The neurodevelopmental role of dopaminergic signaling in neurological disorders

Computational Analysis and Experimental Data Exploring the Role of Hesperetin in Ameliorating ADHD and SIRT1/Nrf2/Keap1/OH-1 Signaling

Attention deficit hyperactivity disorder (ADHD) manifests as poor attention, hyperactivity, as well as impulsive behaviors. Hesperetin (HSP) is a citrus flavanone with strong antioxidant and anti-inflammatory activities. The present study aimed to test hesperetin efficacy in alleviating experimental ADHD in mice and its influence on hippocampal neuron integrity and sirtuin 1 (SIRT1) signaling. An in silico study was performed to test the related proteins. Groups of mice were assigned as control, ADHD model, ADHD/HSP (25 mg/kg), and ADHD/HSP (50 mg/kg). ADHD was induced by feeding with monosodium glutamate (0.4 g/kg, for 8 weeks) and assessed by measuring the motor and attentive behaviors (open filed test, Y-maze test, and marble burying test), histopathological examination of the whole brain tissues, and estimation of inflammatory markers. The in-silico results indicated the putative effects of hesperetin on ADHD by allowing the integration and analysis of large-scale genomic, transcriptomic, and proteomic data. The in vivo results showed that ADHD model mice displayed motor hyperactivity and poor attention in the behavioral tasks and shrank neurons at various hippocampal regions. Further, there was a decline in the mRNA expression and protein levels for SIRT1, the erythroid 2-related factor-2 (Nrf2), kelch like ECH associated protein 1 (Keap1) and hemeoxygenase-1 (OH-1) proteins. Treatment with HSP normalized the motor and attentive behaviors, prevented hippocampal neuron shrinkage, and upregulated SIRT1/Nrf2/Keap1/OH-1 proteins. Taken together, HSP mainly acts by its antioxidant potential. However, therapeutic interventions with hesperetin or a hesperetin-rich diet can be suggested as a complementary treatment in ADHD patients but cannot be suggested as an ADHD treatment per se as it is a heterogeneous and complex disease.

Maternal gestational diabetes mellitus associates with altered gut microbiome composition and head circumference abnormalities in male offspring

The impact of gestational diabetes mellitus (GDM) on maternal or infant microbiome trajectory remains poorly understood. Utilizing large-scale longitudinal fecal samples from 264 mother-baby dyads, we present the gut microbiome trajectory of the mothers throughout pregnancy and infants during the first year of life. GDM mothers had a distinct microbiome diversity and composition during the gestation period. GDM leaves fingerprints on the infant's gut microbiome, which are confounded by delivery mode. Further, Clostridium species positively correlate with a larger head circumference at month 12 in male offspring but not females. The gut microbiome of GDM mothers with male fetuses displays depleted gut-brain modules, including acetate synthesis I and degradation and glutamate synthesis II. The gut microbiome of female infants of GDM mothers has higher histamine degradation and dopamine degradation. Together, our integrative analysis indicates that GDM affects maternal and infant gut composition, which is associated with sexually dimorphic infant head growth.

Unraveling Dysregulated Cell Signaling Pathways, Genetic and Epigenetic Mysteries of Parkinson's Disease

Parkinson's disease (PD) is a prevalent and burdensome neurodegenerative disorder that has been extensively researched to understand its complex etiology, diagnosis, and treatment. The interplay between genetic and environmental factors in PD makes its pathophysiology difficult to comprehend, emphasizing the need for further investigation into genetic and epigenetic markers involved in the disease. Early diagnosis is crucial for optimal management of the disease, and the development of novel diagnostic biomarkers is ongoing. Although many efforts have been made in the field of recognition and interpretation of the mechanisms involved in the pathophysiology of the disease, the current knowledge about PD is just the tip of the iceberg. By scrutinizing genetic and epigenetic patterns underlying PD, new avenues can be opened for dissecting the pathology of the disorder, leading to more precise and efficient diagnostic and therapeutic approaches. This review emphasizes the importance of studying dysregulated cell signaling pathways and molecular processes associated with genes and epigenetic alterations in understanding PD, paving the way for the development of novel therapeutic strategies to combat this devastating disease.

Serum ciliary neurotrophic factor levels in children with attention deficit hyperactivity disorder

Purpose/aim of the study: The study aimed to highlight the possible role of ciliary neurotrophic factor (CNTF) in the pathophysiology of attention deficit hyperactivity disorder (ADHD) and determine whether CNTF can be used as a biomarker for ADHD.Materials and methods: Patients with a diagnosis of ADHD and neurotypical subjects aged 6-12 years were recruited prospectively. The study applied Conners' Teacher Rating Scale (CTRS) to determine the patients' ADHD predominance and severity. Serum CNTF levels were measured with an enzyme-linked immunosorbent assay (ELISA) kit.Results: A total of 43 ADHD patients and 33 healthy controls were included in the study. A significant difference was found between the serum CNTF levels of the ADHD patients (22.17 pg/ml) and the controls (22.80 pg/ml). Correlations between the CNTF levels and CTRS scores were not significant.Conclusions: The study identified an alteration of serum CNTF levels in ADHD patients and thus asserted a link between CNTF and ADHD pathophysiology; children with ADHD had significantly lower serum CNTF levels compared to the neurotypical controls. Further research is needed to understand the mechanisms of CNTF.

