title: Serotonin induces temporally and mechanistically distinct phases of persistent PKA activity in Aplysia sensory neurons.
abstract: The cAMP signaling cascade has been implicated in several stages of memory formation. We have examined activation of this cascade by serotonin (5-HT) in the sensory neurons of Aplysia. We find that different patterns of 5-HT exposure induce three distinct modes of PKA activation. First, a single 5 min pulse induces transient (5 min) PKA activation that requires neither transcription nor translation. Second, 4-5 pulses induce intermediate-term persistent activation (3 hr duration) that requires translation but not transcription. Third, 5 pulses of 5-HT, as well as continuous (90 min) exposure, induce long-term persistent activation 20 hr later, which requires both transcription and translation. Thus, in the sensory neurons, different patterns of 5-HT give rise to three independent phases of PKA activation that differ in their induction requirements, their temporal profiles, and their molecular mechanisms.
authors.affiliation: Institut für Neurobiologie Freie Universität Berlin, Federal Republic of Germany.
authors.forename: U
authors.initials: U
authors.lastname: Müller
authors.forename: T J
authors.initials: TJ
authors.lastname: Carew
mesh_terms: D000818:Animals; D001048:Aplysia; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics* / Q000378:metabolism*; D004789:Enzyme Activation; D017952:Ganglia, Invertebrate / Q000502:physiology*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D007700:Kinetics; D008568:Memory / Q000502:physiology; D009475:Neurons, Afferent / Q000187:drug effects / Q000201:enzymology / Q000502:physiology*; D010766:Phosphorylation; D014176:Protein Biosynthesis; D012701:Serotonin / Q000494:pharmacology*; D015398:Signal Transduction / Q000502:physiology; D013997:Time Factors; D014158:Transcription, Genetic
chemical_list: D012701:Serotonin; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases