Relationship between Sonic hedgehog protein, brain-derived neurotrophic factor and oxidative stress in autism spectrum disorders

Hypothesis: 2 Major Environmental and Pharmaceutical Factors-Acetaminophen Exposure and Gastrointestinal Overgrowth of Clostridia Bacteria Induced By Ingestion of Glyphosate-Contaminated Foods-Dysregulate the Developmental Protein Sonic Hedgehog and Are Major Causes of Autism

Epidemiological studies have found 2 significant factors associated with the increased incidence of autism spectrum disorder (ASD): the increased use of acetaminophen in the 1970s when this drug largely replaced the use of aspirin for many patients because of a fear of Reye syndrome, and the agricultural use in the 1990s of the herbicide glyphosate on crops that were genetically modified (GM) to tolerate glyphosate. The incidence of autism in the United States, where acetaminophen is widely available, is more than 1000 times greater than in Cuba, where acetaminophen is available only by prescription. Metabolites of both glyphosate and acetaminophen likely alter the function of the developmental protein sonic hedgehog (SHH). Glyphosate likely affects SHH indirectly by decreasing the beneficial flora of the gastrointestinal tract and increasing pathogenic Clostridia bacteria, which are resistant to glyphosate. The marked increase of certain Clostridia species caused by glyphosate results in Clostridia production of large amounts of 3-(3-hydroxyphenyl)-3-hydroxypropionate (HPHPA) and 4-cresol (p-cresol). The 4-cresol metabolite 4-methyl-o-hydroquinone and the acetaminophen metabolite N-acetyl-p-benzoquinone imine (NAPQI) likely react with the sulfhydryl group of the N-terminal cysteine of SHH, blocking the function of this critical amino acid required for the activation of SHH. HPHPA and 4-cresol also inhibit dopamine β-hydroxylase, resulting in overproduction of dopamine and its toxic metabolites, such as aminochrome, that cause biochemical damage to mitochondria and structural proteins in brain cells. Elevated amounts of these Clostridia products in body fluids in people with autism and in animals with autistic signs have been documented in laboratories throughout the world. The synthesis of the HPHPA molecule in extremely large quantities depletes the body of free coenzyme A, which is needed for the palmitoylation of SHH. SHH covalently coupled to palmitic acid is 30 times more active than SHH without palmitic acid. These possible modifications of SHH help to explain the significantly altered quantities of SHH in the blood serum of patients with autism. The severity of autism is related to the degree of SHH abnormality. The spread of pathogenic Clostridia worldwide from soil to food animals to humans, which may be promoted by glyphosate use, is a great public health concern, not only for autism but perhaps for all the neuropsychiatric diseases that appear to be related to gastrointestinal Clostridia overgrowth These diseases include seizures, tremors, tic disorders, Parkinson disease, chronic fatigue syndrome, obsessive compulsive disorder, schizophrenia, bipolar and unipolar depression, ADHD, and anorexia nervosa.

Human cytomegalovirus (CMV) dysregulates neurodevelopmental pathways in cerebral organoids

Human cytomegalovirus (CMV) infection is the leading non-genetic aetiology of congenital malformation in developed countries, causing significant fetal neurological injury. This study investigated potential CMV pathogenetic mechanisms of fetal neural malformation using in vitro human cerebral organoids. Cerebral organoids were permissive to CMV replication, and infection dysregulated cellular pluripotency and differentiation pathways. Aberrant expression of dual-specificity tyrosine phosphorylation-regulated kinases (DYRK), sonic hedgehog (SHH), pluripotency, neurodegeneration, axon guidance, hippo signalling and dopaminergic synapse pathways were observed in CMV-infected organoids using immunofluorescence and RNA-sequencing. Infection with CMV resulted in dysregulation of 236 Autism Spectrum Disorder (ASD)-related genes (p = 1.57E-05) and pathways. This notable observation suggests potential links between congenital CMV infection and ASD. Using DisGeNET databases, 103 diseases related to neural malformation or mental disorders were enriched in CMV-infected organoids. Cytomegalovirus infection-related dysregulation of key cerebral cellular pathways potentially provides important, modifiable pathogenetic mechanisms for congenital CMV-induced neural malformation and ASD.

The sonic hedgehog pathway suppresses oxidative stress and senescence in nucleus pulposus cells to alleviate intervertebral disc degeneration via GPX4

Disruption of intervertebral disc (IVD) homeostasis caused by oxidative stress and nucleus pulposus cell (NPC) senescence is a main cause of intervertebral disc degeneration (IDD). The sonic hedgehog (Shh) pathway plays an important role in IVD development, but its roles in IDD are unknown. This study aimed to investigate the effects of the Shh pathway on the alleviation of IDD and the related mechanisms. In vivo, the effect of the Shh pathway on IVD homeostasis was studied by intraperitoneal injection of recombinant Shh (rShh) and GANT61 based on puncture-induced IDD. GANT61, lentivirus-coated sh-Gli1 and rShh were used to investigate the role and mechanism of the Shh pathway in NPCs based on senescence induced by Braco19 and oxidative stress induced by TBHP. Shh pathway expression decreased, and senescence and oxidative stress increased with age. Intraperitoneal injection of rShh activated the Shh pathway to suppress oxidative stress and NPC senescence and consequently alleviated needle puncture-induced IDD. In vitro, the Shh pathway upregulated glutathione peroxidase 4 (GPX4) expression to suppress oxidative stress and senescence in NPCs. Moreover, GPX4 suppression in NPCs by si-GPX4 significantly reduced the protective effect of the Shh pathway on oxidative stress and senescence in NPCs. Our results demonstrate for the first time that the Shh pathway plays a key role in the alleviation of IDD by suppressing oxidative stress and cell senescence in NP tissues. This study provides a new potential target for the prevention and reversal of IDD.

Neuro-protective Effect of Acetyl-11-keto-β-boswellic Acid in a Rat Model of Scopolamine-induced Cholinergic Dysfunction

BACKGROUND

Acetyl-11-keto-β-boswellic acid (AKBA) is a major component of the oleo-gum resin of B. serrata with multiple pharmacological activities. The objective of this study was to explore the underlying mechanisms of neuroprotective potential of AKBA against scopolamine-mediated cholinergic dysfunction and memory deficits in rats.

METHODS

The rats received AKBA (2.5, 5, and 10 mg/kg, oral) for 21 days. In the third week, scopolamine was administered 30 min before the Morris water maze and passive avoidance tests. In order to perform biochemical assessments, the hippocampus and prefrontal cortex were extracted from the rats euthanized under deep anesthesia.

RESULTS

In the MWM test, treatment with AKBA (5 and 10 mg/kg) decreased the latency and distance to find the platform. Moreover, in the PA test, AKBA remarkably increased latency to darkness and stayed time in lightness while decreasing the frequency of entry and time in the darkness. According to the biochemical assessments, AKBA decreased acetylcholinesterase activity and malondialdehyde levels while increasing antioxidant enzymes and total thiol content. Furthermore, AKBA administration restored the hippocampal mRNA and protein levels of brain-derived neurotrophic factor (BDNF) and mRNA expression of B-cell lymphoma (Bcl)- 2 and Bcl-2- associated X genes in brain tissue of scopolamine-injured rats.

CONCLUSION

The results suggested the effectiveness of AKBA in preventing learning and memory dysfunction induced by scopolamine. Accordingly, these protective effects might be produced by modulating BDNF, cholinergic system function, oxidative stress, and apoptotic markers.

The role of Smo-Shh/Gli signaling activation in the prevention of neurological and ageing disorders

Sonic hedgehog (Shh) signaling is an essential central nervous system (CNS) pathway involved during embryonic development and later life stages. Further, it regulates cell division, cellular differentiation, and neuronal integrity. During CNS development, Smo-Shh signaling is significant in the proliferation of neuronal cells such as oligodendrocytes and glial cells. The initiation of the downstream signalling cascade through the 7-transmembrane protein Smoothened (Smo) promotes neuroprotection and restoration during neurological disorders. The dysregulation of Smo-Shh is linked to the proteolytic cleavage of GLI (glioma-associated homolog) into GLI3 (repressor), which suppresses target gene expression, leading to the disruption of cell growth processes. Smo-Shh aberrant signalling is responsible for several neurological complications contributing to physiological alterations like increased oxidative stress, neuronal excitotoxicity, neuroinflammation, and apoptosis. Moreover, activating Shh receptors in the brain promotes axonal elongation and increases neurotransmitters released from presynaptic terminals, thereby exerting neurogenesis, anti-oxidation, anti-inflammatory, and autophagy responses. Smo-Shh activators have been shown in preclinical and clinical studies to help prevent various neurodegenerative and neuropsychiatric disorders. Redox signalling has been found to play a critical role in regulating the activity of the Smo-Shh pathway and influencing downstream signalling events. In the current study ROS, a signalling molecule, was also essential in modulating the SMO-SHH gli signaling pathway in neurodegeneration. As a result of this investigation, dysregulation of the pathway contributes to the pathogenesis of various neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD).Thus, Smo-Shh signalling activators could be a potential therapeutic intervention to treat neurocomplications of brain disorders.

SAG, a sonic hedgehog signaling agonist, alleviates anxiety behavior in high-fat diet-fed mice

Anxiety is a prevalent and disabling psychiatric disorder. Mitochondrial dysfunction due to the high-fat diet (HFD) was regarded as a risk factor in the pathogenesis of anxiety. The Sonic hedgehog (SHH) pathway was known to improve mitochondrial dysfunction through antioxidant and anti-apoptotic effects on some neurological diseases. Nonetheless, its effect on anxiety has not been well studied. In this study, we aimed to explore whether SHH signaling pathway plays a protective role in anxiety by regulating mitochondrial homeostasis. SAG, a typical SHH signaling agonist, was administered intraperitoneally in HFD-fed mice. HFD-induced anxiety-like behavior in mice was confirmed using the open field and elevated plus maze tests. Immunofluorescence staining and Western blotting assays showed that the SHH signaling was downregulated in the prefrontal cortex neurons from HFD-fed mice. Electron microscopy results showed the mitochondria in the prefrontal cortex of HFD-fed mice were fragmented, which appeared small and spherical, and the area, perimeter and circularity of mitochondria were decreased. Mitofusin2 (Mfn2) and dynamin-related protein 1 (Drp1) were the key proteins involved in mitochondrial division and fusion. SAG treatment could rectify the imbalanced expression of Mfn2 and Drp1 in the prefrontal cortex of the HFD-fed mice, and alleviate the mitochondrial fragmentation. Furthermore, SAG decreased anxiety-like behavior in the HFD-fed mice. These findings suggested that SHH signal was neuroprotective in obesity and SAG relieved anxiety-like behavior through reducing mitochondrial fragmentation.

Incomplete hippocampal inversion in patients with mutations in genes involved in sonic hedgehog signaling

Sonic hedgehog (Shh) signaling pathways are known to play an important role in the morphological development of the hippocampus in vivo, but their actual roles in humans have not been clarified. Hypothalamic hamartoma (HH) is known to be associated with germline or somatic gene mutations of Shh signaling. We hypothesized that patients with HH and mutations of Shh-related genes also show hippocampal maldevelopment and an abnormal hippocampal infolding angle (HIA). We analyzed 45 patients (age: 1-37 years) with HH who underwent stereotactic radiofrequency thermocoagulation and found Shh-related gene mutations in 20 patients. In addition, 44 pediatric patients without HH (age: 2-25 years) who underwent magnetic resonance imaging (MRI) examinations under the same conditions during the same period were included in this study as a control group. HIA evaluated on MRI was compared between patients with gene mutations and the control group. The median HIA at the cerebral peduncle slice in patients with the gene mutation was 74.36° on the left and 76.11° on the right, and these values were significantly smaller than the corresponding values in the control group (80.46° and 80.56°, respectively, p < 0.01). Thus, mutations of Shh-related genes were correlated to incomplete hippocampal inversion. The HIA, particularly at the cerebral peduncle slice, is a potential indicator of abnormalities of the Shh-signaling pathway.

Inorganic arsenic alters the development of dopaminergic neurons but not serotonergic neurons and induces motor neuron development via Sonic hedgehog pathway in zebrafish

The mechanism of inorganic arsenic-induced neurotoxicity at the cellular level is not known. In zebrafish, teratological effects of inorganic arsenic have been shown at various concentrations. Here, we used similar concentrations of inorganic arsenic to evaluate the effects on specific neuron types. Exposure of zebrafish embryos at 5 h post fertilization (hpf) to sodium arsenite induced developmental toxicity (reduced body length) in 72 hpf larvae, beginning at a concentration of 300 mg/L concentration. Mortality or overt morphological deformity was detected at 500 mg/L sodium arsenite. While 200 mg/L sodium arsenite induced development of tyrosine hydroxylase-positive (dopaminergic) neurons, there was no significant effect on the development of 5-hydroxytryptamine (serotonergic) neurons. Sodium arsenite reduced acetylcholinesterase activity. In the hb9-GFP transgenic larvae, both 200 and 400 mg/L sodium arsenite produced supernumerary motor neurons in the spinal cord. Inhibition of the Sonic hedgehog (Shh) pathway that is essential for motor neuron development, by Gant61, prevented sodium arsenite-induced supernumerary motor neuron development. Inductively coupled plasma mass spectrometry (ICP-MS) revealed that with 200 mg/L and 400 mg/L sodium arsenite treatment, each larva had an average of 387.8 pg and 847.5 pg arsenic, respectively. The data show for the first time that inorganic arsenic alters the development of dopaminergic and motor neurons in the zebrafish larvae and the latter occurs through the Shh pathway. These results may help understand why arsenic-exposed populations suffer from psychiatric disorders and motor neuron disease and Shh may, potentially, serve as a plasma biomarker of arsenic toxicity.

Investigating and comparing the psychometric properties of the Chinese Mandarin version of social responsiveness scale-2 and its shortened version in preschool-age children with autism spectrum disorder

We aimed to investigate and compare the psychometric properties of the Chinese Mandarin Social Responsiveness Scale-2 (SRS-2) and its shortened version. The study assessed 670 children with autism spectrum disorder (ASD) aged 30-54 months and 138 typical developmental (TD) children of the same age in mainland China. Our item reliability test revealed that only 36 items of the 65 items in the Chinese Mandarin SRS-2 (Preschool) met the reliability criteria. Moreover, the shortened version of SRS-2 (Preschool) with four subscales and 30 items maintained strong correlations (r = 0.961) with the Chinese Mandarin SRS-2 (Preschool), and demonstrated improved psychometric performance on the 4-week test-retest reliability (intraclass correlations was 0.70), internal consistency (Cronbach's alpha 0.71-0.91), construct validity, and convergent validity with the Autism Diagnostic Observation Schedule, Autism Diagnostic Interview-Revised, and Child Behavior Checklist. Receiver operating characteristics (ROC) analyses showed excellent and comparable discriminant validity of the shortened version with an area under the curve of 0.992. Our data suggested a cutoff ≥ 22.5 for the shortened version, with good accuracy in screening autism symptoms (sensitivity=96.9 %, specificity=94.2 %). Our findings demonstrated that the shortened version of SRS-2 (Preschool) was a reliable and valid instrument for identifying preschoolers with ASD in mainland China.

Role of Sonic Hedgehog Signaling Activation in the Prevention of Neurological Abnormalities Associated with Obsessive-Compulsive Disorder

The smoothened sonic hedgehog (Smo-Shh) pathway is one mechanism that influences neurogenesis, including brain cell differentiation and development during childhood. Shh signaling dysregulation leads to decreased target gene transcription, which contributes to increased neuronal excitation, apoptosis, and neurodegeneration, eventually leading to neurological deficits. Neuropsychiatric disorders such as OCD and related neurological dysfunctions are characterized by neurotransmitter imbalance, neuroinflammation, oxidative stress, and impaired neurogenesis, disturbing the cortico-striato-thalamo-cortical (CSTC) link neuronal network. Despite the availability of several treatments, such as selective serotonin reuptake inhibitors, some individuals may not benefit much from them. Several trials on the use of antipsychotics in the treatment of OCD have also produced inadequate findings. This evidence-based review focuses on a potential pharmacological approach to alleviating OCD and associated neuronal deficits by preventing neurochemical alterations, in which sonic hedgehog activators are neuroprotective, lowering neuronal damage while increasing neuronal maintenance and survival. As a result, stimulating SMO-Shh via its potential activators may have neuroprotective effects on neurological impairment associated with OCD. This review investigates the link between SMO-Shh signaling and the neurochemical abnormalities associated with the progression of OCD and associated neurological dysfunctions. Role of Smo-Shh signaling in serotonergic neurogenesis and in maintaining their neuronal identity. The Shh ligand activates two main transcriptional factors known as Foxa2 and Nkx2.2, which again activates another transcriptional factor, GATA (GATA2 and GATA3), in post mitotic precursor cells of serotonergic neurons-following increased expression of Pet-1 and Lmx1b after GATA regulates the expression of many serotonergic enzymes such as TPH2, SERT, VMAT, slc6a4, Htr1a, Htr1b (Serotonin receptor enzymes), and MAO that regulate and control the release of serotonin and maintain their neuronal identity after their maturation. Abbreviation: Foxa2: Forkhead box; GATA: Globin transcription factor; Lmx1b: LIM homeobox transcription factor 1 beta; TPH2: Tryptophan hydroxylase 2; Htr1a: Serotonin receptor 1a; Htr1b: Serotonin receptor 1b; SERT: Serotonin transporter; VMAT: Vesicular monoamine transporter; MAO: Monoamine oxidase.

Elevated ACE Levels Indicate Diabetic Nephropathy Progression or Companied Retina Impaired

Objectives

Renin-angiotensin-aldosterone system plays important roles in the development of diabetic nephropathy (DN), and angiotensin converting enzyme (ACE) is the key factor in the process from angiotensin I to angiotensin II, but the variation and roles of serum ACE in DN patients are still unclear.

Methods

Forty-four type 2 diabetes mellitus (T2DM) patients, 75 DN patients, and 36 age-gender-matched healthy volunteers were recruited who attended Xiangya Hospital of Central South University in this case control study. Serum ACE levels and other indexes were tested with commercial kit.

Results

ACE levels in DN were significantly higher than T2DM and controls (F = 9.66, P < 0.001). Serum ACE levels significantly correlated with UmALB (r = 0.3650, P < 0.001), BUN (r = 0.3102, P < 0.001), HbA1c (r = 0.2046, P = 0.0221), ACR (r = 0.4187, P < 0.001), ALB (r = -0.1885, P = 0.0192), and eGFR (r = -0.3955, P < 0.001), and we got an equation that Y = 2.839 + 0.648X1 + 2.001X2 + 0.003X3 - 6.637X4 +0.416X5 - 0.134X6 (Y: ACE; X1: BUN; X2: HbA1C; X3: UmALB; X4: gender; X5: ALB; X6: eGFR, R2 = 0.655). When DN patients were divided into advanced-stage and early-stage with or without DR, ACE levels would increase when early-stage DN develops into advanced-stage or companied with DR.

Conclusion

Elevated serum ACE levels may hint DN progression or retina impaired of DN patients.

The Overexpression of Sonic Hedgehog Associates with Collateral Development and Amelioration of Oxidative Stress in Stroke Patients

PURPOSE

Sonic hedgehog (SHH) signaling pathway in oxidative stress condition has been acknowledged as a key trigger for angiogenesis and collateral vessel growth in the ischemic brain, and it exerts a protective effect on neuronal cells during oxidative stress.

METHODS

A total of sixty patients (n = 30 good collateral profile and n = 30 poor collateral profile) diagnosed with acute cerebral ischemia were enrolled in this study. qRT-PCR was performed to analyze the expression levels of SHH, Gli1, and superoxide dismutase (SOD), genes. Also, the serum levels of oxidative stress markers were determined in experimental groups.

RESULTS

The expression levels of SHH and Gli1 genes were significantly (p < 0.05) higher in stroke patients with good collateral circulation compared with those with poor collateral circulation, while SOD gene expression was similar between two groups (p > 0.05). A significantly positive correlation was found between the gene expression of SHH and Gli1 (r = 0.604, p < 0.001), SOD and Gli1 (r = 0.372, p < 0.003) genes. Our findings showed that the serum level of total antioxidant capacity (TAC) and Glutathione (GSH) and SOD enzyme activity was significantly (p < 0.05) increased, while serum total oxidant status (TOS) and malondialdehyde (MDA) levels were significantly (p < 0.05) decreased in patients with good collateral circulation as compared with those with poor collateral circulation.

CONCLUSION

Our observations shed light on the association of the SHH/Gli1 signaling pathway with cerebral collateral vessel development following ischemia. Oxidative stress in stroke patients with poor collateral circulation may result in the overexpression of SHH/Gli1 signaling pathway which possibly contribute to oxidative stress attenuation, as well as modulate angiogenesis and collateral vessels development.

Criss-crossing autism spectrum disorder and adult neurogenesis

Autism spectrum disorder (ASD) comprises a group of multifactorial neurodevelopmental disorders primarily characterized by deficits in social interaction and repetitive behavior. Although the onset is typically in early childhood, ASD poses a lifelong challenge for both patients and caretakers. Adult neurogenesis (AN) is the process by which new functional neurons are created from neural stem cells existing in the post-natal brain. The entire event is based on a sequence of cellular processes, such as proliferation, specification of cell fate, maturation, and ultimately, synaptic integration into the existing neural circuits. Hence, AN is implicated in structural and functional brain plasticity throughout life. Accumulating evidence shows that impaired AN may underlie some of the abnormal behavioral phenotypes seen in ASD. In this review, we approach the interconnections between the molecular pathways related to AN and ASD. We also discuss existing therapeutic approaches targeting such pathways both in preclinical and clinical studies. A deeper understanding of how ASD and AN reciprocally affect one another could reveal important converging pathways leading to the emergence of psychiatric disorders.

