Altered expression of glycan patterns and glycan-related genes in the medial prefrontal cortex of the valproic acid rat model of autism.

Autism spectrum disorders (ASD) represent a group of neurodevelopmental defects characterized by social deficits and repetitive behaviors. Alteration in Glycosylation patterns could influence the nervous system development and contribute to the molecular mechanism of ASD. Interaction of environmental factors with susceptible genes may affect expressions of glycosylation-related genes and thus result in abnormal glycosylation patterns. Here, we used an environmental factor-induced model of autism by a single intraperitoneal injection of 400 mg/kg valproic acid (VPA) to female rats at day 12.5 post-conception. Following confirmation of reduced sociability and increased self-grooming behaviors in VPA-treated offspring, we analyzed the alterations in the expression profile of glycan patterns and glycan-related genes by lectin microarrays and RNA-seq, respectively. Lectin microarrays detected 14 significantly regulated lectins in VPA rats, with an up-regulation of high-mannose with antennary and down-regulation of Siaα2-3 Gal/GalNAc. Based on the KEGG and CAZy resources, we assembled a comprehensive list of 961 glycan-related genes to focus our analysis on specific genes. Of those, transcription results revealed that there were 107 differentially expressed glycan-related genes (DEGGs) after VPA treatment. Functional analysis of DEGGs encoding anabolic enzymes revealed that the process trimming to form core structure and glycan extension from core structure primarily changed, which is consistent with the changes in glycan patterns. In addition, the DEGGs encoding glycoconjugates were mainly related to extracellular matrix and axon guidance. This study provides insights into the underlying molecular mechanism of aberrant glycosylation after prenatal VPA exposure, which may serve as potential biomarkers for the autism diagnosis.

Differential Alterations in Striatal Direct and Indirect Pathways Mediate Two Autism-like Behaviors in Valproate-Exposed Mice.

Autism is characterized by two key diagnostic criteria including social deficits and repetitive behaviors. Although recent studies implicated ventral striatum in social deficits and dorsal striatum in repetitive behaviors, here we revealed coexisting and opposite morphologic and functional alterations in the dorsostriatal direct and indirect pathways, and such alterations in these two pathways were found to be responsible, respectively, for the two abovementioned different autism-like behaviors exhibited by male mice prenatally exposed to valproate. The alteration in direct pathway was characterized by a potentiated state of basal activity, with impairment in transient responsiveness of D1-MSNs during social exploration. Concurrent alteration in indirect pathway was a depressed state of basal activity, with enhancement in transient responsiveness of D2-MSNs during repetitive behaviors. A causal relationship linking such differential alterations in these two pathways to the coexistence of these two autism-like behaviors was demonstrated by the cell type-specific correction of abnormal basal activity in the D1-MSNs and D2-MSNs of valproate-exposed mice. The findings support those differential alterations in two striatal pathways mediate the two coexisting autism-like behavioral abnormalities, respectively. This result will help in developing therapeutic options targeting these circuit alterations.SIGNIFICANCE STATEMENT Autism is characterized by two key diagnostic criteria including social deficits and repetitive behaviors. Although a number of recent studies have implicated ventral striatum in social deficits and dorsal striatum in repetitive behaviors, but social behaviors need to be processed by a series of actions, and repetitive behaviors, especially the high-order repetitive behaviors such as restrictive interests, have its scope to cognitive and emotional domains. The current study, for the first time, revealed that prenatal valproate exposure induced coexisting and differential alterations in the dorsomedial striatal direct and indirect pathways, and that these alterations mediate the two coexisting autism-like behavioral abnormalities, respectively. This result will help in developing therapeutic options targeting these circuit alterations to address the behavioral abnormalities.

Acute cannabinoids impair association learning via selectively enhancing synaptic transmission in striatonigral neurons.

