Reduced Consolidation, Reinstatement, and Renewal of Conditioned Fear Memory by Repetitive Treatment of Radix Polygalae in Mice.

Jung-Won Shin,Sungho Maeng,Yoonju Cho,Hyunwoo Park,Jiwon Yoon,Suck Lee

doi:10.3389/fpsyt.2017.00097

Abstract

The therapeutic goal for the treatment of posttraumatic stress disorder (PTSD) is to promote extinction and to prevent the relapse of fearful memories. Research has identified pharmacological treatments that may regulate the formation and extinction of fear memories, but not many reagents that block the relapse of extinguished fear are known. Radix Polygalae (RP) is an Asian herb used for sedation, and its ingredients have anxiolytic and antidepressant properties. As various neurological effects have been identified, we tested whether RP affects the relapse of fear. Freezing in response to a conditioned context and cues was used to measure the effects of RP in mice. In cohort 1 (n = 30), consolidation, extinction, and reinstatement were tested during the course of 18 days of treatment. In cohort 2 (n = 30), consolidation, extinction, and renewal were tested during 10 days of treatment. The consolidation, extinction, reinstatement, and possibly the renewal of context-induced freezing were inhibited due to the administration of RP in animal subjects. However, the effects of RP on the freezing responses of subjects elicited by conditioned auditory cues were less obvious. Because it effectively suppresses the consolidation of fear memories, RP may be used for primary and secondary prevention of symptoms in PTSD patients. Additionally, because it effectively suppresses the reinstatement and renewal of fear memories, RP may be applied for the prevention of fear relapse in PTSD patients who have undergone exposure therapy.

Highlights

Fear is an emotion that makes us alert to potential threats
In the first cohort of mice, conditioned freezing responses of fear consolidation, extinction, extinction retention, and reinstatement were measured during the period of exposure to context and cues (Figures 2 and 3)
We report that Radix Polygalae (RP) inhibits the consolidation, reinstatement and renewal of conditioned fear memories

Summary

Introduction

Fear is an emotion that makes us alert to potential threats. In contrast to preborn innate fear, acquired fear is characterized by associative learning about pertinent stimuli during a fearful threat [1]. Sensory cues can elicit fear, despite the absence of practical threats. Fear conditioning is a wellrecognized research tool into fear memory [2]. While electric foot shocks (EFSs), an example of an unconditioned stimulus (US) are inflicted, environmental context and sounds, the conditioned stimulus (CS), become conditioned cues that induce fear responses. Using these cues, consolidation, extinction, reinstatement, and renewal of fear can be tested [3]

Methods

Results

Conclusion