Inhibitors of protein and RNA synthesis block structural changes that accompany long-term heterosynaptic plasticity in Aplysia.
Synaptic connections between the sensory and motor neurons of Aplysia in culture undergo long-term facilitation in response to serotonin (5-HT) and long-term depression in response to FMRFamide. These long-term functional changes are dependent on the synthesis of macromolecules during the period in which the transmitter is applied and are accompanied by structural changes. There is an increase and a decrease, respectively, in the number of sensory neuron varicosities in response to 5-HT and FMRFamide. To determine whether macromolecular synthesis is also required for the structural changes, we examined in parallel the effects of inhibitors of protein (anisomycin) or RNA (actinomycin D) synthesis on the structural and functional changes. We have found that anisomycin and actinomycin D block both the enduring alterations in varicosity number and the long-lasting changes in synaptic potential. These results indicate that macromolecular synthesis is required for expression of the long-lasting structural changes in the sensory cells and that this synthesis is correlated with the long-term functional modulation of sensorimotor synapses.
Center for Neurobiology and Behavior, College of Physicians and Surgeons, Columbia University, New York, New York 10032.
C H
CH
Bailey
P
P
Montarolo
M
M
Chen
E R
ER
Kandel
S
S
Schacher
D000818:Animals; D000841:Anisomycin / Q000494:pharmacology*; D001048:Aplysia; D002478:Cells, Cultured; D003609:Dactinomycin / Q000494:pharmacology*; D005071:Evoked Potentials / Q000187:drug effects; D019835:FMRFamide; D005724:Ganglia / Q000502:physiology; D009046:Motor Neurons / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D009473:Neuronal Plasticity / Q000187:drug effects*; D009475:Neurons, Afferent / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D009479:Neuropeptides / Q000494:pharmacology; D018377:Neurotransmitter Agents / Q000494:pharmacology; D012701:Serotonin / Q000494:pharmacology; D013569:Synapses / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure
D009479:Neuropeptides; D018377:Neurotransmitter Agents; D003609:Dactinomycin; D012701:Serotonin; D019835:FMRFamide; D000841:Anisomycin