BACKGROUND: Cannabinoids and their derivatives attract strong interest due to the tremendous potential of their psychoactive effects for treating psychiatric disorders and symptoms. However, their clinical application is restricted by various side-effects such as impaired coordination, anxiety, and learning and memory disability. Adverse impact on dorsal striatum-dependent learning is an important side-effect of cannabinoids. As one of the most important forms of learning mediated by the dorsal striatum, reinforcement learning is characterized by an initial association learning phase, followed by habit learning. While the effects of cannabinoids on habit learning have been well-studied, little is known about how cannabinoids influence the initial phase of reinforcement learning. RESULTS: We found that acute activation of cannabinoid receptor type 1 (CB1R) by the synthetic cannabinoid HU210 induced dose-dependent impairment of association learning, which could be alleviated by intra-dorsomedial striatum (DMS) injection of CB1R antagonist. Moreover, acute exposure to HU210 elicited enhanced synaptic transmission in striatonigral "direct" pathway medium spiny neurons (MSNs) but not indirect pathway neurons in DMS. Intriguingly, enhancement of synaptic transmission that is also observed after learning was abolished by HU210, indicating cannabinoid system might disrupt reinforcement learning by confounding synaptic plasticity normally required for learning. Remarkably, the impaired response-reinforcer learning was also induced by selectively enhancing the D1-MSN (MSN that selectively expresses the dopamine receptor type 1) activity by virally expressing excitatory hM3Dq DREADD (designer receptor exclusively activated by a designer drug), which could be rescued by specifically silencing the D1-MSN activity via hM4Di DREADD. CONCLUSION: Our findings demonstrate dose-dependent deleterious effects of cannabinoids on association learning by disrupting plasticity change required for learning associated with the striatal direct pathway, which furthers our understanding of the side-effects of cannabinoids and the underlying mechanisms.

Progranulin promotes hippocampal neurogenesis and alleviates anxiety-like behavior and cognitive impairment in adult mice subjected to cerebral ischemia.

AIMS: Cerebral ischemia can lead to anxiety and cognitive impairment due to the loss of hippocampal neurons. Facilitation of endogenous neurogenesis in the hippocampus is a potential therapeutic strategy for alleviating ischemia-induced anxiety and cognitive impairment. Progranulin (PGRN), a secretory glycoprotein, has been reported to have a mitogentic effect on many cell types. However, it is not clear whether PGRN enhances hippocampal neurogenesis and promotes functional recovery. METHODS: Adult male C57BL/6 mice were subjected to permanent middle cerebral artery occlusion (pMCAO) and injected intracerebroventricularly with recombinant mouse PGRN 30 min after pMCAO. Anxiety-like behavior was detected by the open field and the elevated plus maze tests, and spatial learning and memory abilities were evaluated by Morris water maze. Neurogenesis was examined by double labeling of BrdU and neural stem cells or neurons markers. For mechanism studies, the level of ERK1/2 and AKT phosphorylation were assessed by western blotting. RESULTS: Progranulin significantly alleviated anxiety-like behavior and spatial learning and memory impairment induced by cerebral ischemia in mice. Consistent with the functional recovery, PGRN promoted neural stem cells (NSCs) proliferation and neuronal differentiation in the dentate gyrus (DG) after cerebral ischemia. PGRN upregulated the expression of phosphorylated ERK1/2 and Akt in the DG after cerebral ischemia. CONCLUSIONS: Progranulin alleviates ischemia-induced anxiety-like behavior and spatial learning and memory impairment in mice, probably via stimulation of hippocampal neurogenesis mediated by activation of MAPK/ERK and PI3K/Akt pathways. PGRN might be a promising candidate for coping with ischemic stroke-induced mood and cognitive impairment in clinic.

The Association between 5-Hydroxytryptamine Receptor 1B rs13212041 Polymorphism and Trait Anxiety in Chinese Han College Subjects.

