Novelty promotes recognition memory persistence by D1 dopamine receptor and protein kinase A signalling in rat hippocampus

Strategies for improving memory are increasingly studied, and exposure to a novel experience can be an efficient neuromodulator. Novelty effects on memory depend on D1‐family dopamine receptors (D1Rs) activation. Here, we evaluated the novelty effect on memory persistence of Wistar rats and investig...

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Published in:The European journal of neuroscience 2022-01, Vol.55 (1), p.78-90
Main Authors: Lima, Karine Ramires, Rosa, Ana Carolina de Souza, Picua, Steffanie Severo, Silva, Shara Souza, Soares, Náthaly Marks, Mello‐Carpes, Pâmela Billig
Format: Article
Language:English
Subjects:
Animals
CA1
Cyclic AMP-Dependent Protein Kinases
Dopamine
Dopamine - metabolism
Dopamine D1 receptors
Dopamine D5 receptors
dopaminergic system
Drug delivery
Hippocampus
Hippocampus - physiology
Kinases
Memory - physiology
Neuromodulation
novel object recognition
Pattern recognition
Protein kinase A
Protein kinase C
Proteins
Rats
Rats, Wistar
Receptors, Dopamine D1 - metabolism
Signal transduction
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Summary:Strategies for improving memory are increasingly studied, and exposure to a novel experience can be an efficient neuromodulator. Novelty effects on memory depend on D1‐family dopamine receptors (D1Rs) activation. Here, we evaluated the novelty effect on memory persistence of Wistar rats and investigated the contribution of D1Rs and their signalling pathways by protein kinase A (PKA) and C (PKC). Animals with infusion cannulae inserted into the CA1 hippocampus area were trained on the novel object recognition (NOR) task, which involved exploring two different objects. After training, some rats received intrahippocampal infusions of vehicle or D1Rs agonist; others explored a novel environment for 5 min and were infused with a variety of drugs targeting D1Rs and their signalling pathways. We demonstrated that pharmacological stimulation of D1Rs or novelty exposure promoted NOR memory persistence for 14 days and that the novelty effect depended on D1Rs activation. To determine if the D1 and D5 receptor subtypes were necessary for the impact of novelty exposure on memory, we blocked or stimulated PKA or PKC—protein kinases activated mainly by D1 and D5, respectively. Only PKA inhibition impaired the effect of novelty on memory persistence. After novelty and D1Rs blocking, PKA but not PKC stimulation maintained the memory persistence effect. Thus, we concluded that novelty promoted memory persistence by a mechanism‐dependent on activating hippocampal D1Rs and PKA pathway. In the absence of novelty, 24 h later, training animals only consolidate novel object recognition (NOR) memory, but it does not persist. After training, novelty exposure (an unknown environment) promotes memory consolidation and persistence for 14 days in Wistar rats. Novelty effects on NOR memory persistence depended on the activation of D1‐family dopamine receptors (D1Rs) and protein kinase A (PKA) in the CA1 area of the hippocampus. These mechanisms are essential to NOR memory persistence over the days.
ISSN:0953-816X
1460-9568
DOI:10.1111/ejn.15568