Postsynaptic regulation of long-term facilitation in Aplysia.
Repeated exposure to serotonin (5-HT), an endogenous neurotransmitter that mediates behavioral sensitization in Aplysia[1-3], induces long-term facilitation (LTF) of the Aplysia sensorimotor synapse [4]. LTF, a prominent form of invertebrate synaptic plasticity, is believed to play a major role in long-term learning in Aplysia[5]. Until now, LTF has been thought to be due predominantly to cellular processes activated by 5-HT within the presynaptic sensory neuron [6]. Recent work indicates that LTF depends on the increased expression and release of a sensory neuron-specific neuropeptide, sensorin [7]. Sensorin released during LTF appears to bind to autoreceptors on the sensory neuron, thereby activating critical presynaptic signals, including mitogen-activated protein kinase (MAPK) [8, 9]. Here, we show that LTF depends on elevated postsynaptic Ca2+ and postsynaptic protein synthesis. Furthermore, we find that the increased expression of presynaptic sensorin resulting from 5-HT stimulation requires elevation of postsynaptic intracellular Ca2+. Our results represent perhaps the strongest evidence to date that the increased expression of a specific presynaptic neuropeptide during LTF is regulated by retrograde signals.
Cai
Diancai
D
Department of Physiological Science, UCLA College, University of California, Los Angeles, Los Angeles, CA 90095-1606, USA.
Chen
Shanping
S
Glanzman
David L
DL
D000818:Animals; D001048:Aplysia / Q000502:physiology*; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology*; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology*; D005786:Gene Expression Regulation; D017774:Long-Term Potentiation / Q000187:drug effects* / Q000502:physiology; D009479:Neuropeptides / Q000378:metabolism / Q000494:pharmacology*; D012701:Serotonin / Q000378:metabolism; D015398:Signal Transduction; D013569:Synapses / Q000502:physiology
D009479:Neuropeptides; C419310:sensorin A protein, Aplysia; D012701:Serotonin; D002118:Calcium