Increased Oxidative Parameters and Decreased Cytokine Levels in an Animal Model of Attention-Deficit/Hyperactivity Disorder

Association of impulsive behavior and cerebrospinal fluid/plasma oxidation and antioxidation ratio in Chinese men

OBJECTIVES

Impulsive behavior is the precursor of many psychiatric and neurological conditions. High levels of impulsive behavior will increase health risk behavior and related injuries. Impulsive behavior is produced and regulated by central and peripheral biological factors, and oxidative stress (OS) can aggravate it. However, previous studies only showed that impulsive behavior was related to the level of the peripheral OS. Therefore, this study aims to clarify the relationship between OS and impulsive behavior in the brain and peripheral blood.

METHODS

We recruited 64 Chinese men. We measured superoxide dismutase (SOD) (including copper, zinc and manganese) and nitric oxide synthase (NOS) (including total, inducible and constitutive) in cerebrospinal fluid (CSF) and plasma. The Barratt Impulsiveness Scale version 11 (BIS-11) was used to evaluate impulsive behavior. The relationship between OS and impulsive behavior was evaluated by partial correlation analysis and stepwise multiple regression analysis.

RESULTS

Partial correlation analysis showed that the ratio of total NOS-to-MnSOD and iNOS-to-MnSOD in CSF were negatively correlated with the BIS-11 motor scores (r = -0.431, p = -0.001; r = -0.434, p = -0.001). Stepwise multiple regression analysis showed that the ratio of CSF iNOS-to-MnSOD was the most influential variable on the BIS-11 motor scores(β = -0.434, t = -3.433, 95 %CI(-0.374, -0.098), p = 0.001).

CONCLUSIONS AND RELEVANCE

The imbalance of central oxidation and antioxidation is related to impulsive behavior, which broadens our understanding of the correlation between impulsive behavior and OS.

Selenoprotein T, a potential treatment of attention-deficit/hyperactivity disorder and comorbid pain in neonatal 6-OHDA lesioned mice

pathological pain and Attention-deficit/hyperactivity disorder (ADHD) are two complex multifactorial syndromes. The comorbidity of ADHD and altered pain perception is well documented in children, adolescents, and adults. According to pathophysiological investigations, the dopaminergic system's dysfunction provides a common basis for ADHD and comorbid pain. Growing evidence suggests that oxidative stress may be crucial in both pathologies. Recent studies revealed that a small peptide encompassing the redox-active site of selenoprotein T (PSELT), protects dopaminergic neurons and fibers as well as lesioned nerves in animal models. The current study aims to examine the effects of PSELT treatment on ADHD-like symptoms and pain sensitivity, as well as the role of catecholaminergic systems in these effects. Our results demonstrated that intranasal administration of PSELT reduced the hyperactivity in the open field, decreased the impulsivity displayed by 6-OHDA-lesioned male mice in the 5-choice serial reaction time task test and improved attentional performance. In addition, PSELT treatment significantly increased the nociception threshold in both normal and inflammatory conditions. Furthermore, anti-hyperalgesic activity was antagonized with sulpiride pre-treatment, but not by phentolamine, or propranolol pre-treatments. The present study suggests that PSELT reduces the severity of ADHD symptoms in mice and possesses potent antinociceptive effects which could be related to the involvement of D2/D3 dopaminergic receptors.

Manganese in autism spectrum disorder and attention deficit hyperactivity disorder: The state of the art

The objective of the present narrative review was to synthesize existing clinical and epidemiological findings linking manganese (Mn) exposure biomarkers to autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD), and to discuss key pathophysiological mechanisms of neurodevelopmental disorders that may be affected by this metal. Existing epidemiological data demonstrated both direct and inverse association between Mn body burden and ASD, or lack of any relationship. In contrast, the majority of studies revealed significantly higher Mn levels in subjects with ADHD, as well as direct relationship between Mn body burden with hyperactivity and inattention scores in children, although several studies reported contradictory results. Existing laboratory studies demonstrated that impaired attention and hyperactivity in animals following Mn exposure was associated with dopaminergic dysfunction and neuroinflammation. Despite lack of direct evidence on Mn-induced neurobiological alterations in patients with ASD and ADHD, a plethora of studies demonstrated that neurotoxic effects of Mn overexposure may interfere with key mechanisms of pathogenesis inherent to these neurodevelopmental disorders. Specifically, Mn overload was shown to impair not only dopaminergic neurotransmission, but also affect metabolism of glutamine/glutamate, GABA, serotonin, noradrenaline, thus affecting neuronal signaling. In turn, neurotoxic effects of Mn may be associated with its ability to induce oxidative stress, apoptosis, and neuroinflammation, and/or impair neurogenesis. Nonetheless, additional detailed studies are required to evaluate the association between environmental Mn exposure and/or Mn body burden and neurodevelopmental disorders at a wide range of concentrations to estimate the potential dose-dependent effects, as well as environmental and genetic factors affecting this association.

Hippocampus under Pressure: Molecular Mechanisms of Development of Cognitive Impairments in SHR Rats

Data from clinical trials and animal experiments demonstrate relationship between chronic hypertension and development of cognitive impairments. Here, we review structural and biochemical alterations in the hippocampus of SHR rats with genetic hypertension, which are used as a model of essential hypertension and vascular dementia. In addition to hypertension, dysfunction of the hypothalamic-pituitary-adrenal system observed in SHR rats already at an early age may be a key factor of changes in the hippocampus at the structural and molecular levels. Global changes at the body level, such as hypertension and neurohumoral dysfunction, are associated with the development of vascular pathology and impairment of the blood-brain barrier. Changes in multiple biochemical glucocorticoid-dependent processes in the hippocampus, including dysfunction of steroid hormones receptors, impairments of neurotransmitter systems, BDNF deficiency, oxidative stress, and neuroinflammation are accompanied by the structural alterations, such as cellular signs of neuroinflammation micro- and astrogliosis, impairments of neurogenesis in the subgranular neurogenic zone, and neurodegenerative processes at the level of synapses, axons, and dendrites up to the death of neurons. The consequence of this is dysfunction of hippocampus, a key structure of the limbic system necessary for cognitive functions. Taking into account the available results at various levels starting from the body and brain structure (hippocampus) levels to molecular one, we can confirm translational validity of SHR rats for modeling mechanisms of vascular dementia.

[Recent research on the role of oxidative stress in the pathogenesis of attention deficit hyperactivity disorder]

Attention deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder in children and adolescents, and its etiology and pathogenesis are still unclear. Brain is the organ with the largest oxygen consumption in human body and is easily affected by oxidative imbalance. Oxidative stress has become the key research direction for the pathogenesis of ADHD, but there is still a lack of relevant studies in China. Based on the latest research findings in China and overseas, this article reviews the clinical and experimental studies on oxidative stress in ADHD and explores the association of oxidative stress with neurotransmitter imbalance, neuroinflammation, and cell apoptosis in the pathogenesis of ADHD, so as to provide new research ideas for exploring the pathogenesis of ADHD.

Brain-derived neurotrophic factor (BDNF) levels in children and adolescents before and after stimulant use a systematic review and metanalysis

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder associated with cognitive, social, and academic impairment. Neurotrophins, particularly brain-derived neurotrophic factor (BDNF), have been implicated in the pathophysiology of ADHD and response to stimulant treatment. This review aims to investigate the relationship between BDNF levels in ADHD before and after treatment with stimulants in childhood.

METHODS

This systematic review followed PRISMA-P guidelines and included 19 studies from PubMed, EMBASE, Cochrane, Capes Periodic, and Lilacs databases. The studies were evaluated for risk of bias and level of evidence.

RESULTS

There was no significant difference in peripheral BDNF levels in ADHD children before or after methylphenidate treatment. Additionally, there was no statistically significant difference in BDNF levels between children with ADHD and controls.

DISCUSSION

Understanding the role of BDNF in ADHD may provide insight into the disorder's pathophysiology and facilitate the development of biological markers for clinical use.

CONCLUSION

Our findings suggest that BDNF levels are not significantly affected by methylphenidate treatment in ADHD children and do not differ from controls.

SYSTEMATIC REVIEW REGISTRATION

"Brain-derived neurotrophic factor (BDNF) levels in children and adolescents before and after stimulant use: a systematic review". Number CRD42021261519.

Vinpocetine, a PDE1 modulator, regulates markers of cerebral health, inflammation, and oxidative stress in a rat model of prenatal alcohol-induced experimental attention deficit hyperactivity disorder

Prenatal alcohol exposure (PAE) has been shown to induce symptomatology associated with attention deficit hyperactivity disorder (ADHD) by altering neurodevelopmental trajectories. Phosphodiesterase-1 (PDE1) is expressed centrally and has been used in various experimental brain conditions. We investigated the role of vinpocetine, a PDE1 inhibitor, on behavioral phenotypes and important biochemical deficits associated with a PAE rat model of ADHD. Protein markers of cerebral health (synapsin-IIa, BDNF, and pCREB), inflammation (IL-6, IL-10, and TNF-α), and oxidative stress (TBARS, GSH, and SOD) were analyzed in three brain regions (frontal cortex, striatum, and cerebellum). Hyperactivity, inattention, and anxiety introduced in the offspring due to PAE were assayed using open-field, Y-maze, and elevated plus maze, respectively. Administration of vinpocetine (10 & 20 mg/kg, p.o. [by mouth]) to PAE rat offspring for 4 weeks resulted in improvement of the behavioral profile of the animals. Additionally, levels of protein markers such as synapsin-IIa, BDNF, pCREB, IL-10, SOD, and GSH were found to be significantly increased, with a significant reduction in markers such as TNF-α, IL-6, and TBARS in selected brain regions of vinpocetine-treated animals. Vinpocetine, a selective PDE1 inhibitor, rectified behavioral phenotypes associated with ADHD, possibly by improving cerebral function, reducing brain inflammation, and reducing brain oxidative stress. This study provides preliminary analysis and suggests that the PDE1 enzyme may be an important pharmacological tool to study ADHD as a result of PAE.

Peripheral blood inflammatory markers in patients with attention deficit/hyperactivity disorder (ADHD): A systematic review and meta-analysis

It has been observed that subclinical inflammation might be involved in the pathophysiology of attention deficit/hyperactivity disorder (ADHD). However, studies investigating peripheral blood levels of immune-inflammatory markers have provided mixed findings. We performed a systematic review and meta-analysis of studies comparing unstimulated serum or plasma levels of C-reactive protein (CRP) and cytokines in subjects with ADHD and healthy controls (the PROSPERO registration number: CRD 42021276869). Online searches covered the publication period until 30th Sep 2021 and random-effects meta-analyses were carried out. Out of 1844 publication records identified, 10 studies were included. The levels of interleukin (IL)-6 were significantly higher in studies of participants up to the age of 18 years (k = 10, g = 0.70, 95%CI: 0.10-1.30, p = 0.023) and after including those above the age of 18 years (k = 10, g = 0.71, 95%CI: 0.12-1.31, p = 0.019). In turn, the levels of tumor necrosis factor-α (TNF-α) were significantly lower in subjects with ADHD compared to healthy controls (k = 7, g = -0.16, 95%CI: -0.30 - -0.03, p = 0.020). Individual studies had a high contribution to the overall effect, since the overall effect was no longer significant after removing single studies. No significant differences were found with respect to the levels of CRP, IL-1β, IL-10 and interferon-γ. The present findings indicate that individuals with ADHD tend to show elevated levels of IL-6 and reduced levels of TNF-α. Larger and longitudinal studies recording potential confounding factors and comorbid psychopathology are needed to confirm our findings.

Exposome of attention deficit hyperactivity disorder in Taiwanese children: exploring risks of endocrine-disrupting chemicals

BACKGROUND

Attention-deficit hyperactivity disorder (ADHD) is diagnosed in ~7% of school-aged children. The role of endocrine-disrupting chemicals (EDC) and oxidative stress in ADHD etiology are not clear.

OBJECTIVE

Assessment of the associations between simultaneous exposure to multiple compounds and ADHD in children.

METHODS

The case-control study included 76 clinically diagnosed ADHD cases and 98 controls, aged 4-15 years old. Concentrations quartiles of urinary metabolites of acrylamide, acrolein, nonylphenol, phthalates, and organophosphate pesticides and biomarkers of oxidative stress were used to fit logistic regressions for each compound and weighted quantiles sum (WQS) regression for the mixture.

RESULTS

Positive dose-response relationships with ADHD were observed for 4-hydroxy-2-nonenal-mercapturic acid (HNE-MA) (odds ratio(OR)_Q4 = 3.73, 95%CI [1.32, 11.04], p_trend = 0.003), dimethyl phosphate (DMP) (OR_Q4 = 4.04, 95%CI [1.34, 12.94], p_trend = 0.014) and diethyl phosphate (OR_Q4 = 2.61, 95%CI = [0.93, 7.66], p_trend = 0.030), and for the mixture of compounds (OR_WQS = 3.82, 95%CI = [1.78, 8.19]) with the main contributions from HNE-MA (28.9%) and DMP (18.4%).

CONCLUSIONS

The dose-response relationship suggests enhanced susceptibility to EDC burden in children even at lower levels, whereas the main risk is likely from organophosphate pesticides. HNE-MA is recommended as a sensitive biomarker of lipid peroxidation in the further elucidation of the oxidative stress role in ADHD etiology.

