diagnostic markers and targets for IBD management.
Topics: Humans; Tryptophan; Transcriptome; Inflammatory Bowel Diseases; Intestines; Metabolome
PubMed: 37447212
DOI: 10.3390/nu15132886 -
Frontiers in Neuroendocrinology Jul 2023The rapid and continual development of a number of radiopharmaceuticals targeting different receptor, enzyme and small molecule systems has fostered Positron Emission... (Review)
Review
The rapid and continual development of a number of radiopharmaceuticals targeting different receptor, enzyme and small molecule systems has fostered Positron Emission Tomography (PET) imaging of endocrine system actions in vivo in the human brain for several decades. PET radioligands have been developed to measure changes that are regulated by hormone action (e.g., glucose metabolism, cerebral blood flow, dopamine receptors) and actions within endocrine organs or glands such as steroids (e.g., glucocorticoids receptors), hormones (e.g., estrogen, insulin), and enzymes (e.g., aromatase). This systematic review is targeted to the neuroendocrinology community that may be interested in learning about positron emission tomography (PET) imaging for use in their research. Covering neuroendocrine PET research over the past half century, researchers and clinicians will be able to answer the question of where future research may benefit from the strengths of PET imaging.
Topics: Humans; Neuroendocrinology; Positron-Emission Tomography; Radiopharmaceuticals; Brain
PubMed: 37423505
DOI: 10.1016/j.yfrne.2023.101081 -
East Asian Archives of Psychiatry :... Jun 2023Clozapine is a potent antipsychotic medication with a complex receptor profile. It is reserved for treatment-resistant schizophrenia. We systematically reviewed studies...
OBJECTIVE
Clozapine is a potent antipsychotic medication with a complex receptor profile. It is reserved for treatment-resistant schizophrenia. We systematically reviewed studies of non-psychosis symptoms of clozapine withdrawal.
METHODS
CINAHL, Medline, PsycINFO, PubMed, and the Cochrane Database of Systematic Reviews were searched using the keywords 'clozapine,' and 'withdrawal,' or 'supersensitivity,' 'cessation,' 'rebound,' or 'discontinuation'. Studies related to non-psychosis symptoms after clozapine withdrawal were included.
RESULTS
Five original studies and 63 case reports / series were included in analysis. In 195 patients included in the five original studies, approximately 20% experienced non-psychosis symptoms following discontinuation of clozapine. In 89 patients in four of the studies, 27 experienced cholinergic rebound, 13 exhibited extrapyramidal symptoms (including tardive dyskinesia), and three had catatonia. In 63 case reports / series included, 72 patients with non-psychosis symptoms were reported, which were catatonia (n=30), dystonia or dyskinesia (n=17), cholinergic rebound (n=11), serotonin syndrome (n=4), mania (n=3), insomnia (n=3), neuroleptic malignant syndrome (NMS) [n=3, one of them had both catatonia and NMS], and de novo obsessive compulsive symptoms (n=2). Restarting clozapine appeared to be the most effective treatment.
CONCLUSIONS
Non-psychosis symptoms following clozapine withdrawal have important clinical implications. Clinicians should be aware of the possible presentations of symptoms to ensure early recognition and management. Further research is warranted to better characterise the prevalence, risk factors, prognosis, and optimal drug dosing for each withdrawal symptom.
Topics: Humans; Antipsychotic Agents; Catatonia; Cholinergic Agents; Clozapine; Schizophrenia; Substance Withdrawal Syndrome
PubMed: 37400227
DOI: 10.12809/eaap2261 -
Ondansetron-induced QT prolongation among various age groups: a systematic review and meta-analysis.The Egyptian Heart Journal : (EHJ) :... Jul 2023Ondansetron is a selective 5-hydroxytryptamine type 3 serotonin-receptor antagonist with antiemetic properties used inadvertently in the emergency department for...
BACKGROUND
Ondansetron is a selective 5-hydroxytryptamine type 3 serotonin-receptor antagonist with antiemetic properties used inadvertently in the emergency department for controlling nausea. However, ondansetron is linked with a number of adverse effects, including prolongation of the QT interval. Therefore, the purpose of this meta-analysis was to assess the occurrence of QT prolongation in pediatric, adult, and elderly patients receiving oral or intravenously administered ondansetron.
METHODS
A thorough electronic search was conducted on PubMed (Medline) and Cochrane Library from the databases' inception to August 10, 2022. Only those studies were considered in which ondansetron was administered orally or intravenously to participants for the treatment of nausea and vomiting. The prevalence of QT prolongation in multiple predefined age groups was the outcome variable. Analyses were conducted using Review manager 5.4 (Cochrane collaboration, 2020).
