Dopamine and Noradrenaline in the Brain; Overlapping or Dissociate Functions?

Methylphenidate and P300 in attention deficit hyperactivity disorder: A systematic review and meta-analysis

BACKGROUND

Methylphenidate (MPH) is a stimulant medicine often used to treat attention deficit hyperactivity disorder (ADHD), as it may positively affect behaviour and brain activity. This work aims to systematise the current literature about the effects of MPH on the amplitude of P300 in individuals with ADHD.

METHODS

A systematic review and meta-analysis of empirical studies measuring P300 amplitude and comparing MPH administration to either a pre-MPH condition or healthy controls was conducted, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses.

RESULTS

Our results revealed no overall (n = 13) significant differences between individuals diagnosed with ADHD and medicated with MPH and controls. Although, a moderation analysis by region found differences between both groups on frontal sites. When comparing the pre- and post-effects of MPH on the same individuals (n = 17), it appears that P300 amplitude tends to increase post-administration in central and posterior regions. In this second meta-analysis, a moderation by task revealed a larger effect size for go/no-go.

DISCUSSION

In general, MPH was found to increase P300 amplitude in ADHD, somewhat normalising this aspect of their brain activity. The main limitations of the included studies are the insufficiently explained dosages and the skewness for male participants. Future research directions are discussed.

A genome-wide association study on rumination time in first-lactation dairy cattle

Rumination time (RT) in dairy cattle is a crucial indicator of health, production, reproduction, and greenhouse gas emissions. With moderate heritability estimates for RT, there is potential for further analyses regarding the genetic architecture of the trait. To identify genomic regions associated with RT, we conducted a GWAS on SNPs in a cohort of 452 mid-first-lactation Canadian Holstein cows, followed by the annotation of genes and enrichment analyses of quantitative trait loci (QTL). Animals were genotyped using a medium-density SNP panel (50 K). Quality control measures were used to remove markers residing on nonautosomal chromosomes or with minor allele frequencies <5%, and SNP or animals with call rates lower than 90%. The SNP effects were estimated using single-step genomic BLUP. Significant markers were identified using a chromosome-wise modified Bonferroni correction, based on the expected number of independent chromosome segments. We identified 35 SNPs significantly associated with RT, mapping 34 genes within a 50-kbp interval up and downstream from these SNPs. Additionally, 19 QTL were found enriched in these genomic regions. Notably, genes such as ATP2B4, LDB3,WARS2, and PTPRO were identified, suggesting potential links to muscle fiber activity and milk solids percentage. The enriched QTL were associated with traits related to fat and protein synthesis and deposition in both milk and muscle tissues. Gene Ontology analysis highlighted terms related to muscle contraction and neuronal communication, consistent with the physiological processes underlying RT. Our findings offer new insights into the genetic architecture of RT, advancing the understanding of the physiological mechanisms governing this complex trait.

Optical Fibers Functionalized with Single-Walled Carbon Nanotubes for Flexible Fluorescent Catecholamine Detection

Despite the popularity of drugs that act on catecholamine receptors, our knowledge of catecholamine dynamics in human health and disease remains incomplete. Recent advances in fluorescent sensors have enabled unprecedented access to catecholamine dynamics in preclinical animal models, but the requirements of these technologies to use in model organisms limit their translational value for clinical diagnostics. Here, we introduce proof of principle fluorescent catecholamine detection via optical fibers functionalized with single-walled carbon nanotube (SWNT)-based near-infrared catecholamine sensors (nIRCats), a catecholamine detection form factor that has potential for more convenient and less invasive clinical translation. We show that these near-infrared functionalized (nIRF) fibers respond to dopamine in a biologically relevant concentration range (10 nM through 1 μM), with minimal responsivity loss following 16 h exposure to human blood plasma. We further demonstrate the utility of these fibers in detecting dopamine from as little as 10 μL volumes of clinically relevant biofluids up to 24 weeks after fiber synthesis. We also introduce a compact, mobile dual-near-infrared fiber photometry rig and demonstrate its success detecting dopamine in acute brain slices with nIRF fibers. Together, this fiber-based dopamine detection tool and photometry rig expand the toolset for catecholamine detection.

Biogenic Amine Metabolism and Its Genetic Variations in Autism Spectrum Disorder: A Comprehensive Overview

Autism spectrum disorder (ASD) is a genetically heterogeneous syndrome characterized by repetitive, restricted, and stereotyped behaviors, along with persistent difficulties with social interaction and communication. Despite its increasing prevalence globally, the underlying pathogenic mechanisms of this complex neurodevelopmental disorder remain poorly understood. Therefore, the identification of reliable biomarkers could play a crucial role in enabling early screening and more precise classification of ASD subtypes, offering valuable insights into its physiopathology and aiding the customization of treatment or early interventions. Biogenic amines, including serotonin, histamine, dopamine, epinephrine, norepinephrine, and polyamines, are a class of organic compounds mainly produced by the decarboxylation of amino acids. A substantial portion of the genetic variation observed in ASD has been linked to genes that are either directly or indirectly involved in the metabolism of biogenic amines. Their potential involvement in ASD has become an area of growing interest due to their pleiotropic activities in the central nervous system, where they act as both neurotransmitters and neuromodulators or hormones. This review examines the role of biogenic amines in ASD, with a particular focus on genetic alterations in the enzymes responsible for their synthesis and degradation.

Associations between amino acid levels and autism spectrum disorder severity

BACKGROUND

Autism spectrum disorder (ASD) imposes a significant burden on both patients and society. Amino acid metabolism abnormalities are particularly relevant to ASD pathology due to their crucial role in neurotransmitter synthesis, synaptic function, and overall neurodevelopment. This study aims to explore the association between amino acid metabolic abnormalities and the severity of ASD by analyzing the amino acid concentrations in the blood of children with ASD.

METHODS

Fasting peripheral blood samples were collected from 344 children with ASD, and amino acid concentrations were measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS) while strictly following quality control measures. The association between amino acid concentrations and ASD severity was evaluated using logistic regression and restricted cubic spline (RCS) analysis. The ROC (receiver operating characteristic) curve, decision curve analysis (DCA), and calibration curve were used to construct and validate predictive models and nomograms, thereby assessing their predictive performance.

RESULTS

Multivariate logistic regression analysis showed that aspartic acid (OR = 1.037, 95% CI: 1.009-1.068, P = 0.01), glutamic acid (OR = 1.009, 95% CI: 1.001-1.017, P = 0.03), phenylalanine (OR = 1.036, 95% CI: 1.003-1.072, P = 0.04), and leucine/isoleucine (OR = 1.021, 95% CI: 1.006-1.039, P = 0.01) were significantly positively correlated with the severity of ASD. On the other hand, tryptophan (OR = 0.935, 95% CI: 0.903-0.965, P < 0.01) and valine (OR = 0.987, 95% CI: 0.977-0.997, P = 0.01) were significantly negatively correlated with the severity of ASD. RCS analysis further revealed a nonlinear relationship between the concentrations of aspartic acid, proline, and glutamic acid and the risk of ASD. ROC curve analysis showed that the combined model achieved an AUC (area under the curve) of 0.806, indicating high diagnostic accuracy. Calibration and decision curve analysis further validated the predictive effectiveness and clinical utility of the model.

CONCLUSIONS

This study identifies potential amino acid biomarkers that may contribute to ASD severity assessment. Further research is needed to validate these findings and explore their clinical utility.

Progressive noradrenergic degeneration and motor cortical dysfunction in Parkinson's disease

The locus coeruleus norepinephrine (LC-NE) system plays an important role in regulating brain function, and its neuronal loss has been well-documented in Parkinson's disease (PD). The LC-NE neurodegeneration is believed to underlie various nonmotor symptoms in people with PD, including neuropsychiatric deficits, sleep disruptions, and cognitive impairments. Of particular interest, LC-NE neurons send intensive axonal projections to the motor regions of the cerebral cortex. However, how NE depletion in the motor cortex contributes to PD pathophysiology remains poorly understood. In addition, recent studies provided increasing mechanistic insights into secondary changes in the cerebral cortex as LC-NE degenerates, which might involve its interaction with dopaminergic signaling during the chronic course of the disease. In the present article, we briefly discuss clinical and preclinical studies that support the critical roles of LC-NE neurodegeneration and motor cortical dysfunction in both motor and nonmotor deficits in Parkinsonian states. We focus our discussion on the potential impact of LC-NE neurodegeneration on motor cortical function and the subsequent symptom manifestation. Last, we propose future research directions that can advance our understanding of cortical pathophysiology in PD by integrating noradrenergic degeneration.

Fischer's ratio and DNA damage in hypoxemia-induced brain injury in rat model: prophylactic role of quercetin and mexamine supplementation

Hypoxemia brain injuries arise when the brain's oxygen supply is restricted. Brain cells gradually die and become impaired as a result of the restricted oxygen flow a diversity of signaling pathways are involved in the pathophysiology of brain damage. One of the main concerns when examining the rate of protein breakdown is the measurement of the serum amino acid ratio. Valine, leucine, and isoleucine make up branched-chain amino acids, while phenylalanine and tyrosine make up aromatic amino acids. A vital tool for assessing the severity of hypoxemia is Fischer's ratio. The goal of this article is to determine how quercetin (QUR) and/or mexamine (MEX) prevented synfat (SN)-induced brain damage in a rat models. It also aimed to elucidate the various cross-linked inflammatory pathways, DNA damage, and Fischer's ratio. Following QUR and MEX therapy, synfat-induced hypoxemia. Hemoglobin (Hb) levels were markedly reduced by synfat-intoxication, and oxidative stress and inflammatory biomarkers, including TNF-??, MDA, interleukin-6 (IL-6), and C -reactive protein (CRP), were elevated. Hemoglobin levels, oxidative stress biomarkers, and the aberrant expression of pro-inflammatory cytokines were all altered by QUR and/or MEX therapy. Similarly, the concentration of γ-aminobutyric acid, serotonine, noradrenaline, and intropin in cerebral tissue is restricted. Similarly, the COMET assay and 8-oxo-7,8-dihydro-2'-deoxyguanosine analysis (8-oxodG) demonstrated that QUR and MEX potentially altered synfat-induced brain DNA damage. The results confirmed the potential impact of this combined strategy as a powerful therapy for brain hypoxemia, concluding that treatment via QUR with MEX was superior therapy in modulating synfat-triggered cerebral injury.

Defatted chia (Salvia hispanica L.) flour peptides: Exploring nutritional profiles, techno-functional and bio-functional properties, and future directions

Chia (Salvia hispanica L.) is a summer-blooming herb from the mint family, known for its rich nutritional profile, including high-quality protein, fibre, and a balanced ratio of omega-3 and omega-6 fatty acids. With the rising demand for chia oil, defatted chia flour (DCF), a by-product of oil extraction, has gained attention as a valuable ingredient. DCF is rich in essential macronutrients and amino acids, offering a sustainable alternative to traditional protein sources and supporting global food sustainability and waste reduction efforts. Recent studies have highlighted the techno-functional properties of DCF peptides, showing excellent solubility, water- and oil-absorption capacities, as well as emulsifying, foaming, and gelling abilities. These properties enhance their application in diverse food systems, making DCF an important ingredient in the development of nutritious, innovative, and appealing food products. Beyond their functional roles, chia-derived peptides also exhibit significant bioactive properties, such as antioxidants, antihypertensive, anti-inflammatory, neuroprotective, antidiabetic, antimicrobial, anti-aging, hypolipidemic, and hypoglycaemic effects. These properties make them beneficial for improving health and wellness. Integrating DCF peptides into food products provides a natural approach to managing chronic diseases, promoting longevity, and improving overall health. To fully realize the potential of DCF peptides, future research should focus on understanding their bioactivities at the molecular level and exploring how they interact with various physiological systems. Interdisciplinary collaboration among food science, biotechnology, pharmacology, and nutrition is essential, along with careful evaluation of safety and potential risks. Regulatory frameworks will be crucial for the broader use of DCF peptides in food and nutraceuticals. Additionally, advancements in peptide production, extraction, and purification technologies will be necessary for large-scale, sustainable applications. Focusing on these areas will maximize the benefits of chia peptides for human health, nutrition, and environmental sustainability.

Incentive Cocaine-Seeking Habits and Their Compulsive Manifestation Emerge After a Downregulation of the Dopamine Transporter in Astrocytes Across Functional Domains of the Striatum

The development of compulsive cue-controlled-incentive drug-seeking habits is a hallmark of substance use disorder that is predicated on an intrastriatal shift in the locus of control over behaviour from a nucleus accumbens (Nac) core-dorsomedial striatum network to a Nac core-anterior dorsolateral striatum (aDLS) network. This shift is paralleled by drug-induced (including cocaine) dopamine transporter (DAT) alterations originating in the ventral striatum that spread eventually to encompass the aDLS. Having recently shown that heroin self-administration results in a pan-striatal reduction in astrocytic DAT that precedes the development of aDLS dopamine-dependent incentive heroin-seeking habits, we tested the hypothesis that similar adaptations occur following cocaine exposure. We compared DAT protein levels in whole tissue homogenates, and in astrocytes cultured from ventral and dorsal striatal territories of drug-naïve male Sprague-Dawley rats to those of rats with a history of cocaine taking or an aDLS dopamine-dependent incentive cocaine-seeking habit. Cocaine exposure resulted in a decrease in whole tissue and astrocytic DAT across all territories of the striatum. We further demonstrated that compulsive (i.e., punishment-resistant) incentive cocaine-seeking habits were associated with a reduction in DAT mRNA levels in the Nac shell, but not the Nac core-aDLS incentive habit system. Together with the recent evidence of heroin-induced downregulation of striatal astrocytic DAT, these findings suggest that alterations in astrocytic DAT may represent a common mechanism underlying the development of compulsive incentive drug-seeking habits across drug classes.

Improving brain health via the central executive network

Cognitive and physical stress have significant effects on brain health, particularly through their influence on the central executive network (CEN). The CEN, which includes regions such as the dorsolateral prefrontal cortex, anterior cingulate cortex and inferior parietal lobe, is central to managing the demands of cognitively challenging motor tasks. Acute stress can temporarily reduce connectivity within the CEN, leading to impaired cognitive function and emotional states. However a rebound in these states often follows, driven by motivational signals through the mesocortical and mesolimbic pathways, which help sustain inhibitory control and task execution. Chronic exposure to physical and cognitive challenges leads to long-term improvements in CEN functionality. These changes are supported by neurochemical, structural and systemic adaptations, including mechanisms of tissue crosstalk. Myokines, adipokines, anti-inflammatory cytokines and gut-derived metabolites contribute to a biochemical environment that enhances neuroplasticity, reduces neuroinflammation and supports neurotransmitters such as serotonin and dopamine. These processes strengthen CEN connectivity, improve self-regulation and enable individuals to adopt and sustain health-optimizing behaviours. Long-term physical activity not only enhances inhibitory control but also reduces the risk of age-related cognitive decline and neurodegenerative diseases. This review highlights the role of progressive physical stress through exercise as a practical approach to strengthening the CEN and promoting brain health, offering a strategy to improve cognitive resilience and emotional well-being across the lifespan.

Synapse-specific catecholaminergic modulation of neuronal glutamate release

Norepinephrine in vertebrates and its invertebrate analog, octopamine, regulate the activity of neural circuits. We find that, when hungry, Drosophila larvae switch activity in type II octopaminergic motor neurons (MNs) to high-frequency bursts, which coincide with locomotion-driving bursts in type I glutamatergic MNs that converge on the same muscles. Optical quantal analysis across hundreds of synapses simultaneously reveals that octopamine potentiates glutamate release by tonic type Ib MNs, but not phasic type Is MNs, and occurs via the Gq-coupled octopamine receptor (OAMB). OAMB is more abundant in type Ib terminals and acts through diacylglycerol and its target Unc13A, a key component of the glutamate release machinery. Potentiation varies significantly-by up to 1,000%-across synapses of a single Ib axon, with synaptic Unc13A levels determining both release probability and potentiation. We propose that a dual molecular mechanism-an upstream neuromodulator receptor and a downstream transmitter release controller-fine-tunes catecholaminergic modulation so that strong tonic synapses exhibit large potentiation, while weaker tonic and all phasic synapses maintain consistency, yielding a sophisticated regulation of locomotor behavior.

Characterization of the Astrocyte Calcium Response to Norepinephrine in the Ventral Tegmental Area

Astrocytes from different brain regions respond with Ca2+ elevations to the catecholamine norepinephrine (NE). However, whether this noradrenergic-mediated signaling is present in astrocytes from the ventral tegmental area (VTA), a dopaminergic circuit receiving noradrenergic inputs, has not yet been investigated. To fill in this gap, we applied a pharmacological approach along with two-photon microscopy and an AAV strategy to express a genetically encoded calcium indicator in VTA astrocytes. We found that VTA astrocytes from both female and male young adult mice showed a strong Ca2+ response to NE at both soma and processes. Our results revealed that Gq-coupled α1 adrenergic receptors, which elicit the production of IP3, are the main mediators of the astrocyte response. In mice lacking the IP3 receptor type-2 (IP3R2-/- mice), we found that the astrocyte response to NE, even if reduced, is still present. We also found that in IP3R2-/- astrocytes, the residual Ca2+ elevations elicited by NE depend on the release of Ca2+ from the endoplasmic reticulum, through IP3Rs different from IP3R2. In conclusion, our results reveal VTA astrocytes as novel targets of the noradrenergic signaling, opening to new interpretations of the cellular and molecular mechanisms that mediate the NE effects in the VTA.

Mechanisms and Potential Benefits of Neuroprotective Agents in Neurological Health

The brain contains many interconnected and complex cellular and molecular mechanisms. Injury to the brain causes permanent dysfunctions in these mechanisms. So, it continues to be an area where surgical intervention cannot be performed except for the removal of tumors and the repair of some aneurysms. Some agents that can cross the blood-brain barrier and reach neurons show neuroprotective effects in the brain due to their anti-apoptotic, anti-inflammatory and antioxidant properties. In particular, some agents act by reducing or modulating the accumulation of protein aggregates in neurodegenerative diseases (Alzheimer's disease, Parkinson's disease, Huntington's disease, Amyotrophic lateral sclerosis, and prion disease) caused by protein accumulation. Substrate accumulation causes increased oxidative stress and stimulates the brain's immune cells, microglia, and astrocytes, to secrete proinflammatory cytokines. Long-term or chronic neuroinflammatory response triggers apoptosis. Brain damage is observed with neuronal apoptosis and brain functions are impaired. This situation negatively affects processes such as motor movements, memory, perception, and learning. Neuroprotective agents prevent apoptosis by modulating molecules that play a role in apoptosis. In addition, they can improve impaired brain functions by supporting neuroplasticity and neurogenesis. Due to the important roles that these agents play in central nervous system damage or neurodegenerative diseases, it is important to elucidate many mechanisms. This review provides an overview of the mechanisms of flavonoids, which constitute a large part of the agents with neuroprotective effects, as well as vitamins, neurotransmitters, hormones, amino acids, and their derivatives. It is thought that understanding these mechanisms will enable the development of new therapeutic agents and different treatment strategies.

