Social withdrawal, neophobia, and stereotyped behavior in developing rats exposed to neonatal asphyxia.
ABSTRACT Perinatal asphyxia is a concern for public health and may promote subtle neuropsychiatric disorders. Anoxic insults to neonatal rats cause long-lasting neurobehavioral deficits. In the present study, we focussed on changes in emotional behaviors as a consequence of neonatal asphyxia in Wistar rats. Newborn pups (24 h after birth) underwent a single 30-min exposure to a 100% N2 atmosphere (or air). The offspring was tested for a) locomotor and exploratory activity with or without a d-amphetamine challenge (0, 1, or 2 mg/kg) on postnatal day (pnd) 15; b) social interactions and novelty seeking during adolescence; c) levels of the brain-derived neurotrophic factor (BDNF). In the open-field test (pnd 15), N2-exposed pups injected with the high (2 mg/kg) amphetamine dose exhibited reduced levels of locomotor hyperactivity, and a more marked involvement in stereotyped behaviors. Individual differences emerged in the locomotor response to the novelty-seeking test: two subgroups of rats (separated on the basis of the median value) showed either arousal/attraction or avoidance/inhibition in response to free-choice novelty. The N2-exposed group showed a more marked novelty-induced avoidance and inhibition. Time devoted to allogrooming and play-soliciting behaviors was reduced, whereas object exploration was increased. Levels of BDNF were reduced in the striatum of N2-exposed rats, suggesting poorer synaptic performance of dopamine pathways. In conclusion, these findings suggest an increased risk of developing social withdrawal, neophobia and behavioral stereotypies (common symptoms found in schizophrenia and autism) as a consequence of neonatal asphyxia in preterm humans.
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ABSTRACT: The preclinical study of human disorders associated with comorbidities and for which the aetiology is still unclear may substantially benefit from multi-strain studies conducted in mice. The latter can help isolating experimental populations (strains) exhibiting distinct facets in the parameters isomorphic to the symptoms of a given disorder. Through a reverse-translation approach, multi-strain studies can inform both natural predisposing factors and environmental modulators. Thus, mouse strains selected for a particular trait may be leveraged to generate hypothesis-driven studies aimed at clarifying the potential role played by the environment in modulating the exhibition of the symptoms of interest. Tourette's syndrome (TS) constitutes a paradigmatic example whereby: it is characterized by a core symptom (tics) often associated with comorbidities (attention-deficit-hyperactivity and obsessive-compulsive symptoms); it has a clear genetic origin though specific genes are, as yet, unidentified; its course (exacerbations and remissions) is under the influence of environmental factors. Based on these considerations, we tested four mouse strains (ABH, C57, CD1, and SJL)-varying along a plethora of behavioural, neurochemical, and immunological parameters-on a test battery tailored to address the following domains: tics (through the i.p. administration of the selective 5-HT2 receptor agonist DOI, 5mg/kg); locomotion (spontaneous locomotion in the home-cage); perseverative responding in an attentional set shifting task; and behavioural stereotypies in response to a single amphetamine (10mg/kg, i.p.) injection. Present data demonstrate that while ABH and SJL mice respectively exhibit selective increments in amphetamine-induced sniffing behaviour and DOI-induced tic-like behaviours, C57 and CD1 mice show a distinct phenotype, compared to other strains, in several parameters.Behavioural brain research 03/2014; · 3.22 Impact Factor
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ABSTRACT: Environmental exposures during the prenatal period, perinatal stages, and postnatal life may contribute to onset and course of Tourette syndrome (TS). Pregnancy-related noxious exposures may be more frequent in pregnancies of children who will develop TS, particularly maternal smoking and prenatal life stressors. Lower birth weight and use of forceps at delivery may be associated with tic severity in the offspring; moreover, low birth weight and maternal smoking during pregnancy may affect the risk of co-morbid attention-deficit/hyperactivity and obsessive-compulsive disorders. Group A streptococcal infections as risk-modifier for TS has not been convincingly demonstrated to date, although an interaction with stressors was suggested. The PANDAS hypothesis is currently undergoing a nosological revision. Only limited anecdotal evidence supports a link of TS to other pathogens. Nevertheless, the relationship between infections and TS may be complex. Recent data point to intrinsically altered immune regulation in TS, which might predispose to both infections and autoimmune mechanisms; however, evidence of cell-mediated and antibody-mediated autoimmunity in TS is still insufficient. Psychosocial stress remains the most important contextual factor influencing tic severity, as confirmed by prospective studies. This might in part be related to enhanced reactivity of the stress response in TS patients, the mechanisms of which need to be explored further. New studies on large prospective cohorts of patients of different age and the identification of reliable biomarkers or endophenotypes indicating early, prenatal exposure to environmental insults are needed.Neuroscience & Biobehavioral Reviews 10/2012; · 10.28 Impact Factor
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ABSTRACT: In the present manuscript we review a substantial body of literature describing several pre-clinical animal models designed and developed with the purpose of investigating the biological determinants of Tourette Syndrome (TS). In order to map the animal models onto the theoretical background upon which they have been devised, we first define phenomenological and etiological aspects of TS and then match this information to the available pre-clinical models. Thus, we first describe the characteristic symptoms exhibited by TS patients and then a series of hypotheses attempting to identify the multifactorial causes of TS. With respect to the former, we detail the phenomenology of abnormal repetitive behaviors (tics and stereotypies), obsessive-compulsive behaviors and aberrant sensory-motor gating. With respect to the latter, we describe both potential candidate vulnerability genes and environmental factors (difficult pregnancies, psychosocial stressors and infections). We then discuss how this evidence has been translated in pre-clinical research with respect to both dependent (symptoms) and independent (etiological factors) variables. Thus, while, on the one hand, we detail the methodologies adopted to measure abnormal repetitive and obsessive-compulsive behaviors, and sensory-motor gating, on the other hand, we describe genetic engineering studies and environmental modulations aimed at reproducing the proposed biological determinants in laboratory rodents. A special emphasis is placed upon "programming" events, occurring during critical stages of early development and exerting organizational delayed consequences. In the final section, we outline a heuristic model with the purpose of integrating clinical and pre-clinical evidence in the study of TS.Neuroscience & Biobehavioral Reviews 04/2013; · 10.28 Impact Factor