The effect of neonatal isolation on the developmental downregulation of long term depression in hippocampal CA1 region

• Main Authors: Hsiao-yun Ku, 顧曉耘
• Other Authors: Kuei-Sen Hsu
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/83465255362728218637

碩士 === 國立成功大學 === 藥理學研究所 === 95 === Activity-dependent persistent synaptic modifications are generally thought to be the cellular mechanisms underlying the refinement of neuronal connection in developing nervous systems and for learning and memory in the mature brain. Persistent synaptic modifications can involve alterations in both the function of synaptic transmission and the structure of neuronal connections. Studies of synaptic plasticity have shown that repetitive electrical activity can rapidly induce persistent changes in the strength of synaptic transmission, known as long-term potentiation (LTP) and long-term depression (LTD). Neonatal physiology and development are regulated by the ongoing mother-infant interactions. Maternal care during the first week of postnatal life has been shown to have profound and enduring impacts on hippocampal development and function. We have previously showed that a mild maternal separation paradigm (once per day for 1 h from postnatal days 1-7, P1-P7) can accelerates the developmental switch in the signaling cascades for hippocampal CA1 LTP induction from a cyclic AMP-dependent protein kinase (PKA)- to a Ca2+/calmodulin-dependent protein kinase II (CaMKII)-dependent pattern and that the developmental expression profile of CaMKIIα is highly correlated with the LTP dependence on CaMKII signaling pathway. Here we confirm that the amount of LTD induced by LFS (1 Hz for 15 min) protocol correlates negatively with developmental age and show that mild neonatal isolation may delays this developmental downregulation of hippocampal CA1 LTD induction through chaning the composition of NMDA receptor via corticotrophin-releasing factor (CRF) system. In addition, we VII have demonstrated that this maternal separation model has a profound influence on conditional fear memory aquizition and extinction.