Effects of systemic and intra-hippocampal injections of cycloheximide on the late reconsolidation of fear-based memory in rats

AuthorRoya Maleklooen
AuthorAli Rashidy-Pouren
AuthorAbbas Ali Vafaeien
AuthorHamid Reza Samenien
Issued Date2015-06-30en
Abstract  Introduction : Reactivation of a stabilized memory induces a second wave of consolidation process which is now called as reconsolidation. Recently, a late consolidation process was proposed, suggesting that memory after learning within a delayed time window was labile . This late memory consolidation needs protein synthesis in the hippocampus. The aim of this study was to test whether the re-stabilized memory after reactivation also requires a late-phase protein synthesis in the hippocampus. We also investigated whether memories become increasingly resistant to disruption with age.   Materials and Methods : Male Wistar rats were trained in a one trial passive avoidance task (1mA, 3s). In the first experiment, cycloheximide (CYC, 2.8 mg/kg, i.p.) administrated 15 minutes before the memory reactivation and also 3, 6, 12 and 24 hours after the memory reactivation. In the second experiment, the same dose of CYC administrated to rats with memory age of 7, 14, 28 or 56 days. In the third experiment, CYC administrated (4 µg or 8µg/µl) into hippocampus. In the last experiment, CYC administrated (8µg/µl) into hippocampus of rats with memory age of 7, 14, 28 or 56 days. In all experiments, memory test was done 2 and 7 days after memory reactivation.   Results : Results indicated that systemic administration of CYC only 12h after memory reactivation significantly impaired memory retention. With increasing the age of memory, no effect of CYC was found. This impairing effect also was found when CYC was injected into hippocampus. This impairing effect also was found on memory age with 7 days.   Conclusion : Our findings indicate that protein synthesis, particularly in the hippocampus, plays an important role in the late memory reconsolidation and with increasing the age of memories, they become resistant to disruption.   Keywords : Protein synthesis, Cycloheximide, Dorsal hippocampus, Late memory reconsolidation, Passive avoidance task.en
DOIhttps://doi.org/en
KeywordProtein synthesisen
KeywordCycloheximideen
KeywordDorsal hippocampusen
KeywordLate memory reconsolidationen
KeywordPassive avoidance tasken
Keywordسنتز پروتئینen
Keywordسیکلوهگزامیدen
Keywordناحیه خلفی هیپوکمپen
Keywordبازتثبیت تأخیری حافظهen
Keywordحافظه احترازی غیر فعالen
PublisherBrieflandsen
TitleEffects of systemic and intra-hippocampal injections of cycloheximide on the late reconsolidation of fear-based memory in ratsen
TypeResearch Articleen

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