Imbalance of Excitatory/Inhibitory Neuron Differentiation in Neurodevelopmental Disorders with an NR2F1 Point Mutation

Recent studies have revealed an essential role for embryonic cortical development in the pathophysiology of neurodevelopmental disorders, including autism spectrum disorder (ASD). However, the genetic basis and underlying mechanisms remain unclear. Here, we generate mutant human embryonic stem cell lines (Mut hESCs) carrying an NR2F1-R112K mutation that has been identified in a patient with ASD features and investigate their neurodevelopmental alterations. Mut hESCs overproduce ventral telencephalic neuron progenitors (ventral NPCs) and underproduce dorsal NPCs, causing the imbalance of excitatory/inhibitory neurons. These alterations can be mainly attributed to the aberrantly activated Hedgehog signaling pathway. Moreover, the corresponding Nr2f1 point-mutant mice display a similar excitatory/inhibitory neuron imbalance and abnormal behaviors. Antagonizing the increased inhibitory synaptic transmission partially alleviates their behavioral deficits. Together, our results suggest that the NR2F1-dependent imbalance of excitatory/inhibitory neuron differentiation caused by the activated Hedgehog pathway is one precursor of neurodevelopmental disorders and may enlighten the therapeutic approaches.

Autism Spectrum Disorder: Signaling Pathways and Prospective Therapeutic Targets

The Autism Spectrum Disorder (ASD) consists of a prevalent and heterogeneous group of neurodevelopmental diseases representing a severe burden to affected individuals and their caretakers. Despite substantial improvement towards understanding of ASD etiology and pathogenesis, as well as increased social awareness and more intensive research, no effective drugs have been successfully developed to resolve the main and most cumbersome ASD symptoms. Hence, finding better treatments, which may act as "disease-modifying" agents, and novel biomarkers for earlier ASD diagnosis and disease stage determination are needed. Diverse mutations of core components and consequent malfunctions of several cell signaling pathways have already been found in ASD by a series of experimental platforms, including genetic associations analyses and studies utilizing pre-clinical animal models and patient samples. These signaling cascades govern a broad range of neurological features such as neuronal development, neurotransmission, metabolism, and homeostasis, as well as immune regulation and inflammation. Here, we review the current knowledge on signaling pathways which are commonly disrupted in ASD and autism-related conditions. As such, we further propose ways to translate these findings into the development of genetic and biochemical clinical tests for early autism detection. Moreover, we highlight some putative druggable targets along these pathways, which, upon further research efforts, may evolve into novel therapeutic interventions for certain ASD conditions. Lastly, we also refer to the crosstalk among these major signaling cascades as well as their putative implications in therapeutics. Based on this collective information, we believe that a timely and accurate modulation of these prominent pathways may shape the neurodevelopment and neuro-immune regulation of homeostatic patterns and, hopefully, rescue some (if not all) ASD phenotypes.

Smo-Shh signaling activator purmorphamine ameliorates neurobehavioral, molecular, and morphological alterations in an intracerebroventricular propionic acid-induced experimental model of autism

Autism Spectrum Disorder (ASD) is a complex neurodevelopmental disease characterized by cognitive and sensorimotor impairment. Numerous research findings have consistently shown that alteration of Smo-Shh (smoothened-sonic hedgehog) signaling during the developmental process plays a significant role in ASD and triggers neuronal changes by promoting neuroinflammation and apoptotic markers. Purmorphamine (PUR), a small purine-derived agonist of the Smo-Shh pathway, shows resistance to hippocampal neuronal cell oxidation and decreases neuronal cell death. The goal of this study was to investigate the neuroprotective potential of PUR in brain intoxication induced by intracerebroventricular-propionic acid (ICV-PPA) in rats, with a focus on its effect on Smo-Shh regulation in the brain of rats. In addition, we analyze the impact of PUR on myelin basic protein (MBP) and apoptotic markers such as Caspase-3, Bax (pro-apoptotic), and Bcl-2 (anti-apoptotic) in rat brain homogenates. Chronic ICV-PPA infusion was administered consecutively for 11 days to induce autism in rats. In order to investigate behavioral alterations, rats were tested for spatial learning in the Morris Water Maze (MWM), locomotive alterations using actophotometer, and beam crossing task, while Forced Swimming Test (FST) for depressive behavior. PUR treatment with 5 mg/kg and 10 mg/kg (i.p.) was administered from day 12 to 44. Besides cellular, molecular and neuroinflammatory analyses, neurotransmitter levels and oxidative markers have also been studied in brain homogenates. The results of this study have shown that PUR increases the level of Smo-Shh and restores the neurochemical levels, and potentially prevents morphological changes, including demyelination.

Dysregulation of Multiple Signaling Neurodevelopmental Pathways during Embryogenesis: A Possible Cause of Autism Spectrum Disorder

Understanding the autistic brain and the involvement of genetic, non-genetic, and numerous signaling pathways in the etiology and pathophysiology of autism spectrum disorder (ASD) is complex, as is evident from various studies. Apart from multiple developmental disorders of the brain, autistic subjects show a few characteristics like impairment in social communications related to repetitive, restricted, or stereotypical behavior, which suggests alterations in neuronal circuits caused by defects in various signaling pathways during embryogenesis. Most of the research studies on ASD subjects and genetic models revealed the involvement of mutated genes with alterations of numerous signaling pathways like Wnt, hedgehog, and Retinoic Acid (RA). Despite significant improvement in understanding the pathogenesis and etiology of ASD, there is an increasing awareness related to it as well as a need for more in-depth research because no effective therapy has been developed to address ASD symptoms. Therefore, identifying better therapeutic interventions like "novel drugs for ASD" and biomarkers for early detection and disease condition determination are required. This review article investigated various etiological factors as well as the signaling mechanisms and their alterations to understand ASD pathophysiology. It summarizes the mechanism of signaling pathways, their significance, and implications for ASD.

Exploring Sonic Hedgehog Cell Signaling in Neurogenesis: Its Potential Role in Depressive Behavior

Depression is the most prevalent form of neuropsychiatric disorder affecting all age groups globally. As per the estimation of the World Health Organization (WHO), depression will develop into the foremost reason for disability globally by the year 2030. The primary neurobiological mechanism implicated in depression remains ambiguous; however, dysregulation of molecular and signaling transductions results in depressive disorders. Several theories have been developed to explain the pathogenesis of depression, however, none of them completely explained all aspects of depressive-pathogenesis. In the current review, we aimed to explore the role of the sonic hedgehog (Shh) signaling pathway in the development of the depressive disorder and its potential as the therapeutic target. Shh signaling has a crucial function in neurogenesis and neural tube patterning during the development of the central nervous system (CNS). Shh signaling performs a basic function in embryogenesis and hippocampal neurogenesis. Moreover, antidepressants are also known to enhance neurogenesis in the hippocampus, which further suggests the potential of Shh signaling. Furthermore, there is decreased expression of a glioma-associated oncogene (Gli1) and Smoothened (Smo) in depression. Moreover, antidepressants also regulate brain-derived neurotrophic factor (BDNF) and wingless protein (Wnt) signaling, therefore, Shh may be implicated in the pathogenesis of the depressive disorder. Deregulation of Shh signaling in CNS results in neurological disorders such as depression.

Molecular Pathways within Autism Spectrum Disorder Endophenotypes

Autism spectrum disorder (ASD) is a condition that includes a number of neurodevelopmental mental disorders. Recent genetic/genomic investigations have reported an increased prevalence of copy number variations (CNVs) in individuals with autism. Despite the extensive evidence of a genetic component, the genes involved are not known and the background is heterogeneous among subjects. As such, it is highly likely that multiple events (molecular cascades) are implicated in the development of autism. The aim of this work was to shed some light on the biological background behind this condition. We hypothesized that the heterogeneous alterations found within different individuals may converge into one or more specific biological functions (pathways) linked to the heterogeneous phenotypes commonly observed in subjects with ASD. We analyzed a sample of 107 individuals for CNV alterations and checked the genes located within the altered loci (1366). Then, we characterized the subjects for distinct phenotypes. After creating subsamples based on symptoms, the CNVs related to each specific symptom were used to create distinct networks associated with each phenotype (18 in total in the sample under analysis). These networks were independently clustered and enriched to identify potential common pathways involved in autism and variably combined with the clinical phenotype. The first 10 pathways of the analysis are discussed.

