Parallel molecular pathways mediate expression of distinct forms of intermediate-term facilitation at tail sensory-motor synapses in Aplysia.
Three distinct temporal phases of synaptic facilitation (short-, intermediate-, and long-term) are induced by serotonin (5-HT) at sensory (SN) to motor (MN) synapses in Aplysia. Here, we characterize two mechanistically distinct forms of intermediate-term facilitation (ITF) at tail SN-MN synapses. One form, activity-independent ITF, is produced by five spaced pulses of 5-HT in the absence of SN activity. Its induction requires protein synthesis, and its expression requires persistent activation of PKA but not PKC. The other form, activity-dependent ITF, is produced by a single pulse of 5-HT coincident with SN activation. Its induction does not require protein synthesis, and its expression requires persistent activation of PKC but not PKA. These results demonstrate that SN-MN synapses can exhibit two distinct forms of ITF that are mediated by parallel molecular pathways.
Sutton
M A
MA
Interdepartmental Neuroscience Program, Yale University, New Haven, Connecticut 06520, USA.
Carew
T J
TJ
D000818:Animals; D001048:Aplysia; D017868:Cyclic AMP-Dependent Protein Kinases / Q000187:drug effects / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology*; D016166:Free Radical Scavengers / Q000494:pharmacology; D011493:Protein Kinase C / Q000187:drug effects / Q000378:metabolism*; D012701:Serotonin / Q000494:pharmacology; D013569:Synapses / Q000187:drug effects / Q000378:metabolism*; D013623:Tail / Q000187:drug effects / Q000502:physiology
D004791:Enzyme Inhibitors; D016166:Free Radical Scavengers; D012701:Serotonin; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C