Safety and efficacy of antioxidant therapy in children and adolescents with attention deficit hyperactivity disorder: A systematic review and network meta-analysis

OBJECTIVE

To systematically evaluate the safety and efficacy of antioxidant therapy in children and adolescents with attention deficit hyperactivity disorder (ADHD).

METHODS

Randomized controlled trials and prospective studies on antioxidant therapy in children and adolescents with ADHD were searched in PubMed, Embase, and Cochrane Library from the inception of databases to November 12, 2022. Two investigators independently screened the literature, extracted data, and evaluated the quality of the included studies. Network meta-analysis (PROSPERO registration number CRD 42023382824) was carried out by using R Studio 4.2.1.

RESULTS

48 studies involving 12 antioxidant drugs (resveratrol, pycnogenol, omega-3, omega-6, quercetin, phosphatidylserine, almond, vitamin D, zinc, folic acid, ginkgo biloba, Acetyl-L-carnitine) were finally included, with 3,650 patients. Network meta-analysis showed that omega-6 (0.18), vitamin D (0.19), and quercetin (0.24) were the top three safest drugs according to SUCRA. The omega-3 (SUCRA 0.35), pycnogenol (SUCRA 0.36), and vitamin D (SUCRA 0.27) were the most effective in improving attention, hyperactivity, and total score of Conners' parent rating scale (CPRS), respectively. In terms of improving attention, hyperactivity, and total score of Conners' teacher rating scale (CTRS), pycnogenol (SUCRA 0.32), phosphatidylserine+omega-3 (SUCRA 0.26), and zinc (SUCRA 0.34) were the most effective, respectively. In terms of improving attention, hyperactivity and total score of ADHD Rating Scale-Parent, the optimal agents were phosphatidylserine (SUCRA 0.39), resveratrol+MPH (SUCRA 0.24), and phosphatidylserine (SUCRA 0.34), respectively. In terms of improving attention, hyperactivity and total score of ADHD Rating Scale-Teacher, pycnogenol (SUCRA 0.32), vitamin D (SUCRA 0.31) and vitamin D (SUCRA 0.18) were the optimal agents, respectively. The response rate of omega-3+6 was the highest in CGI (SUCRA 0.95) and CPT (SUCRA 0.42).

CONCLUSION

The rankings of safety and efficacy of the 12 antioxidants vary. Due to the low methodological quality of the included studies, the probability ranking cannot fully explain the clinical efficacy, and the results need to be interpreted with caution. More high-quality studies are still needed to verify our findings.

Developmental dopaminergic signaling modulates neural circuit formation and contributes to autism spectrum disorder (ASD)-related phenotypes

Autism spectrum disorder (ASD) is a prevalent neurodevelopmental disorder with a complex etiology. Recent evidence suggests that dopamine plays a crucial role in neural development. However, it remains unclear whether and how disrupted dopaminergic signaling during development contributes to ASD. In this study, human brain RNA-seq transcriptome analysis revealed a significant correlation between changes in dopaminergic signaling pathways and neural developmental signaling in ASD patients. In the zebrafish model, disrupted developmental dopaminergic signaling led to neural circuit abnormalities and behavior reminiscent of autism. Dopaminergic signaling may impact neuronal specification by potentially modulating integrins. These findings shed light on the mechanisms underlying the link between disrupted developmental dopamine signaling and ASD, and they point to the possibility of targeting dopaminergic signaling in early development for ASD treatment.

Prenatal cannabinoid exposure and early language development

Introduction

The effect of prenatal cannabis exposure (PCE) on childhood neurodevelopment remains poorly understood. There is a paucity of studies describing the neurodevelopment impact of PCE in infancy. The Mullen Scale of Early Learning (MSEL) is a cognitive screening tool that can be used from birth to 68 months and includes language and motor domains. Here we aim to explore the association between PCE during pregnancy and neurodevelopmental outcomes at 12 months of age.

Methods

Participants were pregnant persons/infant pairs enrolled in The Safe Passage Study, a large prospective cohort study. Inclusion criteria included data available on PCE with associated MSEL scores at 12 months of age. Exposed participants were defined as early exposure (1st trimester only) or late exposure (2nd or 3rd trimester) and were randomly matched with unexposed participants. Multiple linear regression models were performed to test associations between prenatal cannabis exposure and the five Mullen subscales: gross motor, fine motor, expressive language, receptive language, and visual reception.

Results

Sixty-nine exposed and 138 randomly matched unexposed infants were included in the analyses. Mothers of children with PCE were younger with the mean age 23.7 years for early exposure (n = 51) and 22.8 years for late exposure (n = 18). Maternal characteristics with prenatal cannabis use include a high-school education, American Indian or Alaska Native descent, lower socioeconomic status and co-use of tobacco. There were no gestational age or sex difference among the groups. Expressive (95% CI: 2.54-12.76; p = 0.0036,) and receptive language scores (95% CI: 0.39-8.72; p = 0.0322) were significantly increased between late-exposed infants compared to unexposed infants following adjustment for covariates. Gross motor scores (95% CI: 1.75-13; p = 0.0105) were also significantly increased for early-exposed infants with no difference in visual reception scores.

Conclusion

Preclinical studies have shown abnormal brain connectivity in offspring exposed to cannabis affecting emotional regulation, hyperactivity, and language development. Results from this study link PCE to altered early language development within the first year of life. Exposed infants demonstrated increased expressive and receptive language scores at 12 months of age, which can translate to better performance in school. However, further research is needed to determine the implications of these results later in childhood.

Maternal transfer of F-53B inhibited neurobehavior in zebrafish offspring larvae and potential mechanisms: Dopaminergic dysfunction, eye development defects and disrupted calcium homeostasis

Maternal exposure to environment toxicants is an important risk factor for neurobehavioral health in their offspring. In our study, we investigated the impact of maternal exposure to chlorinated polyfluoroalkyl ether sulfonic acids (Cl-PFESAs, commercial name: F-53B) on behavioral changes and the potential mechanism in the offspring larvae of zebrafish. Adult zebrafish exposed to Cl-PFESAs (0, 0.2, 2, 20 and 200 μg/L) for 21 days were subsequently mated their embryos were cultured for 5 days. Higher concentrations of Cl-PFESAs in zebrafish embryos were observed, along with, reduced swimming speed and distance travelled in the offspring larvae. Molecular docking analysis revealed that Cl-PFESAs can form hydrogen bonds with brain-derived neurotropic factor (BDNF), protein kinase C, alpha, (PKCα), Ca2+-ATPase and Na, K - ATPase. Molecular and biochemical studies evidenced Cl-PFESAs induce dopaminergic dysfunction, eye developmental defects and disrupted Ca2+ homeostasis. Together, our results showed that maternal exposure to Cl-PFESAs lead to behavioral alteration in offspring mediated by disruption in Ca2+ homeostasis, dopaminergic dysfunction and eye developmental defects.

Identification of signaling pathways modifying human dopaminergic neuron development using a pluripotent stem cell-based high-throughput screening automated system: purinergic pathways as a proof-of-principle

Introduction: Alteration in the development, maturation, and projection of dopaminergic neurons has been proposed to be associated with several neurological and psychiatric disorders. Therefore, understanding the signals modulating the genesis of human dopaminergic neurons is crucial to elucidate disease etiology and develop effective countermeasures. Methods: In this study, we developed a screening model using human pluripotent stem cells to identify the modulators of dopaminergic neuron genesis. We set up a differentiation protocol to obtained floorplate midbrain progenitors competent to produce dopaminergic neurons and seeded them in a 384-well screening plate in a fully automated manner. Results and Discussion: These progenitors were treated with a collection of small molecules to identify the compounds increasing dopaminergic neuron production. As a proof-of-principle, we screened a library of compounds targeting purine- and adenosine-dependent pathways and identified an adenosine receptor 3 agonist as a candidate molecule to increase dopaminergic neuron production under physiological conditions and in cells invalidated for the HPRT1 gene. This screening model can provide important insights into the etiology of various diseases affecting the dopaminergic circuit development and plasticity and be used to identify therapeutic molecules for these diseases.

Mood and behavior regulation: interaction of lithium and dopaminergic system

Lithium is one of the most effect mood-stabilizing drugs prescribed especially for bipolar disorder. Lithium has wide range effects on different molecular factors and neural transmission including dopaminergic signaling. On the other hand, mesolimbic and mesocortical dopaminergic signaling is significantly involved in the pathophysiology of neuropsychiatric disorders. This review article aims to study lithium therapeutic mechanisms, dopaminergic signaling, and the interaction of lithium and dopamine. We concluded that acute and chronic lithium treatments often reduce dopamine synthesis and level in the brain. However, some studies have reported conflicting results following lithium treatment, especially chronic treatment. The dosage, duration, and type of lithium administration, and the brain region selected for measuring dopamine level were not significant differences in different chronic treatments used in previous studies. It was suggested that lithium has various mechanisms affecting dopaminergic signaling and mood, and that many molecular factors can be involved, including brain-derived neurotrophic factor (BDNF), cAMP response element-binding protein (CREB), β-catenin, protein kinase B (Akt), and glycogen synthase kinase-3 beta (GSK-3β). Thus, molecular effects of lithium can be the most important mechanisms of lithium that also alter neural transmissions including dopaminergic signaling in mesolimbic and mesocortical pathways.

Prolonged Differentiation of Neuron-Astrocyte Co-Cultures Results in Emergence of Dopaminergic Neurons

Dopamine is present in a subgroup of neurons that are vital for normal brain functioning. Disruption of the dopaminergic system, e.g., by chemical compounds, contributes to the development of Parkinson's disease and potentially some neurodevelopmental disorders. Current test guidelines for chemical safety assessment do not include specific endpoints for dopamine disruption. Therefore, there is a need for the human-relevant assessment of (developmental) neurotoxicity related to dopamine disruption. The aim of this study was to determine the biological domain related to dopaminergic neurons of a human stem cell-based in vitro test, the human neural progenitor test (hNPT). Neural progenitor cells were differentiated in a neuron-astrocyte co-culture for 70 days, and dopamine-related gene and protein expression was investigated. Expression of genes specific for dopaminergic differentiation and functioning, such as LMX1B, NURR1, TH, SLC6A3, and KCNJ6, were increasing by day 14. From day 42, a network of neurons expressing the catecholamine marker TH and the dopaminergic markers VMAT2 and DAT was present. These results confirm stable gene and protein expression of dopaminergic markers in hNPT. Further characterization and chemical testing are needed to investigate if the model might be relevant in a testing strategy to test the neurotoxicity of the dopaminergic system.

Sex-specific susceptibility to psychotic-like states provoked by prenatal THC exposure: Reversal by pregnenolone

Sociocultural attitudes towards cannabis legalization contribute to the common misconception that it is a relatively safe drug and its use during pregnancy poses no risk to the fetus. However, longitudinal studies demonstrate that maternal cannabis exposure results in adverse outcomes in the offspring, with a heightened risk for developing psychopathology. One of the most reported psychiatric outcomes is the proneness to psychotic-like experiences during childhood. How exposure to cannabis during gestation increases psychosis susceptibility in children and adolescents remains elusive. Preclinical research has indicated that in utero exposure to the major psychoactive component of cannabis, delta-9-tetrahydrocannabinol (THC), deranges brain developmental trajectories towards vulnerable psychotic-like endophenotypes later in life. Here, we present how prenatal THC exposure (PCE) deregulates mesolimbic dopamine development predisposing the offspring to schizophrenia-relevant phenotypes, exclusively when exposed to environmental challenges, such as stress or THC. Detrimental effects of PCE are sex-specific because female offspring do not display psychotic-like outcomes upon exposure to these challenges. Moreover, we present how pregnenolone, a neurosteroid that showed beneficial properties on the effects elicited by cannabis intoxication, normalizes mesolimbic dopamine function and rescues psychotic-like phenotypes. We, therefore, suggest this neurosteroid as a safe "disease-modifying" aid to prevent the onset of psychoses in vulnerable individuals. Our findings corroborate clinical evidence and highlight the relevance of early diagnostic screening and preventative strategies for young individuals at risk for mental diseases, such as male PCE offspring.

Spatiotemporal dynamics of 5-HT6 receptor ciliary localization during mouse brain development

The serotonin 5-HT₆ receptor (5-HT₆R) is a promising target to improve cognitive symptoms of psychiatric diseases of neurodevelopmental origin, such as autism spectrum disorders and schizophrenia. However, its expression and localization at different stages of brain development remain largely unknown, due to the lack of specific antibodies to detect endogenous 5-HT₆R. Here, we used transgenic mice expressing a GFP-tagged 5-HT₆R under the control of its endogenous promoter (Knock-in) as well as embryonic stem cells expressing the GFP-tagged receptor to extensively characterize its expression at cellular and subcellular levels during development. We show that the receptor is already expressed at E13.5 in the cortex, the striatum, the ventricular zone, and to a lesser extent the subventricular zone. In adulthood, it is preferentially found in projection neurons of the hippocampus and cerebral cortex, in striatal medium-sized spiny neurons, as well as in a large proportion of astrocytes, while it is expressed in a minor population of interneurons. Whereas the receptor is almost exclusively detected in the primary cilia of neurons at embryonic and adult stages and in differentiated stem cells, it is located in the somatodendritic compartment of neurons from some brain regions at the neonatal stage and in the soma of undifferentiated stem cells. Finally, knocking-out the receptor induces a shortening of the primary cilium, suggesting that it plays a role in its function. This study provides the first global picture of 5-HT₆R expression pattern in the mouse brain at different developmental stages. It reveals dynamic changes in receptor localization in neurons at the neonatal stage, which might underlie its key role in neuronal differentiation and psychiatric disorders of neurodevelopmental origin.

The inhibition of NCS-1 binding to Ric8a rescues fragile X syndrome mice model phenotypes

Fragile X syndrome (FXS) is caused by the loss of function of Fragile X mental retardation protein (FMRP). FXS is one of the leading monogenic causes of intellectual disability (ID) and autism. Although it is caused by the failure of a single gene, FMRP that functions as an RNA binding protein affects a large number of genes secondarily. All these genes represent hundreds of potential targets and different mechanisms that account for multiple pathological features, thereby hampering the search for effective treatments. In this scenario, it seems desirable to reorient therapies toward more general approaches. Neuronal calcium sensor 1 (NCS-1), through its interaction with the guanine-exchange factor Ric8a, regulates the number of synapses and the probability of the release of a neurotransmitter, the two neuronal features that are altered in FXS and other neurodevelopmental disorders. Inhibitors of the NCS-1/Ric8a complex have been shown to be effective in restoring abnormally high synapse numbers as well as improving associative learning in FMRP mutant flies. Here, we demonstrate that phenothiazine FD44, an NCS-1/Ric8a inhibitor, has strong inhibition ability in situ and sufficient bioavailability in the mouse brain. More importantly, administration of FD44 to two different FXS mouse models restores well-known FXS phenotypes, such as hyperactivity, associative learning, aggressive behavior, stereotype, or impaired social approach. It has been suggested that dopamine (DA) may play a relevant role in the behavior and in neurodevelopmental disorders in general. We have measured DA and its metabolites in different brain regions, finding a higher metabolic rate in the limbic area, which is also restored with FD44 treatment. Therefore, in addition to confirming that the NCS-1/Ric8a complex is an excellent therapeutic target, we demonstrate the rescue effect of its inhibitor on the behavior of cognitive and autistic FXS mice and show DA metabolism as a FXS biochemical disease marker.