Influence of the inflammasome complex on psychiatric disorders: clinical and preclinical studies

INTRODUCTION

The innate immune complex, an inflammasome complex, has a role in the etiology of psychiatric disorders. Preclinical studies have demonstrated that the inflammasome activation leads to psychiatric disorders and clinical studies have proved that specific psychiatric illnesses are associated with aberrant levels of inflammatory cytokines and inflammasome. The inflammasome complex could be a major factor in the progression and pathology of psychiatric disorders.

AREA COVERED

We discuss the pathogenesis of psychiatric disorders with respect to the activation of the inflammasome complex. Inflammasome-associated inflammatory cytokines are observed in patients and animal models of psychiatric disorders. The article also reflects on inflammasome regulatory options for the prevention and treatment of psychiatric disorders. Relevant literature available on PubMed from 1992 to 2021 has been included in this review.

EXPERT OPINION

Modulating the inflammasome complex is a potential therapeutic strategy to treat symptom severity for patients with psychiatric disorders, particularly those with inflammasome-associated disorders. However, the nature of the psychiatric disorders should be considered when targeting inflammasome.

Targeting Xanthine Oxidase by Natural Products as a Therapeutic Approach for Mental Disorders

Mental disorders comprise diverse human pathologies, including depression, bipolar affective disorder, schizophrenia, and dementia that affect millions of people around the world. The causes of mental disorders are unclear, but growing evidence suggests that oxidative stress and the purine/adenosine system play a key role in their development and progression. Xanthine oxidase (XO) is a flavoprotein enzyme essential for the catalysis of the oxidative hydroxylation of purines -hypoxanthine and xanthine- to generate uric acid. As a consequence of the oxidative reaction of XO, reactive oxygen species (ROS) such as superoxide and hydrogen peroxide are produced and, further, contribute to the pathogenesis of mental disorders. Altered XO activity has been associated with free radical-mediated neurotoxicity inducing cell damage and inflammation. Diverse studies reported a direct association between an increased activity of XO and diverse mental diseases including depression or schizophrenia. Small-molecule inhibitors, such as the well-known allopurinol, and dietary flavonoids, can modulate the XO activity and subsequent ROS production. In the present work, we review the available literature on XO inhibition by small molecules and their potential therapeutic application in mental disorders. In addition, we discuss the chemistry and molecular mechanism of XO inhibitors, as well as the use of structure-based and computational methods to design specific inhibitors with the capability of modulating XO activity.

SHR/NCrl rats as a model of ADHD can be discriminated from controls based on their brain, blood, or urine metabolomes

Attention-Deficit Hyperactivity Disorder (ADHD) is one of the most common neurodevelopmental disorder characterized by inattention, impulsivity, and hyperactivity. The neurobiological mechanisms underlying ADHD are still poorly understood, and its diagnosis remains difficult due to its heterogeneity. Metabolomics is a recent strategy for the holistic exploration of metabolism and is well suited for investigating the pathophysiology of diseases and finding molecular biomarkers. A few clinical metabolomic studies have been performed on peripheral samples from ADHD patients but are limited by their access to the brain. Here, we investigated the brain, blood, and urine metabolomes of SHR/NCrl vs WKY/NHsd rats to better understand the neurobiology and to find potential peripheral biomarkers underlying the ADHD-like phenotype of this animal model. We showed that SHR/NCrl rats can be differentiated from controls based on their brain, blood, and urine metabolomes. In the brain, SHR/NCrl rats displayed modifications in metabolic pathways related to energy metabolism and oxidative stress further supporting their importance in the pathophysiology of ADHD bringing news arguments in favor of the Neuroenergetic theory of ADHD. Besides, the peripheral metabolome of SHR/NCrl rats also shared more than half of these differences further supporting the importance of looking at multiple matrices to characterize a pathophysiological condition of an individual. This also stresses out the importance of investigating the peripheral energy and oxidative stress metabolic pathways in the search of biomarkers of ADHD.

A Different View on the Etiopathogenesis of Attention-deficit Hyperactivity Disorder from an Inflammation Perspective

Objective

Attention-deficit hyperactivity disorder (ADHD) has a complex etiology and genetic, environmental and biological factors are considered to play a role in the etiology of ADHD by mutually interacting. Recent studies have emphasized that inflammation may be present in the etiology of ADHD. This study aims to investigate the possible role of visfatin, IL-6, IL-1β and TNF-α molecules in the etiology of ADHD.

Methods

The study included 60 patients and 20 healthy controls between the ages of 6−18. Serum visfatin, IL-6, IL-1β and TNF-α levels were evaluated with enzyme-linked immunosorbent assay (ELISA) kits at a biochemistry laboratory.