Peripheral blood neurotrophic factor levels in children with autism spectrum disorder: a meta-analysis

Increasing evidence suggests that abnormal regulation of neurotrophic factors is involved in the etiology and pathogenesis of Autism Spectrum Disorder (ASD). However, clinical data on neurotrophic factor levels in children with ASD were inconsistent. Therefore, we performed a systematic review of peripheral blood neurotrophic factors levels in children with ASD, and quantitatively summarized the clinical data of peripheral blood neurotrophic factors in ASD children and healthy controls. A systematic search of PubMed and Web of Science identified 31 studies with 2627 ASD children and 4418 healthy controls to be included in the meta-analysis. The results of random effect meta-analysis showed that the peripheral blood levels of brain-derived neurotrophic factor (Hedges’ g = 0.302; 95% CI = 0.014 to 0.591; P = 0.040) , nerve growth factor (Hedges’ g = 0.395; 95% CI = 0.104 to 0.686; P = 0.008) and vascular endothelial growth factor (VEGF) (Hedges’ g = 0.097; 95% CI = 0.018 to 0.175; P = 0.016) in children with ASD were significantly higher than that of healthy controls, whereas blood neurotrophin-3 (Hedges’ g =  − 0.795; 95% CI =  − 1.723 to 0.134; P = 0.093) and neurotrophin-4 (Hedges’ g = 0.182; 95% CI =  − 0.285 to 0.650; P = 0.445) levels did not show significant differences between cases and controls. Taken together, these results clarified circulating neurotrophic factor profile in children with ASD, strengthening clinical evidence of neurotrophic factor aberrations in children with ASD.

The crosstalk of hedgehog, PI3K and Wnt pathways in diabetes

Hyperglycaemia causes pancreatic β-cells to release insulin that then attaches to a specific expression of receptor isoform and reverses high glucose concentrations. It is well known that insulin is capable of initiating insulin-receptor substrate (IRS)/phosphatidylinositol 3-kinase (PI3K)/protein kinase B (PKB) signaling pathways in target cells; such as liver, adipose tissues, and muscles. However, recent discoveries indicate that many other pathways, such as the Hedgehog (Hh) and growth factor-stimulating Wingless-related integration (Wnt) signaling pathways; are activated in hyperglycaemia as well. Although these two pathways are traditionally thought to have a decisive role in cellular growth and differentiation only, recent reports show that they are involved in regulating cellular homeostasis and energy balance. While insulin-activated IRS/PI3K/PKB pathway cascades are primarily known to reduce glucose production, it was recently discovered to increase the Hh signaling pathway's stability, thereby activating the PI3K/PKB/mammalian target of rapamycin complex 2 (mTORC2) signaling pathway. The Hh signaling pathway not only plays a role in lipid metabolism, insulin sensitivity, inflammatory response, diabetes-related complications, but crosstalks with the Wnt signaling pathway resulting in improved insulin sensitivity and decrease inflammatory response in diabetes.

Understanding Abnormal SMO-SHH Signaling in Autism Spectrum Disorder: Potential Drug Target and Therapeutic Goals

Autism is a multifactorial neurodevelopmental condition; it demonstrates some main characteristics, such as impaired social relationships and increased repetitive behavior. The initiation of autism spectrum disorder is mostly triggered during brain development by the deregulation of signaling pathways. Sonic hedgehog (SHH) signaling is one such mechanism that influences neurogenesis and neural processes during the development of the central nervous system. SMO-SHH signaling is also an important part of a broad variety of neurological processes, including neuronal cell differentiation, proliferation, and survival. Dysregulation of SMO-SHH signaling leads to many physiological changes that lead to neurological disorders such as ASD and contribute to cognitive decline. The aberrant downregulation of SMO-SHH signals contributes to the proteolytic cleavage of GLI (glioma-associated homolog) into GLI3 (repressor), which increases oxidative stress, neuronal excitotoxicity, neuroinflammation, and apoptosis by suppressing target gene expression. We outlined in this review that SMO-SHH deregulation plays a crucial role in the pathogenesis of autism and addresses the current status of SMO-SHH pathway modulators. Additionally, a greater understanding of the SHH signaling pathway is an effort to improve successful treatment for autism and other neurological disorders.

Smoothened receptor signaling regulates the developmental shift of GABA polarity in rat somatosensory cortex

Sonic hedgehog (Shh) and its patched-smoothened receptor complex control a variety of functions in the developing central nervous system, such as neural cell proliferation and differentiation. Recently, Shh signaling components have been found to be expressed at the synaptic level in the postnatal brain, suggesting a potential role in the regulation of synaptic transmission. Using in utero electroporation of constitutively active and negative-phenotype forms of the Shh signal transducer smoothened (Smo), we studied the role of Smo signaling in the development and maturation of GABAergic transmission in the somatosensory cortex. Our results show that enhancing Smo activity during development accelerates the shift from depolarizing to hyperpolarizing GABA in a manner dependent on functional expression of potassium-chloride cotransporter type 2 (KCC2, also known as SLC12A5). On the other hand, blocking Smo activity maintains the GABA response in a depolarizing state in mature cortical neurons, resulting in altered chloride homeostasis and increased seizure susceptibility. This study reveals unexpected functions of Smo signaling in the regulation of chloride homeostasis, through control of KCC2 cell-surface stability, and the timing of the GABA excitatory-to-inhibitory shift in brain maturation.

Laser Acupuncture Effects on Speech and Social Interaction in Patients with Autism Spectrum Disorder

Objective: Disorders of speech ability and social interaction are the most-common symptoms in children with autism spectrum disorder (ASD). Acupuncture, as an adjunctive therapy, is known to help improve speech ability and social interaction in children with this condition. One of the acupuncture modalities with minimal side-effects, and that is safe for children, is laser acupuncture or laserpuncture. This study's aim was to determine laserpuncture's effects on speech ability and social interactions in patients with ASD. Materials and Methods: This randomized, double-blinded clinical trial involved 46 patients in 2 groups. All respondents qualified, and none dropped out. The treatment group (n = 23) received sensory-occupational integrative therapy and verum laserpuncture therapy and the control group (n = 23) received sensory-occupational integrative therapy and placebo laserpuncture. The groups' speech ability and social interaction were evaluated with a WeeFIM^® questionnaire; parental reports were collected, using sensory profiles before and after treatment. Results: There were improvements in speech ability and social interaction in the verum laserpuncture group more than in the placebo group after treatment. Perception score was P < 0.001; odds ratio (OR): 18.8; 95% confidence interval (CI): 4.09-87.17. Expression score was P < 0.001; OR: 50.2; 95% CI: 5.61-450.2. Social interaction score was P = 0.005; OR:7.2; 95% CI: 1.68-31.42. Parental report score was P = 0.765. Conclusions: Verum laserpuncture in this clinical trial improved speech ability and social interaction scores more effectively than placebo laserpuncture did in patients with ASD.

