Signaling pathways involved with serotonin1A agonist-mediated neuroprotection against ethanol-induced apoptosis of fetal rhombencephalic neurons.
Previously, this laboratory demonstrated that developing serotonin (5-HT) neurons and other fetal rhombencephalic neurons are reduced by in vivo and in vitro exposure to ethanol, effects that are related to ethanol's augmentation of apoptosis. We also found that 5-HT1A agonists diminished the ethanol-associated reduction of 5-HT neurons and other fetal rhombencephalic neurons by attenuating the pro-apoptotic effects of ethanol. Presently, we investigated the hypothesis that the protective/anti-apoptotic effects of a 5-HT1A agonist on fetal rhombencephalic neurons are mediated by activation of the phosphatidylinositol 3' kinase (PI-3K) and/or the mitogen-activated protein kinase kinase (MAPKK) pathway. Apoptotic and non-apoptotic fetal rhombencephalic neurons were quantitated in primary cultures that were treated with 50 mM ethanol and with 100 nM of a 5-HT1A agonist such as 8-OH-DPAT [8-hydroxy 2-(di-n-propylamino)tetralin], ipsapirone, or buspirone. Analysis of neurons stained with Hoechst 33342 demonstrated the anti-apoptotic effects of 5-HT1A agonists and implicated the involvement of the PI-3K pathway and possibly the MAPKK pathway with the protective effects of these drugs. The protective effects were blocked by a 5-HT1A antagonist (WAY 100635), an inhibitor of PI-3K (LY294002), and an inhibitor of MAPKK (PD98059). Western blot analyses showed that ethanol treatment reduces basal pAkt levels. These analyses also provide support for the involvement of the PI-3K pathway; ipsapirone stimulated the phosphorylation of Akt in control and ethanol-treated neurons, and these effects were antagonized by LY294002.
Druse
Mary
M
Division of Molecular and Cellular Biochemistry, Loyola University Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL 60153, USA. mmanteu@lumc.edu
Tajuddin
Nuzhath F
NF
Gillespie
Roberta A
RA
Le
Phong
P
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D019610:Cytoprotection / Q000187:drug effects / Q000502:physiology; D004195:Disease Models, Animal; D004791:Enzyme Inhibitors / Q000494:pharmacology; D000431:Ethanol / Q000633:toxicity; D005260:Female; D063647:Fetal Alcohol Spectrum Disorders / Q000378:metabolism; D009421:Nervous System Malformations / Q000139:chemically induced / Q000378:metabolism; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D018696:Neuroprotective Agents / Q000494:pharmacology*; D011247:Pregnancy; D011903:Raphe Nuclei / Q000187:drug effects / Q000196:embryology / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D044282:Receptor, Serotonin, 5-HT1A / Q000378:metabolism; D012249:Rhombencephalon / Q000187:drug effects* / Q000196:embryology / Q000378:metabolism; D012701:Serotonin / Q000378:metabolism; D058825:Serotonin 5-HT1 Receptor Agonists; D012702:Serotonin Antagonists / Q000494:pharmacology; D017366:Serotonin Receptor Agonists / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology
D004791:Enzyme Inhibitors; D018696:Neuroprotective Agents; D058825:Serotonin 5-HT1 Receptor Agonists; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; D044282:Receptor, Serotonin, 5-HT1A; D012701:Serotonin; D000431:Ethanol