Pilot study indicate role of preferentially transmitted monoamine oxidase gene variants in behavioral problems of male ADHD probands

Effect of MAOA rs1465108 polymorphism on susceptibility to substance/alcohol use disorder: a novel PCR-RFLP assay for the detection of MAOA rs1465108

BACKGROUND

The health and social consequences of substance/alcohol use disorders are harmful. Most of the individuals cannot stop using them due to more likely their genetic background. The current study aimed both to develop a novel PCR-RFLP method for genotyping of MAOA rs1465108 and to analyze the effect of MAOA rs1465108 on the risk of alcohol (AUD), opioid (OUD) or methamphetamine (MUD) use disorders and on the depressive and anxiety symptoms in a Turkish population.

METHODS AND RESULTS

A total of 353 individual with AUD (n = 154), OUD (n = 160) or MUD (n = 39) and 109 healthy subjects were included. The intensity of anxiety and depressive symptoms and craving and opioid withdrawal were measured by appropriate scales. Logistic regression analysis revealed no association between MAOA rs1465108 polymorphism and substance/alcohol use disorder (p > 0.05). Healthy subjects (3.0) had significantly lower levels of depressive symptoms than individuals with OUD (27.0), AUD (21.0) and MUD (25.5) groups. The severity of depressive symptoms was significantly higher in OUD as compared to AUD. There was a statistically significant difference between individuals with AUD, OUD and MUD in view of the average ages of first use (17, 19 and 20 years, respectively) (p < 0.05).

CONCLUSIONS

The results presented here do not support the hypothesis that MAOA rs1465108 is associated with substance/alcohol use disorders. The intensity of depressive symptoms could be changed according to the abused substance type. A novel PCR-RFLP was developed for genotyping of MAOA rs1465108 polymorphism, which could be a better option for laboratories without high technology equipment.

A three-pronged analysis confirms the association of the serotoninergic system with attention deficit hyperactivity disorder

BACKGROUND

The serotonin transporter (SERT), encoded by the solute carrier family 6 number 4 (SLC6A4) gene, controls serotonin (5-HT) availability and is essential for the regulation of behavioral traits. Two SLC6A4 genetic variants, 5-HTTLPR and STin2, were widely investigated in patients with various neurobehavioral disorders, including attention deficit hyperactivity disorder (ADHD).

METHODS

We analyzed the association of the 5-HTTLPR (L/S) and STin2 (10/12) variants, plasma 5-HT, and 5-hydroxyindole acetic acid (5-HIAA), as well as SERT messenger RNA (mRNA) with ADHD in the eastern Indian subjects. Nuclear families with ADHD probands (n = 274) and ethnically matched controls (n = 367) were recruited following the Diagnostic and Statistical Manual of Mental Disorders. Behavioral traits, executive function, and intelligence quotient (IQ) of the probands were assessed using the Conner's Parent Rating Scale - Revised, Parental Account of Children's Symptoms (PACS), Barkley Deficit in Executive Functioning-Child and Adolescent Scale, and Wechsler Intelligence Scale for Children-III, respectively. After obtaining informed written consent, peripheral blood was collected to analyze genetic variants, plasma 5-HT, 5-HIAA, and SERT mRNA expression.

RESULTS

ADHD probands showed a higher frequency of the 5-HTTLPR "L" allele and "L/L" genotype (P < 0.05), lower 5-HIAA level, and higher SERT mRNA expression. Scores for behavioral problems and hyperactivity were higher in the presence of the "S" allele and "S/S" genotype, while executive deficit was higher in the presence of the "L" allele. IQ score was lower in the presence of the STin2 "12" allele and L-12 haplotype.

CONCLUSION

Data obtained indicate a significant association of the serotoninergic system with ADHD, warranting further in-depth investigation.

“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.

ADHD co-morbidities: A review of implication of gene × environment effects with dopamine-related genes

ADHD is a major burden in adulthood, where co-morbid conditions such as depression, substance use disorder and obesity often dominate the clinical picture. ADHD has substantial shared heritability with other mental disorders, contributing to comorbidity. However, environmental risk factors exist but their interaction with genetic makeup, especially in relation to comorbid disorders, remains elusive. This review for the first time summarizes present knowledge on gene x environment (GxE) interactions regarding the dopamine system. Hitherto, mainly candidate (GxE) studies were performed, focusing on the genes DRD4, DAT1 and MAOA. Some evidence suggest that the variable number tandem repeats in DRD4 and MAOA may mediate GxE interactions in ADHD generally, and comorbid conditions specifically. Nevertheless, even for these genes, common variants are bound to suggest risk only in the context of gender and specific environments. For other polymorphisms, evidence is contradictory and less convincing. Particularly lacking are longitudinal studies testing the interaction of well-defined environmental with polygenic risk scores reflecting the dopamine system in its entirety.

Attention deficit/hyperactivity disorder in adults: A case study

Attention-Deficit/Hyperactivity Disorder (ADHD) is often misdiagnosed or mistreated in adults because it is often thought of as a childhood problem. If a child is diagnosed and treated for the disorder, it often persists into adulthood. In adult ADHD, the symptoms may be comorbid or mimic other conditions making diagnosis and treatment difficult. Adults with ADHD require an in-depth assessment for proper diagnosis and treatment. The presentation and treatment of adults with ADHD can be complex and often requires interdisciplinary care. Mental health and non-mental health providers often overlook the disorder or feel uncomfortable treating adults with ADHD. The purpose of this manuscript is to discuss the diagnosis and management of adults with ADHD.

Biosynthesis and Characterization of Zinc Oxide Nanoparticles and Their Impact on the Composition of Gut Microbiota in Healthy and Attention-Deficit Hyperactivity Disorder Children

Attention-deficit hyperactivity disorder (ADHD) seriously affects children’s health, and the gut microbiome has been widely hypothesized to play a role in the regulation of ADHD behavior. The present study aims to the biosynthesize of zinc oxide nanoparticles (ZnONPs) by using Acinetobacter johnsonii strain RTN1, followed by their characterization through state-of-the-art material characterization techniques, viz., UV–vis spectroscopy, Fourier transform infrared spectroscopy, and transmission and scanning electron microscopic analyses with energy dispersive spectrometry. Moreover, we investigated and compared the population composition of gut microbiota and their susceptibility to biogenic ZnONPs between healthy and ADHD children based on the traditional plate method and 16S rRNA amplicon sequence analysis. The antibacterial effect of ZnONPs against gut bacteria was also determined by measurement of live cell number, living/dead bacterial staining test, and flow cytometry observation. The present study revealed that the number of live gut bacteria in healthy children was more than 10-fold higher than that in ADHD children; however, the community structure of gut bacteria has changed, while greater diversity was found in gut bacteria from ADHD children. In addition, we found that the number of live gut bacteria in healthy and ADHD children was reduced by ZnONPs, which shows an increased and reduced effect in composition of gut bacteria from healthy and ADHD children, respectively. It was also noted that the main mechanism of ZnONPs may be to inhibit the growth of gut bacteria rather than to kill them, while the nanoparticle-resistant strains in healthy children is also different from that in ADHD children. Some representative bacteria, in particular nanoparticle-resistant bacteria, were successfully isolated and identified. Overall, this study revealed the potential correlation of ADHD with gut bacteria and provided a new possibility to prevent ADHD by the combination of nanoparticle and its resistant bacteria.

Case-Control Study of the Effects of Gut Microbiota Composition on Neurotransmitter Metabolic Pathways in Children With Attention Deficit Hyperactivity Disorder

Background

Attention-deficit/hyperactivity disorder (ADHD) is a neuropsychiatric condition that may be related to an imbalance of neural transmitters. The gut microbiota is the largest ecosystem in the human body, and the brain-gut axis theory proposes that the gut microbiome can affect brain function in multiple ways. The purpose of this study was to explore the gut microbiota in children with ADHD and assess the possible role of the gut microbiota in disease pathogenesis to open new avenues for ADHD treatment.

Methods

A case-control design was used. We enrolled 17 children aged 6-12 years with ADHD who were treated in the Pediatric Outpatient Department of the First Medical Center of the Chinese PLA General Hospital from January to June, 2019. Seventeen children aged 6-12 years were selected as the healthy control (HC) group. Fecal samples of cases and controls were analyzed by shotgun metagenomics sequencing. Alpha diversity and the differences in the relative abundances of bacteria were compared between the two groups. Functional annotations were performed for the microbiota genes and metabolic pathways were analyzed using the Kyoto Encyclopedia of Genes and Genomes (KEGG).

Results

There was no significant difference in the alpha diversity of gut microbiota between the ADHD and HC groups. Compared with HCs, Faecalibacterium and Veillonellaceae were significantly reduced in children with ADHD (P < 0.05), Odoribacter and Enterococcus were significantly increased [linear discriminant analysis (LDA) > 2]. At the species level, Faecalibacterium prausnitzii, Lachnospiraceae bacterium, and Ruminococcus gnavus were significantly reduced in the ADHD group (P < 0.05), while Bacteroides caccae, Odoribacter splanchnicus, Paraprevotella xylaniphila, and Veillonella parvula were increased (P < 0.05). Metabolic pathway analysis revealed significant between-group differences in the metabolic pathways of neurotransmitters (e.g., serotonin and dopamine) (P < 0.05).

