Article

Behavioral Alterations in Rats Prenatally Exposed to Valproic Acid: Animal Model of Autism

Department of Molecular Neuropharmacology, Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland.
Neuropsychopharmacology (Impact Factor: 7.83). 02/2005; 30(1):80-9. DOI: 10.1038/sj.npp.1300518
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ABSTRACT Autism is a severe behavioral disorder characterized by pervasive impairments in social interactions, deficits in verbal and nonverbal communication, and stereotyped, repetitive patterns of behaviors and interests. Recently, a new rodent model of autism was created by exposure of rat fetuses to valproic acid (VPA) on the 12.5th day of gestation (VPA rats). The model has striking anatomical, pathological, and etiological similarities to human data; however, it has not been characterized behaviorally. In order to determine if VPA rats present behavioral aberrations observed in autism, their behavior was extensively evaluated in a battery of tests. The results of the present experiments demonstrate that VPA rats exhibit: (1) lower sensitivity to pain and higher sensitivity to nonpainful stimuli, (2) diminished acoustic prepulse inhibition, (3) locomotor and repetitive/stereotypic-like hyperactivity combined with lower exploratory activity, and (4) decreased number of social behaviors and increased latency to social behaviors. In addition, VPA rats showed delayed maturation, lower body weight, delayed motor development, and attenuated integration of a coordinated series of reflexes, delayed nest-seeking response mediated by olfactory system, and normal negative geotaxis. Interestingly, all behavioral aberrations described in this paper appear before puberty, which could distinguish the VPA rat model of autism from other animal models of neurodevelopmental disorders, especially rodent models of schizophrenia. Our results bring further support to validity of the proposed VPA animal model of autism, suggesting similarities between the observed pattern of behavioral alterations in VPA rats and features of disturbed behavior in autistic patients.

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    • ", 2006 ; Markram et al . , 2008 ; Felix - Ortiz and Febo , 2012 ) Pup isolation - induced USVs ( Schneider and Przewlocki , 2005 ; Dufour - Rainfray et al . , 2010 ; Gandal et al . "
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    ABSTRACT: Autism spectrum disorders (ASD) are among the most severe developmental psychiatric disorders known today, characterized by impairments in communication and social interaction and stereotyped behaviors. However, no specific treatments for ASD are as yet available. By enabling selective genetic, neural, and pharmacological manipulations, animal studies are essential in ASD research. They make it possible to dissect the role of genetic and environmental factors in the pathogenesis of the disease, circumventing the many confounding variables present in human studies. Furthermore, they make it possible to unravel the relationships between altered brain function in ASD and behavior, and are essential to test new pharmacological options and their side-effects. Here, we first discuss the concepts of construct, face, and predictive validity in rodent models of ASD. Then, we discuss how ASD-relevant behavioral phenotypes can be mimicked in rodents. Finally, we provide examples of environmental and genetic rodent models widely used and validated in ASD research. We conclude that, although no animal model can capture, at once, all the molecular, cellular, and behavioral features of ASD, a useful approach is to focus on specific autism-relevant behavioral features to study their neural underpinnings. This approach has greatly contributed to our understanding of this disease, and is useful in identifying new therapeutic targets.
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    • "First we evaluated whether the developmental effects of VPA exposure corresponded to previously reported features of this animal model (Schneider and Przewlocki, 2005), we compared the developmental features after VPA or saline exposure. Initial visual observation did not reveal any abnormalities in rats prenatally exposed to VPA. "
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    • "Considering this link, animal model has been shown to be a reliable tool as it produces morphological, behavioral and pathophysiological alteration similar to the human. In animal, a single VPA administration in the prenatal stage results in poor cognitive performance [8], deficits in social interaction [9] [10] [11], and repetitive and stereotyped behavior [12] [13] in the postnatal offspring. These findings open an opportunity to develop an animal model of autism to study the effect of VPA during pregnancy. "
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    ABSTRACT: Prenatal exposure to valproic acid on gestational day 12.5 may lead to the impaired behaviour in the offspring, which is similar to the human autistic symptoms. To the contrary, astaxanthin shows neuroprotective effect by its antioxidant mechanism. We aimed to (i) develop mice model of autism and (ii) investigate the effect of astaxanthin on such model animals. Valproic acid (600 mg/kg) was administered intraperitoneally to the pregnant mice on gestational day 12.5. Prenatal valproic acid-exposed mice were divided into 2 groups on postnatal day 25 and astaxanthin (2 mg/kg) was given to the experimental group (VPA_AST, n = 10) while saline was given to the control group (VPA, n = 10) for 4 weeks. Behavioural test including social interaction, open field and hot-plate were conducted on postnatal day 25 and oxidative stress markers such as lipid peroxidation, advanced protein oxidation product, nitric oxide, glutathione, and activity of superoxide dismutase and catalase were estimated on postnatal day 26 to confirm mice model of autism and on postnatal day 56 to assess the effect of astaxanthin. On postnatal day 25, prenatal valproic acid-exposed mice exhibited (i) delayed eye opening (ii) longer latency to respond painful stimuli, (iii) poor sociability and social novelty and (iv) high level of anxiety. In addition, an increased level of oxidative stress was found by determining different oxidative stress markers. Treatment with astaxanthin significantly (p < 0.05) improved the behavioural disorder and reduced the oxidative stress in brain and liver. In conclusion, prenatal exposure to valproic day in pregnant mice leads to the development of autism-like features. Astaxanthin improves the impaired behaviour in animal model of autism presumably by its antioxidant activity.
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