The administration of a phentolamine infusion into the basolateral amygdala enhances long-term memory and diminishes anxiety-like behavior in stressed rats

The basolateral amygdala (BLA) contains adrenergic receptors, which are known to be involved in stress, anxiety, and memory. The objective of this study was to explore whether inhibition of α-adrenergic receptors (by phentolamine, an α-adrenergic receptor antagonist) in the BLA can reduce foot-shock stress-induced anxiety-like behavior, memory deficits, and long-term potentiation (LTP) deficits within the CA1 region of the rat hippocampus. Forty male Wistar rats were assigned to the intact, control, stress (Str), Phent (phentolamine), and Phent + Str groups. Animals were subjected to six shocks on 4 consecutive days, and phentolamine was injected into BLA 20 min before the animals were placed in the foot-shock stress apparatus. Results from the elevated plus maze test (EPM) revealed a reduction in anxiety-like behaviors (by an increased number of entries into the open arm, percentage of time spent in the open arm, and rearing and freezing) among stressed animals upon receiving injections of phentolamine into the BLA. The open-field test results (increased rearing, grooming, and freezing behaviors) were consistent with the EPM test results. Phentolamine infusion into the BLA enhanced spatial memory, reducing errors in finding the target hole and decreasing latency time in the Barnes maze test for stress and nonstress conditions. Injecting phentolamine into the BLA on both sides effectively prevented LTP impairment in hippocampal CA1 neurons after being subjected to foot-shock stress. It has been suggested that phentolamine in the BLA can effectively improve anxiety-like behaviors and memory deficits induced by foot-shock stress.

Effects of voluntary exercise and electrical muscle stimulation on reaction time in the Go/No-Go task

INTRODUCTION

Acute exercise improves cognitive performance. However, it remains unclear what triggers cognitive improvement. Electrical muscle stimulation (EMS) facilitates the examination of physiological changes derived from peripheral muscle contraction during exercise. Thus, we compared the effects of EMS and voluntary exercise at low- or moderate-intensity on reaction time (RT) in a cognitive task to understand the contribution of central and peripheral physiological factors to RT improvement.

METHODS

Twenty-four young, healthy male participants performed a Go/No-Go task before and after EMS/exercise. In the EMS condition, EMS was applied to the lower limb muscles. In the low-intensity exercise condition, the participants cycled an ergometer while maintaining their heart rate (HR) at the similar level during EMS. In the moderate-intensity exercise condition, exercise intensity corresponded to ratings of perceived exertion of 13/20. The natural log-transformed root mean square of successive differences between adjacent inter-beat (R-R) intervals (LnRMSSD), which predominantly reflects parasympathetic HR modulation, was calculated before and during EMS/exercise.

RESULTS

RT improved following moderate-intensity exercise (p = 0.002, Cohen' d = 0.694), but not following EMS (p = 0.107, Cohen' d = 0.342) and low-intensity exercise (p = 0.076, Cohen' d = 0.380). Repeated measures correlation analysis revealed that RT was correlated with LnRMSSD (Rrm(23) = 0.599, p = 0.002) in the moderate-intensity exercise condition.

CONCLUSION

These findings suggest that the amount of central neural activity and exercise pressor reflex may be crucial for RT improvement. RT improvement following moderate-intensity exercise may, at least partly, be associated with enhanced sympathetic nervous system activity.

Task-irrelevant stimuli reliably boost phasic pupil-linked arousal but do not affect decision formation

The arousal systems of the brainstem, specifically the locus coeruleus-noradrenaline system, respond "phasically" during decisions. These central arousal transients are accompanied by dilations of the pupil. Mechanistic attempts to understand the impact of phasic arousal on cognition would benefit from temporally precise experimental manipulations. Here, we evaluated a non-invasive candidate approach to manipulate arousal in humans: presenting task-irrelevant auditory stimuli at different latencies during the execution of a challenging task. Task-irrelevant auditory stimuli drive responses of brainstem nuclei involved in the control of pupil size, but it is unknown whether such sound-evoked responses mimic the central arousal transients evoked during cognitive computations. A large body of evidence has implicated central arousal transients in reducing bias during challenging perceptual decisions. We thus used challenging visual decisions as a testbed, combining them with task-irrelevant sounds of varying onset latency or duration. Across three experiments, the sounds consistently elicited well-controlled pupil responses that superimposed onto task-evoked responses. While we replicated a negative correlation between task-evoked pupil responses and bias, the task-irrelevant sounds had no behavioral effect. This dissociation suggests that cognitive task engagement and task-irrelevant sounds may recruit distinct neural systems contributing to the control of pupil size.

Copper in Human Health and Disease: A Comprehensive Review

This comprehensive review discusses the crucial role of copper in human health and disease as an essential trace mineral. It emphasizes the significance of copper while addressing potential risks from imbalances in copper levels, be it excessive or inadequate. The review outlines various challenges in copper research, including toxicity concerns, data limitations, metabolic complexities, genetic influences, nutrient interactions, and resource constraints. Despite these challenges, the review identifies specific research areas needing exploration, such as copper homeostasis regulation, transport mechanisms, gut microbiome interactions, immune function, neurodegenerative diseases, cardiovascular health, cancer, fertility, and reproductive health. The purpose of this review is to explore the important role of copper in human health and disease, which highlights the delicate balance required to avoid deficiency or toxicity. For the researchers and scientists, it provides the gaps in the research, so it aims to provide insights that could advance diagnostic and therapeutic strategies across various medical disciplines.

Microbiota-gut-brain axis: Natural antidepressants molecular mechanism

BACKGROUND

Major depressive disorder (MDD) is a severe mental health condition characterized by persistent depression, impaired cognition, and reduced activity. Increasing evidence suggests that gut microbiota (GM) imbalance is closely linked to the emergence and advancement of MDD, highlighting the potential significance of regulating the "Microbiota-Gut-Brain" (MGB) axis to impact the development of MDD. Natural products (NPs), characterized by broad biological activities, low toxicity, and multi-target characteristics, offer unique advantages in antidepressant treatment by regulating MGB axis.

PURPOSE

This review was aimed to explore the intricate relationship between the GM and the brain, as well as host responses, and investigated the mechanisms underlying the MGB axis in MDD development. It also explored the pharmacological mechanisms by which NPs modulate MGB axis to exert antidepressant effects and addressed current research limitations. Additionally, it proposed new strategies for future preclinical and clinical applications in the MDD domain.

METHODS

To study the effects and mechanism by which NPs exert antidepressant effects through mediating the MGB axis, data were collected from Web of Science, PubMed, ScienceDirect from initial establishment to March 2024. NPs were classified and summarized by their mechanisms of action.

RESULTS

NPs, such as flavonoids,alkaloids,polysaccharides,saponins, terpenoids, can treat MDD by regulating the MGB axis. Its mechanism includes balancing GM, regulating metabolites and neurotransmitters such as SCAFs, 5-HT, BDNF, inhibiting neuroinflammation, improving neural plasticity, and increasing neurogenesis.

CONCLUSIONS

NPs display good antidepressant effects, and have potential value for clinical application in the prevention and treatment of MDD by regulating the MGB axis. However, in-depth study of the mechanisms by which antidepressant medications affect MGB axis will also require considerable effort in clinical and preclinical research, which is essential for the development of effective antidepressant treatments.

Dopamine and Norepinephrine Differentially Mediate the Exploration-Exploitation Tradeoff

Dopamine (DA) and norepinephrine (NE) have been repeatedly implicated in neuropsychiatric vulnerability, in part via their roles in mediating the decision-making processes. Although two neuromodulators share a synthesis pathway and are coactivated under states of arousal, they engage in distinct circuits and modulatory roles. However, the specific role of each neuromodulator in decision-making, in particular the exploration-exploitation tradeoff, remains unclear. Revealing how each neuromodulator contributes to exploration-exploitation tradeoff is important in guiding mechanistic hypotheses emerging from computational psychiatric approaches. To understand the differences and overlaps of the roles of these two catecholamine systems in regulating exploration, a direct comparison using the same dynamic decision-making task is needed. Here, we ran male and female mice in a restless two-armed bandit task, which encourages both exploration and exploitation. We systemically administered a nonselective DA antagonist (flupenthixol), a nonselective DA agonist (apomorphine), a NE beta-receptor antagonist (propranolol), and a NE beta-receptor agonist (isoproterenol) and examined changes in exploration within subjects across sessions. We found a bidirectional modulatory effect of dopamine on exploration. Increasing dopamine activity decreased exploration and decreasing dopamine activity increased exploration. The modulatory effect of beta-noradrenergic receptor activity on exploration was mediated by sex. Reinforcement learning model parameters suggested that dopamine modulation affected exploration via decision noise and norepinephrine modulation affected exploration via sensitivity to outcome. Together, these findings suggested that the mechanisms that govern the exploration-exploitation transition are sensitive to changes in both catecholamine functions and revealed differential roles for NE and DA in mediating exploration.

Altered intrinsic neural activity and its molecular analyses in first-episode schizophrenia with auditory verbal hallucinations

Background

Auditory verbal hallucinations (AVHs) are one of the signature positive symptoms of schizophrenia, affecting a substantial portion of patients with schizophrenia. These hallucinations seriously impact the lives of patients, resulting in a substantial social burden. Recent studies have shown a significant correlation between abnormal local brain activity and the neurobiological mechanisms of AVHs. However, it is not fully clear whether altered intrinsic brain activity in schizophrenia patients with AVHs is correlated with specific neurotransmitter systems.

Methods

We included 50 first-episode, drug-naïve schizophrenia patients with AVHs, 50 patients without AVHs (NAVHs), and 50 age- and sex-matched healthy controls (HCs). The amplitude of low-frequency fluctuation (ALFF) was utilized to explore the altered intrinsic brain activity in the AVH group. Subsequently, we spatially correlated the altered ALFF with neurotransmitter maps using JuSpace.

Results

In our study, compared to HCs, the AVH group exhibited significantly reduced ALFF in multiple brain regions, mainly including the left precuneus, bilateral supplementary motor areas, bilateral paracentral lobules, bilateral precentral gyri, and bilateral postcentral gyri. The NAVH group showed significantly reduced ALFF in the left inferior occipital gyrus, left calcarine gyrus, and left lingual gyrus compared to HCs. Furthermore, the AVH group showed higher ALFF in the right inferior frontal gyrus compared to the NAVH group. Additionally, these ALFF alterations in the AVH group were closely related to three neurotransmitters, including dopamine, serotonin and norepinephrine.

Conclusion

We link neurotransmitters to abnormal intrinsic brain activity in first-episode, drug-naïve schizophrenia patients with AVHs, contributing to a comprehensive understanding of the pathophysiological processes and treatment pathways underlying AVHs.

Hypocretin-1 receptor antagonism improves inhibitory control during the Go/No-Go task in highly motivated, impulsive male mice

RATIONALE

Motivation and inhibitory control are dominantly regulated by the dopaminergic (DA) and noradrenergic (NA) systems, respectively. Hypothalamic hypocretin (orexin) neurons provide afferent inputs to DA and NA nuclei and hypocretin-1 receptors (HcrtR1) are implicated in reward and addiction. However, the role of the HcrtR1 in inhibitory control is not well understood.

OBJECTIVES

To determine the effects of HcrtR1 antagonism and motivational state in inhibitory control using the go/no-go task in mice.

METHODS

n = 23 male C57Bl/6JArc mice were trained in a go/no-go task. Decision tree dendrogram analysis of training data identified more and less impulsive clusters of animals. A HcrtR1 antagonist (BI001, 12.5 mg/kg, per os) or vehicle were then administered 30 min before go/no-go testing, once daily for 5 days, under high (food-restricted) and low (free-feeding) motivational states in a latin-square crossover design. Compound exposure levels were assessed in a satellite group of animals.

RESULTS

HcrtR1 antagonism increased go accuracy and decreased no-go accuracy in free-feeding animals overall, whereas it decreased go accuracy and increased no-go accuracy only in more impulsive, food restricted mice. HcrtR1 antagonism also showed differential effects in premature responding, which was increased in response to the antagonist in free-feeding, less impulsive animals, and decreased in food restricted, more impulsive animals. HcrtR1 receptor occupancy by BI001 was estimated at ~ 66% during the task.

CONCLUSIONS

These data indicate that hypocretin signalling plays roles in goal-directed behaviour and inhibitory control in a motivational state-dependant manner. While likely not useful in all settings, HcrtR1 antagonism may be beneficial in improving inhibitory control in impulsive subpopulations.

Exploring the Therapeutic Potential of Terpenoids for Depression and Anxiety

This review focus on the terpenoids as potential therapeutic agents for depression and anxiety disorders, which naturally found in a variety of plants and exhibit a wide range of biological activities. Among the terpenoids discussed in this review are α-pinene, β-caryophyllene, α-phellandrene, limonene, β-linalool, 1, 8-cineole, β-pinene, caryophyllene oxide, p-cymene, and eugenol. All of these compounds have been studied extensively regarding their pharmacological properties, such as neuroprotective effect, anti-inflammation, antibacterial, regulation of neurotransmitters and antioxidant effect. Preclinical evidence are reviewed to highlight their diverse mechanisms of action and therapeutic potential to support antidepressant and anxiolytic properties. Additionally, challenges and future directions are also discussed to emphasize therapeutic utility of terpenoids for mental health disorders. Overall, this review provides a promising role of terpenoids as novel therapeutic agents for depression and anxiety, with potential implications for the development of more effective and well-tolerated treatments in the field of psychopharmacology.

Simulating combined monoaminergic depletions in a PD animal model through a bio-constrained differential equations system

Introduction

Historically, Parkinson's Disease (PD) research has focused on the dysfunction of dopamine-producing cells in the substantia nigra pars compacta, which is linked to motor regulation in the basal ganglia. Therapies have mainly aimed at restoring dopamine (DA) levels, showing effectiveness but variable outcomes and side effects. Recent evidence indicates that PD complexity implicates disruptions in DA, noradrenaline (NA), and serotonin (5-HT) systems, which may underlie the variations in therapy effects.

Methods

We present a system-level bio-constrained computational model that comprehensively investigates the dynamic interactions between these neurotransmitter systems. The model was designed to replicate experimental data demonstrating the impact of NA and 5-HT depletion in a PD animal model, providing insights into the causal relationships between basal ganglia regions and neuromodulator release areas.

Results

The model successfully replicates experimental data and generates predictions regarding changes in unexplored brain regions, suggesting avenues for further investigation. It highlights the potential efficacy of alternative treatments targeting the locus coeruleus and dorsal raphe nucleus, though these preliminary findings require further validation. Sensitivity analysis identifies critical model parameters, offering insights into key factors influencing brain area activity. A stability analysis underscores the robustness of our mathematical formulation, bolstering the model validity.

Discussion

Our holistic approach emphasizes that PD is a multifactorial disorder and opens promising avenues for early diagnostic tools that harness the intricate interactions among monoaminergic systems. Investigating NA and 5-HT systems alongside the DA system may yield more effective, subtype-specific therapies. The exploration of multisystem dysregulation in PD is poised to revolutionize our understanding and management of this complex neurodegenerative disorder.

The Locus Coeruleus in Chronic Pain

Pain perception is the consequence of a complex interplay between activation and inhibition. Noradrenergic pain modulation inhibits nociceptive transmission and pain perception. The main source of norepinephrine (NE) in the central nervous system is the Locus Coeruleus (LC), a small but complex cluster of cells in the pons. The aim of this study is to review the literature on the LC-NE inhibitory system, its influence on chronic pain pathways and its frequent comorbidities. The literature research showed that pain perception is the consequence of nociceptive and environmental processing and is modulated by the LC-NE system. If perpetuated in time, nociceptive inputs can generate neuroplastic changes in the central nervous system that reduce the inhibitory effects of the LC-NE complex and facilitate the development of chronic pain and frequent comorbidities, such as anxiety, depression or sleeping disturbances. The exact mechanisms involved in the LC functional shift remain unknown, but there is some evidence that they occur through plastic changes in the medial and lateral pathways and their brain projections. Additionally, there are other influencing factors, like developmental issues, neuroinflammatory glial changes, NE receptor affinity and changes in LC neuronal firing rates.

To update or to create? The influence of novelty and prior knowledge on memory networks

Schemas are foundational mental structures shaped by experience. They influence behaviour, guide the encoding of new memories and are shaped by associated information. The adaptability of memory schemas facilitates the integration of new information that aligns with existing knowledge structures. First, we discuss how novel information consistent with an existing schema can be swiftly assimilated when presented. This cognitive updating is facilitated by the interaction between the hippocampus and the prefrontal cortex. Second, when novel information is inconsistent with the schema, it likely engages the hippocampus to encode the information as part of an episodic memory trace. Third, novelty may enhance hippocampal dopamine through either the locus coeruleus or ventral tegmental area pathways, with the pathway involved potentially depending on the type of novelty encountered. We propose a gradient theory of schema and novelty to elucidate the neural processes by which schema updating or novel memory traces are formed. It is likely that experiences vary along a familiarity-novelty continuum, and the degree to which new experiences are increasingly novel will guide whether memory for a new experience either integrates into an existing schema or prompts the creation of a new cognitive framework. This article is part of the theme issue 'Long-term potentiation: 50 years on'.

A combination treatment based on drug repurposing demonstrates mutation-agnostic efficacy in pre-clinical retinopathy models

Inherited retinopathies are devastating diseases that in most cases lack treatment options. Disease-modifying therapies that mitigate pathophysiology regardless of the underlying genetic lesion are desirable due to the diversity of mutations found in such diseases. We tested a systems pharmacology-based strategy that suppresses intracellular cAMP and Ca2+ activity via G protein-coupled receptor (GPCR) modulation using tamsulosin, metoprolol, and bromocriptine coadministration. The treatment improves cone photoreceptor function and slows degeneration in Pde6βrd10 and RhoP23H/WT retinitis pigmentosa mice. Cone degeneration is modestly mitigated after a 7-month-long drug infusion in PDE6A-/- dogs. The treatment also improves rod pathway function in an Rpe65-/- mouse model of Leber congenital amaurosis but does not protect from cone degeneration. RNA-sequencing analyses indicate improved metabolic function in drug-treated Rpe65-/- and rd10 mice. Our data show that catecholaminergic GPCR drug combinations that modify second messenger levels via multiple receptor actions provide a potential disease-modifying therapy against retinal degeneration.