RESULTS
A total of 10 studies involving 687 ondansetron group participants were statistically analyzed. The administration of ondansetron was associated with a statistically significant prevalence of QT prolongation in all age groups. An age-wise subgroup analysis was conducted which revealed that the prevalence of QT prolongation among participants younger than 18 years was not statistically significant, whereas it was statistically significant among participants aged 18-50 years and among patients older than 50 years.
CONCLUSIONS
The present meta-analysis provides further evidence that oral or intravenous administration of Ondansetron may lead to QT prolongation, particularly among patients older than 18 years of age.
PubMed: 37395900
DOI: 10.1186/s43044-023-00385-y -
Journal of Psychoactive Drugs Jun 2023Evidence suggests that psilocybin has therapeutic benefit for treating depression. However, there is little consensus regarding the mechanism by which psilocybin elicits... (Review)
Review
Evidence suggests that psilocybin has therapeutic benefit for treating depression. However, there is little consensus regarding the mechanism by which psilocybin elicits antidepressant effects. This systematic review summarizes existing evidence. Ovid MEDLINE, EMBASE, psychINFO, and Web of Science were searched, for both human and animal studies, using a combination of MeSH Terms and free-text keywords in September 2021. No other mood disorders or psychiatric diagnoses were included. Original papers in English were included. The PRISMA framework was followed for the screening of papers. Two researchers screened the retrieved articles from the literature search, and a third researcher resolved any conflicts. Of 2,193 papers identified, 49 were selected for full-text review. 14 articles were included in the qualitative synthesis. Six supported psilocybin's mechanism of antidepressant action via changes to serotonin or glutamate receptor activity and three papers found an increase in synaptogenesis. Thirteen papers investigated changes in non-receptor or pathway-specific brain activity. Five papers found changes in functional connectivity or neurotransmission, most commonly in the hippocampus or prefrontal cortex. Several neuroreceptors, neurotransmitters, and brain areas are thought to be involved in psilocybin's ability to mitigate depressive symptoms. Psilocybin appears to alter cerebral blood flow to the amygdala and prefrontal cortex, but the evidence on changes in functional connectivity and specific receptor activity remains sparse. The lack of consensus between studies suggests that psilocybin's mechanism of action may involve a variety of pathways, demonstrating the need for more studies on psilocybin's mechanism of action as an antidepressant.
PubMed: 37385217
DOI: 10.1080/02791072.2023.2223195 -
The Cochrane Database of Systematic... Apr 2023This is the second update of the original Cochrane review published in 2013 (issue 6), which was updated in 2016 (issue 11). Pruritus occurs in patients with disparate... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
This is the second update of the original Cochrane review published in 2013 (issue 6), which was updated in 2016 (issue 11). Pruritus occurs in patients with disparate underlying diseases and is caused by different pathologic mechanisms. In palliative care patients, pruritus is not the most prevalent but is a burdening symptom. It can cause considerable discomfort and negatively affect patients' quality of life.
OBJECTIVES
To assess the effects of different pharmacological treatments compared with active control or placebo for preventing or treating pruritus in adult palliative care patients.
SEARCH METHODS
For this update, we searched CENTRAL (the Cochrane Library), MEDLINE (OVID) and Embase (OVID) up to 6 July 2022. In addition, we searched trial registries and checked the reference lists of all relevant studies, key textbooks, reviews and websites, and we contacted investigators and specialists in pruritus and palliative care regarding unpublished data.
SELECTION CRITERIA
We included randomised controlled trials (RCTs) assessing the effects of different pharmacological treatments, compared with a placebo, no treatment, or an alternative treatment, for preventing or treating pruritus in palliative care patients.
DATA COLLECTION AND ANALYSIS
Two review authors independently assessed the identified titles and abstracts, performed data extraction and assessed the risk of bias and methodological quality. We summarised the results descriptively and quantitatively (meta-analyses) according to the different pharmacological interventions and the diseases associated with pruritus. We assessed the evidence using GRADE and created 13 summary of findings tables.