The role of Shh signalling pathway in central nervous system development and related diseases

Sonic hedgehog (Shh) plays important roles in developmental of vertebrate animal central nervous system (CNS), and Gli is its downstream signal molecule. Shh signalling is essential for pattern formation, cell-fate specification, axon guidance, proliferation, survival and differentiation of neurons in CNS development. The abnormal signalling pathway of Shh leads to the occurrence of many nervous system diseases. The mechanism of Shh signalling is complex and remains incompletely understood. Nevertheless, studies have revealed that Shh signalling pathway is classified into canonical and non-canonical pathways. Here we review the role of the Shh signalling pathway and its impact in CNS development and related diseases. Specifically, we discuss the role of Shh in the spinal cord and brain development, cell differentiation and proliferation in CNS and related diseases such as brain tumour, Parkinson's diseases, epilepsy, autism, depression and traumatic brain injury. We also highlight future directions of research that could help to clarify the mechanisms and consequences of Shh signalling in the process of CNS development and related diseases. SIGNIFICANCE OF THE STUDY: This review summarized the role of Shh signalling pathway in CNS development and related diseases such as brain tumour, Parkinson's diseases, epilepsy, autism, depression and traumatic brain injury. It also presented the author's opinions on the future research direction of Shh signalling pathway.

The Neocortical Progenitor Specification Program Is Established through Combined Modulation of SHH and FGF Signaling

Neuronal progenitors in the developing forebrain undergo dynamic competence states to ensure timely generation of specific excitatory and inhibitory neuronal subtypes from distinct neurogenic niches of the dorsal and ventral forebrain, respectively. Here we show evidence of progenitor plasticity when Sonic hedgehog (SHH) signaling is left unmodulated in the embryonic neocortex of the mammalian dorsal forebrain. We found that, at early stages of corticogenesis, loss of Suppressor of Fused (Sufu), a potent inhibitor of SHH signaling, in neocortical progenitors, altered the transcriptomic landscape of male mouse embryos. Ectopic activation of SHH signaling occurred, via degradation of Gli3R, resulting in significant upregulation of fibroblast growth factor 15 (FGF15) gene expression in all E12.5 Sufu-cKO neocortex regardless of sex. Consequently, activation of FGF signaling, and its downstream effector the MAPK signaling, facilitated expression of genes characteristic of ventral forebrain progenitors. Our studies identify the importance of modulating extrinsic niche signals such as SHH and FGF15, to maintain the competency and specification program of neocortical progenitors throughout corticogenesis.SIGNIFICANCE STATEMENT Low levels of FGF15 control progenitor proliferation and differentiation during neocortical development, but little is known on how FGF15 expression is maintained. Our studies identified SHH signaling as a critical activator of FGF15 expression during corticogenesis. We found that Sufu, via Gli3R, ensured low levels of FGF15 was expressed to prevent abnormal specification of neocortical progenitors. These studies advance our knowledge on the molecular mechanisms guiding the generation of specific neocortical neuronal lineages, their implications in neurodevelopmental diseases, and may guide future studies on how progenitor cells may be used for brain repair.

Sonic Hedgehog Signaling Agonist (SAG) Triggers BDNF Secretion and Promotes the Maturation of GABAergic Networks in the Postnatal Rat Hippocampus

Sonic hedgehog (Shh) signaling plays critical roles during early central nervous system development, such as neural cell proliferation, patterning of the neural tube and neuronal differentiation. While Shh signaling is still present in the postnatal brain, the roles it may play are, however, largely unknown. In particular, Shh signaling components are found at the synaptic junction in the maturing hippocampus during the first two postnatal weeks. This period is characterized by the presence of ongoing spontaneous synaptic activity at the cellular and network levels thought to play important roles in the onset of neuronal circuit formation and synaptic plasticity. Here, we demonstrate that non-canonical Shh signaling increases the frequency of the synchronized electrical activity called Giant Depolarizing Potentials (GDP) and enhances spontaneous GABA post-synaptic currents in the rodent hippocampus during the early postnatal period. This effect is mediated specifically through the Shh co-receptor Smoothened via intracellular Ca²⁺ signal and the activation of the BDNF-TrkB signaling pathway. Given the importance of these spontaneous events on neuronal network maturation and refinement, this study opens new perspectives for Shh signaling on the control of early stages of postnatal brain maturation and physiology.

Impaired neurodevelopmental pathways in autism spectrum disorder: a review of signaling mechanisms and crosstalk

Background

The development of an autistic brain is a highly complex process as evident from the involvement of various genetic and non-genetic factors in the etiology of the autism spectrum disorder (ASD). Despite being a multifactorial neurodevelopmental disorder, autistic patients display a few key characteristics, such as the impaired social interactions and elevated repetitive behaviors, suggesting the perturbation of specific neuronal circuits resulted from abnormal signaling pathways during brain development in ASD. A comprehensive review for autistic signaling mechanisms and interactions may provide a better understanding of ASD etiology and treatment.

Main body

Recent studies on genetic models and ASD patients with several different mutated genes revealed the dysregulation of several key signaling pathways, such as WNT, BMP, SHH, and retinoic acid (RA) signaling. Although no direct evidence of dysfunctional FGF or TGF-β signaling in ASD has been reported so far, a few examples of indirect evidence can be found. This review article summarizes how various genetic and non-genetic factors which have been reported contributing to ASD interact with WNT, BMP/TGF-β, SHH, FGF, and RA signaling pathways. The autism-associated gene ubiquitin-protein ligase E3A (UBE3A) has been reported to influence WNT, BMP, and RA signaling pathways, suggesting crosstalk between various signaling pathways during autistic brain development. Finally, the article comments on what further studies could be performed to gain deeper insights into the understanding of perturbed signaling pathways in the etiology of ASD.

Conclusion

The understanding of mechanisms behind various signaling pathways in the etiology of ASD may help to facilitate the identification of potential therapeutic targets and design of new treatment methods.

An Endogenous Anti-aging Factor, Sonic Hedgehog, Suppresses Endometrial Stem Cell Aging through SERPINB2

Endometrial stem cells are located in the basal layer of the endometrium, and they are responsible for the cyclic regeneration of the uterus during the menstrual cycle. Recent studies have revealed that recurrent pregnancy loss is associated with an age-related stem cell deficiency in the endometrium. Therefore, intensive study of endometrial stem cell aging may provide new insights for preventing recurrent pregnancy loss. Sonic hedgehog (SHH) signaling has been identified as a morphogen during the embryonic development processes. In addition to this canonical function, we found that the age-associated decline in regenerative potential in the endometrium may be due to decreased SHH-signaling integrity in local stem cells with aging. Importantly, the current study also showed that SHH activity clearly declines with aging both in vitro and in vivo, and exogenous SHH treatment significantly alleviates various aging-associated declines in multiple endometrial stem cell functions, suggesting that SHH may act as an endogenous anti-aging factor in human endometrial stem cells. Moreover, we found that stem cell senescence may enhance SERPINB2 expression, which in turn mediates the effect of SHH on alleviating senescence-induced endometrial stem cell dysfunctions, suggesting that SERPINB2 is a master regulator of SHH signaling during the aging process.

Sonic hedgehog signaling regulates hypoxia/reoxygenation-induced H9C2 myocardial cell apoptosis

The sonic hedgehog (Shh) signaling pathway has been reported to protect cells against hypoxia/reoxygenation (H/R) injury; however, the role of Shh and relevant molecular mechanisms remain unclear. In the present study, the rat cardiomyoblast cell line H9C2 was subjected to hypoxia and serum-starvation for 4 h. Cells were subsequently reoxygenated using 95% O₂ and 5% CO₂. Reverse transcription-quantitative polymerase chain reaction was performed to quantify the expression of Shh mRNA, while cell apoptosis was assessed using flow cytometry. Caspase-3 activity and p53 expression were measured by western blotting and an MTT assay was subsequently used to assess cell viability. In addition, reactive oxygen species levels were measured using dichlorofluorescein and H/R-induced changes in the activation of superoxide dismutase, catalase, phosphorylated-endothelial nitric oxide synthase, phosphorylated-protein kinase B (Akt) and mammalian target of rapamycin activation were assessed using western blotting. H/R treatment decreased the cell viability of H9C2 cells, but activated endogenous Shh signaling. The activation of Shh signaling protected H9C2 myocardial cells from H/R-induced apoptosis and restored cell viability. In the present study, Shh signaling was demonstrated to serve a protective role against H/R by activating the phosphoinositol 3-kinase (PI3K)/Akt pathway and promoting the expression of anti-oxidant enzymes to ameliorate oxidative stress. In summary, Shh signaling attenuated H/R-induced apoptosis through via the PI3K/Akt pathway.

