Article

The teratology of autism.

Department of Obstetrics and Gynecology, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, USA.
International Journal of Developmental Neuroscience (Impact Factor: 2.92). 04/2005; 23(2-3):189-99. DOI: 10.1016/j.ijdevneu.2004.11.001
Source: PubMed

ABSTRACT Autism spectrum disorders affect behaviors that emerge at ages when typically developing children become increasingly social and communicative, but many lines of evidence suggest that the underlying alterations in the brain occur long before the period when symptoms become obvious. Studies of the behavior of children in the first year of life demonstrate that symptoms are often detectable in the first 6 months. The environmental factors known to increase the risk of autism have critical periods of action during embryogenesis. Minor malformations that occur frequently in people with autism are known to arise in the same stages of development. Anomalies reported from histological studies of the brain are consistent with an early alteration of development. Congenital syndromes with high rates of autism include somatic that originate early in the first trimester. In addition, it is possible to duplicate a number of anatomic and behavioral features characteristic of human cases by exposing rat embryos to a teratogenic dose of valproic acid at the time of neural tube closure.

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    Necesidades Educativas Especiales: Una mirada diferente, Edited by Moreno Osella E, 01/2015: chapter Trastornos del Espectro Autista; FEDUNE., ISBN: 978-84-606-6197-9
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    ABSTRACT: A growing body of evidence indicates that valproic acid (VPA), a histone deacetylase (HDAC) inhibitor used to treat epilepsy and mood disorders, has HDAC-related and -unrelated neurotoxic activity, the mechanism of which is still poorly understood. We report that VPA induces neuronal cell death through an atypical calpain-dependent necroptosis pathway that initiates with downstream activation of c-Jun N-terminal kinase 1 (JNK1) and increased expression of receptor-interacting protein 1 (RIP-1) and is accompanied by cleavage and mitochondrial release/nuclear translocation of apoptosis-inducing-factor (AIF), mitochondrial release of Smac/DIABLO, and inhibition of the anti-apoptotic protein X-linked inhibitor of apoptosis (XIAP). Coinciding with AIF nuclear translocation, VPA induces phosphorylation of the necroptosis-associated histone H2A family member H2AX, which is known to contribute to lethal DNA degradation. These signals are inhibited in neuronal cells that express constitutively activated MEK/ERK and/or PI3-K/Akt survival pathways, allowing them to resist VPA-induced cell death. The data indicate that VPA has neurotoxic activity and identify a novel calpain-dependent necroptosis pathway that includes JNK1 activation and RIP-1 expression.This article is protected by copyright. All rights reserved.
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    ABSTRACT: The aim of this study was to test the hypothesis that long-term fetal valproic acid (VPA) exposure at doses relevant to the human clinic interferes with normal brain development. Pregnant rats were given intraperitoneal injections of VPA (20 mg/kg or 100 mg/kg) continuously during the last 9-12 days of pregnancy and during the lactation period until sacrifice on the 23rd postnatal day. Total number of neocortical neurons was estimated using the optical fractionator and frontal cortical thicknesses were sampled in VPA exposed pups compared with an unexposed control group. We found that pups exposed to 20 mg/kg and 100 mg/kg doses of VPA had statistically significant higher total number of neurons in neocortex by 15.8% and 12.3%, respectively, (p < 0.05) compared to controls amounting to 15.5 × 106 neocortical neurons (p < 0.01). There was no statistical difference between the two VPA groups. Pups exposed to 100 mg/kg, but not to 20 mg/kg VPA displayed a significant (p < 0.05) broader (7.5%) of frontal cortical thickness compared to controls. Our results support the hypothesis that fetal exposure of VPA may interfere with normal brain development by disturbing neocortical organization, resulting in overgrowth of frontal lobes and increased neuronal cell numbers. The results indirectly suggest that prenatal VPA may contribute as a causative factor in the brain developmental disturbances equivalent to those seen in human autism spectrum disorders. We therefore suggest that this version of the VPA model may provide a translational model of autism.
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