Ethanol Exposure Affects Glial Fibrillary Acidic Protein Gene Expression and Transcription During Rat Brain Development

Abstract

Exposure to ethanol during fetal development reduces the astroglial-specific marker glial fibrillary acidic protein (GFAP) and its mRNA levels in brains of fetal rats and in radial glia in primary culture, affecting the proliferation and differentiation of astrocytes. The objectives of this study were to evaluate the possible effect of ethanol on GFAP mRNA levels in astrocytes and to investigate the molecular mechanism(s) involved in ethanol-induced changes in GFAP expression by analyzing the GFAP transcription rate, GFAP mRNA stability, and GFAP DNA methylation. We show here that prenatal exposure to ethanol reduces significantly GFAP immunoreactivity and its mRNA levels in both astrocytes in primary culture and brains of pups from alcohol-fed mothers. Runoff experiments from nuclei of astrocytes indicate that ethanol exposure decreases GFAP transcription rate significantly and reduces GFAP mRNA stability slightly. DNA methylation analysis indicates that prenatal ethanol exposure induces a hypermethylated state of the GFAP DNA in fetal brains. Methylation-mediated repression of GFAP transcription could be a mechanism involved in ethanolinduced reduction of GFAP expression. Ethanol-induced alterations in GFAP expression and astroglial development may underlie the CNS dysfunctions observed after prenatal alcohol exposure. Key Words: Prenatal ethanol exposure-Brain development-Astrocytes in cultureGlial fibrillary acidic protein-Vimentin-mRNA-Transcription-Runoff-mRNA stability-Methylation-Fetal alcohol syndrome.

Developmental neurotoxicity of chlorpyrifos: what is the vulnerable period?

“…Differences in the rate of resynthesis of cholinesterase may also account for the smaller effects on enzyme activity in the brainstem compared with forebrain; certainly, pharmacokinetic disparities between these two regions would seem extremely unlikely. Second, recent data suggest that CPF targets development of glial cells to a greater extent than it does neuronal cell development (Aschner 2000;Garcia et al 2001Garcia et al , 2002Monnet-Tschudi et al 2000;Qiao et al 2001); glial development peaks during the postnatal period Valles et al 1997;Zawia and Harry 1996), whereas neurogenesis occurs much earlier (Rodier 1988), so the neonatal brain may be inherently more sensitive to CPF than is the fetal brain. Third, in light of the recent recognition that CPF itself is a developmental neurotoxicant Pope 1999;Rice and Barone 2000;Slotkin 1999), over and above inhibition of cholinesterase by its metabolite, chlorpyrifos oxon, there are likely to be substantial differences of effects reflecting the dissimilarities in fetal versus neonatal pharmacokinetics (Hunter et al , 1999Padilla et al 2000); it is highly likely that more unchanged CPF reaches the neonatal brain after direct administration to pups than is achieved with fetal exposure paradigms that involve maternal administration .…”

The RhoA/ROCK-I/MLC pathway is involved in the ethanol-induced apoptosis by anoikis in astrocytes

“…Ethanol is one of the most important teratogens that profoundly affect the developing foetal brain, and its consumption during gestation can produce mental retardation and neurobehavioural disorders, as well as foetal alcohol syndrome (FAS) (Guerri, 2002). Astroglial cells are affected by prenatal ethanol exposure (Valles et al, 1997), which suggests that alterations in glial-neuron interactions may underlie the CNS abnormalities associated with ethanolinduced neurotoxic effects (Eriksen and Druse, 2001;Guerri and Renau-Piqueras, 1997;Valles et al, 1997). Indeed, we have reported that in vivo alcohol exposure induces astroglial death (Climent et al, 2002), and we recently demonstrated that ethanol induces a reorganization of both the actin cytoskeleton and focal adhesions in astrocytes (Guasch et al, 2003).…”

Dual Mechanisms for Ethanol-Induced Inhibition of Monocyte Chemotactic Protein-3 mRNA Expression in Activated Glial Cells

“…Ethanol can affect DNA, RNA, and protein synthesis in primary cultures of rat cortical astrocytes and can suppress astrocyte mitogenesis (Aroor and Baker, 1997). Ethanol also reduces the capacity of astrocytes to secrete growth factors (Valles et al, 1994), induces oxidative stress in astrocytes (Montoliu et al, 1995), and alters the development, content, and distribution of several cytoskeletal proteins, including transcription of the astrocyte marker glial acidic fibrillary protein (Valles et al, 1997). Thus, ethanol-induced alterations in astrocyte gene expression could be important mechanisms underlying the CNS dysfunction observed after prenatal exposure to ethanol .…”