Maternal Separation Impairs Memory Function through Suppressing Synaptic Plasticity in Rat Pups

국문 초록 (Abstract)

신생아기는 발달과정에 중요한 시기이며, 모성분리는 생후 뇌의 발달에 지장을 초래하여 인지력 및 행동장애를 유발시키는 심각한 스트레스로 작용한다. 본 연구에서는 어미 쥐의 분리가 새끼 쥐의 기억력에 미치는 영향을 신경 가소성과 관련시켜 연구하였다. 생후 14일째, 새끼 쥐는 어미 쥐의 보호를 받는 군과 어미 쥐와 분리된 군으로 나누었다 (각군 8마리씩). 어미 쥐의 분리는 생후 15일째 시작하여 10일 동안 지속되었다. 기억력을 검사하기 위하여 step-down avoidance task를 실시하였으며, brain-derived neurotrophic factor (BDNF)와 이의 수용체 tyrosine kinase (TrkB), 그리고 phosphorylated synapsin (p-synpasin)의 발현을 western blot으로 측정하였다. 본 실험 결과, 어미 쥐와 분리된 새끼쥐는 step-down avoidance task에서 latency가 감소하였고, 해마의 BDNF, TrkB, 그리고 p-synpasin의 발현이 억제되었다. 본 연구에서 어미 쥐와의 분리는 새끼 쥐의 해마에서 p-synpasin의 발현을 억제함으로써 해마의 신경가소성이 감소되어 기억력 감퇴를 초래하는 것으로 나타났다.

다국어 초록 (Multilingual Abstract)

Maternal separation during the early postnatal period is a stressful state that can disturb postnatal brain development, which induces cognitive and behavioral impairment. In this study, we investigated the effect of maternal separation on memory function in relation to synaptic plasticity in the brain of rat pups. On postnatal day 14, the rat pups were divided into one of two groups: the maternal care group and the maternal separation group (n=8 in each group). The rat pups in the maternal care group were housed with their respective mothers under standard conditions, while the rat pups in the maternal separation groups were separated from their dams and housed individually. The maternal separation started on postnatal day 15 and was continued for 10 consecutive days. To evaluate memory function of the rat pups, step-down avoidance task was performed. Expressions of brain-derived neurotrophic factor (BDNF), its receptor tyrosine kinase (TrkB), and phosphorylated synapsin (p-synapsin) were determined by western blot analysis. In the present results, latency in the step-down avoidance task was decreased in the rat pups of the maternal separation group. Expressions of BDNF, TrkB, and p-synapsin in the hippocampus were decreased in the rat pups of the maternal separation group. These results suggest that maternal separation impaired memory function with suppressing BDNF, TrkB, and p-synapsin expressions in the hippocampus. Maternal separation-induced memory impairment in the rat pups can be ascribed to the decreased synaptic plasticity through suppression of p-synapsin expression in the hippocampus. (Korean J Str Res 2012;20:97∼103)

목차 (Table of Contents)

• INTRODUCTION
• MATERIALS AND METHODS
• RESULTS
• DISCUSSION
• REFERENCES
• 국문초록