Glial-derived neurotrophic factor (GDNF) prevents ethanol (EtOH) induced B92 glial cell death by both PI3K/AKT and MEK/ERK signaling pathways

• Published in: Brain research bulletin 2006-12, Vol.71 (1), p.116-126
• Main Authors: Villegas, Santiago Nahuel, Njaine, Brian, Linden, Rafael, Carri, Néstor Gabriel
• Format: Article
• Language: English
• Subjects: Actin Cytoskeleton - drug effects; Actin Cytoskeleton - metabolism; Alcohol-Induced Disorders, Nervous System - drug therapy; Alcohol-Induced Disorders, Nervous System - metabolism; Alcohol-Induced Disorders, Nervous System - physiopathology; Animals; Apoptosis; Apoptosis - drug effects; Apoptosis - physiology; Brain - drug effects; Brain - metabolism; Brain - physiopathology; Cell Line, Tumor; Central Nervous System Depressants - antagonists & inhibitors; Central Nervous System Depressants - toxicity; Cytoprotection - drug effects; Cytoprotection - physiology; Cytoskeleton; Dose-Response Relationship, Drug; Enzyme Inhibitors - pharmacology; Ethanol - antagonists & inhibitors; Ethanol - toxicity; Glial Cell Line-Derived Neurotrophic Factor - metabolism; Glial Cell Line-Derived Neurotrophic Factor - pharmacology; JNK; JNK Mitogen-Activated Protein Kinases - antagonists & inhibitors; JNK Mitogen-Activated Protein Kinases - metabolism; MAP Kinase Kinase 1 - antagonists & inhibitors; MAP Kinase Kinase 1 - metabolism; MAP Kinase Signaling System - drug effects; MAP Kinase Signaling System - physiology; Neuroglia - drug effects; Neuroglia - metabolism; Neuroprotection; Neuroprotective Agents - metabolism; Neuroprotective Agents - pharmacology; Phosphatidylinositol 3-Kinases - antagonists & inhibitors; Phosphatidylinositol 3-Kinases - metabolism; Rats; Trophic factor
• ISSN: 0361-9230; 1873-2747
• DOI: 10.1016/j.brainresbull.2006.08.014

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.