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)

• Keywords: Maternal separation, Memory, Synaptic plasticity, Brain-derived neurotrophic factor, Rat pups