MAIN RESULTS
In total, we included 91 studies and 4652 participants in the review. We added 42 studies with 2839 participants for this update. Altogether, we included 51 different treatments for pruritus in four different patient groups. The overall risk of bias profile was heterogeneous and ranged from high to low risk. The main reason for giving a high risk of bias rating was a small sample size (fewer than 50 participants per treatment arm). Seventy-nine of 91 studies (87%) had fewer than 50 participants per treatment arm. Eight (9%) studies had low risk of bias in the specified key domains; the remaining studies had an unclear risk of bias (70 studies, 77%) or a high risk of bias (13 studies, 14%). Using GRADE criteria, we judged that the certainty of evidence for the primary outcome (i.e. pruritus) was high for kappa-opioid agonists compared to placebo and moderate for GABA-analogues compared to placebo. Certainty of evidence was low for naltrexone, fish-oil/omega-3 fatty acids, topical capsaicin, ondansetron and zinc sulphate compared to placebo and gabapentin compared to pregabalin, and very low for cromolyn sodium, paroxetine, montelukast, flumecinol, and rifampicin compared to placebo. We downgraded the certainty of the evidence mainly due to serious study limitations regarding risk of bias, imprecision, and inconsistency. For participants suffering from uraemic pruritus (UP; also known as chronic kidney disease (CKD)-associated pruritus (CKD-aP)), treatment with GABA-analogues compared to placebo likely resulted in a large reduction of pruritus (visual analogue scale (VAS) 0 to 10 cm): mean difference (MD) -5.10, 95% confidence interval (CI) -5.56 to -4.55; five RCTs, N = 297, certainty of evidence: moderate. Treatment with kappa-opioid receptor agonists (difelikefalin, nalbuphine, nalfurafine) compared to placebo reduced pruritus slightly (VAS 0 to 10 cm, MD -0.96, 95% CI -1.22 to -0.71; six RCTs, N = 1292, certainty of evidence: high); thus, this treatment was less effective than GABA-analogues. Treatment with montelukast compared to placebo may result in a reduction of pruritus, but the evidence is very uncertain (two studies, 87 participants): SMD -1.40, 95% CI -1.87 to -0.92; certainty of evidence: very low. Treatment with fish-oil/omega-3 fatty acids compared to placebo may result in a large reduction of pruritus (four studies, 160 observations): SMD -1.60, 95% CI -1.97 to -1.22; certainty of evidence: low. Treatment with cromolyn sodium compared to placebo may result in a reduction of pruritus, but the evidence is very uncertain (VAS 0 to 10 cm, MD -3.27, 95% CI -5.91 to -0.63; two RCTs, N = 100, certainty of evidence: very low). Treatment with topical capsaicin compared with placebo may result in a large reduction of pruritus (two studies; 112 participants): SMD -1.06, 95% CI -1.55 to -0.57; certainty of evidence: low. Ondansetron, zinc sulphate and several other treatments may not reduce pruritus in participants suffering from UP. In participants with cholestatic pruritus (CP), treatment with rifampicin compared to placebo may reduce pruritus, but the evidence is very uncertain (VAS: 0 to 100, MD -42.00, 95% CI -87.31 to 3.31; two RCTs, N = 42, certainty of evidence: very low). Treatment with flumecinol compared to placebo may reduce pruritus, but the evidence is very uncertain (RR > 1 favours treatment group; RR 2.32, 95% CI 0.54 to 10.1; two RCTs, N = 69, certainty of evidence: very low). Treatment with the opioid antagonist naltrexone compared to placebo may reduce pruritus (VAS: 0 to 10 cm, MD -2.42, 95% CI -3.90 to -0.94; two RCTs, N = 52, certainty of evidence: low). However, effects in participants with UP were inconclusive (percentage of difference -12.30%, 95% CI -25.82% to 1.22%, one RCT, N = 32). In palliative care participants with pruritus of a different nature, the treatment with the drug paroxetine (one study), a selective serotonin reuptake inhibitor, compared to placebo may reduce pruritus slightly by 0.78 (numerical analogue scale from 0 to 10 points; 95% CI -1.19 to -0.37; one RCT, N = 48, certainty of evidence: low). Most adverse events were mild or moderate. Two interventions showed multiple major adverse events (naltrexone and nalfurafine).
AUTHORS CONCLUSIONS
Different interventions (GABA-analogues, kappa-opioid receptor agonists, cromolyn sodium, montelukast, fish-oil/omega-3 fatty acids and topical capsaicin compared to placebo) were effective for uraemic pruritus. GABA-analogues had the largest effect on pruritus. Rifampin, naltrexone and flumecinol tended to be effective for cholestatic pruritus. However, therapies for patients with malignancies are still lacking. Due to the small sample sizes in most meta-analyses and the heterogeneous methodological quality of the included trials, the results should be interpreted cautiously in terms of generalisability.