Trait anxiety is a vulnerable personality factor for anxiety and depression. High levels of trait anxiety confer an elevated risk for the development of anxiety and other psychiatric disorders. There is evidence that 5-hydroxytryptamine receptor 1B (5-HT1B) gene polymorphisms play an important role in emotional disorders. Genotyping for four single-nucleotide polymorphisms (SNP) (rs11568817, rs130058, rs6297, and rs13212041) was conducted for 388 high trait anxious (HTA) individuals and 463 low traitanxious (LTA) individuals in Chinese Han college subjects. The results showed that the frequencies of the C-allele and TC + CC genotype of rs13212041 in the LTA individuals were higher than that in the HTA individuals (p = 0.025 and p = 0.014, respectively). Both the C-allele and TC + CC genotype were associated with trait anxiety decreasing (OR = 0.771 and OR = 0.71, respectively). Furthermore, different gene model analysis also showed that the C allele was a protective factor for trait anxiety in Chinese Han college subjects. These findings suggest that 5-HT1B rs13212014 may play a role in trait anxiety among China Han college subjects. The rs13212014 polymorphism may be involved in decreasing the risk of trait anxiety. These results also provide a novel insight into the molecular mechanism underlying trait anxiety.

Involvement of Midbrain Dopamine Neuron Activity in Negative Reinforcement Learning in Mice.

The activity of the midbrain dopamine system reflects the valence of environmental events and modulates various brain structures to modify an organism's behavior. A series of recent studies reported that the direct and indirect pathways in the striatum are critical for instrumental learning, but the dynamic changes in dopamine neuron activity that occur during negative reinforcement learning are still largely unclear. In the present study, by using a negative reinforcement learning paradigm employing foot shocks as aversive stimuli, bidirectional changes in substantia nigra pars compacta (SNc) dopamine neuron activity in the learning and habituation phases were observed. The results showed that in the learning phase, before mice had mastered the skill of escaping foot shocks, the presence of foot shocks induced a transient reduction in the activity of SNc dopamine neurons; however, in the habituation phase, in which the learned skill was automated, it induced a transient increase. Microinjection of a dopamine D1 receptor (D1R) or D2 receptor (D2R) antagonist into the dorsomedial striatum (DMS) significantly impaired learning behavior, suggesting that the modulatory effects of dopamine on both the direct and indirect pathways are required. Moreover, during the learning phase, excitatory synaptic transmission to DMS D2R-expressing medium spiny neurons (D2-MSNs) was potentiated. However, upon completion of the learning and habituation phases, the synapses onto D1R-expressing medium spiny neurons (D1-MSNs) were potentiated, and those onto D2-MSNs were restored to normal levels. The bidirectional changes in both SNc dopamine neuron activity and DMS synaptic plasticity might be the critical neural correlates for negative reinforcement learning.

Stress Controllability Modulates Basal Activity of Dopamine Neurons in the Substantia Nigra Compacta.

Prolonged stress induces neural maladaptations in the mesolimbic dopamine (DA) system and produces emotional and behavioral disorders. However, the effects of stress on activity of DA neurons are diverse and complex that hinge on the type, duration, intensity, and controllability of stressors. Here, controlling the duration, intensity, and type of the stressors to be identical, we observed the effects of stressor controllability on the activity of substantia nigra pars compacta (SNc) DA neurons in mice. We found that both lack and loss of control (LOC) over shock enhance the basal activity and intrinsic excitability of SNc DA neurons via modulation of Ih current, but not via corticosterone serum level. Moreover, LOC over shock produces more significant enhancement in the basal activity of SNc DA neurons than that produced by shock per se, and therefore attenuates the response to natural reward. This attenuation can be reversed by control over shock. These results indicate that although chronic stress per se tends to enhance the basal activity of SNc DA neurons, LOC over the stressor is able to induce a larger enhancement in the basal activity of SNc DA neurons and produce more severe behavioral deficits. However, control over stress ameliorates the deleterious effects of stress, highlighting the role of stress controllability.

