The Retrotransposition of L1 is Involved in the Reconsolidation of Contextual Fear Memory in Mice

Title:The Retrotransposition of L1 is Involved in the Reconsolidation of Contextual Fear Memory in Mice

Volume: 20 Issue: 3

Author(s): Wen-Juan Zhang, Yan-Qing Huang, Ao Fu, Kang-Zhi Chen, Song-Ji Li, Qi Zhang, Guang-Jing Zou, Yu Liu, Jing-Zhi Su, Shi-Fen Zhou, Jun-Wen Liu, Fang Li, Fang-Fang Bi*Chang-Qi Li*

Affiliation:

• Department of Neurology, XiangYa Hospital, Central South University, Changsha 410008, Hunan,China

• Department of Anatomy and Neurobiology, School of Basic Medical Science, Central South University, Changsha 410013,China

Keywords: Fear memory reconsolidation, L1, lamivudine, hippocampus, prefrontal cortex (PFC), DNA methyltransferase.

Abstract:

Background: The long interspersed element-1 (L1) participates in memory formation, and DNA methylation patterns of L1 may suggest resilience or vulnerability factors for Post-Traumatic Stress Disorder (PTSD), of which the principal manifestation is a pathological exacerbation of fear memory. However, the unique roles of L1 in the reconsolidation of fear memory remain poorly understood.

Objective: The study aimed to investigate the role of L1 in the reconsolidation of context-dependent fear memory.

Methods: Mice underwent fear conditioning and fear recall in the observation chambers. Fear memory was assessed by calculating the percentage of time spent freezing in 5 min. The medial prefrontal cortex (mPFC) and hippocampus were removed for further analysis. Open Reading Frame 1 (ORF1) mRNA and ORF2 mRNA of L1 were analyzed by real-time quantitative polymerase chain reaction. After reactivation of fear memory, lamivudine was administered and its effects on fear memory reconsolidation were observed.

Results: ORF1 and ORF2 mRNA expressions in the mPFC and hippocampus after recent (24 h) and remote (14 days) fear memory recall exhibited augmentation via different temporal and spatial patterns. Reconsolidation of fear memory was markedly inhibited in mice treated with lamivudine, which could block L1. DNA methyltransferase mRNA expression declined following lamivudine treatment in remote fear memory recall.

Conclusion: The retrotransposition of L1 participated in the reconsolidation of fear memory after reactivation of fear memory, and with lamivudine treatment, spontaneous recovery decreased with time after recent and remote fear memory recall, providing clues for understanding the roles of L1 in fear memory.

Cite this article as:

Zhang Wen-Juan , Huang Yan-Qing , Fu Ao , Chen Kang-Zhi, Li Song-Ji , Zhang Qi, Zou Guang-Jing, Liu Yu , Su Jing-Zhi , Zhou Shi-Fen , Liu Jun-Wen , Li Fang , Bi Fang-Fang *, Li Chang-Qi *, The Retrotransposition of L1 is Involved in the Reconsolidation of Contextual Fear Memory in Mice, CNS & Neurological Disorders - Drug Targets 2021; 20 (3) . https://dx.doi.org/10.2174/1871527319666200812225509