Reduced brain-derived neurotrophic factor expression in cortex and hippocampus involved in the learning and memory deficit in molarless SAMP8 mice  

作　　者：JIANG Qing-song LIANG Zi-liang WU Min-Jie FENG Lin LIU Li-li ZHANG Jian-jun 

机构地区：[1]Department of Prosthodontics, Beijing Stomatological Hospital and School of Stomatology, Capital Medical University, Beijing 100050, China [2]Department of Pharmacology, Institute of Materia Medica Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China [3]School and Hospital of Stomatology, Peking University, Beijing 100081, China

出　　处：《Chinese Medical Journal》2011年第10期1540-1544,共5页中华医学杂志（英文版）

基　　金：This work was supported by grants from the National Natural Science Foundation of China （No. 30801311）, Beijing NOVA Program （No. 2008B60）, Beijing Natural Science Foundation （No. 7073091）, National Basic Research Program （973 Program, No. 2007CB507400） and National S＆T Major Special Project on Major New Drug Innovation （No. 2009ZX09301-003）.

摘　　要：Background The molarless condition has been reported to compromise learning and memory functions. However, it remains unclear how the molarless condition directly affects the central nervous system, and the functional consequences on the brain cortex and hippocampus have not been described in detail. The aim of this study was to find the molecular mechanism related with learning and memory deficit after a bilateral molarless condition having been surgically induced in senescence-accelerated mice/prone8 （SAMP8） mice, which may ultimately provide an experimental basis for clinical prevention of senile dementia.Methods Mice were either sham-operated or subjected to complete molar removal. The animals＇ body weights were monitored every day. Learning ability and memory were measured in a water maze test at the end of the 1 st, 2nd, and 3rd months after surgery. As soon as significantly prolonged escape latency in the molarless group was detected, the locomotor activity was examined in an open field test. Subsequently, the animals were decapitated and the cortex and hippocampus were dissected for Western blotting to measure the expression levels of brain-derived neurotrophic factor （BDNF） and the tropomyosin related kinase B （TrkB）, the high affinity receptor of BDNF.Results Slightly lower weights were consistently observed in the molarless group, but there was no significant difference in weights between the two groups （P〉0.05）. Compared with the sham group, the molarless group exhibited lengthened escape latency in the water maze test three months after surgery, whereas no difference in locomotor activity was observed. Meanwhile, in the cortex and hippocampus, BDNF levels were significantly decreased in the molarless group （P〈0.05）; but the expression of its receptor, TrkB, was not significantly affected.Conclusion These results suggested that the molarless condition impaired learning and memory abilities in SAMP8mice three months after teeth extraction, and this effect was accompanied by siBackground The molarless condition has been reported to compromise learning and memory functions. However, it remains unclear how the molarless condition directly affects the central nervous system, and the functional consequences on the brain cortex and hippocampus have not been described in detail. The aim of this study was to find the molecular mechanism related with learning and memory deficit after a bilateral molarless condition having been surgically induced in senescence-accelerated mice/prone8 （SAMP8） mice, which may ultimately provide an experimental basis for clinical prevention of senile dementia.Methods Mice were either sham-operated or subjected to complete molar removal. The animals＇ body weights were monitored every day. Learning ability and memory were measured in a water maze test at the end of the 1 st, 2nd, and 3rd months after surgery. As soon as significantly prolonged escape latency in the molarless group was detected, the locomotor activity was examined in an open field test. Subsequently, the animals were decapitated and the cortex and hippocampus were dissected for Western blotting to measure the expression levels of brain-derived neurotrophic factor （BDNF） and the tropomyosin related kinase B （TrkB）, the high affinity receptor of BDNF.Results Slightly lower weights were consistently observed in the molarless group, but there was no significant difference in weights between the two groups （P〉0.05）. Compared with the sham group, the molarless group exhibited lengthened escape latency in the water maze test three months after surgery, whereas no difference in locomotor activity was observed. Meanwhile, in the cortex and hippocampus, BDNF levels were significantly decreased in the molarless group （P〈0.05）; but the expression of its receptor, TrkB, was not significantly affected.Conclusion These results suggested that the molarless condition impaired learning and memory abilities in SAMP8mice three months after teeth extraction, and this effect was accompanied by si

关 键 词：molarless learning and memory water maze brain-derived neurotrophic Jactor TRKB 

分 类 号：R[医药卫生]