Acute administration of a permeant analog of cAMP and a phosphodiesterase inhibitor improve long-term habituation in the crab Chasmagnathus.
A shadow passing overhead acts as a danger stimulus and elicits an escape response in the crab Chasmagnathus that habituates promptly and for a long period. Robust retention is shown at 24 h after 15 trials of shadow presentation or at 120 h after 30 trials, but no significant retention is disclosed at 24 h after 5 trials or at 72 h after 15. A cocktail of the cAMP membrane permeable analog 8-(4-chlorophenylthio)-cAMP (CPT-cAMP), plus the phosphodiesterase inhibitor isobutyl methylxanthine (IBMX), was given by systemic administration. Pretraining injection of the cocktail (25 or 50 microM, 15 min before a 5-trial session) failed to affect short-term habituation, but induced significant retention when tested at 24 h. This facilitatory effect was not shown when a lower dose (5 microM) was used. A post-training injection of 25 microM, immediately after a 5- or 15-trial session, induced retention when tested at 24 or 72 h, respectively. Thus, the administration of CPT-cAMP + IBMX during acquisition of a habituated response or immediately after, improves long-term habituation, a result supporting the view that an increase in the cAMP level is one of the steps in long-term memory consolidation.
Romano
A
A
Departamento de Biología, Facultad de Ciencias Exactas y Naturales, Buenos Aires University, Argentina.
Delorenzi
A
A
Pedreira
M E
ME
Tomsic
D
D
Maldonado
H
H
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000818:Animals; D003386:Brachyura / Q000502:physiology*; D000242:Cyclic AMP / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004924:Escape Reaction / Q000187:drug effects; D006185:Habituation, Psychophysiologic / Q000187:drug effects*; D008297:Male; D008568:Memory / Q000187:drug effects; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D013873:Thionucleotides / Q000494:pharmacology*
D010726:Phosphodiesterase Inhibitors; D013873:Thionucleotides; C015929:8-((4-chlorophenyl)thio)cyclic-3',5'-AMP; D000242:Cyclic AMP; D015056:1-Methyl-3-isobutylxanthine