Dopamine D1-like receptor signalling in the hippocampus and amygdala modulates the acquisition of contextual fear conditioning.

Florence C Heath,Regimantas Jurkus,Marie A Pezze,J Peter Voigt,Carl W Stevenson,Tobias Bast,Jonathan L C Lee

doi:10.1007/s00213-015-3897-y

Florence C Heath, Regimantas Jurkus + Show 5 more

Open Access

https://doi.org/10.1007/s00213-015-3897-y

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Abstract

RationaleDopamine D1-like receptor signalling is involved in contextual fear conditioning, but the brain regions involved and its role in other contextual fear memory processes remain unclear.ObjectivesThe objective of this study was to investigate (1) the effects of SCH 23390, a dopamine D1/D5 receptor antagonist, on contextual fear memory encoding, retrieval and reconsolidation, and (2) if the effects of SCH 23390 on conditioning involve the dorsal hippocampus (DH) and/or basolateral amygdala (BLA).MethodsRats were used to examine the effects of systemically administering SCH 23390 on the acquisition, consolidation, retrieval and reconsolidation of contextual fear memory, and on locomotor activity and shock sensitivity. We also determined the effects of MK-801, an NMDA receptor antagonist, on contextual fear memory reconsolidation. The effects of infusing SCH 23390 locally into DH or BLA on contextual fear conditioning and locomotor activity were also examined.ResultsSystemic administration of SCH 23390 impaired contextual fear conditioning but had no effects on fear memory consolidation, retrieval or reconsolidation. MK-801 was found to impair reconsolidation, suggesting that the behavioural parameters used allowed for the pharmacological disruption of memory reconsolidation. The effects of SCH 23390 on conditioning were unlikely the result of any lasting drug effects on locomotor activity at memory test or any acute drug effects on shock sensitivity during conditioning. SCH 23390 infused into either DH or BLA impaired contextual fear conditioning and decreased locomotor activity.ConclusionsThese findings suggest that dopamine D1-like receptor signalling in DH and BLA contributes to the acquisition of contextual fear memory.

Highlights

The neurotransmitter dopamine plays a crucial role in memory processing
SCH 23390 infused into either dorsal hippocampus (DH) or basolateral amygdala (BLA) impaired contextual fear conditioning and decreased locomotor activity
These findings suggest that dopamine D1-like receptor signalling in DH and BLA contributes to the acquisition of contextual fear memory

Summary

Introduction

The neurotransmitter dopamine plays a crucial role in memory processing. well known for its involvement in appetitive learning and memory (Schultz 2013), dopamine mediates certain aversive memory processes (Pezze and Feldon 2004; Iordanova 2009; Volman et al 2013). Dopamine D1-like receptor signalling is involved in Pavlovian fear conditioning to discrete and contextual cues. One prevalent view is that contextual representations are encoded by DH and associated with the US in BLA (Anagnostaras et al 2001) Both DH and BLA receive dopamine projections from the ventral tegmental area (VTA) and show D1/D5 receptor expression (Huang et al 1992; Scibilia et al 1992; Gasbarri et al 1997; Pinard et al 2008; Muller et al 2009). SCH 23390 suppresses long-term potentiation in DH and BLA, suggesting that D1like receptor signalling is involved in synaptic plasticity in these regions (Otmakhova and Lisman 1996; Huang and Kandel 1995, 2007).

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