Effect of ethanol on neurotrophin-mediated cell survival and receptor expression in cultures of cortical neurons.
The interaction of ethanol and neurotrophin-mediated cell survival was examined in primary cultures of cortical neurons. Cells were obtained from rat fetuses on gestational day 16 and maintained in a medium supplemented with either 10% or 1.0% fetal calf serum (FCS). Exogenous nerve growth factor (NGF; 20 ng/ml), brain-derived neurotrophic factor (BDNF; 20 ng/ml) or neurotrophin 3 (NT-3; 20 ng/ml) was added to the cultures alone, or in combination with ethanol (400 mg/dl). The number of viable neurons was determined after a 48 h treatment with a growth factor and/or ethanol. The effects of ethanol on the expression of high affinity neurotrophin receptors (trkA, trkB, and trkC) and the low-affinity receptor (p75), were analyzed using Western immunoblots. In untreated cultures, 22.7% and 26.3% of the cells raised in a medium containing 10% and 1.0% FCS, respectively, were lost. Only NGF prevented the death of the cultured cortical neurons. Ethanol was toxic; it caused a 23.5% and 16.7% loss of cells (for cells grown in a medium containing 10% and 1.0% FCS, respectively) beyond that occurring 'naturally' in an untreated culture. Ethanol completely blocked the NGF-mediated cell survival. In general, BDNF and NT-3 did not offset the toxic effect of ethanol. Immunoblotting studies showed that the expression of p75 was significantly (p < 0.05) lower (40%) in ethanol-treated cultures, but ethanol did not affect trk expression. Thus, ethanol has specific effects upon NGF-mediated cell survival and the effects on the low affinity receptor imply that p75 specifically plays an important role in NGF signaling.
Department of Psychiatry, University of Iowa College of Medicine, Iowa City 52242-1000, USA.
G K
GK
Seabold
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J
Luo
M W
MW
Miller
D000818:Animals; D019208:Brain-Derived Neurotrophic Factor / Q000378:metabolism; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D002492:Central Nervous System Depressants / Q000494:pharmacology*; D002540:Cerebral Cortex / Q000166:cytology*; D000431:Ethanol / Q000494:pharmacology*; D005260:Female; D005333:Fetus / Q000737:chemistry / Q000187:drug effects; D009414:Nerve Growth Factors / Q000378:metabolism*; D009474:Neurons / Q000737:chemistry / Q000166:cytology / Q000187:drug effects*; D018696:Neuroprotective Agents / Q000032:analysis; D020933:Neurotrophin 3; D011247:Pregnancy; D011518:Proto-Oncogene Proteins / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D020794:Receptor Protein-Tyrosine Kinases / Q000032:analysis; D020801:Receptor, Ciliary Neurotrophic Factor; D020800:Receptor, Nerve Growth Factor; D020917:Receptor, trkA; D020812:Receptor, trkC; D017475:Receptors, Nerve Growth Factor / Q000032:analysis
D019208:Brain-Derived Neurotrophic Factor; D002492:Central Nervous System Depressants; D009414:Nerve Growth Factors; D018696:Neuroprotective Agents; D020933:Neurotrophin 3; D011518:Proto-Oncogene Proteins; D020801:Receptor, Ciliary Neurotrophic Factor; D020800:Receptor, Nerve Growth Factor; D017475:Receptors, Nerve Growth Factor; D000431:Ethanol; D020794:Receptor Protein-Tyrosine Kinases; D020917:Receptor, trkA; D020812:Receptor, trkC