Distinct long non-coding RNA and mRNA expression profiles in the hippocampus of an attention deficit hyperactivity disorder model in spontaneously hypertensive rats and control wistar Kyoto rats

Effect of Short-Term Restraint Stress on the Hypothalamic Transcriptome Profiles of Rats with Inherited Stress-Induced Arterial Hypertension (ISIAH) and Normotensive Wistar Albino Glaxo (WAG) Rats

Emotional stress is one of the health risk factors in the modern human lifestyle. Stress exposure can provoke the manifestation of various pathological conditions, one of which is a sharp increase in the blood pressure level. In the present study, we analyzed changes in the transcriptome profiles of the hypothalamus of hypertensive ISIAH and normotensive WAG rats exposed to a single short-term restraint stress (the rat was placed in a tight wire-mesh cage for 2 h). This type of stress can be considered emotional stress. The functional annotation of differentially expressed genes allowed us to identify the most significantly altered biological processes in the hypothalamus of hypertensive and normotensive rats. The study made it possible to identify a group of genes that describe a general response to stress, independent of the rat genotype, as well as a hypothalamic response to stress specific to each strain. The alternatively changing expression of the Npas4 (neuronal PAS domain protein 4) gene, which is downregulated in the hypothalamus of the control WAG rats and induced in the hypothalamus of hypertensive ISIAH rats, is suggested to be the key event for understanding inter-strain differences in the hypothalamic response to stress. The stress-dependent ISIAH strain-specific induction of Fos and Jun gene transcription may play a crucial role in neuronal activation in this rat strain. The data obtained can be potentially useful in the selection of molecular targets for the development of pharmacological approaches to the correction of stress-induced pathologies related to neuronal excitability, taking into account the hypertensive status of the patients.

Evaluation of the Regulatory Role of Circadian Rhythm Related Long Non-Coding RNAs in ADHD Etiogenesis

OBJECTIVE

ADHD is associated with increased sleep problems and circadian rhythm disturbances. This study aimed to examine ADHD patients and healthy controls in terms of chronotypic features and expression levels of CLOCK, PER1, lncRNA HULC, lncRNA UCA1.

METHOD

Eighty-three children were included (43 ADHD). Conner's Parent Rating Scale-Revised Short Form, Childhood Chronotype Questionnaire, Children's Sleep Disorders Scale were administered. Gene expression levels were studied from peripheral blood.

RESULTS

Evening chronotype, sleep initiation/maintenance disorder, sleep-wake transition disorder, excessive sleepiness disorder were higher in the ADHD group compared to the controls in the scales reported by the parents. Expression levels of all examined genes were statistically significantly higher in the ADHD group. There was no significant relationship between genes and sleep parameters in the ADHD group.

CONCLUSION

Our study provides the first evidence that lncRNA HULC and lncRNA UCA1 might have a role in the etiology of ADHD.

Focus on your locus with a massively parallel reporter assay

A growing number of variants associated with risk for neurodevelopmental disorders have been identified by genome-wide association and whole genome sequencing studies. As common risk variants often fall within large haplotype blocks covering long stretches of the noncoding genome, the causal variants within an associated locus are often unknown. Similarly, the effect of rare noncoding risk variants identified by whole genome sequencing on molecular traits is seldom known without functional assays. A massively parallel reporter assay (MPRA) is an assay that can functionally validate thousands of regulatory elements simultaneously using high-throughput sequencing and barcode technology. MPRA has been adapted to various experimental designs that measure gene regulatory effects of genetic variants within cis- and trans-regulatory elements as well as posttranscriptional processes. This review discusses different MPRA designs that have been or could be used in the future to experimentally validate genetic variants associated with neurodevelopmental disorders. Though MPRA has limitations such as it does not model genomic context, this assay can help narrow down the underlying genetic causes of neurodevelopmental disorders by screening thousands of sequences in one experiment. We conclude by describing future directions of this technique such as applications of MPRA for gene-by-environment interactions and pharmacogenetics.

Vitamin A supplementation ameliorates prenatal valproic acid-induced autism-like behaviors in rats

INTRODUCTION

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by social deficits and repetitive stereotyped behaviors. Prenatal exposure to the anticonvulsant drug valproic acid (VPA) is reported to induce ASD in human and ASD-like phenotypes in rodents. Unfortunately, the etiology and pathogenesis of ASD remains unclear.

METHODS

Pregnant rats received an intraperitoneal injection of 600 mg/kg VPA on E12.5 to construct the ASD rat model in offspring. The different expression of long non-coding RNA (lncRNA) and mRNA profiles in the hippocampus were determined by RNA sequencing to investigate potential mechanisms of VPA-induced ASD. Gene Ontology (GO) and pathway enrichment analysis were performed to predict the function of dysregulated lncRNAs. Co-expression network and real-time polymerase chain reaction (RT-PCR) analysis were conducted to validate the potential regulatory lncRNA-mRNA network.

RESULTS

VPA increased the total distance, time spent in the central zone and self-grooming (open field test) in rats. Meanwhile, VPA induced social impairment (three-chamber sociability test) and repetitive behaviors (marble burying test). A total of 238 lncRNAs and 354 mRNAs were differentially expressed in the VPA group. In addition, the dysregulated lncRNAs were involved in neural function and developmental processes of ASD. 5 lncRNAs and 7 mRNAs were differently expressed and included in the lncRNA-mRNA co-expression network. RT-PCR confirmed the upregulation of 4 lncRNAs and 6 mRNAs, and identified a potential regulatory network of NONRATT021475.2 (lncRNA) and Desert hedgehog (Dhh). Moreover, VPA decreased the serum vitamin A (VA) levels in offspring rats on postnatal day (PND) 21 and 49. Importantly, VA supplementation significantly restored VPA-induced autism-related behaviors and upregulation of NONRATT021475.2 and Dhh in the hippocampus of ASD rats.

CONCLUSION

This study not only contributed to understand the importance of lncRNAs and mRNAs in the progression of ASD, but also identified VA as a potential therapy for the condition.

DATA AVAILABILITY

The data that support the findings of this study are available from the corresponding author with reasonable request.

The protective effect and potential mechanism of NRXN1 on learning and memory in ADHD rat models

The learning and memory network is highly complex and remains unclear. The hippocampus is the location of learning and memory function. Impairment of synaptic morphology and synaptic plasticity (i.e., long-term potentiation) appears to cause learning and memory deficits. Several studies have indicated the role of NRXN1 in regulating the synaptic function, but little is known on its role in learning and memory dysfunction associated with attention deficit and hyperactivity disorder (ADHD). Our results showed that overexpression and interference of NRXN1 in vivo, respectively, affected learning and memory, as was assessed by Morris water maze tests, in spontaneously hypertensive rats (SHRs) and Sprague Dawley (SD) rats. We found that SD rats performed better after methylphenidate (MPH) treatment in salvage trials. Accordingly, the change of NRXN1 led to altered synapse-related gene (PSD95, SYN1, GAP43, NLGN1) expression, further providing evidence of its role in the maintenance of synaptic plasticity. We also verified that the expression of synapse-related genes synchronously changed with NRXN1expression in the behavioral assessment. The expression of NRXN1 was confirmed to affect the expression of synapse-related genes after its interference and overexpression in the primary hippocampal neurons in vitro. These results confirmed our hypothesis that NRXN1 might nucleate an overall trans-synaptic signaling network that controls synaptic plasticity and is responsible for impairments in learning and memory in ADHD. These findings suggest a possible protective role of NRXN1 in learning and memory in ADHD. Further RNA-seq sequencing revealed significant differences in the expression of 5-hydroxytryptamine receptor (5-HT₆R), which was further verified at the cellular level, and the mechanism of NRXN1 affecting synaptic plasticity was preliminarily discussed.

A potential association of RNF219-AS1 with ADHD: Evidence from categorical analysis of clinical phenotypes and from quantitative exploration of executive function and white matter microstructure endophenotypes

AIMS

Attention-deficit/hyperactivity disorder (ADHD) is a neuropsychiatric disorder of substantial heritability, yet emerging evidence suggests that key risk variants might reside in the noncoding regions of the genome. Our study explored the association of lncRNAs (long noncoding RNAs) with ADHD as represented at three different phenotypic levels guided by the Research Domain Criteria (RDoC) framework: (i) ADHD caseness and symptom dimension, (ii) executive functions as functional endophenotype, and (iii) potential genetic influence on white matter architecture as brain structural endophenotype.

METHODS

Genotype data of 107 tag single nucleotide polymorphisms (SNP) from 10 candidate lncRNAs were analyzed in 1040 children with ADHD and 630 controls of Chinese Han descent. Executive functions including inhibition and set-shifting were assessed by STROOP and trail making tests, respectively. Imaging genetic analyses were performed in a subgroup of 33 children with ADHD and 55 controls using fractional anisotropy (FA).

RESULTS

One SNP rs3908461 polymorphism in RNF219-AS1 was found to be significantly associated with ADHD caseness: with C-allele detected as the risk genotype in the allelic model (P = 8.607E-05) and dominant genotypic model (P = 9.628E-05). Nominal genotypic effects on inhibition (p = 0.020) and set-shifting (p = 0.046) were detected. While no direct effect on ADHD core symptoms was detected, mediation analysis suggested that SNP rs3908461 potentially exerted an indirect effect through inhibition function [B = 0.21 (SE = 0.12), 95% CI = 0.02-0.49]. Imaging genetic analyses detected significant associations between rs3908461 genotypes and FA values in corpus callosum, left superior longitudinal fasciculus, left posterior limb of internal capsule, left posterior thalamic radiate (include optic radiation), and the left anterior corona radiate (P FWE corrected  < 0.05).

CONCLUSION

Our present study examined the potential roles of lncRNA in genetic etiological of ADHD and provided preliminary evidence in support of the potential RNF219-AS1 involvement in the pathophysiology of ADHD in line with the RDoC framework.