A biphasic response to blueberry supplementation on depressive symptoms in emerging adults: a double-blind randomized controlled trial

PURPOSE

The aim of the present study was to examine the acute and chronic effects of wild blueberry supplementation on mood, executive function, and serum biomarkers of neuroplasticity, inflammation, and oxidative stress in emerging adults with moderate-to-severe depressive symptoms.

METHODS

In this double-blind trial, 60 emerging adults (Mage = 20.0 years, 32% male) with self-reported depressive symptoms were randomly assigned to receive a single blueberry drink (acute phase), followed by 6 weeks of daily blueberry supplementation (chronic phase), or a matched placebo drink. The primary outcome was Beck Depression Inventory-II (BDI-II) scores at 6-week follow-up. Further measures included momentary affect (PANAS-X) and accuracy on an executive function task. The data were analyzed using ANCOVAs adjusted for baseline values, sex, and habitual fruit and vegetable intake. Estimated marginal means were calculated to compare the treatment arms.

RESULTS

The blueberry drink significantly improved positive affect (p = 0.026) and executive function (p = 0.025) at 2 h post-ingestion, with change scores being positively correlated in the blueberry group (r = 0.424, p = 0.017). However, after six weeks of supplementation the reduction in BDI-II scores was greater in the placebo group by 5.8 points (95% CI: 0.8-10.7, p = 0.023). Generalized anxiety and anhedonia also decreased significantly more in the placebo group. No significant differences were found for any of the biomarkers.

CONCLUSIONS

Six weeks of wild blueberry supplementation were inferior to placebo in reducing depressive symptoms. Nevertheless, the correlated improvements in positive affect and executive function after a single dose of blueberries point to a beneficial, albeit transient, psychological effect. These contrasting results suggest a biphasic, hormetic-like response that warrants further investigation.

TRIAL REGISTRATION

NCT04647019, dated 30 November, 2020.

A Computational Model for the Simulation of Prepulse Inhibition and Its Modulation by Cortical and Subcortical Units

The sensorimotor gating is a nervous system function that modulates the acoustic startle response (ASR). Prepulse inhibition (PPI) phenomenon is an operational measure of sensorimotor gating, defined as the reduction of ASR when a high intensity sound (pulse) is preceded in milliseconds by a weaker stimulus (prepulse). Brainstem nuclei are associated with the mediation of ASR and PPI, whereas cortical and subcortical regions are associated with their modulation. However, it is still unclear how the modulatory units can influence PPI. In the present work, we developed a computational model of a neural circuit involved in the mediation (brainstem units) and modulation (cortical and subcortical units) of ASR and PPI. The activities of all units were modeled by the leaky-integrator formalism for neural population. The model reproduces basic features of PPI observed in experiments, such as the effects of changes in interstimulus interval, prepulse intensity, and habituation of ASR. The simulation of GABAergic and dopaminergic drugs impaired PPI by their effects over subcortical units activity. The results show that subcortical units constitute a central hub for PPI modulation. The presented computational model offers a valuable tool to investigate the neurobiology associated with disorder-related impairments in PPI.

Functionality of arousal-regulating brain circuitry at rest predicts human cognitive abilities

Arousal state is regulated by subcortical neuromodulatory nuclei, such as locus coeruleus, which send wide-reaching projections to cortex. Whether higher-order cortical regions have the capacity to recruit neuromodulatory systems to aid cognition is unclear. Here, we hypothesized that select cortical regions activate the arousal system, which, in turn, modulates large-scale brain activity, creating a functional circuit predicting cognitive ability. We utilized the Human Connectome Project 7T functional magnetic resonance imaging dataset (n = 149), acquired at rest with simultaneous eye tracking, along with extensive cognitive assessment for each subject. First, we discovered select frontoparietal cortical regions that drive large-scale spontaneous brain activity specifically via engaging the arousal system. Second, we show that the functionality of the arousal circuit driven by bilateral posterior cingulate cortex (associated with the default mode network) predicts subjects' cognitive abilities. This suggests that a cortical region that is typically associated with self-referential processing supports cognition by regulating the arousal system.

Trigeminal nerve direct current stimulation causes sustained increase in neural activity in the rat hippocampus

BACKGROUND

Transcranial direct current stimulation (tDCS) is a noninvasive neuromodulation method that can modulate many brain functions including learning and memory. Recent evidence suggests that tDCS memory effects may be caused by co-stimulation of scalp nerves such as the trigeminal nerve (TN), and not the electric field in the brain. The TN gives input to brainstem nuclei, including the locus coeruleus that controls noradrenaline release across brain regions, including hippocampus. However, the effects of TN direct current stimulation (TN-DCS) are currently not well understood.

HYPOTHESIS

In this study we tested the hypothesis that stimulation of the trigeminal nerve with direct current manipulates hippocampal activity via an LC pathway.

METHODS

We recorded neural activity in rat hippocampus using multichannel silicon probes. We applied 3 min of 0.25 mA or 1 mA TN-DCS, monitored hippocampal activity for up to 1 h and calculated spikes-rate and spike-field coherence metrics. Subcutaneous injections of xylocaine were used to block TN, while intraperitoneal and intracerebral injection of clonidine were used to block the LC pathway.

RESULTS

We found that 1 mA TN-DCS caused a significant increase in hippocampal spike-rate lasting 45 min in addition to significant changes in spike-field coherence, while 0.25 mA TN-DCS did not. TN blockage prevented spike-rate increases, confirming effects were not caused by the electric field in the brain. When 1 mA TN-DCS was delivered during clonidine blockage no increase in spike-rate was observed, suggesting an important role for the LC-noradrenergic pathway.

CONCLUSION

These results support our hypothesis and provide a neural basis to understand the tDCS TN co-stimulation mechanism. TN-DCS emerges as an important tool to potentially modulate learning and memory.

Expression pattern of nicotinic acetylcholine receptor subunit transcripts in neurons and astrocytes in the ventral tegmental area and locus coeruleus

Acetylcholine is the endogenous agonist for the neuronal nicotinic acetylcholine receptor (nAChR) system, which is involved in attention, memory, affective behaviours and substance use disorders. Brain nAChRs are highly diverse with 11 different subunits that can form multiple receptor subtypes, each with distinct receptor and pharmacological properties. Different neuronal cell types can also express different nAChR subtypes, resulting in highly complex cholinergic signalling. Identifying which nAChR subunit transcripts are expressed in cell types can provide an indication of which nAChR combinations are possible and which receptor subtypes may be most pharmacologically relevant to target. In addition to differences in expression across cell types, nAChRs also undergo changes in expression levels from adolescence to adulthood. In this study, we used fluorescent in situ hybridization to identify and quantify the expression of α4, α5, α6, β2 and β3 nAChR subunit transcripts in dopaminergic, GABAergic, glutamatergic and noradrenergic neurons and astrocytes in the ventral tegmental area (VTA) and locus coeruleus (LC) in adult and adolescent, male and female C57BL/6J mice. There were distinct differences in the pattern of nAChR subunit transcript expression between the two brain regions. LC noradrenergic neurons had high prevalence of α6, β2 and β3 expression, with very low expression of α4, suggesting the α6(non-α4)β2β3 receptor as a main subtype in these neurons. VTA astrocytes from adult mice showed greater prevalence of α5, α6, β2 and β3 transcript compared with adolescent mice. These data highlight the complex nAChR expression patterns across brain region and cell type.

Ongoing effects of preterm birth on the dopaminergic and noradrenergic pathways in the frontal cortex and hippocampus of guinea pigs

Children born preterm have an increased likelihood of developing neurobehavioral disorders such as attention-deficit hyperactivity disorder (ADHD) and anxiety. These disorders have a sex bias, with males having a higher incidence of ADHD, whereas anxiety disorder tends to be more prevalent in females. Both disorders are underpinned by imbalances to key neurotransmitter systems, with dopamine and noradrenaline in particular having major roles in attention regulation and stress modulation. Preterm birth disturbances to neurodevelopment may affect this neurotransmission in a sexually dimorphic manner. Time-mated guinea pig dams were allocated to deliver by preterm induction of labor (gestational age 62 [GA62]) or spontaneously at term (GA69). The resultant offspring were randomized to endpoints as neonates (24 h after term-equivalence age) or juveniles (corrected postnatal day 40, childhood equivalence). Relative mRNA expressions of key dopamine and noradrenaline pathway genes were examined in the frontal cortex and hippocampus and quantified with real-time PCR. Myelin basic protein and neuronal nuclei immunostaining were performed to characterize the impact of preterm birth. Within the frontal cortex, there were persisting reductions in the expression of dopaminergic pathway components that occurred in preterm males only. Conversely, preterm-born females had increased expression of key noradrenergic receptors and a reduction of the noradrenergic transporter within the hippocampus. This study demonstrated that preterm birth results in major changes in dopaminergic and noradrenergic receptor, transporter, and synthesis enzyme gene expression in a sex- and region-based manner that may contribute to the sex differences in susceptibility to neurobehavioral disorders. These findings highlight the need for the development of sex-based treatments for improving these conditions.

Using caffeine as a chemical means to induce flow states

Flow is an intrinsically rewarding state characterised by positive affect and total task absorption. Because cognitive and physical performance are optimal in flow, chemical means to facilitate this state are appealing. Caffeine, a non-selective adenosine receptor antagonist, has been emphasized as a potential flow-inducer. Thus, we review the psychological and biological effects of caffeine that, conceptually, enhance flow. Caffeine may facilitate flow through various effects, including: i) upregulation of dopamine D1/D2 receptor affinity in reward-associated brain areas, leading to greater energetic arousal and 'wanting'; ii) protection of dopaminergic neurons; iii) increases in norepinephrine release and alertness, which offset sleep-deprivation and hypoarousal; iv) heightening of parasympathetic high frequency heart rate variability, resulting in improved cortical stress appraisal, v) modification of striatal endocannabinoid-CB1 receptor-signalling, leading to enhanced stress tolerance; and vi) changes in brain network activity in favour of executive function and flow. We also discuss the application of caffeine to treat attention deficit hyperactivity disorder and caveats. We hope to inspire studies assessing the use of caffeine to induce flow.

Functionality of arousal-regulating brain circuitry at rest predicts human cognitive abilities

Arousal state is regulated by subcortical neuromodulatory nuclei, such as locus coeruleus, which send wide-reaching projections to cortex. Whether higher-order cortical regions have the capacity to recruit neuromodulatory systems to aid cognition is unclear. Here, we hypothesized that select cortical regions activate the arousal system, which in turn modulates large-scale brain activity, creating a functional circuit predicting cognitive ability. We utilized the Human Connectome Project 7T functional magnetic resonance imaging dataset (N=149), acquired at rest with simultaneous eye tracking, along with extensive cognitive assessment for each subject. First, we discovered select frontoparietal cortical regions that drive large-scale spontaneous brain activity specifically via engaging the arousal system. Second, we show that the functionality of the arousal circuit driven by bilateral posterior cingulate cortex (associated with the default mode network) predicts subjects' cognitive abilities. This suggests that a cortical region that is typically associated with self-referential processing supports cognition by regulating the arousal system.

Combined and sequential exposure to prenatal second hand smoke and postnatal maternal distress is associated with cingulo-opercular global efficiency and attention problems in school-age children

BACKGROUND

Prenatal exposure to secondhand (environmental) tobacco smoke (SHS) is associated with adverse neurodevelopmental outcomes, including altered functional activation of cognitive control brain circuitry and increased attention problems in children. Exposure to SHS is more common among Black youth who are also disproportionately exposed to socioeconomic disadvantage and concomitant maternal distress. We examine the combined effects of exposure to prenatal SHS and postnatal maternal distress on the global efficiency (GE) of the brain's cingulo-opercular (CO) and fronto-parietal control (FP) networks in childhood, as well as associated attention problems.

METHODS

Thirty-two children of non-smoking mothers followed in a prospective longitudinal birth cohort at the Columbia Center for Children's Environmental Health (CCCEH) completed magnetic resonance imaging (MRI) at ages 7-9 years old. GE scores were extracted from general connectivity data collected while children completed the Simon Spatial Incompatibility functional magnetic resonance imaging (fMRI) task. Prenatal SHS was measured using maternal urinary cotinine from the third trimester; postnatal maternal distress was assessed at child age 5 using the Psychiatric Epidemiology Research Interview (PERI-D). The Child Behavior Checklist (CBCL) measured Attention and Attention Deficit Hyperactivity Disorder (ADHD) problems at ages 7-9. Linear regressions examined the interaction between prenatal SHS and postnatal maternal distress on the GE of the CO or FP networks, as well as associations between exposure-related network alterations and attention problems. All models controlled for age, sex, maternal education at prenatal visit, race/ethnicity, global brain correlation, and mean head motion.

RESULTS

The prenatal SHS by postnatal maternal distress interaction term associated with the GE of the CO network (β = 0.673, Bu = 0.042, t(22) = 2.427, p = .024, D = 1.42, 95% CI [0.006, 0.079], but not the FP network (β = 0.138, Bu = 0.006, t(22) = 0.434, p = .668, 95% CI [-0.022, 0.033]). Higher GE of the CO network was associated with more attention problems (β = 0.472, Bu = 43.076, t(23) = 2.780, p = .011, D = 1.74, n = 31, 95% CI [11.024, 75.128], n = 31) and ADHD risk (β = 0.436, Bu = 21.961, t(29) = 2.567, p = .018, D = 1.81, 95% CI [4.219, 39.703], n = 30).

CONCLUSIONS

These preliminary findings suggest that sequential prenatal SHS exposure and postnatal maternal distress could alter the efficiency of the CO network and increase risk for downstream attention problems and ADHD. These findings are consistent with prior studies showing that prenatal SHS exposure is associated with altered function of brain regions that support cognitive control and with ADHD problems. Our model also identifies postnatal maternal distress as a significant moderator of this association. These data highlight the combined neurotoxic effects of exposure to prenatal SHS and postnatal maternal distress. Critically, such exposures are disproportionately distributed among youth from minoritized groups, pointing to potential pathways to known mental health disparities.

Does gut brain axis has an impact on Parkinson's disease (PD)?

Parkinson's Disease (PD) is becoming a growing global concern by being the second most prevalent disease next to Alzheimer's Disease (AD). Henceforth new exploration is needed in search of new aspects towards the disease mechanism and origin. Evidence from recent studies has clearly stated the role of Gut Microbiota (GM) in the maintenance of the brain and as a root cause of various diseases and disorders including other neurological conditions. In the case of PD, with an unknown etiology, the GM is said to have a larger impact on the disease pathophysiology. Although GM and its metabolites are crucial for maintaining the normal physiology of the host, it is an undeniable fact that there is an influence of GM in the pathophysiology of PD. As such the Enteroendocrine Cells (EECs) in the epithelium of the intestine are one of the significant regulators of the gut-brain axis and act as a communication mediator between the gut and the brain. The communication is established via the molecules of neuroendocrine which are said to have a crucial part in neurological diseases such as AD, PD, and other psychiatry-related disorders. This review is focused on understanding the proper role of GM and EECs in PD. Here, we also focus on some of the metabolites and compounds that can interact with the PD genes causing various dysfunctions in the cell and facilitating the disease conditions using bioinformatical tools. Various mechanisms concerning EECs and PD, their identification, the latest studies, and available current therapies have also been discussed.

The neuromodulatory role of dopamine in improved reaction time by acute cardiovascular exercise

Acute cardiovascular physical exercise improves cognitive performance, as evidenced by a reduction in reaction time (RT). However, the mechanistic understanding of how this occurs is elusive and has not been rigorously investigated in humans. Here, using positron emission tomography (PET) with [11 C]raclopride, in a multi-experiment study we investigated whether acute exercise releases endogenous dopamine (DA) in the brain. We hypothesized that acute exercise augments the brain DA system, and that RT improvement is correlated with this endogenous DA release. The PET study (Experiment 1: n = 16) demonstrated that acute physical exercise released endogenous DA, and that endogenous DA release was correlated with improvements in RT of the Go/No-Go task. Thereafter, using two electrical muscle stimulation (EMS) studies (Experiments 2 and 3: n = 18 and 22 respectively), we investigated what triggers RT improvement. The EMS studies indicated that EMS with moderate arm cranking improved RT, but RT was not improved following EMS alone or EMS combined with no load arm cranking. The novel mechanistic findings from these experiments are: (1) endogenous DA appears to be an important neuromodulator for RT improvement and (2) RT is only altered when exercise is associated with central signals from higher brain centres. Our findings explain how humans rapidly alter their behaviour using neuromodulatory systems and have significant implications for promotion of cognitive health. KEY POINTS: Acute cardiovascular exercise improves cognitive performance, as evidenced by a reduction in reaction time (RT). However, the mechanistic understanding of how this occurs is elusive and has not been rigorously investigated in humans. Using the neurochemical specificity of [11 C]raclopride positron emission tomography, we demonstrated that acute supine cycling released endogenous dopamine (DA), and that this release was correlated with improved RT. Additional electrical muscle stimulation studies demonstrated that peripherally driven muscle contractions (i.e. exercise) were insufficient to improve RT. The current study suggests that endogenous DA is an important neuromodulator for RT improvement, and that RT is only altered when exercise is associated with central signals from higher brain centres.

Biochemical characterization of chamomile essential oil: Antioxidant, antibacterial, anticancer and neuroprotective activity and potential treatment for Alzheimer's disease

Alzheimer's disease (AD) causes dementia among older adults, increasing the global burden of dementia. Therefore, this study investigates the potential neuroprotective, antioxidant, and anticancer effects of chamomile essential oil (CCO) in Alzheimer's disease. CCO's main volatile compounds (VOCs) were α-bisabolol, camazulene, and bisabolol oxide A, representing 81 % of all VOCs. CCO scavenged 93 % of DPPH free radicals and inhibited the pathogenic bacteria, i.e., Staphylococcus aureus and Salmonella typhi, besides reducing 89 % of brain cancer cell lines (U87). Eighty albino rats were randomized into four groups: standard control, Alzheimer's disease group caused by AlCl3, and treated groups. The results indicated that the mean value of tumor necrosis factor α (TNF-α), amyloid precursor protein (APP), amyloid beta (Aβ), caspase-3, & B-cell lymphoma 2 (Bcl-2) was significantly elevated due to the harmful effect of AlCl3; however, CCO downregulated these values, and this effect was attributed to the considerable volatile compounds and phenolic compounds content. Additionally, CCO rats showed a significant increment in noradrenergic (NE), dopaminergic (DO), and serotoninergic systems with relative increases of 50, 50, and 14 % compared to diseased rats. The brain histology of CCO-treated rats showed a significant reduction in neuronal degeneration and improved brain changes, and its histology was close to that of the control brain. The results indicated that CCO offers a new strategy that could be used as an antioxidant and neuroprotective agent for AD due to its considerable contents of antioxidants and anti-inflammatory compounds.

Subsecond Codetection of Dopamine and Estradiol at a Modified Sharkfin Waveform

17β-Estradiol (E2) is a ubiquitously expressed hormone that is active in a wide range of neuroprotective and regenerative roles throughout the brain. In particular, it is a well-known dopamine (DA) regulator and is responsible for modulating the expression of dopaminergic receptors and transporters. Recent studies point to E2 release occurring on a rapid time scale and having impacts on DA activity within seconds to minutes. As such, tools capable of monitoring the release of both E2 and DA in real time are essential for developing an accurate understanding of their interactive roles in neurotransmission and regulation. Currently, no analytical techniques capable of codetection of both analytes with high sensitivity, spatiotemporal resolution, extended monitoring, and minimal tissue damage exist. We describe a modified waveform using fast-scan cyclic voltammetry that is capable of low nanomolar detection of both DA and E2 on a subsecond time scale. Both analytes have limits of detection at or below 30 nM and high sensitivity: 11.31 ± 0.55 nA/μM for DA and 9.47 ± 0.36 nA/μM for E2. The waveform is validated in a tissue matrix, confirming its viability for measurement in a biologically relevant setting. This is the first method capable of codetection of fluctuations in DA and E2 with the temporal, spatial, and sensitivity requirements necessary for studying real-time neurochemical signaling.

Fear extinction rescuing effects of dopamine and L-DOPA in the ventromedial prefrontal cortex

The ventromedial prefrontal cortex (vmPFC; rodent infralimbic cortex (IL)), is posited to be an important locus of fear extinction-facilitating effects of the dopamine (DA) bio-precursor, L-DOPA, but this hypothesis remains to be formally tested. Here, in a model of impaired fear extinction (the 129S1/SvImJ inbred mouse strain; S1), we monitored extracellular DA dynamics via in vivo microdialysis in IL during fear extinction and following L-DOPA administration. Systemic L-DOPA caused sustained elevation of extracellular DA levels in IL and increased neuronal activation in a subpopulation of IL neurons. Systemic L-DOPA enabled extinction learning and promoted extinction retention at one but not ten days after training. Conversely, direct microinfusion of DA into IL produced long-term fear extinction (an effect that was insensitive to ɑ-/ß-adrenoreceptor antagonism). However, intra-IL delivery of a D1-like or D2 receptor agonist did not facilitate extinction. Using ex vivo multi-electrode array IL neuronal recordings, along with ex vivo quantification of immediate early genes and DA receptor signalling markers in mPFC, we found evidence of reduced DA-evoked mPFC network responses in S1 as compared with extinction-competent C57BL/6J mice that were partially driven by D1 receptor activation. Together, our data demonstrate that locally increasing DA in IL is sufficient to produce lasting rescue of impaired extinction. The finding that systemic L-DOPA increased IL DA levels, but had only transient effects on extinction, suggests L-DOPA failed to reach a threshold level of IL DA or produced opposing behavioural effects in other brain regions. Collectively, our findings provide further insight into the neural basis of the extinction-promoting effects of DA and L-DOPA in a clinically relevant animal model, with possible implications for therapeutically targeting the DA system in anxiety and trauma-related disorders.

The Anti-Apoptotic Effect of Ranolazine on Cerebral Protection during Cardiopulmonary Bypass and Carotid Artery Surgery

Background

We aimed to determine the usability of ranolazine (Rn) as a neuroprotective during cardiac surgeries and carotid artery interventions where cerebral blood flow is interrupted.

Methods

Female Wistar albino rats were used. The rats were divided into 4 groups of 8 rats each. The first group (Group 1) was the control group. Group 2 underwent ischemia induction but was not treated with Rn. Group 3 received 25 mg/kg/day and Group 4 50 mg/kg/day Rn intraperitoneally, starting 3 days before ischemia induction. Bilateral carotid arteries were explored and clamped simultaneously. Ischemia was induced for 15 minutes. After 72 hours, the experimental animals were sacrificed.

Results

Superoxide dismutase, alkaline phosphatase, and interleukin 6 levels were similar among the 4 groups. Acetylcholine esterase (Group 3: p = 0.007, Group 4: p = 0.002), tumor necrosis factor-alpha (Group 4: p = 0.01), and annexin V (Group 3: p = 0.001) levels were statistically significantly lower in the Rn-treated groups. Malondialdehyde (Group 3: p = 0.003, Group 4: p = 0.009), reduced glutathione (Group 4: p = 0.04), acid phosphatase (Group 3: p = 0.04), noradrenaline (Group 3: p = 0.01), and Bcl-2 (Group 4: p = 0.004) levels were significantly higher in the Rn-treated groups.

Conclusions

The results of this study demonstrated the antiapoptotic effect of Rn in a brain ischemia-reperfusion model of rats receiving Rn before the procedure.

Atomoxetine and reward size equally improve task engagement and perceptual decisions but differently affect movement execution

Our ability to engage and perform daily activities relies on balancing the associated benefits and costs. Rewards, as benefits, act as powerful motivators that help us stay focused for longer durations. The noradrenergic (NA) system is thought to play a significant role in optimizing our performance. Yet, the interplay between reward and the NA system in shaping performance remains unclear, particularly when actions are driven by external incentives (reward). To explore this interaction, we tested four female rhesus monkeys performing a sustained Go/NoGo task under two reward sizes (low/high) and three pharmacological conditions (saline and two doses of atomoxetine, a NA reuptake inhibitor: ATX-0.5 mg/kg and ATX-1 mg/kg). We found that increasing either reward or NA levels equally enhanced the animal's engagement in the task compared to low reward saline; the animals also responded faster and more consistently under these circumstances. Notably, we identified differences between reward size and ATX. When combined with ATX, high reward further reduced the occurrence of false alarms (i.e., incorrect go trials on distractors), implying that it helped further suppress impulsive responses. In addition, ATX (but not reward size) consistently increased movement duration dose-dependently, while high reward did not affect movement duration but decreased its variability. We conclude that noradrenaline and reward modulate performance, but their effects are not identical, suggesting differential underlying mechanisms. Reward might energize/invigorate decisions and action, while ATX might help regulate energy expenditure, depending on the context, through the NA system.

Trigeminal nerve direct current stimulation causes sustained increase in neural activity in the rat hippocampus

Transcranial direct current stimulation (tDCS) is a noninvasive neuromodulation method that can modulate many brain functions including learning and memory. Recent evidence suggests that tDCS memory effects may be caused by co-stimulation of scalp nerves such as the trigeminal nerve (TN), and not the electric field in the brain. The TN gives input to brainstem nuclei, including the locus coeruleus that controls noradrenaline release across brain regions, including hippocampus. However, the effects of TN direct current stimulation (TN-DCS) are currently not well understood. In this study we hypothesized that TN-DCS manipulates hippocampal activity via an LC-noradrenergic bottom-up pathway. We recorded neural activity in rat hippocampus using multichannel silicon probes. We applied 3 minutes of 0.25 mA or 1 mA TN-DCS, monitored hippocampal activity for up to 1 hour and calculated spikes-rate and spike-field coherence metrics. Subcutaneous injections of xylocaine were used to block TN and intraperitoneal injection of clonidine to block the LC pathway. We found that 1 mA TN-DCS caused a significant increase in hippocampal spike-rate lasting 45 minutes in addition to significant changes in spike-field coherence, while 0.25 mA TN-DCS did not. TN blockage prevented spike-rate increases, confirming effects were not caused by the electric field in the brain. When 1 mA TN-DCS was delivered during clonidine blockage no increase in spike-rate was observed, suggesting an important role for the LC-noradrenergic pathway. These results provide a neural basis to support a tDCS TN co-stimulation mechanism. TN-DCS emerges as an important tool to potentially modulate learning and memory.

Highlights

Trigeminal nerve direct current stimulation (TN-DCS) boosts hippocampal spike ratesTN-DCS alters spike-field coherence in theta and gamma bands across the hippocampus.Blockade experiments indicate that TN-DCS modulated hippocampal activity via the LC-noradrenergic pathway.TN-DCS emerges as a potential tool for memory manipulation.