"Jing-Ning Granules" Can Alleviate Attention Deficit Hyperactivity Disorder in Rats by Modulating Dopaminergic D2/D1-Like Receptor-Mediated Signaling Pathways

Background

Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by attention deficit, hyperactivity, and impulsivity. Jing-Ning Granules (JNG) is a traditional Chinese medicine (TCM) that can alleviate ADHD. Although JNG is commonly used for the effective treatment of ADHD and has obtained the national invention patent, the exact mechanism of action remains unclear.

Objective

In this study, we examined the effect and mechanism of JNG in spontaneously hypertensive rats (SHRs). We hypothesized that JNG affects dopaminergic D2/D1-like receptors and related pathways.

Materials and Methods

Six rat groups were used in the experiment: Wistar-Kyoto rats (WKY, control group) and five SHR groups, including a model group; atomoxetine (ATX, positive control) group; and low, medium, and high-dose JNG groups. The corresponding treatments were daily administered to each group for 6 weeks. A behavioral test, including a step-down test and open field test (OFT), was carried out at the end of treatment. After the behavioral test, all animals were sacrificed, and the brain tissue was collected and analyzed ex vivo; histopathological analysis was performed to assess the pathological changes of the hippocampus; expression of D1-like and D2-like receptors, sensor protein calmodulin (CaM), protein kinase A (PKA), and calcium/calmodulin-dependent serine/threonine protein kinase (CaMKII) in the striatum and hippocampus was measured by western blot and real-time quantitative PCR (RT-PCR); cyclic adenosine monophosphate (cAMP) levels in the striatum were analyzed using an enzyme-linked immunosorbent assay (ELISA), while the level of Ca2+ in the striatum was analyzed by a calcium kit.

Results

Our results showed that ATX or JNG could ameliorate the hyperactive/impulsive behavior and cognitive function of ADHD by promoting neuroprotection. Mechanistically, ATX or JNG could prompt the expressions of Dl-like and D2-like receptors and improve the mRNA and protein levels of cAMP/PKA and Ca2+/CAM/CAMKII signaling pathways.

Conclusion

These results indicate that JNG can produce therapeutic effects by regulating the balance of D2/D1-like receptor-mediated cAMP/PKA and Ca2+/CaM/CaMKII signaling pathways.

Comprehensive analysis of omics data identifies relevant gene networks for Attention-Deficit/Hyperactivity Disorder (ADHD)

Attention-deficit/hyperactivity disorder (ADHD) is a highly prevalent neurodevelopmental disorder that results from the interaction of both genetic and environmental risk factors. Genome-wide association studies have started to identify multiple genetic risk loci associated with ADHD, however, the exact causal genes and biological mechanisms remain largely unknown. We performed a multi-step analysis to identify and characterize modules of co-expressed genes associated with ADHD using data from peripheral blood mononuclear cells of 270 ADHD cases and 279 controls. We identified seven ADHD-associated modules of co-expressed genes, some of them enriched in both genetic and epigenetic signatures for ADHD and in biological pathways relevant for psychiatric disorders, such as the regulation of gene expression, epigenetics and immune system. In addition, for some of the modules, we found evidence of potential regulatory mechanisms, including microRNAs and common genetic variants. In conclusion, our results point to promising genes and pathways for ADHD, supporting the use of peripheral blood to assess gene expression signatures in psychiatric disorders. Furthermore, they highlight that the combination of multi-omics signals provides deeper and broader insights into the biological mechanisms underlying ADHD.

Oxidative Stress and Apoptosis in Bisphenol AF-Induced Neurotoxicity in Zebrafish Embryos

Bisphenol AF (BPAF) is a structural counterpart of bisphenol A that is utilized in the food and beverage industry. The present study investigated the potential mechanisms in BPAF-induced neurotoxicity in zebrafish embryos. The BPAF concentrations (0.03, 0.1, 0.3, and 1.0 µM) had no obvious effect on hatching, mortality, and body length of zebrafish larvae, while curved tail and pericardial edema were observed in the 1.0 μM group at 72 and 96 h postfertilization (hpf). Locomotor activity of the larvae (at 120 hpf) significantly decreased from dark to light but increased from light to dark transitions in BPAF groups (0.1, 0.3, and 1.0 μM). Acridine orange showed that BPAF significantly increased green fluorescence protein intensity (22.6%) in the 1.0 μM group. Consistently, the induced apoptosis significantly up-regulated caspase 3 at 0.3 μM (1.95-fold) and 1.0 μM (2.26-fold) and bax at 0.3 μM (1.60-fold) and 1.0 μM (1.78-fold), whereas bcl-2 expression was significantly decreased at 0.3 μM (0.72-fold) and 1.0 μM (0.53-fold). In addition, increased reactive oxygen species concentrations at 0.3 μM (27%) and 1.0 μM (61.4%) resulted in suppressed superoxide dismutase and catalase activities. Moreover, quantitative polymerase chain reaction results showed that BPAF (0.3 and 1.0 μM) significantly altered normal dopaminergic signaling where dat was up-regulated, while drd2a and th1 were down-regulated, in a concentration-dependent manner. Aberrations in dopamine-related genes were congruous with the dysregulations in neurodevelopment genes (sox11b, pax6a, syn2a, and rob2). Our findings suggest that BPAF-evoked oxidative stress and apoptosis could translate into phenotypical behavioral and neurodevelopmental abnormalities. These highlights could provide theoretical reference for risk assessment and act as an early indicator to BPAF exposure. Environ Toxicol Chem 2022;41:2273-2284. © 2022 SETAC.

Curcumin for attention-deficit-hyperactivity disorder: a systematic review and preliminary behavioral investigation

Curcumin has protective actions in neuropsychiatric disorders, acting as a neuroprotective agent. As a first approach, the study aimed at a systematic review of the potential effects of curcumin on cognitive performance for attention-deficit-hyperactivity disorder (ADHD). This research was carried out in the databases of PubMed, Embase, SciELO, the Cochrane Central Register of Controlled Trials (CENTRAL), the Web of Science, and the Grey literature. Upon discovering the scarcity of relevant studies, and knowing that curcumin might have an ADHD hyperactive and anxious behavior, the study proposed to evaluate the effects of curcumin in an ADHD phenotype of spontaneously hypertensive Wistar rats (SHR). No studies were found that related to curcumin and ADHD. Fifteen SHRs were then divided into separate groups that received water (1 mg/kg/day), curcumin (50 mg/kg/day), or methylphenidate (1 mg/kg/day) for 42 days. Behavioral tests to assess activity (Open Field Test), anxiety and impulsivity (Elevated Plus-Maze, and Social Interaction), and memory (Y-Maze, and the Object Recognition Test) were all performed. The animals that were treated with curcumin showed less anxious and hyperactive behavior, as seen in the Open Field Test and the Social Interaction Test. Anxious behavior was measured by the EPM and was not modulated by any treatment. The results of the Y-Maze Test demonstrated that curcumin improved spatial memory. In the Object Recognition Test, neither the short nor the long-term memory was improved. The treatments that were used in this study beneficially modulated the anxious and hyperactive behavior of the SHR.

Mutant D620N and VPS35 induces motor dysfunction and impairs DAT-mediated dopamine recycling pathway

The D620N mutation in vacuolar protein sorting protein 35 (VPS35) gene has been identified to be linked to late onset familial Parkinson disease (PD). However, the pathophysiological roles of VPS35-D620N in PD remain unclear. Here, we generated the transgenic C. elegans overexpressing either human wild type or PD-linked mutant VPS35-D620N in neurons. C. elegans expressing VPS35-D620N, compared with non-transgenic controls, showed movement disorders and dopaminergic neuron loss. VPS35-D620N worms displayed more swimming induced paralysis but showed no defects in BSR assays, thus indicating the disruption of dopamine (DA) recycling back inside neurons. Moreover, VPS35 formed a protein interaction complex with DA transporter (DAT), RAB5, RAB11, and FAM21. In contrast, the VPS35-D620N mutant destabilized these interactions, thus disrupting DAT transport from early endosomes to recycling endosomes, and decreasing DAT at the cell suffice. These effects together increased DA in synaptic clefts, and led to dopaminergic neuron degeneration and motor dysfunction. Treatment with reserpine significantly decreased the swimming induced paralysis in VPS35-D620N worms, as compared with vehicle treated VPS35-D620N worms. Our studies not only provide novel insight into the mechanisms of VPS35-D620N-induced dopaminergic neuron degeneration and motor dysfunction via disruption of DAT function and the DA signaling pathway, but also indicate a potential strategy to treat VPS35-D620N related PD and other disorders.

Neurotransmitters-Key Factors in Neurological and Neurodegenerative Disorders of the Central Nervous System

Neurotransmitters are molecules that amplify, transmit, and convert signals in cells, having an essential role in information transmission throughout the nervous system. Hundreds of such chemicals have been discovered in the last century, continuing to be identified and studied concerning their action on brain health. These substances have been observed to influence numerous functions, including emotions, thoughts, memories, learning, and movements. Thus, disturbances in neurotransmitters' homeostasis started being correlated with a plethora of neurological and neurodegenerative disorders. In this respect, the present paper aims to describe the most important neurotransmitters, broadly classified into canonical (e.g., amino acids, monoamines, acetylcholine, purines, soluble gases, neuropeptides) and noncanonical neurotransmitters (e.g., exosomes, steroids, D-aspartic acid), and explain their link with some of the most relevant neurological conditions. Moreover, a brief overview of the recently developed neurotransmitters' detection methods is offered, followed by several considerations on the modulation of these substances towards restoring homeostasis.

