A Single Dose of Methylprednisolone Improves Aversive Memory Consolidation and Extinction in Rats.

Rithiele Gonçalves,Pâmela B Mello-Carpes,Liane Da Silva De Vargas

doi:10.3389/fnins.2019.01167

Rithiele Gonçalves, Pâmela B Mello-Carpes + Show 1 more

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https://doi.org/10.3389/fnins.2019.01167

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Abstract

Aversive memory is essential for survival, but in some situations its exacerbation can be potentially dangerous. There are several ways to modulate memory, among them, through stress-related hormones physiological release or administration of exogenous substances analogous to them. Recently, our group shown that a chronic treatment with a low dose of methylprednisolone (MP) is able to promote memory persistence in rats. Herein, we evaluate if a single intraperitoneal (IP) dose of MP (5 mg/kg) is able to modulate aversive memory consolidation and promote memory persistence and extinction in rats. For this, two experiments were carried out. In the first one, we demonstrated that a single IP MP administration in specific times after inhibitory avoidance (IA) training improved memory consolidation and persistence. In the second experiment, we verified that a single IP MP administration 2 h after IA extinction training promoted memory extinction. This results suggest a possible new clinical applicability for MP on the aversive memory disorders, as post-traumatic stress.

Highlights

The aversive memory corresponds to our ability to identify dangerous situations when certain trigger stimuli promotes the retrieval of memories related to a prior fear experience
Based on our previous results, here we aim to investigate the effects of a single MP dose on aversive memory consolidation and persistence, as well as on the extinction of an aversive memory
Our results demonstrated that a single dose of MP administrated in an specific time after to memory acquisition is able to improve

Summary

Introduction

The aversive memory corresponds to our ability to identify dangerous situations when certain trigger stimuli promotes the retrieval of memories related to a prior fear experience These memories are fundamental to activate circuits related to survival and necessary to avoid harmful circumstances to the individual (Ozawa et al, 2017). The extinction is used in a way by which the individuals are exposed to stimuli related to the one that have led them to a traumatic experience until they suppress the inadequate responses upon perceiving the absence of danger, becoming able to lead a normal life (Hendriks et al, 2018) In this way, the extinction is considered the formation of a new memory without erasing the original memory, but overlapping it (de Carvalho Myskiw et al, 2015). It is characterized by a progressive decrease in the intensity and/or frequency of the conditioned response caused by the repeated memory evocation in the absence of the unconditioned stimulus (Cammarota et al, 2005)

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