Contextual Fear Memory Formation and Destabilization Induce Hippocampal RyR2 Calcium Channel Upregulation. (5th July 2018)

• Record Type: Journal Article
• Authors: More, Jamileth; Casas, María Mercedes; Sánchez, Gina; Hidalgo, Cecilia; Haeger, Paola
• Other Names: Wu Long-Jun Academic Editor.
• Is Part Of: Neural plasticity. Volume 2018(2018)
• Publication Date: 2018-07-05
• Subjects: Neuroplasticity -- Periodicals; 612.82
• DOI: 10.1155/2018/5056181
• Languages: English
• ISSNs: 2090-5904

Abstract

Abstract : Hippocampus-dependent spatial and aversive memory processes entail Ca 2+ signals generated by ryanodine receptor (RyR) Ca 2+ channels residing in the endoplasmic reticulum membrane. Rodents exposed to different spatial memory tasks exhibit significant hippocampal RyR upregulation. Contextual fear conditioning generates robust hippocampal memories through an associative learning process, but the effects of contextual fear memory acquisition, consolidation, or extinction on hippocampal RyR protein levels remain unreported. Accordingly, here we investigated if exposure of male rats to contextual fear protocols, or subsequent exposure to memory destabilization protocols, modified the hippocampal content of type-2 RyR (RyR2) channels, the predominant hippocampal RyR isoforms that hold key roles in synaptic plasticity and spatial memory processes. We found that contextual memory retention caused a transient increase in hippocampal RyR2 protein levels, determined 5 h after exposure to the conditioning protocol; this increase vanished 29 h after training. Context reexposure 24 h after training, for 3, 15, or 30 min without the aversive stimulus, decreased fear memory and increased RyR2 protein levels, determined 5 h after reexposure. We propose that both fear consolidation and extinction memories induce RyR2 protein upregulation in order to generate the intracellular Ca 2+ signals required for these distinct memory processes.