Long-term exposure of mice to 890 ppm atmospheric CO2 alters growth trajectories and elicits hyperactive behaviours in young adulthood

Atmospheric carbon dioxide (CO₂ ) levels are currently at 418 parts per million (ppm), and by 2100 may exceed 900 ppm. The biological effects of lifetime exposure to CO₂ at these levels is unknown. Previously we have shown that mouse lung function is altered by long-term exposure to 890 ppm CO₂ . Here, we assess the broader systemic physiological responses to this exposure. Mice were exposed to either 460 or 890 ppm from preconception to 3 months of age, and assessed for effects on developmental, renal and osteological parameters. Locomotor, memory, learning and anxiety-like behaviours of the mice were also assessed. Exposure to 890 ppm CO₂ increased birthweight, decreased female body weight after weaning, and, as young adults, resulted in reduced engagement in memory/learning tasks, and hyperactivity in both sexes in comparison to controls. There were no clear anxiety, learning or memory changes. Renal and osteological parameters were minimally affected. Overall, this study shows that exposure of mice to 890 ppm CO₂ from preconception to young adulthood alters growth and some behaviours, with limited evidence of compensatory changes in acid-base balance. These findings highlight the potential for a direct effect of increased atmospheric CO₂ on mammalian health outcomes. KEY POINTS: Long-term exposure to elevated levels of atmospheric CO₂ is an uncontrolled experiment already underway. This is the first known study to assess non-respiratory physiological impacts of long-term (conception to young adulthood) exposure of mice to CO₂ at levels that may arise in the atmosphere due to global emissions. Exposure to elevated CO₂ , in comparison to control mice, altered growth patterns in early life and resulted in hyperactive behaviours in young adulthood. Renal and bone parameters, which are important to balance acid-base levels to compensate for increased CO₂ exposure, remained relatively unaffected. This work adds to the body of evidence regarding the effects of carbon emissions on mammalian health and highlights a potential future burden of disease.

Animal Models for Assessing Impact of C-Section Delivery on Biological Systems

There has been a significant increase in Caesarean section (C-section) births worldwide over the past two decades and although it is can be a life-saving procedure, the enduring effects on host physiology are now undergoing further scrutiny. Indeed, epidemiological data have linked C-section birth with multiple immune, metabolic and neuropsychiatric diseases. Birth by C-section is known to alter the colonisation of the neonatal gut microbiota (with C-section delivered infants lacking vaginal microbiota associated with passing along the birth canal), which in turn can impact the development and maintenance of many important biological systems. Appropriate animal models are key to disentangling the role of missing microbes in brain health and disease in C-section births. In this review of preclinical studies, we interrogate the effects of C-section birth on the development (and maintenance) of several biological systems and we discuss the involvement of the gut microbiome on C-section-related alterations.

Somatostatin-Mediated Regulation of Retinoic Acid-Induced Differentiation of SH-SY5Y Cells: Neurotransmitters Phenotype Characterization

During brain development, neurite formation plays a critical role in neuronal communication and cognitive function. In the present study, we compared developmental changes in the expression of crucial markers that govern the functional activity of neurons, including somatostatin (SST), choline acetyltransferase (ChAT), tyrosine hydroxylase (TH), brain nitric oxide synthase (bNOS), gamma-aminobutyric acid (GABA), glutamic acid decarboxylase (GAD-65) and synaptic vesicle protein synaptophysin (SYP) in non-differentiated and retinoic acid (RA)-induced differentiated SH-SY5Y cells. We further determined the role of SST in regulating subcellular distribution and expression of neurotransmitters. Our results indicate that SST potentiates RA-induced differentiation of SH-SY5Y cells and involves regulating the subcellular distribution and expression of neurotransmitter markers and synaptophysin translocation to neurites in a time-dependent manner, anticipating the therapeutic implication of SST in neurodegeneration.

Long-lasting behavioral effects of quinpirole exposure on zebrafish

The human brain matures into a complex structure, and to reach its complete development, connections must occur along exact paths. If at any stage, the processes are altered, interrupted, or inhibited, the consequences can be permanent. Dopaminergic signaling participates in the control of physiological functions and behavioral processes, and alterations in this signaling pathway are related to the pathogenesis of several neurological disorders. For this reason, the use of pharmacological agents able to interact with the dopaminergic signaling may elucidate the biological bases of such disorders. We investigated the long-lasting behavioral effects on adult zebrafish after quinpirole (a dopamine D2/D3 receptor agonist) exposure during early life stages of development (24 h exposure at 5 days post-fertilization, dpf) to better understand the mechanisms underlying neurological disorders related to the dopaminergic system. Quinpirole exposure at the early life stages of zebrafish led to late behavioral alterations. When evaluated at 120 dpf, zebrafish presented increased anxiety-like behaviors. At the open tank test, fish remained longer at the bottom of the tank, indicating anxiety-like behavior. Furthermore, quinpirole-treated fish exhibited increased absolute turn angle, likely an indication of elevated erratic movements and a sign of increased fear or anxiety. Quinpirole-treated fish also showed altered swimming patterns, characterized by stereotypic swimming. During the open tank test, exposed zebrafish swims from corner to corner in a repetitive manner at the bottom of the tank. Moreover, quinpirole exposure led to memory impairment compared to control fish. However, quinpirole administration had no effects on social and aggressive behavior. These findings demonstrate that dopaminergic signaling altered by quinpirole administration in the early life stages of development led to late alterations in behavioral parameters of adult zebrafish.