Results

The study showed no statistically significant difference between children with ADHD and healthy controls in terms of visfatin, IL-6, IL-1β and TNF-α levels. When ADHD subgroups (combined and predominantly inattentive types) and the control group were compared in terms of visfatin, IL-6, IL-1β and TNF-α levels, no statistically significant difference was recorded.

Conclusion

Data on the relationship between ADHD and IL-6, IL-1β and TNF-α in this study are in compliance with the literature. However, no study was found on visfatin in ADHD. This study is the first one evaluating the ADHD-Visfatin relationship.

Papaverine ameliorates prenatal alcohol-induced experimental attention deficit hyperactivity disorder by regulating neuronal function, inflammation, and oxidative stress

Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder with complex aetiology and phenotypes. Phosphodiesterase10A (PDE10A) has been shown to provide benefits in various brain conditions. We investigated the role of papaverine, a selective PDE10A inhibitor on core phenotypes in prenatal alcohol exposure (PAE) model of ADHD. In order to identify probable mechanisms involved, the effects on several protein markers of neuronal function such as, neuronal survival-BDNF, neuronal transcription factor-pCREB, brain inflammation (IL-6, IL-10, and TNF-α), and brain oxidative stress (TBARS and GSH) were studied in frontal cortex, cerebellum, and striatum. PAE resulting hyper-locomotion, inattention, and anxiety were studied by the use of open-field, y-maze, and elevated plus maze, respectively. Administration of papaverine (15/30 mg kg-1 ) to PAE group of animals resulted in amelioration of hyperactivity, inattention, and anxiety. Also, papaverine resulted in significant increase of the levels in BDNF, pCREB, IL-10, and GSH along with significant decrease of TNF-α, IL-6, and TBARS in different brain areas of PAE group. Papaverine, a selective PDE10A inhibitor rectified behavioural phenotypes associated with ADHD, possibly by altering the protein markers associated with neuronal survival, neuronal transcription factor, brain inflammation, and brain oxidative stress. Implicating PDE10A as a possible target for furthering our understanding of ADHD phenotypes.

Role of Oxidative Stress and Neuroinflammation in Attention-Deficit/Hyperactivity Disorder

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder of childhood. Although abnormalities in several brain regions and disturbances of the catecholaminergic pathway have been demonstrated, the pathophysiology of ADHD is not completely understood, but as a multifactorial disorder, has been associated with an increase in oxidative stress and neuroinflammation. This review presents an overview of factors that increase oxidative stress and neuroinflammation. The imbalance between oxidants and antioxidants and also the treatment with medications are two factors that can increase oxidative damage, whereas the comorbidity between ADHD and inflammatory disorders, altered immune response, genetic and environmental associations, and polymorphisms in inflammatory-related genes can increase neuroinflammation. Evidence of an association with these factors has become valuable for research on ADHD. Such evidence opens up new intervention routes for the use of natural products as antioxidants that could have potential as a treatment against oxidative stress and neuroinflammation in ADHD.

Increased vulnerability to impulsive behavior after streptococcal antigen exposure and antibiotic treatment in rats

RATIONALE

The inflammation induced by Group A Streptococcus (GAS) infection has been viewed as a vulnerability factor in mental disorders characterized by inhibitory control deficits, such as attention-deficit/hyperactivity disorder or obsessive-compulsive disorder. Antibiotic treatment reduces GAS symptoms; however, its effects on impulsivity have not been fully assessed.

OBJECTIVES

We investigated whether GAS exposure during early adolescence might be a vulnerability factor for adult impulsivity, if antibiotic treatment acts as a protective factor, and whether these differences are accompanied by changes in the inflammatory cytokine frontostriatal regions.

METHODS

Male Wistar rats were exposed to the GAS antigen or to vehicle plus adjuvants at postnatal day (PND) 35 (with two boosts), and they received either ampicillin (supplemented in the drinking water) or water alone from PND35 to PND70. Adult impulsivity was assessed using two different models, the 5-choice serial reaction time task (5-CSRT task) and the delay discounting task (DDT). The levels of interleukin-6 (IL-6) and IL-17 were measured in the prefrontal cortex (PFc), and the tumor necrosis factor α levels (TNFα) were measured in the PFc and nucleus accumbens (NAcc).

RESULTS

GAS exposure and ampicillin treatment increased the waiting impulsivity by a higher number of premature responses when the animals were challenged by a long intertrial interval during the 5-CSRT task. The GAS exposure revealed higher impulsive choices at the highest delay (40 s) when tested by DDT, while coadministration with ampicillin prevented the impulsive choice. GAS exposure and ampicillin reduced the IL-6 and IL-17 levels in the PFc, and ampicillin treatment increased the TNFα levels in the NAcc. A regression analysis revealed a significant contribution of GAS exposure and TNFα levels to the observed effects.

