| Summary: | 博士 === 國立成功大學 === 基礎醫學研究所 === 97 === Learning and memory usually involve various synaptic proteins and neurotrophic factors in the limbic system. Among these molecules, synaptic protein such as synaptotagmin (Syt), a Ca2+-dependent synaptic vesicle protein, the brain-derived neurotrophic factor (BDNF) and its receptor, tropomyosin-related kinase B (TrkB) have been discovered to play some roles in hippocampus or amygdala associated learning and memory. Recent studies indicate that both treadmill exercise and voluntary wheel running can improve aversive memory and spatial memory in rodents. Whether treadmill exercise training can improve learning and memory by upregulating some of these molecules and whether different types of exercise affect different learning/memory behavior tasks, BDNF-TrkB signaling and Syt expression differentially remains unclear. To answer these questions, BALB/c mice were trained by treadmill exercise or voluntary wheel running for 4 weeks. The ability of learning and memory after exercise was evaluated by passive avoidance (PA) test and Morris water maze. Hippocampal or amygdalar TrkB and Syt I protein expression after exercise were determined by Western blotting and BDNF was evaluated by ELISA. Our results showed that 1) both treadmill exercise and wheel running improve spatial learning and memory in Morris water maze, but only treadmill exercise improves aversive memory in PA test; 2) Both two exercises transiently increased the hippocampal BDNF level and persistently increased the hippocampal protein levels of full-length TrkB and Syt; 3) Only treadmill exercise transiently increased the amygdalar BDNF level and persistently increased the amygdalar protein levels of Syt; 4) Local administration of K252a into the hippocampus or basolateral amygdala to blunt TrkB signaling abolished treadmill exercise-enhanced PA performance and related protein expression; 5) Local administration of Syt I lentiviral-shRNA into the basolateral amygdala to inhibit Syt I expression also abolished treadmill exercise-enhanced PA performance and amygdalar Syt I expression. In conclusion, these data suggest that the upregulation of TrkB and Syt I may contribute to the exercise-facilitated aversive memory. Furthermore, moderate treadmill exercise and voluntary wheel running have differential effects on the aversive learning and memory, possibly due to the diverse influences on synaptic plasticity-related proteins in the amygdala.
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