Topics: Animals; Humans; Capsaicin; Cromolyn Sodium; gamma-Aminobutyric Acid; Naltrexone; Ondansetron; Palliative Care; Paroxetine; Receptors, Opioid; Rifampin; Zinc Sulfate
PubMed: 37314034
DOI: 10.1002/14651858.CD008320.pub4 -
Life Sciences Aug 2023Cortical spreading depolarization (CSD) is a wave of pathologic neuronal dysfunction that spreads through cerebral gray matter, causing neurologic disturbance in... (Review)
Review
AIMS
Cortical spreading depolarization (CSD) is a wave of pathologic neuronal dysfunction that spreads through cerebral gray matter, causing neurologic disturbance in migraine and promoting lesion development in acute brain injury. Pharmacologic interventions have been found to be effective in migraine with aura, but their efficacy in acutely injured brains may be limited. This necessitates the assessment of possible adjunctive treatments, such as nonpharmacologic methods. This review aims to summarize currently available nonpharmacological techniques for modulating CSDs, present their mechanisms of action, and provide insight and future directions for CSD treatment.
MAIN METHODS
A systematic literature review was performed, generating 22 articles across 3 decades. Relevant data is broken down according to method of treatment.
KEY FINDINGS
Both pharmacologic and nonpharmacologic interventions can mitigate the pathological impact of CSDs via shared molecular mechanisms, including modulating K/Ca/Na/Cl ion channels and NMDA, GABA, serotonin, and CGRP ligand-based receptors and decreasing microglial activation. Preclinical evidence suggests that nonpharmacologic interventions, including neuromodulation, physical exercise, therapeutic hypothermia, and lifestyle changes can also target unique mechanisms, such as increasing adrenergic tone and myelination and modulating membrane fluidity, which may lend broader modulatory effects. Collectively, these mechanisms increase the electrical initiation threshold, increase CSD latency, slow CSD velocity, and decrease CSD amplitude and duration.
SIGNIFICANCE
Given the harmful consequences of CSDs, limitations of current pharmacological interventions to inhibit CSDs in acutely injured brains, and translational potentials of nonpharmacologic interventions to modulate CSDs, further assessment of nonpharmacologic modalities and their mechanisms to mitigate CSD-related neurologic dysfunction is warranted.
Topics: Humans; Cortical Spreading Depression; Migraine Disorders; Serotonin; Neurons; Brain Injuries
PubMed: 37302793
DOI: 10.1016/j.lfs.2023.121833 -
Cureus Apr 2023Obsessive-compulsive disorder (OCD) is a neuropsychiatric disorder that affects approximately 2% of the human population. Traditional treatment of OCD includes selective... (Review)
Review
Obsessive-compulsive disorder (OCD) is a neuropsychiatric disorder that affects approximately 2% of the human population. Traditional treatment of OCD includes selective serotonin reuptake inhibitor (SSRI) or serotonin reuptake inhibitor (SRI) treatment along with cognitive behavioral therapy (CBT). Nearly 25%-30% of OCD patients do not respond to SSRIs. Glutamatergic agents are currently being studied for the treatment of OCD due to the glutamatergic pathway in the brain, related to OCD, and the role of the cortico-striato-thalamic circuit (CSTC). This review assesses the clinical effectiveness of N-methyl-D-aspartate (NMDA) antagonists, ketamine/esketamine, memantine, and amantadine, for adult patients with OCD. Inclusion criteria include human studies published within the last 15 years, with patients diagnosed with OCD, aged over 18 years, with only psychiatric comorbidities, and full-text articles. Papers that included interventions other than CBT, exposure with response prevention (ERP), and SSRI/SRI were excluded. Articles were searched for using PubMed, PubMed Central, Medical Literature Analysis and Retrieval System Online, GeorgiA LIbrary LEarning Online, EBSCO Information Services, OpenAthens, Multidisciplinary Digital Publishing Institute, and Google Scholar databases, last searched on December 2, 2022. The risk of bias was assessed using Cochrane Risk of Bias tools, the Scale for the Assessment of Narrative Review Articles (SANRA) checklist for literature reviews, and the Joanna Briggs Institute (JBI) Critical Appraisal Checklist for quasi-experimental studies. Results were presented and synthesized by Excel spreadsheet analysis. The database search yielded 4,221 articles, which was cut down to 18 articles by inclusion/exclusion criteria, including duplications. 80% of the ketamine studies resulted in a significant reduction of obsessions and compulsions based on the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS), and each of the memantine and amantadine studies displayed clinical effectiveness, also. Limitations include the small number of amantadine studies and the limited availability of other NMDA receptor (NMDAR) antagonist-focused studies. This systematic review shows that ketamine is an effective drug for the treatment of non-refractory, mild to moderate OCD, and memantine and amantadine are effective augmentation agents for the treatment of mild to severe OCD.
PubMed: 37213965
DOI: 10.7759/cureus.37833