The effects of extinction training on DNA methylation protein and hippocampal newborn neurons in the conditioned-fear rat model
10.3760/cma.j.issn.1674-6554.2019.01.007
- VernacularTitle:消退训练对条件恐惧记忆模型大鼠海马DNA甲基化蛋白及新生神经元的影响
- Author:
Yahong LI
1
;
Zhipeng XU
;
Xiaohong TIAN
Author Information
1. 中南民族大学教育学院心理学系
- Keywords:
Extinction training;
Hippocampus;
Conditioned fear;
DNA methylation protein;
Newborn neurons;
Rat
- From:
Chinese Journal of Behavioral Medicine and Brain Science
2019;28(1):38-43
- CountryChina
- Language:Chinese
-
Abstract:
Objective To investigate the effect of different extinction training on fear memory,DNA methylation protein and hippocampal newborn neurons in adult rats.Methods Male SD rats were randomly divided into four groups:naive group,conditioned fear group,traditional-extinction group and retrieval-extinction group.Conditioned fear models were established by tone paired foot shock,and retrieval-extinction training or traditional-extinction training were performed in adult rats.Retention test,Western blot and immunnohischemistry were used to detect the no-freezing time percentage,the DNA methylation protein level,the newborn neurons respectively at 1d,4d and 7d after different extinction training.Results The traditional-extinction group((28.06± 11.33) ％) or retrieval-extinction group((30.28± 11.48) ％) had higher percentage of no-freezing time than that of conditioned fear group((21.35±9.45) ％),and lower percentage of no-freezing time than that of naive group ((75.65±8.69)％) (t=2.204,2.517,7.955,7.023,all P＜0.05) at the fourth day after extinction training.At the seventh day after extinotion training,the retrieval-extinction group ((69.72±13.62)％) had higher percentage of no-freezing time than traditional-extinction group((24.27± 11.67)％,t=7.052,P＜0.01) or conditioned fear group((50.64± 12.51)％,t=2.451,P＜0.05),and showed no significant difference compared with naive group((72.03±9.36) ％,t=0.251,P＞0.05).The expressions of Dnmt-1 and MBD-2 in traditional-extinction group or retrieval-extinction group were lower than those in conditioned fear group,and higher than those in naive group (P＜0.05) at 4 d after extinction.training.At 7 d after extinction training,the expressions of Dnmt-1 and MBD-2 in retrieval-extinction group were lower than those in traditional-extinction group or conditioned fear group (P＜0.05),and there was no significant difference between retrieval-extinction group and naive group.The Brdu-positive cells of traditional-extinction group or retrieval-extinction training were higher than conditioned fear group,and less than naive group (P＜0.05) at the fourth day after extinction training.At the seventh day after extinction training,the Brdu-positive cells in retrieval-extinction group were higher than those in traditional-extinction group or conditioned fear group (P＜0.05),and there was no significant difference between retrieval-extinction group and naive group.Conclusion The extinction training can decrease fear memory of rats with conditioned fear memory,and the effect of retrieval-extinction training were better than traditional-extinction training,which may be associated with the increases of hippocampus newborn neurons and the decline of DNA methylation.