Maternal folic acid supplementation prevents autistic behaviors in a rat model induced by prenatal exposure to valproic acid.

Maternal vitamin supplementation has been demonstrated to reduce the risks of a number of neurodevelopmental diseases in children. Autism spectrum disorder (ASD) is a group of neurodevelopment defects with high prevalence but without satisfactory therapy. The present work detected the effects of pregnancy supplementation with folic acid (FA) at different doses on rat models of ASD induced by prenatal exposure to valproic acid (VPA), an anti-epileptic increasing the risk of ASD when administered during pregnancy. The results show that maternal FA supplementation at a high dose (4 mg kg-1) prevented the delay in growth and development, and the deficits in social communicative behaviors and repetitive behaviors, possibly by restoring the increased dendritic spine density and rectifying the over-expression of synaptic proteins associated with excitatory neurons and the lower expression with inhibitory ones. The results provided experimental evidence suggesting a possible role of maternal FA supplementation in preventing ASD.

Single Exposure to Cocaine Impairs Reinforcement Learning by Potentiating the Activity of Neurons in the Direct Striatal Pathway in Mice.

Plasticity in the glutamatergic synapses on striatal medium spiny neurons (MSNs) is not only essential for behavioral adaptation but also extremely vulnerable to drugs of abuse. Modulation on these synapses by even a single exposure to an addictive drug may interfere with the plasticity required by behavioral learning and thus produce impairment. In the present work, we found that the negative reinforcement learning, escaping mild foot-shocks by correct nose-poking, was impaired by a single in vivo exposure to 20 mg/kg cocaine 24 h before the learning in mice. Either a single exposure to cocaine or reinforcement learning potentiates the glutamatergic synapses on MSNs expressing the striatal dopamine 1 (D1) receptor (D1-MSNs). However, 24 h after the cocaine exposure, the potentiation required for reinforcement learning was disrupted. Specific manipulation of the activity of striatal D1-MSNs in D1-cre mice demonstrated that activation of these MSNs impaired reinforcement learning in normal D1-cre mice, but inhibition of these neurons reversed the reinforcement learning impairment induced by cocaine. The results suggest that cocaine potentiates the activity of direct pathway neurons in the dorsomedial striatum and this potentiation might disrupt the potentiation produced during and required for reinforcement learning.

Progranulin promotes functional recovery and neurogenesis in the subventricular zone of adult mice after cerebral ischemia.

Progranulin (PGRN), a secreted glycosylated protein, has been reported to attenuate ischemia-induced cerebral injury through anti-inflammation, attenuation of blood-brain barrier disruption and neuroprotection. However, the effect of PGRN on neurogenesis in the subventricular zone (SVZ) after cerebral ischemia remains unclear. In this study, adult C57BL/6 mice were subjected to permanent middle cerebral artery occlusion (pMCAO), and different doses of recombinant mouse PGRN (r-PGRN, 0.3 ng, 1 ng, 5 ng) were intracerebroventricularly administered 30 min after pMCAO. Results showed that 1 ng r-PGRN markedly reduced infarct volume and rescued functional deficits 24 h after pMCAO. Meanwhile, 1 ng r-PGRN increased SVZ cell proliferation, as shown by a high number of bromodeoxyuridine-positive (BrdU+) cells and Ki-67+ cells in the ischemic ipsilateral SVZ 7 d after pMCAO. Additionally, PGRN increased the percentage of BrdU+/Doublecortin (DCX)+ cells in the ipsilateral SVZ 14 d after pMCAO and increased the percentage of new neurons (BrdU+/NeuN+ cells) in the peri-infarct striatum 28 d after pMCAO, suggesting that PGRN promotes neuronal differentiation. PGRN also upregulated phosphorylation of ERK1/2 and Akt in the ipsilateral SVZ 3 d after pMCAO. Our data indicate that PGRN treatment promotes acute functional recovery; most importantly, it also stimulates neurogenesis in the SVZ, which could be beneficial for long-term recovery after cerebral ischemia. The increase in neurogenesis could be associated with activation of the MAPK/ERK and PI3K/Akt pathways. These results suggest a potential new strategy utilizing PGRN in ischemic stroke therapy.

Abnormal reinforcement learning in a mice model of autism induced by prenatal exposure to valproic acid.

Individuals with autism spectrum disorder (ASD) display dysfunction in learning from environmental stimulus that have positive or negative emotional values, posing obstacles to their everyday life. Unfortunately, mechanisms of the dysfunction are still unclear. Although early intervention for ASD victims based on reinforcement learning are commonly used, the mechanisms and characteristics of the improvement are also unknown. By using a mice model of ASD produced by prenatal exposure to valproic acid (VPA), the present work discovered a delayed response-reinforcer forming, and an impaired habit forming in a negative reinforcement learning paradigm in VPA exposure male offspring. But the extinction of the learned skills was found to become faster than normal male animals. Since escape action of nosepoking and the motility remain unchanged in the VPA male offspring, the impaired learning and the accelerated extinction are caused by deficits in higher brain functions underlying association between the animals' behavioral responses and the outcomes of such responses. The results further suggest that the rodent ASD model produced by prenatal exposure to VPA reproduces the deficits in reasoning or building the contingency between one's own behaviors and the consequent outcomes of the behavior seen in ASD patients.

Hippocampal µ-opioid receptors on GABAergic neurons mediate stress-induced impairment of memory retrieval.

Stressful life events induce abnormalities in emotional and cognitive behaviour. The endogenous opioid system plays an essential role in stress adaptation and coping strategies. In particular, the µ-opioid receptor (µR), one of the major opioid receptors, strongly influences memory processing in that alterations in µR signalling are associated with various neuropsychiatric disorders. However, it remains unclear whether µR signalling contributes to memory impairments induced by acute stress. Here, we utilized pharmacological methods and cell-type-selective/non-cell-type-selective µR depletion approaches combined with behavioural tests, biochemical analyses, and in vitro electrophysiological recordings to investigate the role of hippocampal µR signalling in memory-retrieval impairment induced by acute elevated platform (EP) stress in mice. Biochemical and molecular analyses revealed that hippocampal µRs were significantly activated during acute stress. Blockage of hippocampal µRs, non-selective deletion of µRs or selective deletion of µRs on GABAergic neurons (µRGABA) reversed EP-stress-induced impairment of memory retrieval, with no effect on the elevation of serum corticosterone after stress. Electrophysiological results demonstrated that stress depressed hippocampal GABAergic synaptic transmission to CA1 pyramidal neurons, thereby leading to excitation/inhibition (E/I) imbalance in a µRGABA-dependent manner. Pharmaceutically enhancing hippocampal GABAA receptor-mediated inhibitory currents in stressed mice restored their memory retrieval, whereas inhibiting those currents in the unstressed mice mimicked the stress-induced impairment of memory retrieval. Our findings reveal a novel pathway in which endogenous opioids recruited by acute stress predominantly activate µRGABA to depress GABAergic inhibitory effects on CA1 pyramidal neurons, which subsequently alters the E/I balance in the hippocampus and results in impairment of memory retrieval.

Loss of control over mild aversive events produces significant helplessness in mice.

Most of the pathophysiology of depression are still unknown because of its numerous disease states of distinct etiology and pathogenesis. Stressful rodent models have been used to test a number of hypotheses regarding the etiology of depression. The learned helplessness rodent model demonstrates that having no control at all over aversive events produces helplessness and depression, but the role of loss of control over aversive events in helplessness is still not reliably modelled or deeply investigated. A rodent model of helplessness produced by loss of control is closer to human conditions and is therefore more useful for novel mechanistic and pre-clinic studies. The present work proposed a triadic experimental design in which a Loss Of Control (LOC) group of mice was firstly exposed to escapable mild footshocks to acquire control, and then to inescapable shocks to lose control, with a yoked (L-Yoked) group receiving identical but always uncontrollable shocks. Although both the LOC and the L-Yoked groups developed helplessness, as compared with the naive control group, the helplessness exhibited in the LOC group was significantly more serious than that in the L-Yoked group. The difference in severity between the LOC and the L-Yoked groups demonstrates the effects of loss of control over aversive events, in addition to the effects of the aversive events per se. The LOC paradigm can be used to reproduce pathology of depression induced by loss of control over aversive life events, with a good constructive validity.