Emerging Roles of Sonic Hedgehog in Adult Neurological Diseases: Neurogenesis and Beyond

Sonic hedgehog (Shh), a member of the hedgehog (Hh) family, was originally recognized as a morphogen possessing critical characters for neural development during embryogenesis. Recently, however, Shh has emerged as an important modulator in adult neural tissues through different mechanisms such as neurogenesis, anti-oxidation, anti-inflammation, and autophagy. Therefore, Shh may potentially have clinical application in neurodegenerative diseases and brain injuries. In this article, we present some examples, including ours, to show different aspects of Shh signaling and how Shh agonists or mimetics are used to alter the neuronal fates in various disease models, both in vitro and in vivo. Other potential mechanisms that are discussed include alteration of mitochondrial function and anti-aging effect; both are critical for age-related neurodegenerative diseases. A thorough understanding of the protective mechanisms elicited by Shh may provide a rationale to design innovative therapeutic regimens for various neurodegenerative diseases.

Convergent Pathways in Idiopathic Autism Revealed by Time Course Transcriptomic Analysis of Patient-Derived Neurons

Potentially pathogenic alterations have been identified in individuals with autism spectrum disorders (ASDs) within a variety of key neurodevelopment genes. While this hints at a common ASD molecular etiology, gaps persist in our understanding of the neurodevelopmental mechanisms impacted by genetic variants enriched in ASD patients. Induced pluripotent stem cells (iPSCs) can model neurodevelopment in vitro, permitting the characterization of pathogenic mechanisms that manifest during corticogenesis. Taking this approach, we examined the transcriptional differences between iPSC-derived cortical neurons from patients with idiopathic ASD and unaffected controls over a 135-day course of neuronal differentiation. Our data show ASD-specific misregulation of genes involved in neuronal differentiation, axon guidance, cell migration, DNA and RNA metabolism, and neural region patterning. Furthermore, functional analysis revealed defects in neuronal migration and electrophysiological activity, providing compelling support for the transcriptome analysis data. This study reveals important and functionally validated insights into common processes altered in early neuronal development and corticogenesis and may contribute to ASD pathogenesis.

Brain-derived neurotrophic factor (BDNF) in children with ASD and their parents: a 3-year follow-up

OBJECTIVE

Several lines of evidence point to a probable relationship between brain-derived neurotrophic factor (BDNF) and autism spectrum disorder (ASD), but studies have yielded inconsistent findings on the BDNF serum level in ASD. The study aimed to assess those levels in children with ASD and their families.

METHOD

BDNF serum levels were measured in 45 ASD children without intellectual disability (ID) and allergies, age 30-42 months and age-matched normal controls. BDNF serum levels in the parents of the ASD subjects were compared to normal controls. BDNF serum levels in the ASD subjects were followed up for 3 years and correlated with adaptive functioning changes.

RESULTS

BDNF serum levels were measured to be lower in children with ASD and independent of all the major baseline characteristics of the subjects. Having a child with ASD raises the BDNF levels in parents comparing to controls. Prospectively, no correlation between the change of BDNF variables in time and the change of the Vineland scores was found.

CONCLUSIONS

Our results contradict those from recent published meta-analyses with the age, the presence of ID and allergies being possible contributing factors. The parents' data indeed point to a role of BDNF in the pathophysiology of ASD.

Meta-Analysis of BDNF Levels in Autism

Brain-derived neurotrophic factor (BDNF) centrally mediates growth, differentiation and survival of neurons, and the synaptic plasticity that underlies learning and memory. Recent meta-analyses have reported significantly lower peripheral BDNF among individuals with schizophrenia, bipolar disorder, and depression, compared with controls. To evaluate the role of BDNF in autism, and to compare autism to psychotic-affective disorders with regard to BDNF, we conducted a meta-analysis of BDNF levels in autism. Inclusion criteria were met by 15 studies, which included 1242 participants. The meta-analysis estimated a significant summary effect size of 0.33 (95 % CI 0.21-0.45, P < 0.001), suggesting higher BDNF in autism than in controls. The studies showed notable heterogeneity, but no evidence of publication biases. Higher peripheral BDNF in autism is concordant with several neurological and psychological theories on the causes and symptoms of this condition, and it contrasts notably with the lower levels of BDNF found in schizophrenia, bipolar disorder, and depression.

Targeting sonic hedgehog signaling in neurological disorders

Sonic hedgehog (Shh) signaling influences neurogenesis and neural patterning during the development of central nervous system. Dysregulation of Shh signaling in brain leads to neurological disorders like autism spectrum disorder, depression, dementia, stroke, Parkinson's diseases, Huntington's disease, locomotor deficit, epilepsy, demyelinating disease, neuropathies as well as brain tumors. The synthesis, processing and transport of Shh ligand as well as the localization of its receptors and signal transduction in the central nervous system has been carefully reviewed. Further, we summarize the regulation of small molecule modulators of Shh pathway with potential in neurological disorders. In conclusion, further studies are warranted to demonstrate the potential of positive and negative regulators of the Shh pathway in neurological disorders.

Sustained lentiviral-mediated overexpression of microRNA124a in the dentate gyrus exacerbates anxiety- and autism-like behaviors associated with neonatal isolation in rats

Autism spectrum disorders (ASD) are highly disabling psychiatric disorders. Despite a strong genetic etiology, there are no efficient therapeutic interventions that target the core symptoms of ASD. Emerging evidence suggests that dysfunction of microRNA (miR) machinery may contribute to the underlying molecular mechanisms involved in ASD. Here, we report a stress model demonstrating that neonatal isolation-induced long-lasting hippocampal elevation of miR124a was associated with reduced expression of its target BDNF mRNA. In addition, we investigated the impact of lentiviral-mediated overexpression of miR124a into the dentate gyrus (DG) on social interaction, repetitive- and anxiety-like behaviors in the neonatal isolation (Iso) model of autism. Rats isolated from the dams on PND 1 to PND 11 were assessed for their social interaction, marble burying test (MBT) and repetitive self-grooming behaviors as adults following miR124a overexpression. Also, anxiety-like behavior and locomotion were evaluated in the elevated plus maze (EPM) and open-field (OF) tests. Results show that, consistent with previously published reports, Iso rats displayed decreased social interaction contacts but increased repetitive- and anxiety-like behaviors. Interestingly, across both autism- and anxiety-like behavioral assays, miR124a overexpression in the DG significantly exacerbated repetitive behaviors, social impairments and anxiety with no effect on locomotor activity. Our novel findings attribute neonatal isolation-inducible cognitive impairments to induction of miR124a and consequently suppressed BDNF mRNA, opening venues for intercepting these miR124a-mediated damages. They also highlight the importance of studying microRNAs in the context of ASD and identify miR124a as a novel potential therapeutic target for improving mood disorders.

