Synaptic facilitation by ectopic octopamine and 5-HT receptors in Aplysia.
The cAMP pathway plays a critical role in synaptic plasticity. We assessed using the ectopic expression of octopamine (OA) receptor, the contribution of the cAMP pathway to short-term facilitation of sensory-motor synapses in Aplysia. When synaptic connections were depressed to 20-30% of their initial EPSP amplitude, the application of OA to sensory cells expressing OA receptor showed significant synaptic facilitation, but this was less than the synaptic facilitation shown by 5-HT treatment. We also found that synaptic facilitation was further enhanced when OA was treated in the presence of 5-HT at non-depressed synapses, but not at depressed synapses. These results imply that the role of cAMP in synaptic facilitation is reduced as the synapse becomes depressed due to repeated activity.
National Research Laboratory of Neurobiology, Institute of Molecular Biology and Genetics, School of Biological Sciences, College of Natural Sciences, Seoul National University, San 56-1 Silim-dong Kwanak-gu, Seoul 151-742, South Korea.
Deok-Jin
DJ
Chang
Chae-Seok
CS
Lim
Jin-A
JA
Lee
Bong-Kiun
BK
Kaang
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000818:Animals; D001048:Aplysia; D002478:Cells, Cultured; D004247:DNA / Q000008:administration & dosage; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004558:Electric Stimulation; D017952:Ganglia, Invertebrate / Q000187:drug effects / Q000378:metabolism; D015870:Gene Expression; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009046:Motor Neurons / Q000187:drug effects / Q000502:physiology; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology; D009475:Neurons, Afferent / Q000187:drug effects / Q000502:physiology; D009655:Octopamine / Q000494:pharmacology*; D017982:Receptors, Biogenic Amine / Q000187:drug effects / Q000235:genetics; D011985:Receptors, Serotonin / Q000502:physiology*; D012701:Serotonin / Q000494:pharmacology; D013569:Synapses / Q000187:drug effects / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects; D013997:Time Factors; D014162:Transfection
D000316:Adrenergic alpha-Agonists; D008164:Luminescent Proteins; D017982:Receptors, Biogenic Amine; D011985:Receptors, Serotonin; C027604:norsynephrine receptor; D049452:Green Fluorescent Proteins; D009655:Octopamine; D012701:Serotonin; D004247:DNA