Epigenetic modifications of GABAergic interneurons are associated with the schizophrenia-like phenotype induced by prenatal stress in mice.

Department of Physiology and Pharmacology, University of Rome "Sapienza", Piazzale Aldo Moro 5, 00185 Rome, Italy.
Neuropharmacology (Impact Factor: 4.82). 04/2012; DOI: 10.1016/j.neuropharm.2012.04.013
Source: PubMed

ABSTRACT Human studies suggest that a variety of prenatal stressors are related to high risk for cognitive and behavioral abnormalities associated with psychiatric illness (Markham and Koenig, 2011). Recently, a downregulation in the expression of GABAergic genes (i.e., glutamic acid decarboxylase 67 and reelin) associated with DNA methyltransferase (DNMT) overexpression in GABAergic neurons has been regarded as a characteristic phenotypic component of the neuropathology of psychotic disorders (Guidotti et al., 2011). Here, we characterized mice exposed to prenatal restraint stress (PRS) in order to study neurochemical and behavioral abnormalities related to development of schizophrenia in the adult. Offspring born from non-stressed mothers (control mice) showed high levels of DNMT1 and 3a mRNA expression in the frontal cortex at birth, but these levels progressively decreased at post-natal days (PND) 7, 14, and 60. Offspring born from stressed mothers (PRS mice) showed increased levels of DNMTs compared to controls at all time-points studied including at birth and at PND 60. Using GAD67-GFP transgenic mice, we established that, in both control and PRS mice, high levels of DNMT1 and 3a were preferentially expressed in GABAergic neurons of frontal cortex and hippocampus. Importantly, the overexpression of DNMT in GABAergic neurons was associated with a decrease in reelin and GAD67 expression in PRS mice in early and adult life. PRS mice also showed an increased binding of DNMT1 and MeCP2, and an increase in 5-methylcytosine and 5-hydroxymethylcytosine in specific CpG-rich regions of the reelin and GAD67 promoters. Thus, the epigenetic changes in PRS mice are similar to changes observed in the post-mortem brains of psychiatric patients. Behaviorally, adult PRS mice showed hyperactivity and deficits in social interaction, prepulse inhibition, and fear conditioning that were corrected by administration of valproic acid (a histone deacetylase inhibitor) or clozapine (an atypical antipsychotic with DNA-demethylation activity). Taken together, these data show that prenatal stress in mice induces abnormalities in the DNA methylation network and in behaviors indicative of a schizophrenia-like phenotype. Thus, PRS mice may be a valid model for the investigation of new drugs for schizophrenia treatment targeting DNA methylation. This article is part of a Special Issue entitled 'Neurodevelopment Disorder'.


Available from: Dennis Robert Grayson, Feb 12, 2014
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Psychosis is an abnormal mental state characterized by disorganization, delusions and hallucinations. Animal models have become an increasingly important research tool in the effort to understand both the underlying pathophysiology and treatment of psychosis. There are multiple animal models for psychosis, with each formed by the coupling of a manipulation and a measurement. In this manuscript we do not address the diseases of which psychosis is a prominent comorbidity. Instead, we summarize the current state of affairs and future directions for animal models of psychosis. To accomplish this, our manuscript will first discuss relevant behavioral and electrophysiological measurements. We then provide an overview of the different manipulations that are combined with these measurements to produce animal models. The strengths and limitations of each model will be addressed in order to evaluate its cross-species comparability.
    06/2014; 1(2). DOI:10.1007/s40473-014-0013-2
  • [Show abstract] [Hide abstract]
    ABSTRACT: Methylation of the fifth carbon of cytosine was the first epigenetic modification to be discovered in DNA. Recently, three new DNA modifications have come to light: hydroxymethylcytosine, formylcytosine, and carboxylcytosine, all generated by oxidation of methylcytosine by Ten Eleven Translocation (TET) enzymes. These modifications can initiate full DNA demethylation, but they are also likely to participate, like methylcytosine, in epigenetic signalling per se. A scenario is emerging in which coordinated regulation at multiple levels governs the participation of TETs in a wide range of physiological functions, sometimes via a mechanism unrelated to their enzymatic activity. Although still under construction, a sophisticated picture is rapidly forming where, according to the function to be performed, TETs ensure epigenetic marking to create specific landscapes, and whose improper build-up can lead to diseases such as cancer and neurodegenerative disorders.
    The EMBO Journal 05/2014; 33(11). DOI:10.15252/embj.201488290 · 10.75 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The British epidemiologist Dr. David J. Barker documented the relationship between infant birth weight and later onset of hypertension, coronary heart disease, insulin resistance, and type II diabetes. A stressful in utero environment can cause long-term consequences for offspring through prenatal programming. Prenatal programming most commonly occurs through epigenetic mechanisms and can be dependent on the type and timing of exposure as well as the sex of the fetus. In this review, we highlight the most recent evidence that prenatal programming is implicated in the development of psychiatric disorders in offspring exposed to maternal stress during pregnancy. Methodological differences between studies contribute to unavoidable heterogeneity in study findings. Current data suggest that fetal exposure to maternal hypothalamic-pituitary-adrenal axis dysregulation, excessive glucocorticoids, and inflammation with resulting epigenetic changes at both the placental and fetal levels are important areas of continued investigation.
    Current Psychiatry Reports 02/2015; 17(2):546. DOI:10.1007/s11920-014-0546-9 · 3.05 Impact Factor