CONCLUSIONS

GAS exposure and ampicillin treatment induced an inhibitory control deficit in a different manner depending on the form of impulsivity measured here, with inflammatory long-term changes in the PFc and NAcc that might increase the vulnerability to impulsivity-related neuropsychiatric disorders.

Antioxidants as a Potential Target against Inflammation and Oxidative Stress in Attention-Deficit/Hyperactivity Disorder

Psychostimulants and non-psychostimulants are the medications prescribed for the treatment of attention-deficit/hyperactivity disorder (ADHD). However, several adverse results have been linked with an increased risk of substance use and side effects. The pathophysiology of ADHD is not completely known, although it has been associated with an increase in inflammation and oxidative stress. This review presents an overview of findings following antioxidant treatment for ADHD and describes the potential amelioration of inflammation and oxidative stress using antioxidants that might have a future as multi-target adjuvant therapy in ADHD. The use of antioxidants against inflammation and oxidative conditions is an emerging field in the management of several neurodegenerative and neuropsychiatric disorders. Thus, antioxidants could be promising as an adjuvant ADHD therapy.

Atomoxetine produces oxidative stress and alters mitochondrial function in human neuron-like cells

Atomoxetine (ATX) is a non-stimulant drug used in the treatment of attention-deficit/hyperactivity disorder (ADHD) and is a selective norepinephrine reuptake inhibitor. It has been shown that ATX has additional effects beyond the inhibition of norepinephrine reuptake, affecting several signal transduction pathways and alters gene expression. Here, we study alterations in oxidative stress and mitochondrial function in human differentiated SH-SY5Y cells exposed over a range of concentrations of ATX. We found that the highest concentrations of ATX in neuron-like cells, caused cell death and an increase in cytosolic and mitochondrial reactive oxygen species, and alterations in mitochondrial mass, membrane potential and autophagy. Interestingly, the dose of 10 μM ATX increased mitochondrial mass and decreased autophagy, despite the induction of cytosolic and mitochondrial reactive oxygen species. Thus, ATX has a dual effect depending on the dose used, indicating that ATX produces additional active therapeutic effects on oxidative stress and on mitochondrial function beyond the inhibition of norepinephrine reuptake.

Vitamin D receptor activation regulates microglia polarization and oxidative stress in spontaneously hypertensive rats and angiotensin II-exposed microglial cells: Role of renin-angiotensin system

Hypertension is one of the major predisposing factors for neurodegenerative disease characterized with activated renin-angiotensin system (RAS) in both periphery and brain. Vitamin D (VitD) is recently recognized as a pleiotropic hormone with strong neuroprotective properties. While multiple lines of evidence suggest that VitD can act on RAS, the evidence concerning the crosstalk between VitD and RAS in the brain is limited. Therefore, this study aims to evaluate whether VitD can modulate brain RAS to trigger neuroprotective actions in the brain of spontaneously hypertensive rats (SHR). Our data showed that calcitriol treatment induced VDR expression and inhibited neural death in the prefrontal cortex of SHR. Sustained calcitriol administration also inhibited microglia M1 polarization, but enhanced M2 polarization, accompanied with decreased expression of proinflammatory cytokines. We then further explored the potential mechanisms and showed that SHR exhibited overactivated classical RAS with increased expression of angiotensin II (Ang II) receptor type 1 (AT1), angiotensin converting enzyme (ACE) and Ang II production, whereas the counteracting arm of traditional RAS, ACE2/Ang(1-7)/MasR, was impaired in the SHR brain. Calcitriol nonsignificantly suppressed AT1 and ACE but markedly reduced Ang II formation. Intriguingly, calcitriol exerted pronouncedly impact on ACE2/Ang(1-7)/MasR axis with enhanced expression of ACE2, MasR and Ang(1-7) generation. Meanwhile, calcitriol ameliorated the overactivation of NADPH-oxidase (Nox), the downstream of RAS, in SHR, and also mitigated oxidative stress. In microglial (BV2) cells, we further found that calcitriol induced ACE2 and MasR with no significant impact on ACE and AT1. In accordance, calcitriol also attenuated Ang II-induced Nox activation and ROS production, and shifted the microglia polarization from M1 to M2 phenotype. However, co-treatment with A779, a specific MasR antagonist, abrogated the antioxidant and neuroimmune modulating actions of VitD. These findings strongly indicate the involvement of ACE2/Ang(1-7)/MasR pathway in the neuroprotective mechanisms of VitD in the hypertensive brain.

Relationship between Antioxidant Status and Attention Deficit Hyperactivity Disorder Among Children

Background:

Attention deficit hyperactivity disorder (ADHD) is one of the prevalent neuropsychiatric disorders in childhood. In general, diagnoses of ADHD include inattention, hyperactivity, and impulsivity. Recent studies have reported increased oxidative stress in psychiatric disorders such as ADHD, but the results are conflicting. This research aimed to study the relationship between antioxidant status and ADHD in children of 6–13 years old.

Methods:

From schools, 32 ADHD students whose diseases were diagnosed by child and adolescence psychiatrist based on Diagnostic and Statistical Manual of Mental Disorders-IV index were recruited; moreover, 32 healthy subjects, which according to the medical history questionnaire of psychiatric disorder had not had chronic disease, were selected. Total antioxidant capacity (TAC), catalase (CAT), glutathione (GSH), and malondiadehyde (MDA) were measured. General information, health history, and medication history were collected. All participants completed a 168-item food frequency questionnaire. Dietary intakes of antioxidants were obtained through this questionnaire.

Results:

There was no significant difference between mean of energy intake and Zn, Se, vitamin E, C, and β-carotene as antioxidants between the two groups. The mean of serum TAC, GSH level, and CAT level in the patients were significantly lower than the healthy group (P < 0.001), but the mean of MDA was not significantly different between the two groups (P = 0.18).

Conclusions:

The result of this study indicates that, in ADHD, the serum levels of GSH, CAT, and TAC decrease; the level of antioxidant in the serum has been compromised to fight oxidative stress. More perspective studies with large sample sizes are essential to confirm these findings.

Therapeutic Potential of Exogenous Ketone Supplement Induced Ketosis in the Treatment of Psychiatric Disorders: Review of Current Literature

Globally, psychiatric disorders, such as anxiety disorder, bipolar disorder, schizophrenia, depression, autism spectrum disorder, and attention-deficit/hyperactivity disorder (ADHD) are becoming more prevalent. Although the exact pathological alterations are not yet clear, recent studies have demonstrated that widespread changes of very complex metabolic pathways may partially underlie the pathophysiology of many psychiatric diseases. Thus, more attention should be directed to metabolic-based therapeutic interventions in the treatment of psychiatric disorders. Emerging evidence from numerous studies suggests that administration of exogenous ketone supplements, such as ketone salts or ketone esters, generates rapid and sustained nutritional ketosis and metabolic changes, which may evoke potential therapeutic effects in cases of central nervous system (CNS) disorders, including psychiatric diseases. Therefore, the aim of this review is to summarize the current information on ketone supplementation as a potential therapeutic tool for psychiatric disorders. Ketone supplementation elevates blood levels of the ketone bodies: D-β-hydroxybutyrate (βHB), acetoacetate (AcAc), and acetone. These compounds, either directly or indirectly, beneficially affect the mitochondria, glycolysis, neurotransmitter levels, activity of free fatty acid receptor 3 (FFAR3), hydroxycarboxylic acid receptor 2 (HCAR2), and histone deacetylase, as well as functioning of NOD-like receptor pyrin domain 3 (NLRP3) inflammasome and mitochondrial uncoupling protein (UCP) expression. The result of downstream cellular and molecular changes is a reduction in the pathophysiology associated with various psychiatric disorders. We conclude that supplement-induced nutritional ketosis leads to metabolic changes and improvements, for example, in mitochondrial function and inflammatory processes, and suggest that development of specific adjunctive ketogenic protocols for psychiatric diseases should be actively pursued.

The Therapeutic Effect of the Chinese Herbal Medicine, Rehmanniae Radix Preparata, in Attention Deficit Hyperactivity Disorder via Reversal of Structural Abnormalities in the Cortex

Rehmanniae radix preparata is extracted from wine-steaming the Rehmannia root, a scrophulariaceae plant. It has been used for thousands of years with effects of nourishing kidney-yin, benefiting essence and filling marrow based on traditional Chinese medicine (TCM) theory. Rehmanniae radix preparata has antioxidant, antisenescence, anti-inflammatory, and neuroprotective properties. It is the most popular Traditional Chinese medicinal compound (TCMC) used in attention deficit hyperactivity disorder (ADHD) therapy. However, few studies have been conducted exploring the effects and potential mechanisms of Rehmanniae radix preparata alone on ADHD. Recent studies have shown that Rehmanniae radix preparata inhibits spontaneous activity in mice, improves learning and memory in rats following thalamic arcuate nucleus injury, and exhibits antidepressant effects. Catalpol, an active component of Rehmanniae radix preparata, elevates brain-derived neurotrophic factor (BDNF), and attenuates neuronal apoptosis and energy metabolism failure. ADHD is characterized by hyperactivity-impulsivity and impairments in learning and memory. Its pathomechanism is closely related to structural abnormalities in the cortex that is mediated by dysfunction in neuronal development, apoptosis, and energy metabolism. We hypothesize that Rehmanniae radix preparata may be effective at treating ADHD by alleviating neurodevelopmental abnormalities, neuronal apoptosis, and energy metabolism failure.

Why is there selective subcortical vulnerability in ADHD? Clues from postmortem brain gene expression data

Sub-cortical volumetric differences were associated with attention-deficit/hyperactivity disorder (ADHD) in a recent multi-site, mega-analysis of 1713 ADHD persons and 1529 controls. As there was a wide range of effect sizes among the sub-cortical volumes, it is possible that selective neuronal vulnerability has a role in these volumetric losses. To address this possibility, we used data from Allen Brain Atlas to investigate variability in gene expression profiles between subcortical regions of typically developing brains. We tested the hypothesis that the expression of genes in a set of curated ADHD candidate genes and five a priori selected, biological pathways would be associated with the Enhancing NeuroImaging Genetics through Meta-Analysis (ENIGMA) findings. Across the subcortical regions studied by ENIGMA, gene expression profiles for three pathways were significantly correlated with ADHD-associated volumetric reductions: apoptosis, oxidative stress and autophagy. These correlations were strong and significant for children with ADHD, but not for adults. Although preliminary, these data suggest that variability of structural brain anomalies in ADHD can be explained, in part, by the differential vulnerability of these regions to mechanisms mediating apoptosis, oxidative stress and autophagy.

The link of organophosphorus pesticides with neurodegenerative and neurodevelopmental diseases based on evidence and mechanisms

Organophosphorus (OP) compounds have been known as the most widely used pesticides during the past half century and there have been a huge body of literature regarding their association with human chronic diseases. Neurodegenerative and neurodevelopmental disorders including Alzheimer, Parkinson, amyotrophic lateral sclerosis (ALS), attention deficit hyperactivity disorder (ADHD), and autism are among the afflicting neurological diseases which overshadow human life and their higher risk in relation to OP exposures have been uncovered by epidemiological studies. In addition, experimental studies exploring the underlying mechanisms have provided some evidence for involvement of cholinergic deficit, oxidative stress, neuro-inflammation, and epigenetic modifications as the processes which are common in the toxicity of the OP and pathophysiology of the mentioned diseases. In addition, genetic mutations and polymorphisms of different variants of some genes like paraoxonase have been shown to be implicated in both susceptibility to OPs toxicity and neurological diseases. In this article, we reviewed the epidemiological as well as experimental studies evidencing the association of exposure to OPs and incidence of neurodegenerative and neurodevelopmental diseases.

Prenatal paracetamol exposure and child neurodevelopment: A review

BACKGROUND

The non-prescription medication paracetamol (acetaminophen, APAP) is currently recommended as a safe pain and fever treatment during pregnancy. However, recent studies suggest a possible association between APAP use in pregnancy and offspring neurodevelopment.

OBJECTIVES

To conduct a review of publications reporting associations between prenatal APAP use and offspring neurodevelopmental outcomes.

METHODS

Relevant sources were identified through a key word search of multiple databases (Medline, CINAHL, OVID and TOXNET) in September 2016. All English language observational studies of pregnancy APAP and three classes of neurodevelopmental outcomes (autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), and intelligence quotient (IQ)) were included. One reviewer (AZB) independently screened all titles and abstracts, extracted and analyzed the data.

RESULTS

64 studies were retrieved and 55 were ineligible. Nine prospective cohort studies fulfilled all inclusion criteria. Data pooling was not appropriate due to heterogeneity in outcomes. All included studies suggested an association between prenatal APAP exposure and the neurodevelopmental outcomes; ADHD, ASD, or lower IQ. Longer duration of APAP use was associated with increased risk. Associations were strongest for hyperactivity and attention-related outcomes. Little modification of associations by indication for use was reported.

CONCLUSIONS

Together, these nine studies suggest an increased risk of adverse neurodevelopmental outcomes following prenatal APAP exposure. Further studies are urgently needed with; precise indication of use and exposure assessment of use both in utero and in early life. Given the current findings, pregnant women should be cautioned against indiscriminate use of APAP. These results have substantial public health implications.