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Prenatal exposure to excess glucocorticoid has been shown to have adverse effects on the developing nervous system that may lead to alterations of fetal and adult neurogenesis, resulting in behavioral changes. In addition, an imbalance of the redox state, with an increased susceptibility to oxidative stress, has been observed in rodent neural stem cells exposed to the synthetic glucocorticoid analog dexamethasone (Dex). In the present study, we used the induced pluripotent stem cells (IPSC)-derived lt-NES AF22 cell line, representative of the neuroepithelial stage in central nervous system development, to investigate the heritable effects of Dex on reactive oxygen species (ROS) balance and its impact on neuronal differentiation. By analysing gene expression in daughter cells that were never directly exposed to Dex, we could observe a downregulation of four key antioxidant enzymes, namely Catalase , superoxide dismutase 1, superoxide dismutase 2 and glutathione peroxidase7 , along with an increased intracellular ROS concentration. The imbalance in the intracellular REDOX state was associated to a significant downregulation of major neuronal markers and a concomitant increase of glial cells. Interestingly, upon treatment with the antioxidant N-acetyl-cysteine (NAC), the misexpression of both neuronal and glial markers analyzed was recovered. These novel findings point to the increased ROS concentration playing a direct role in the heritable alterations of the differentiation potential induced by Dex exposure. Moreover, the data support the hypothesis that early insults may have detrimental long-lasting consequences on neurogenesis. Based on the positive effects exerted by NAC, it is conceivable that therapeutic strategies including antioxidants may be effective in the treatment of neuropsychiatric disorders that have been associated to increased ROS and impaired neurogenesis. [ABSTRACT FROM AUTHOR]

Exposure to prenatal insults has been associated with an increased risk for neuropsychiatric disorders, including depression, but the mechanisms are still poorly understood. Persistent alterations of the HPA axis feedback mechanism as well as adult impaired neurogenesis are believed to play a relevant role in the etiology of depression. In addition, growing evidence points at epigenetic reprogramming as a key factor. We have previously shown that prenatal exposure to the synthetic glucocorticoid dexamethasone (DEX) impairs neurogenesis and leads to late onset of depression-like behavior that does not respond to the SSRI antidepressant fluoxetine (FLX). The aims of this study were to assess the effect of DEX prenatal exposure on the morphology of hippocampal granule neurons and on the expression of genes related to plasticity; and to test whether the SNRI antidepressant desipramine (DMI), unlike FLX, could counteract the effect of prenatal-DEX. C57Bl/6 mice were exposed to DEX (0.05 mg/kg/day) in utero and received intra-hippocampal injection of GFP expressing retroviral vector for labeling of newborn granule cells at eleven months. By twelve months, DEX mice showed depression-like behavior associated with decreased neurogenesis and morphological alterations of the newborn granule cells in the dentate gyrus (DG). Furthermore DEX mice displayed altered expression of genes controlling neurogenesis and neuronal morphology, such as Cdkn1c, p16, TrkB, DISC1 and Reelin. Chronic treatment with DMI led to a significant decrease in immobility time in the forced swim test. In addition, DMI restored neurogenesis, neuronal morphology in the DG, as well as the expression of all related genes. Our results suggest that (1) prenatal DEX induces early and persistent reprogramming effects resulting in altered neurogenesis and neuronal morphology; and (2) DMI treatment reverses DEX-induced depression by restoring the expression of genes relevant to neuronal plasticity. [ABSTRACT FROM AUTHOR]