Effects of prenatal ethanol exposure on rat brain radial glia and neuroblast migration María Paula Aronne, Tamara Guadagnoli, Paula Fontanet, Sergio Gustavo Evrard, Alicia Brusco ⁎ Instituto de Biología Celular y Neurociencias "Prof. Eduardo De Robertis", Facultad de Medicina, Universidad de Buenos Aires (UBA), Paraguay 2155 3rd fl., (C1121ABG) Buenos Aires, Argentina abstract article info Article history: Received 15 March 2010 Revised 4 January 2011 Accepted 7 March 2011 Available online 14 March 2011 Keywords: Prenatal ethanol exposure Pax6 Neuronal migration Corticogenesis Cortical dysplasia Fetal alcohol syndrome Prenatal ethanol exposure (PEE) induces morphologic and functional alterations in the developing central nervous system. The orderly migration of neuroblasts is a key process in the development of a layered structure such as the cerebral cortex (CC). From initial stages of corticogenesis, the transcription factor Pax6 is intensely expressed in neuroepithelial and radial glia cells (RGCs) and is involved in continual regulation of cell surface properties responsible for both cellular identity and radial migration. In the present work, one month before mating, during pregnancy and lactation, a group of female Wistar rats were fed a liquid diet with 5.9% (w/w) ethanol (EtOH), rendering moderate blood EtOH concentrations. Maternal gestational weight progression and fetal CC thickness were measured. CC from E12-P3 rats were examined for expression of vimentin, nestin, S-100b, Pax6 and doublecortin using immunohistochemical assays. RGCs expressing vimentin, nestin, S-100b and Pax6 had abnormal morphologies. The migration distance through the CC and the number of doublecortin-ir neuroblasts in germinative zones were decreased. We found significant morphologic defects on RGCs, a marked delay in neuronal migration, decreased numbers of neuroblasts, and decreased numbers of Pax6-ir cells in the CC as a consequence of exposure to ethanol during development. These observations suggest a sequence of toxic events that contribute to cortical dysplasia in offspring exposed to EtOH during gestation. © 2011 Elsevier Inc. All rights reserved. Introduction Fetal alcohol syndrome (FAS) represents a public health issue associated with maternal alcohol abuse during pregnancy. Central nervous system (CNS) developmental defects, which can lead to microcephaly and mental retardation, are among the most signi ficant characteristics of FAS. Different types of cortical dysplasia occur after prenatal ethanol exposure (PEE) due to, among other factors, disorders in neuroblasts migration (Miller, 1986). Although maturation of the cerebral cortex (CC) is completed during postnatal period, most CC gross architecture is established prenatally and crucially involves the orderly migration of neuroblasts from the proliferative ventricular zone (VZ), at the inner surface of the telencephalon, through the overlying interme- diate zone to the cortical plate (Angevine and Sidman, 1961; Rakic, 1974). Neuroblasts, the precursors of neurons, migrate mainly attached to the cellular processes of radial glia cells (RGCs) by using them as living scaffolding. During corticogenesis, RGCs perform a dual function: they behave as precursor cells (Choi and Lapham, 1978; Levitt et al., 1981, 1983; Misson et al., 1991) and as migratory substrates for neuroblasts (Rakic, 1972; Gadisseux et al., 1990; Hatten and Mason, 1990). RGCs are ultrastructurally similar to glial cells, e.g., they show bundles of filaments and glycogen accumulation (Rakic, 1972). They express nestin, a cytoskeletal type VI intermediate filament commonly used as a marker for immature cells in the developing CNS (Alberts et al., 2007; Hockfield and McKay, 1985); they also express vimentin, another cytoskeletal protein, a type III intermediate filament (Alberts et al., 2007; Pixley and DeVellis, 1984). Moreover, by the end of neurogenesis and during neuroblast migration, RGCs differentiate into astrocytes in some regions such as the CC ( Pixley and DeVellis, 1984; Voigt, 1989). Upon differentiation into astrocytes, RGCs stop expressing vimentin and upregulate glial fibrillary acidic protein (GFAP; another type III intermediate filament) with an overlapping period when they express both (Bignami and Dahl, 1974; Levitt et al., 1983; Voigt, 1989). As mature astrocytes, RGCs also express S-100b protein, a dimeric neurotrophic and neurite outgrowth-promoting protein with many important actions during both pre- and postnatal life. Among these multiple functions, S-100b acts as a promoter of cytoskeletal stabilization (Donato, 2003; Donato et al., 2009; Huttunen et al., 2000). The correct specification of RGCs is therefore essential for normal corticogenesis (Pinto-Lord et al., 1982). Pax6, a paired box family transcription factor, plays an important role in development of the brain and other organs (Chi and Epstein, 2002; Buckingham and Relaix, 2007). Pax6 is specifically expressed by RGCs and controls their differentiation in the CC (Götz, 1998; Götz et al, 1998; Simpson and Price, 2002). In Experimental Neurology 229 (2011) 364–371 ⁎ Corresponding author. Fax: +54 11 5950 9626. E-mail address: hbrusco@fmed.uba.ar (A. Brusco). 0014-4886/$ – see front matter © 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.expneurol.2011.03.002 Contents lists available at ScienceDirect Experimental Neurology journal homepage: www.elsevier.com/locate/yexnr