Persistence of a fear motivated memory is dependent on hippocampal protein synthesis during a

PEDRO BEKINSCHTEIN; LIONEL MÜLLER IGAZ; IVAN IZQUIERDO; MARTÍN CAMMAROTA; JORGE H. MEDINA

Innsbruck, Austria

Congreso; ISN – ESN 20th BIENNIAL MEETING; 2005

International Society for Neurochemistry-European Society for Neurochemistry

  To the present time, memory research has been extensively and successfully devoted to the study of the mechanisms and brain circuits involved in long term memory formation. It is widely accepted that consolidation for several learning tasks is dependent upon hippocampal de novo protein synthesis. In this sense, it has been demonstrated that many learning tasks, including Inhibitory Avoidance (IA), require de novo protein synthesis during the first 6 hr after acquisition. However, the role of early hippocampal protein synthesis in memory persistence has never been addressed. Intra-hippocampal inhibition of protein synthesis by anisomycin caused amnesia for IA learning in a 7-day retention test, but not in a 2-day retention test in a time-dependent manner. A learning-dependent increase in the level of five hippocampal proteins that peaked at 24 hr was detected by immunoblot. Anisomycin infusion that caused a memory deficit at 7 days, prevented c-Fos, Homer-1a and Akt increases at 24 hr. Our results reveal that early and time-restricted protein synthesis in rat hippocampus is required after acquisition for persistence, but not formation of IA memory. This hippocampal mechanism for memory persistence may involve c-Fos and Homer-1a expression around 24 hr after acquisition.