Angiogenic Gene Profiles in Laser-Microdissected Microvessels and Neurons from Ischemic Penumbra of Rat Brain.

Angiogenesis is induced immediately after cerebral ischemia and plays a pivotal role in the strategy against ischemic injury. We hypothesized that the coordinated interaction between microvessels and neurons was altered immediately after stroke, and microvessels and neurons would show the temporal specificity of angiogenic gene profiles after cerebral ischemia. Microvessels and neurons were harvested in the ischemic penumbra of rat brain using the PixCell II laser capture microdissection (LCM) instrument. After RNA isolation, T7 and gene-specific primer RNA linear amplification were performed, and angiogenic functional grouping cDNA profiling was analyzed in LCM samples. cDNA microarray results showed there were 35 (36.46%) and 27 (28.13%) genes expression changes in the microvessels, while 25 (26.04%) and 31 (32.29%) genes were changed in the neurons at 2 h and 24 h after cerebral ischemia. Members of growth factors and receptors, cytokines and chemokines, adhesion molecules, matrix proteins, proteases, and inhibitors showed temporal and spatial differentiation in the microvessels and neurons after cerebral ischemia. This finding will help to understand the coordination and interaction between microvessels and neurons, and to elucidate the molecular mechanisms of angiogenesis after brain ischemic injury.

RNA-Seq data on prefrontal cortex in valproic acid model of autism and control rats.

The transcriptome sequencing data of valproic acid (VPA) model of autism and control rats are presented. VPA model of autism was induced by a single intraperitoneal injection of 600 mg/kg sodium valproic acid to female rats at day 12.5 post-conception, and the control rats were injected with saline. Male offspring of VPA- or saline-injected dams from different litters were sacrificed on PND 35 (n = three rats/three litters/group). Prefrontal cortex was dissected from both hemispheres, and RNA was isolated. Libraries were prepared and RNA Sequencing (RNA-Seq) was performed following Illumina's recommendations. Samples are described in the SRA portal (SRP115258) and FASTQ files have been deposited in Sequence Read Archive (accession numbers: SRR5950172 to SRR5950177). The interpretation of these data is presented in the following research article: "Transcriptional and splicing dysregulation in prefrontal cortex of valproic acid induced rat models of autism" (Zhang et al., 2018) [1].

Transcriptional and splicing dysregulation in the prefrontal cortex in valproic acid rat model of autism.

Gene-environmental interaction could be the major cause of autism. The aim of the current study is to detect the effects of valproic acid on gene expression profiles and alternatively spliced genes in the prefrontal cortex in rat models of autism. Female rats received a single intraperitoneal injection of 600 mg/kg valproic acid at day 12.5 post-conception, and controls were injected with saline. Only male offspring were employed in the current study. RNA sequencing was used to investigate transcriptome in the prefrontal cortex of VPA-exposed rats. There were 3228 differently expressed genes and 637 alternative spliced genes, in VPA rats compared to controls. Pathways enrichment among the differently expressed genes and alternatively spliced genes were associated with neurological diseases and neural system development. The results implied VPA affected transcriptional and splicing events genome-wide and the transcriptional and splicing events may be associated with the autistic behaviors of VPA rats.

Parthenolide attenuates cerebral ischemia/reperfusion injury via Akt/GSK-3ß pathway in PC12 cells.

Parthenolide (PN), a sesquiterpene lactone isolated from the herbal medicine feverfew (Tanacetum parthenium), was reported to possess neuroprotective activity. However, the neuroprotective effect of PN against cerebral ischemia/reperfusion (I/R) injury remains unclear. Therefore, the aim of the present study was to explore the neuroprotective effects of PN against oxygen-glucose deprivation (OGD)-induced apoptosis in PC12 cells and the underlying mechanisms. Our results demonstrated that PN ameliorated OGD/R-evoked neuronal injury and oxidative stress in PC12 cells. In addition, PN notably decreased HIF-1α expression, as well as inhibited apoptosis in PC12 cells after OGD/R. Furthermore, PN pretreatment significantly enhanced the phosphorylation of Akt and GSK-3ß in PC12 cells exposed to OGD/R. In conclusion, the present study demonstrated that PN exhibits a neuroprotective effect against OGD/R through activation of the Akt/GSK-3ß signaling pathway. Our findings suggest that PN has the potential to serve as a novel therapeutic agent for cerebral I/R injury.

Overexpression of MicroRNA-216a Suppresses Proliferation, Migration, and Invasion of Glioma Cells by Targeting Leucine-Rich Repeat-Containing G Protein-Coupled Receptor 5.

Increasing studies have suggested that microRNAs (miRNAs) are involved in the development of gliomas. MicroRNA-216a has been reported to be a tumor-associated miRNA in many types of cancer, either as an oncogene or as a tumor suppressor. However, little is known about the function of miR-216a in gliomas. The present study was designed to explore the potential role of miR-216a in gliomas. We found that miR-216a was significantly decreased in glioma tissues and cell lines. Overexpression of miR-216a significantly suppressed the proliferation, migration, and invasion of glioma cells. Leucine-rich repeat-containing G protein-coupled receptor 5 (LGR5) was identified as a target gene of miR-216a in glioma cells by bioinformatics analysis, dual-luciferase reporter assay, real-time quantitative polymerase chain reaction, and Western blot analysis. Moreover, miR-216a overexpression inhibited the Wnt/ß-catenin signaling pathway. The restoration of LGR5 expression markedly reversed the antitumor effect of miR-216a in glioma cells. Taken together, these findings suggest a tumor suppressor role for miR-216a in gliomas, which inhibits glioma cell proliferation, migration, and invasion by targeting LGR5. Our study suggests that miR-216a may serve as a potential therapeutic target for future glioma treatment.

Validation of reference genes for quantitative real-time PCR in valproic acid rat models of autism.

Autism is a neurodevelopmental disorder, and embryonic exposure to valproic acid (VPA) in rodents is the most frequently studied environmentally triggered autism models. Valproic acid can affect gene transcription as a histone deacetylase inhibitor, and thus may alter the expression of the most genes including reference genes. The aim of the current study is to validate suitable reference genes for quantitative real-time PCR (qPCR) quantification in prefrontal cortex and hippocampus of VPA rat models of autism. Female rats received a single intraperitoneal injection of 400 mg/kg sodium VPA at day 12.5 post-conception and controls were injected with saline. Male offspring were used to observe the expression of nine commonly used reference genes by qPCR, and the data were analyzed by four commonly used reference selection program including geNorm, BestKeeper, NormFinder and RefFinder. The results showed that VPA affected the expression of these commonly used reference genes in prefrontal cortex and hippocampus on postnatal 3, 5 weeks and 80 days, Gapdh and Actin, two very frequently used reference genes, were identified as the least stable genes in VPA group. Hprt1 was selected as the most stable gene, and Hmbs and Tbp were the optimum gene pair in prefrontal cortex and hippocampus across all VPA and controls. Problematically, the use of unstable reference genes results in calculation of different PGRN mRNA expression levels. The results suggest that selection of suitable references is critical for accurate mRNA quantification, and specifically in VPA induced rat models of autism.