LRP2, an auxiliary receptor that controls sonic hedgehog signaling in development and disease

To fulfill their multiple roles in organ development and adult tissue homeostasis, hedgehog (HH) morphogens act through their receptor Patched (PTCH) on target cells. However, HH actions also require HH binding proteins, auxiliary cell surface receptors that agonize or antagonize morphogen signaling in a context-dependent manner. Here, we discuss recent findings on the LDL receptor-related protein 2 (LRP2), an exemplary HH binding protein that modulates sonic hedgehog activities in stem and progenitor cell niches in embryonic and adult tissues. LRP2 functions are crucial for developmental processes in a number of tissues, including the brain, the eye, and the heart, and defects in this receptor pathway are the cause of devastating congenital diseases in humans. Developmental Dynamics 245:569-579, 2016. © 2016 Wiley Periodicals, Inc.

Elevated Serum Brain-Derived Neurotrophic Factor (BDNF) but not BDNF Gene Val66Met Polymorphism Is Associated with Autism Spectrum Disorders

The aim of our study was to illuminate the potential role of brain-derived neurotrophic factor (BDNF) in autism spectrum disorder (ASD). We measured the circulating levels of BDNF in serum and BDNF gene (Val66Met) polymorphisms, in which two indicators were then compared between ASD and normal controls. A total of 82 drug-naïve ASD children and 82 age- and gender-matched normal controls were enrolled in the study. Their serum BDNF levels were detected by the ELISA. BDNF Val66Met polymorphism genotyping was conducted as according to the laboratory's standard protocol in laboratory. The ASD severity assessment was mainly determined by the score of the Childhood Autism Rating Scale (CARS). ELISA assay showed that the mean serum BDNF level of children with ASD was significantly (P < 0.0001) higher than that of the control cases (17.75 ± 5.43 vs. 11.49 ± 2.85 ng/ml; t = 9.236). Besides, the serum BDNF levels and CARS scores (P < 0.0001) were positively related. And, the BDNF genotyping results showed that there was no difference between the ASD cases and the control. Among the children with ASD, the mean serum BDNF level of Met/Met group was lower than other groups. According to the ROC curve generated from our clinical data, the optimal cutoff value of serum BDNF levels, an indicator for diagnosis of ASD, was projected to be 12.50 ng/ml. Thus, it yielded a corresponding sensitivity of 81.7 % and the specificity of 66.9 %. Accordingly, area value under the curve was 0.836 (95 % CI, 0.774-0.897); the positive predictive value (PPV) and the negative predictive value (NPV) were 70.1 and 79.1 %, respectively. These results suggested that rather than Val66Met polymorphism, BDNF was more possible to impact the pathogenesis of ASD.

Roles of phosphoinositide-specific phospholipase Cγ1 in brain development

Over the past decade, converging evidence suggests that PLCγ1 signaling has key roles in controlling neural development steps. PLCγ1 functions as a signal transducer that converts an extracellular stimulus into intracellular signals by generating second messengers such as DAG and IP3. DAG functions as an activator of either PKC or transient receptor potential cation channels (TRPCs), while IP3 induces the calcium release from intracellular calcium stores. These second messengers regulate the morphological change of neuron, such as neurite outgrowth, migration, axon pathfinding, and synapse formation. These morphological changes depend on finely tuned calcium signaling following receptor tyrosine kinase-mediated PLCγ1 signaling. Thus, deregulation of PLCγ1 signaling causes various abnormalities of neuronal development and it may be associated with diverse neurological disorders. Herein, we discuss the current understanding of the PLCγ1 signaling pathway in neural development and provide recent advances of how PLCγ1 signaling is involved in the formation of neuronal processes for functionally faithful brain development.

Molecular underpinnings of prefrontal cortex development in rodents provide insights into the etiology of neurodevelopmental disorders

The prefrontal cortex (PFC), seat of the highest-order cognitive functions, constitutes a conglomerate of highly specialized brain areas and has been implicated to have a role in the onset and installation of various neurodevelopmental disorders. The development of a properly functioning PFC is directed by transcription factors, guidance cues and other regulatory molecules and requires the intricate and temporal orchestration of a number of developmental processes. Disturbance or failure of any of these processes causing neurodevelopmental abnormalities within the PFC may contribute to several of the cognitive deficits seen in patients with neurodevelopmental disorders. In this review, we elaborate on the specific processes underlying prefrontal development, such as induction and patterning of the prefrontal area, proliferation, migration and axonal guidance of medial prefrontal progenitors, and their eventual efferent and afferent connections. We furthermore integrate for the first time the available knowledge from genome-wide studies that have revealed genes linked to neurodevelopmental disorders with experimental molecular evidence in rodents. The integrated data suggest that the pathogenic variants in the neurodevelopmental disorder-associated genes induce prefrontal cytoarchitectonical impairments. This enhances our understanding of the molecular mechanisms of prefrontal (mis)development underlying the four major neurodevelopmental disorders in humans, that is, intellectual disability, autism spectrum disorders, attention deficit hyperactivity disorder and schizophrenia, and may thus provide clues for the development of novel therapies.

Brain derived neurotrophic factor (BDNF) and autism spectrum disorders (ASD) in childhood

BACKGROUND

Neurotrophic factors are essential regulators of neuronal maturation including synaptic synthesis. Among those, Brain derived neurotrophic factor (BDNF) has been in particular focus in the understanding of autism spectrum disorders (ASD).

PURPOSE

The aim of our study was to investigate whether BNDF could be used as diagnostic/biological marker for ASD. For this purpose we examined the plasma levels of BDNF and the precursors pro- BDNF in patients with ASD and compared it with non-autistic controls; determined whether there was a correlation between the BDNF and proBDNF levels and clinical severity. We also investigated the coding region of BDNF identify for well-variations which could be associated to ASD.

METHODS

The 65 ASD patients (51 boys) were enrolled from a recent completed epidemiological survey covering two counties (Oppland and Hedmark) in Norway. The mean age of the total number of children who participated in this study was 11,7 years. 30 non-autistic children were included as controls, 14 boys and 16 girls. The mean age was 11.3 years. Exclusion criteria for control group were individuals suffering from either neurological, endocrine, or immune insuffiency.

RESULTS AND CONCLUSIONS

Patients with ASD were characterized by moderately but significantly elevated plasma levels of BDNF compared to matched controls. No differences were observed in the proBDNF level between patients and controls. Within the ASD group, children with intellectual disability demonstrated increased BDNF, but not proBDNF levels, while the presence of ADHD had no impact on circulating proBDNF or BDNF. No further associations between plasma proBDNF or BDNF and other clinical demographics were observed.

Activation of Sonic Hedgehog Leads to Survival Enhancement of Astrocytes via the GRP78-Dependent Pathway in Mice Infected with Angiostrongylus cantonensis

Angiostrongylus cantonensis infection may cause elevation of ROS and antioxidants in the CSF of infected mice. Astrocytes may protect the surrounding neurons from oxidative stress-induced cell death by secreting Sonic hedgehog (Shh) via the PI3-K/AKT/Bcl-2 pathway. This study was conducted to determine the role of the Shh signaling pathway in A. cantonensis-infected BABL/c mice by coculturing astrocytes with living fifth-stage larvae or soluble antigens. The Shh pathway was activated with corresponding increases in the level of the Shh. Glial fibrillary acidic protein (GFAP) and Shh were increased in astrocyte cocultured with living fifth-stage larvae or soluble antigens. The survival of astrocytes pretreated with Shh was significantly elevated in cocultures with the antigens but reduced by its inhibitor cyclopamine. The expression of GRP78 and Bcl-2 was significantly higher in astrocytes pretreated with recombinant Shh. These findings suggest that the expression of Shh may inhibit cell death by activating Bcl-2 through a GRP78-dependent pathway.