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Brain-derived neurotrophic factor (BDNF) is a key regulator of neuronal plasticity and cognitive functions. BDNF val66met polymorphism, a human single-nucleotide polymorphism (SNP) in the pro-domain of BDNF gene, is associated with deficits in activity-dependent BDNF secretion and hippocampus-dependent memory. However, the underlying mechanism remains unclear. Here we show that in the BDNFMet/Met mouse line mimicking the human SNP, BDNF expression in the hippocampus was decreased. There was a reduction in the total number of cells in hippocampal CA1 region, while hippocampal expression of mRNAs for NR2a, 2b, GluR1, 2 and GABAARß3 subunits were up-regulated. Although basal glutamatergic neurotransmission was unaltered, hippocampal long-term depression (LTD) induced by low-frequency stimulation was impaired, which was partially rescued by exogenous application of BDNF. Interestingly, 5-HT3a receptors were down-regulated in the hippocampus of BDNFMet/Met mice, whereas 5-HT2c receptors were up-regulated. Moreover, impaired LTD in BDNFMet/Met mice was reversed by 5-HT3aR agonist. Thus, these observations indicate that BDNF val66met polymorphism changes hippocampal synaptic plasticity via down-regulation of 5-HT3a receptors, which may underlie cognition dysfunction of Met allele carriers.
RESUMO
[This corrects the article on p. 306 in vol. 11, PMID: 29075179.].
RESUMO
BACKGROUND & OBJECTIVE: Our previous study showed that aloe polysaccharides (AP) could evidently decrease the mortality of irradiated mice mainly through increasing the amount of hemocytes and ameliorating immune function of mice. Whether AP can protect the cells in vitro from irradiation damage is unknown. This study was to explore radioprotective effect of AP on 3 non-tumor cell lines, and its effect on cell cycle. METHODS: MTT assay was used to detect cytotoxicities of AP to normal human liver cell line Chang Liver (C. Liver), normal human embryo kidney cell line 293, and normal human umbilicus vein endothelial cell line ECV304. The 3 cell lines were treated with AP before or after irradiation. After 7-10 days normal culture, survival rate of cells was calculated by clone formation assay. Cell cycle was analyzed by flow cytometry (FCM) at different time points after irradiation. RESULTS: 293 cells were treated with AP at different time points before and after x-ray irradiation. Survival rate of 293 cells treated with AP 30 min before x-ray irradiation was the highest (64.2%) among all groups. Evident dosage-effect relationship of AP appeared in concentration range of 12.5-50 microg/ml. After treatment of 50 microg/ml of AP, survival rates of 293, ECV304, and C. Liver cells increased from 41.5%, 46.5%, and 40.9% to 49.4%, 72.1%, and 89.1%, respectively. Irradiation caused a distinct G(2)/M block and decreased G(0)/G(1) phase population in 293 and C. Liver cells. In C. Liver cells, pretreatment of 50 mug/ml of AP increased G(0)/G(1) phase population from 31.8% to 43.8%, decreased G(2)/M phase population from 38.5% to 13.8% 6 h after irradiation; and decreased G(2)/M phase population from 22.9% to 8.7% 24 h after irradiation. In 293 cells, the same pretreatment increased G(0)/G(1) phase population from 30.1% to 45.9% 6 h after irradiation, and from 40.4% to 45.2% 24 h after irradiation accompanied by decrease of G(2)/M population from 59.6% to 54.1%. CONCLUSIONS: AP has radioprotective effect on non-tumor cells. This effect might relate to alleviating of cell cycle turbulence.