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.
