title: Nitric oxide signaling participates in norepinephrine-induced activity of neuronal intracellular survival pathways.
abstract: Much evidence has gathered that nitric oxide (NO) signaling, via cGMP-dependent mechanisms, may activate pro-survival pathways in hippocampal neurons and inhibit apoptosis. Past research has revealed that the enhancement of monoaminergic neurotransmission via exercise or treatment with antidepressant medications leads to an enhanced expression of brain-derived neurotrophic factor (BDNF). In isolated hippocampal neurons, norepinephrine (NE) application also increases the immunoreactivity of BDNF and several pro-survival signaling molecules. The data herein support the possibility that NO signaling plays an important role in enhancing neurotrophin expression and activation of the pro-survival phosphatidylinositol 3' kinase (PI-3K) pathway stimulated by NE. In isolated hippocampal neurons, the NO donor, sodium nitroprusside, increases BDNF, PI-3K, and phospho-ERK1 immunoreactivity. Specific inhibitors of the NO system suggest that NE-induced increases in hippocampal BDNF and the PI-3K pathway, but not stimulation of the MAPK pathway, depend upon NO signaling. In addition, inhibiting cGMP suggest that the effects of NE on BDNF immunoreactivity and Akt phosphorylation are also cGMP-dependent. Finally, the application of l-NAME to hippocampal neurons increases cell death. This is the first study of its kind demonstrating the involvement of NE-induced pro-survival signaling in three distinct signaling pathways: PI-3K, MAPK, and NO/cGMP. Possible mechanisms are discussed in light of the results.
authors.affiliation: Department of Biological Sciences, California State University, 5151 State University Drive, Los Angeles, CA 90032, USA. mjchen@calstatela.edu
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Chen
authors.forename: Amelia A
authors.initials: AA
authors.lastname: Russo-Neustadt
mesh_terms: D000818:Animals; D015153:Blotting, Western; D019208:Brain-Derived Neurotrophic Factor / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D006152:Cyclic GMP / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005865:Gestational Age; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors; D006624:Hippocampus / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D009638:Norepinephrine / Q000494:pharmacology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction
chemical_list: D019208:Brain-Derived Neurotrophic Factor; D004791:Enzyme Inhibitors; D020030:Nitric Oxide Donors; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D019869:Phosphatidylinositol 3-Kinases; D020929:Mitogen-Activated Protein Kinase Kinases; D006162:Guanylate Cyclase; D006152:Cyclic GMP; D009638:Norepinephrine