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Objective To explore the effect and potential mechanism of tenuigenin (TEN) treatment on ameliorating cognitive impairment of Alzheimer's disease (AD) model mice. Methods 6-month-old APP/PS1 transgenic mice (n=18) were randomly divided into the saline group and TEN group (9 each), 9 wild-type mice of the same age were selected as control group. Mice in TEN group were intraperitoneally injected with TEN at a dose of 8 mg/(kg.d) for 8 weeks, those in both saline group and control group were intraperitoneally injected with same dose of saline for 8 weeks. The Morris water maze test was carried out with all the mice of the three groups to assess the spatial memory level, and immunohistochemistry was performed to detect the distribution and expression of postsynaptic density protein 95 (PSD-95) in hippocampal area of brain, and thioflavin staining was performed to check the senile plaque in hippocampus. ELISA was used to assess the Aβ42 level. Western blotting was used to detect the levels of PSD-95 and p-tau protein (Ser231, Ser214, Ser396) in brain. Results In the Morris water maze test, mice in saline group exhibited greater escape latency compared with that of mice in control group after the second day, the difference was statistically significant (P0.05); mice in TEN group exhibited longer escape latency compared with that of control group at the 5th day. Space search trial found that mice in saline group spent obviously longer time to find the original position of the platforms than those in control group [(40.428±3.408) s vs. (14.142±7.289) s, P0.05). It was found that mice in saline group exhibited fewer times of crossing platform than those in control group (0.428±0.035 vs. 2.285±1.380, P0.05). The relative amount of PSD-95 was lower in mice of saline group than that in control group (0.570±0.700 vs. 0.740±0.054), the difference was statistically significant (P0.05). The number of plaques and Aβ42 level in hippocampus decreased significantly in TEN group than those in saline group [(8.889±1.692 vs. 18.000±2.000) and (2.859±0.864) ng/mg vs. (5.154±0.735) ng/mg, P<0.05]. As to the expression level of protein p-tau Ser231, Ser214 and Ser396 in mice hippocampus, they were higher significantly in saline group than those in control group (0.947±0.131 vs. 0.540±0.076, 0.832±0.161 vs. 0.305±0.088 and 0.819±0.053 vs. 0.338±0.052, P<0.05), while they were obviously lower in TEN group than in saline group (0.568±0.051 vs. 0.947±0.131, 0.472±0.094 vs. 0.832±0.161 and 0.452±0.071 vs. 0.819±0.053, P<0.05). The expression levels of protein p-tau Se214 and Ser396 in mice hippocampus of TEN group were higher than those in control group with statistical significance (0.472±0.094 vs. 0.305±0.088 and 0.452±0.071 vs. 0.338±0.052, P<0.05), but the expression level of p-tau Ser231 showed no significant difference between TEN group and control group (0.568±0.051 vs. 0.540±0.076). Conclusion Tenuigenin may attenuate cognitive deficits by up-regulating the PSD-95 level in APP/PS1 mice, decrease Aβ deposition and excessive phosphorylation of protein p-tau, and might be a potential therapeutic agent for Alzheimer's disease.
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Objective To observe the effect of Sirt1 on the phosphorylation of Tau protein in neuroblastoma SK-N-SH cell line.Methods We cultured SK-N-SH cells in vitro with adenovirus packaging of Sirt1 and SirtM (Sirt mutant),and then observed the expression of Sirt1 under an inverted fluorescence microscope.The expressions of Sirt1and SirtM were detected by Western blot;t-Tau protein and phosphorylation of Tau protein were detected by Western blot,Real-time PCR,immunohistochemistry and immunofluorescence;and the effect of Sirt1 on SK-N-SH apoptosis was investigated by flow cytometry.Results The t-Tau protein level and its phosphorylation were significantly decreased in Sirt1 and SirtM groups compared with those in control group,and Sirt1 group showed more significantly decreased ser404,thr231 phosphorylation of tau protein and the mRNA level of Tau.Flow cytometry showed that Sirt1 could significantly reduce the apoptosis of SK-N-SH cells compared with the control group.Conclusion Sirt1 can decrease the phosphorylation of Tau protein and reduce the apoptosis of SK-N-SH,which provides an important laboratory basis for studies on Tau protein disease and other neurodegenerative diseases.
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Objective To investigate the plasma total tau(T-tau)and phosphorylated protein tau(P-tau)protein in the diagnosis of Alzheimer's disease(AD).Methods 22 352 medical patients aged over 60 years in Beichen Area Community Service Center were involved in this survey.Random sampling principle was used for screening.Mini-mental state examination(MMSE)and activities of daily living assessment form(ADL)were conducted for the cognitive function and ability of daily score firstly.When the score below the standard,the Hamilton depression scale and Hachinski ischemic scale were re-used for diagnostic score.Related laboratory tests were conducted to exclude other central nervous system and other systems and material causes of dementia patients.Ultimately,105 cases of AD,diagnosed by the neurologist,and 42 cases of non central nervous system disease,non dementia non nervous system disease patients as the normal control group were involved.T-tau and P-tau levels in the two groups were determined by ELISA.Results the T-tau concentration in AD group(15.93+6.59)ng/L was higher than control group(14.10±6.32)ng/L,no significant difference was found (P ＞ 0.05).However,compared with control group (0.69 ± 0.24) ng/L,P-tau protein in AD group (1.26 ± 0.75)ng/L increased significantly(P＜0.05).Conclusion Plasma levels of phosphorylated tau protein might have diagnostic value for AD patients.
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Aim To explore the protective effects of lithium chloride ( LiCl ) on neurous injuries and phos-phorylation of tau protein at serine262 induced by okada-ic acid( OA) . Methods The neuroblastoma SK-N-SH cells were differentiated by all-trans-retinoic acid ( AT-RA) . The differentiated SK-N-SH cells were treated with OA to establish the Alzheimer′s disease cellular model. SK-N-SH cells′ viability and proliferation were measured by SRB test. Giemsa staining was used to observe cell morphology. The neurite length of SK-N-SH cells was measured by Image-Proplus software. Syn-aptophysin and phosphorylated tau protein at serine262 expression levels were tested by Western blot. Results The SK-N-SH cells which were treated with 10 μmol ·L-1 ATRA for 7 days displayed mature neuronal fea-tures. The synaptic length of SK-N-SH cells became longer. And the levels of serine262 phospho-tau was sig-nificantly elevated. 20~100 nmol·L-1 OA effectively inhibited the viability of differentiated SK-N-SH cells in a concentration-dependent manner and in a time-de-pendent manner. The OA treatment induced obvious synaptic atrophy in differentiated SK-N-SH cells. And the phosphorylation level of tau protein serine262 also greatly increased. The pretreatment with 10 mmol · L-1 LiCl significantly ameliorated the synaptic atrophy, the decrease of synaptophysin expression and the in-crease of tau phosphorylation at serine262 induced by OA in differentiated SK-N-SH cells. Conclusion LiCl could effectively inhibit OA-induced synaptic atro-phy in differentiated SK-N-SH cells, and it could also result in the increase of synaptophysin expression and the decrease of the phosphorylation of tau protein at serine262 .