title: 5-Hydroxytryptamine 1A and 2B serotonin receptors in neurite outgrowth: involvement of early growth response protein 1.
abstract: Neurotransmitters play important roles in neurogenesis; in particular, acetylcholine and serotonin may regulate neurite elongation. Acetylcholine may also activate transcription factors such as early growth response protein 1 (EGR-1), which plays a role in neurite extension. N18TG2 neuroblastoma cells (which do not produce neurotransmitters and constitutively express muscarinic acetylcholine receptors) were transfected with constructs containing the cDNA for choline acetyltransferase, 5-hydroxytryptamine 1A (5-HT1A) and 5-HT2B serotonin receptors to study acetylcholine and serotonin interplay in neurite outgrowth. 5-HT1A receptor stimulation causes a decrease in EGR-1 levels and inhibition of neurite outgrowth; 5-HT2B stimulation, however, has no effect. Muscarinic cholinergic stimulation, on the other end, increases EGR-1 levels and fiber outgrowth. Inhibition of EGR-1 binding reduces fiber outgrowth activity. When both cholinergic and 5-HT1A receptors are stimulated, fiber outgrowth is restored; therefore, acetylcholine counterbalances the inhibitory effect of serotonin on neurite outgrowth. These results suggest that EGR-1 plays a role in the interplay of acetylcholine and serotonin in the regulation of neurite extension during development.
authors.affiliation: Dipartimento di Biologia e Biotecnologie 'Charles Darwin', Unità di Ricerca in Neurobiologia e Centro di Ricerca in Neurobiologia 'Daniel Bovet', Sapienza Università di Roma, Rome, Italy.
authors.forename: Tonino
authors.initials: T
authors.lastname: Anelli
authors.forename: Silvia
authors.initials: S
authors.lastname: Cardarelli
authors.forename: Michela
authors.initials: M
authors.lastname: Ori
authors.forename: Irma
authors.initials: I
authors.lastname: Nardi
authors.forename: Stefano
authors.initials: S
authors.lastname: Biagioni
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Poiana
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000502:physiology; D051766:Early Growth Response Protein 1 / Q000378:metabolism*; D051379:Mice; D016501:Neurites / Q000378:metabolism*; D055495:Neurogenesis / Q000502:physiology; D009474:Neurons / Q000378:metabolism*; D044282:Receptor, Serotonin, 5-HT1A / Q000378:metabolism*; D044403:Receptor, Serotonin, 5-HT2B / Q000378:metabolism*; D011976:Receptors, Muscarinic / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology
chemical_list: D051766:Early Growth Response Protein 1; D044403:Receptor, Serotonin, 5-HT2B; D011976:Receptors, Muscarinic; D044282:Receptor, Serotonin, 5-HT1A; D012701:Serotonin