Behavioral effects of early-life exposure to perfluorooctanoic acid might synthetically link to multiple aspects of dopaminergic neuron development and dopamine functions in zebrafish larvae

Perfluorooctanoic acid (PFOA) is known as an environmental endocrine disruptor and has developmental neurotoxicity that could be associated with behavior changes in human and animal studies. Previous studies have shown that PFOA might affect the dopaminergic nervous system. However, the mode of action underlying the effects of PFOA remains poorly understood. Our study used zebrafish as an animal model to investigate the effects of early-life PFOA exposure on dopaminergic neuron development and dopamine functions in zebrafish larvae. Zebrafish fertilized eggs were exposed to different concentrations of PFOA (0, 10, 100, 1000 μg/L). After exposure to PFOA for 7 days, the locomotor activity of zebrafish was decreased; the mRNA levels of nuclear receptor subfamily 4 group a member 2b (nr4a2b), paired box 2 and 5 (pax2, pax5), tyrosine hydroxylase 1/2 (th1/th2) and dopamine transporter (dat) were increased; mRNA and protein level of mesencephalic astrocyte-derived neurotrophic factor (manf) were decreased. Neural cell proliferation in the preoptic area of hypothalamus was increased. In conclusion, dopaminergic neuron development might be one of the targets of early-life PFOA exposure. The neurobehavior changes induced by PFOA exposure might link to multiple aspects of dopaminergic neuron development and dopamine functions in zebrafish larvae.

Gestational and peripubertal phthalate exposure in relation to attention performance in childhood and adolescence

The prevalence of Attention Deficit/Hyperactivity Disorder (ADHD) has been increasing. Research suggests that exposure to endocrine disrupting chemicals such as phthalates may play a role, but studies of in utero phthalate exposure and ADHD-related symptoms beyond early childhood are limited. We investigated associations between measures of in utero phthalate exposure and ADHD symptoms, such as inattention and impulsivity, in childhood (age 6-11 years, n = 221) and in adolescence (age 9-18 years, n = 200), as well as cross-sectional relationships between phthalate exposure and ADHD symptoms in adolescence (n = 491) among participants in the Early Life Exposure in Mexico to Environmental Toxicants (ELEMENT) cohort. Women provided urine samples up to three times during pregnancy and adolescents provided a urine sample at 9-18 years of age for phthalate metabolite measurement. We administered the Conners' Continuous Performance Test (CPT) when children were age 6-11 years and again at 9-18 years of age. We used multivariable linear regression to examine associations between the geometric mean of phthalate metabolite levels across pregnancy and CPT scores in childhood or adolescence separately, adjusting for age, years schooling (at 9-18 only), maternal education, and specific gravity. Although average in utero phthalate concentrations were not associated with CPT scores in childhood, interquartile range (IQR) increases of in utero MBzP, MCPP, and MBP were associated with 4.2%, 4.7%, and 4.5% (p < 0.05) higher Omissions scores in adolescence, respectively, indicating higher inattention. In utero MiBP levels were also associated with higher Inter-Stimulus Interval (ISI) and Variability scores (5.4% and 5.5% per IQR, p < 0.05) in adolescence. In addition, urinary DEHP metabolite levels during adolescence were cross-sectionally associated with poorer scores on several CPT indices indicating greater inattention. These findings suggest that in utero phthalate exposure may have adverse effects on attention, but these effects may not appear until adolescence, a period of extensive neurodevelopment. Future research investigating the long-term effects of in utero phthalate exposure on attention and ADHD in adolescence, as well as identification of potential mechanisms involved, is needed.

ADHD: Reviewing the Causes and Evaluating Solutions

Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder in which patients present inattention, hyperactivity, and impulsivity. The etiology of this condition is diverse, including environmental factors and the presence of variants of some genes. However, a great diversity exists among patients regarding the presence of these ADHD-associated factors. Moreover, there are variations in the reported neurophysiological correlates of ADHD. ADHD is often treated pharmacologically, producing an improvement in symptomatology, albeit there are patients who are refractory to the main pharmacological treatments or present side effects to these drugs, highlighting the importance of developing other therapeutic options. Different non-pharmacological treatments are in this review addressed, finding diverse results regarding efficacy. Altogether, ADHD is associated with different etiologies, all of them producing changes in brain development, leading to the characteristic symptomatology of this condition. Given the heterogeneous etiology of ADHD, discussion is presented about the convenience of personalizing ADHD treatment, whether pharmacological or non-pharmacological, to reach an optimum effect in the majority of patients. Approaches to personalizing both pharmacological therapy and neurofeedback are presented.