Conclusion

Composition differences of gut microbiota in subjects with ADHD may contribute to brain-gut axis alterations and affect neurotransmitter levels, which could contribute to ADHD symptoms.

miR-522 facilitates the prosperities of endometrial carcinoma cells by directly binding to monoamine oxidase B

It is well known that microRNAs (miRNAs) are crucial regulatory factors in tumorigenesis, as tumor suppressors or cancer-promoting factors. However, the study of endometrial carcinoma relevance in miR-522 is rare, indicating an undefined molecular mechanism for its role. Therefore, we performed this study to examine the role of miR-522 on the biological behaviors of endometrial carcinoma. In this work, we found that miR-522 was highly expressed in endometrial carcinoma and negatively regulated monoamine oxidase B (MAOB) expression. They also have the opposite effect on prognosis of endometrial carcinoma patients. More importantly, miR-522 could decreased MAOB expression by binding to MAOB with a putative site, thereby promoting cell proliferation, migration, and invasion through in vitro functional analyses, including MTT assay, wound-healing and transwell invasion experiments. Upregulation of MAOB rescued the impacts of miR-522 mimic on cell behaviors. In conclusion, our observations demonstrated that miR-522 accelerated the progression of endometrial carcinoma by inhibiting MAOB, which might lead to a novel therapeutic therapy for endometrial carcinoma.

Association of Monoamine Oxidase A (MAOA) Gene uVNTR and rs6323 Polymorphisms with Attention Deficit and Hyperactivity Disorder in Korean Children

Objective: Attention deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder. The genetic cause of ADHD is still unclear, but the dopaminergic, serotonergic, and noradrenergic pathways have shown a strong association. In particular, monoamine oxidase A (MAOA) plays an important role in the catabolism of these neurotransmitters, suggesting that the MAOA gene is associated with ADHD. Therefore, we evaluated the relationship between the MAOA gene polymorphisms (uVNTR and rs6323) and ADHD. Materials and methods: We collected a total of 472 Korean children (150 ADHD cases and 322 controls) using the Korean version of the Dupaul Attention Deficit Hyperactivity Disorder Rating Scales (K-ARS). Genotyping was performed by PCR and PCR-RFLP. The Behavior Assessment System for Children Second Edition (BASC-2) was used to evaluate the problem behaviors within ADHD children. Results: We observed significant associations between the rs6323 and ADHD in girls (p < 0.05) and the TT genotype was observed as a protective factor against ADHD in the recessive model (OR 0.31, 95% CI 0.100⁻0.950, p = 0.022). The 3.5R-G haplotype showed a significant association in ADHD boys (p = 0.043). The analysis of subtype also revealed that the 4.5R allele of uVNTR was a risk factor for the development of ADHD in the combined symptom among girls (OR 1.87, 95% CI 1.014⁻3.453, p = 0.031). In the BASC-2 analysis, the MAOA uVNTR polymorphism was associated with activities of daily living in ADHD boys (p = 0.017). Conclusion: These results suggest the importance of the MAOA gene polymorphisms in the development of ADHD in Korean children. A larger sample set and functional studies are required to further elucidate of our findings.

From aggression to autism: new perspectives on the behavioral sequelae of monoamine oxidase deficiency

The two monoamine oxidase (MAO) enzymes, A and B, catalyze the metabolism of monoamine neurotransmitters, such as serotonin, norepinephrine, and dopamine. The phenotypic outcomes of MAO congenital deficiency have been studied in humans and animal models, to explore the role of these enzymes in behavioral regulation. The clinical condition caused by MAOA deficiency, Brunner syndrome, was first described as a disorder characterized by overt antisocial and aggressive conduct. Building on this discovery, subsequent studies were focused on the characterization of the role of MAOA in the neurobiology of antisocial conduct. MAO A knockout mice were found to display high levels of intermale aggression; however, further analyses of these mutants unveiled additional behavioral abnormalities mimicking the core symptoms of autism-spectrum disorder. These findings were strikingly confirmed in newly reported cases of Brunner syndrome. The role of MAOB in behavioral regulation remains less well-understood, even though Maob-deficient mice have been found to exhibit greater behavioral disinhibition and risk-taking responses, supporting previous clinical studies showing associations between low MAO B activity and impulsivity. Furthermore, lack of MAOB was found to exacerbate the severity of psychopathological deficits induced by concurrent MAOA deficiency. Here, we summarize how the convergence of clinical reports and behavioral phenotyping in mutant mice has helped frame a complex picture of psychopathological features in MAO-deficient individuals, which encompass a broad spectrum of neurodevelopmental problems. This emerging knowledge poses novel conceptual challenges towards the identification of the endophenotypes shared by autism-spectrum disorder, antisocial behavior and impulse-control problems, as well as their monoaminergic underpinnings.