Figure Graphic Abstract

Geraniol attenuates behavioral and neurochemical impairments by inhibitions of HPA-axis and oxido-inflammatory perturbations in mice exposed to post-traumatic stress disorder

Geraniol is an acyclic isoprenoid monoterpenoid analogue that has been shown to elicit neuroprotective functions, primarily through its ability to stimulate antioxidant and anti-inflammatory systems. An increase in inflammatory cytokines and oxidative stress exacerbate activation hypothalamic-pituitary-adrenal axis (HPA), leading to neurochemical dysfunction, which has important roles in the pathogenesis of post-traumatic disorder (PTSD), a mental health disorder characterized of post-trauma-induced intense fear. The aim of this study was to evaluate the anti-PTSD-like effects and underlying mechanisms of geraniol against single-prolonged-stress (SPS)-induced PTSD in mice. Following concomitant exposure to SPS (triple-paradigm traumatic events) and isolation for 7 days, mice (n = 9) were treated with geraniol (50 and 100 mg/kg, p.o.) or fluoxetine (10 mg/kg, p.o.) from days 8-21. Mice were assessed for behavioral changes. Neurochemical changes, inflammatory, oxido-nitrergic markers, adrenal weight, serum glucose and corticosterone concentrations were assayed. Geraniol inhibits SPS-induced anxiety- and depressive-like features as well as behavioral despair in the depression paradigms. SPS-induced locomotor and memory impairments were also abated by geraniol treatment similarly to fluoxetine. SPS-induced adrenal hypertrophy and increased blood glucose and corticosterone concentrations, were attenuated by the geraniol treatment. Elevated levels of TNF-α and IL-6, and malondialdehyde, nitrite, acetylcholinesterase enzyme were reduced by geraniol. Geraniol also increased glutathione, superoxide-dismutase, and catalase levels as well as dopamine, serotonin concentrations and GABAergic glutamic acid decarboxylase enzyme activity in the striatum, prefrontal cortex and hippocampus in the PTSD-mice relative to SPS control. In conclusion, geraniol attenuates behavioral impairments and neurochemical dysregulations by inhibitions of HPA-axis and oxido-inflammatory perturbations in mice exposed to PTSD.

Systemic perturbations in amino acids/amino acid derivatives and tryptophan pathway metabolites associated with murine influenza A virus infection

BACKGROUND

Influenza A virus (IAV) is the only influenza virus causing flu pandemics (i.e., global epidemics of flu disease). Influenza (the flu) is a highly contagious disease that can be deadly, especially in high-risk groups. Worldwide, these annual epidemics are estimated to result in about 3 to 5 million cases of severe illness and in about 290,000 to 650,000 respiratory deaths. We intend to reveal the effect of IAV infection on the host's metabolism, immune response, and neurotoxicity by using a mouse IAV infection model.

METHODS

51 metabolites of murine blood plasma (33 amino acids/amino acid derivatives (AADs) and 18 metabolites of the tryptophan pathway) were analyzed by using Ultra-High-Performance Liquid Chromatography-Mass Spectrometry with Electrospray Ionization at the acute (7 days post-infection (dpi)), resolution (14 dpi), and recovery (21 dpi) stages of the virus infection in comparison with controls.

RESULTS

Among the 33 biogenic amino acids/AADs, the levels of five amino acids/AADs (1-methylhistidine, 5-oxoproline, α-aminobutyric acid, glutamine, and taurine) increased by 7 dpi, whereas the levels of ten amino acids/AADs (4-hydroxyproline, alanine, arginine, asparagine, cysteine, citrulline, glycine, methionine, proline, and tyrosine) decreased. By 14 dpi, the levels of one AAD (3-methylhistidine) increased, whereas the levels of five amino acids/AADs (α-aminobutyric acid, aminoadipic acid, methionine, threonine, valine) decreased. Among the 18 metabolites from the tryptophan pathway, the levels of kynurenine, quinolinic acid, hydroxykynurenine increased by 7 dpi, whereas the levels of indole-3-acetic acid and nicotinamide riboside decreased.

CONCLUSIONS

Our data may facilitate understanding the molecular mechanisms of host responses to IAV infection and provide a basis for discovering potential new mechanistic, diagnostic, and prognostic biomarkers and therapeutic targets for IAV infection.

Measuring neuron-regulated immune cell physiology via the alpha-2 adrenergic receptor in an ex vivo murine spleen model

The communication between the nervous and immune systems plays a crucial role in regulating immune cell function and inflammatory responses. Sympathetic neurons, which innervate the spleen, have been implicated in modulating immune cell activity. The neurotransmitter norepinephrine (NE), released by sympathetic neurons, influences immune cell responses by binding to adrenergic receptors on their surface. The alpha-2 adrenergic receptor (α2AR), expressed predominantly on sympathetic neurons, has received attention due to its autoreceptor function and ability to modulate NE release. In this study, we used fast-scan cyclic voltammetry (FSCV) to provide the first subsecond measurements of NE released in the white pulp region of the spleen and validated it with yohimbine, a known antagonist of α2AR. For further application of FSCV in neuroimmunology, we investigated the extent to which subsecond NE from sympathetic neurons is important for immune cell physiology and cytokine production, focusing on tumor necrosis factor-alpha (TNF-α), interleukin-10 (IL-10), and interleukin-6 (IL-6). Our findings provide insights into the regulatory mechanisms underlying sympathetic-immune interactions and show the significance of using FSCV, a traditional neurochemistry technique, to study these neuroimmune mechanisms.

Synergistic photoactivation of VTA-catecholaminergic and BLA-glutamatergic projections induces long-term potentiation in the insular cortex

The presentation of novel stimuli induces a reliable dopamine release in the insular cortex (IC) from the ventral tegmental area (VTA). The novel stimuli could be associated with motivational and emotional signals induced by cortical glutamate release from the basolateral amygdala (BLA). Dopamine and glutamate are essential for acquiring and maintaining behavioral tasks, including visual and taste recognition memories. In this study, we hypothesize that the simultaneous activation of dopaminergic and glutamatergic projections to the neocortex can underlie synaptic plasticity. High-frequency stimulation of the BLA-IC circuit has demonstrated a reliable long-term potentiation (LTP), a widely acknowledged synaptic plasticity that underlies memory consolidation. Therefore, the concurrent optogenetic stimulation of the insula's glutamatergic and dopaminergic terminal fibers would induce reliable LTP. Our results confirmed that combined photostimulation of the VTA and BLA projections to the IC induces a slow-onset LTP. We also found that optogenetically-induced LTP in the IC relies on both glutamatergic NMDA receptors and dopaminergic D1/D5 receptors, suggesting that the combined effects of these neurotransmitters can trigger synaptic plasticity in the neocortex. Overall, our findings provide compelling evidence supporting the essential role of both dopaminergic and glutamatergic projections in modulating synaptic plasticity within the IC. Furthermore, our results suggest that the synergistic actions of these projections have a pivotal influence on the formation of motivational memories.

Knowledge mapping of the relationship between norepinephrine and memory: a bibliometric analysis

Introduction

Memory is a fundamental cognitive function for successful interactions with a complex environment. Norepinephrine (NE) is an essential component of catecholamine induced by emotional arousal, and numerous studies have demonstrated that NE is a key regulator in memory enhancement. We therefore conducted a bibliometric analysis to represent the knowledge pattern of the literature on the theme of NE-memory relationship.

Methods

The WOSCC database was selected to extract literature published during 2003-2022. The collected data of annual production, global cooperation, research structure and hotspots were analyzed and visualized.

Results

Our results showed that research on the links between NE and memory displayed a considerable development trend over the last two decades. The USA had a leading position in terms of scientific outputs and collaborations. Meanwhile, University of California Irvine contributed the most publications. Benno Roozendaal and James McGaugh were the most prolific authors in this field, and Neurobiology of Learning and Memory had the highest number of publications on this topic. The research emphasis has evolved from memory-related diseases and brain regions to neural mechanisms for different types of memory at neural circuit levels.

Conclusion

Our bibliometric analysis systematically analyzed the literature on the links between NE and memory from a bibliometric perspective. The demonstrated results of the knowledge mapping would provide valuable insights into the global research landscape.

Addictive drugs modify neurogenesis, synaptogenesis and synaptic plasticity to impair memory formation through neurotransmitter imbalances and signaling dysfunction

Drug abuse changes neurophysiological functions at multiple cellular and molecular levels in the addicted brain. Well-supported scientific evidence suggests that drugs negatively affect memory formation, decision-making and inhibition, and emotional and cognitive behaviors. The mesocorticolimbic brain regions are involved in reward-related learning and habitual drug-seeking/taking behaviors to develop physiological and psychological dependence on the drugs. This review highlights the importance of specific drug-induced chemical imbalances resulting in memory impairment through various neurotransmitter receptor-mediated signaling pathways. The mesocorticolimbic modifications in the expression levels of brain-derived neurotrophic factor (BDNF) and the cAMP-response element binding protein (CREB) impair reward-related memory formation following drug abuse. The contributions of protein kinases and microRNAs (miRNAs), along with the transcriptional and epigenetic regulation have also been considered in memory impairment underlying drug addiction. Overall, we integrate the research on various types of drug-induced memory impairment in distinguished brain regions and provide a comprehensive review with clinical implications addressing the upcoming studies.

A miniaturized nigrostriatal-like circuit regulating locomotor performance in a protochordate

To gain insight into the evolution of motor control systems at the origin of vertebrates, we have investigated higher-order motor circuitry in the protochordate Oikopleura dioica. We have identified a highly miniaturized circuit in Oikopleura with a projection from a single pair of dopaminergic neurons to a small set of synaptically coupled GABAergic neurons, which in turn exert a disinhibitory descending projection onto the locomotor central pattern generator. The circuit is reminiscent of the nigrostriatopallidal system in the vertebrate basal ganglia, in which disinhibitory circuits release specific movements under the modulatory control of dopamine. We demonstrate further that dopamine is required to optimize locomotor performance in Oikopleura, mirroring its role in vertebrates. A dopamine-regulated disinhibitory locomotor control circuit reminiscent of the vertebrate nigrostriatopallidal system was thus already present at the origin of ancestral chordates and has been maintained in the face of extreme nervous system miniaturization in the urochordate lineage.