title: Glial-derived neurotrophic factor (GDNF) prevents ethanol (EtOH) induced B92 glial cell death by both PI3K/AKT and MEK/ERK signaling pathways.
abstract: We investigated the neuroprotective effect of glial-derived neurotrophic factor (GDNF) upon alcohol-exposed B92 cultures, as well as the role of the cytoskeleton and mitogen-activated protein kinase (MAPK) pathways in this effect. Ethanol (EtOH) was added to cultures, either alone or in combination with 30 ng/ml GDNF. Exposure to EtOH (86 and 172 mM; 60 and 120 min) increased the frequency of apoptotic cells identified by nuclear DNA staining with 4,6-diamidino-2-phenylindole (DAPI). Cultures treated with GDNF showed a decrease in ethanol-induced apoptosis. A jun N-terminal kinase (JNK) pathway is activated by EtOH and their pharmacological inhibition (by SP600125) neutralized ethanol-induced apoptosis, suggesting a role for JNK in EtOH neurotoxicity. Immunocytochemically detected phospho-JNK (p-JNK) showed an unusual filamental expression, and localized together with actin stress fibers. Examination of the cytoskeleton showed that EtOH depolymerized actin filaments, inducing p-JNK dissociation and translocation to the nucleus, which suggests that released p-JNK may contribute to glial cell death after EtOH exposure. Treatment with GDNF, in turn, may neutralize the ethanol-induced cell death pathway. Either a phosphatidylinositol 3-kinase (PI3K)/AKT pathway inhibitor (LY294002) or an inhibitor of the extracellular signal-regulated kinase (ERK) 1, 2 pathways (UO126) failed to neutralize GDNF protective effects. However, the simultaneous use of both inhibitors blocked the protective effect of GDNF, suggesting a role for both signaling cascades in the GDNF protection. These findings provide further insight into the mechanism involved in ethanol-induced apoptosis and the neurotrophic protection of glial cells.
authors.affiliation: Molecular Biology, IMBICE, Camino Belgrano y 526, CC 403, 1900 La Plata, Argentina; Instituto de Biofísica da UFRJ, CCS, Bloco G, Cidade Universitaria, 21949-900 Rio de Janeiro, Brazil. neurobio@imbice.org.ar
authors.forename: Santiago Nahuel
authors.initials: SN
authors.lastname: Villegas
authors.forename: Brian
authors.initials: B
authors.lastname: Njaine
authors.forename: Rafael
authors.initials: R
authors.lastname: Linden
authors.forename: Néstor Gabriel
authors.initials: NG
authors.lastname: Carri
mesh_terms: D008841:Actin Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D020268:Alcohol-Induced Disorders, Nervous System / Q000188:drug therapy / Q000378:metabolism / Q000503:physiopathology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D001921:Brain / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D045744:Cell Line, Tumor; D002492:Central Nervous System Depressants / Q000037:antagonists & inhibitors / Q000633:toxicity; D019610:Cytoprotection / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D000431:Ethanol / Q000037:antagonists & inhibitors* / Q000633:toxicity; D051100:Glial Cell Line-Derived Neurotrophic Factor / Q000378:metabolism / Q000494:pharmacology*; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D048369:MAP Kinase Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects* / Q000502:physiology; D009457:Neuroglia / Q000187:drug effects* / Q000378:metabolism; D018696:Neuroprotective Agents / Q000378:metabolism / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051381:Rats
chemical_list: D002492:Central Nervous System Depressants; D004791:Enzyme Inhibitors; D000431:Ethanol; D051100:Glial Cell Line-Derived Neurotrophic Factor; D048031:JNK Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; D018696:Neuroprotective Agents; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors