Self-assembling nanofibers improve cognitive impairment in a transgenic mice model of Alzheimer's disease.

The peptide amphiphile (PA) with a laminin epitope IKVAV (IKVAV-PA) can be trigged into three-dimensional nanostructures in vivo. Application of IKVAV-PA to the injured spinal cord resulted in significant functional improvement in rodents with remarkable axonal regeneration at the lesion site. Here we showed that injection of IKVAV-PA into the hippocampus of a transgenic (Tg) mice model of Alzheimer's disease (AD) significantly improved cognitive impairment, accompanied by an enhanced neurogenesis in the hippocampus. Further examination demonstrated that IKVAV-PA injections also significantly reduced the levels of soluble Aβ1-40, Aβ1-42, and amyloid-beta (Aβ) plaques in these brains. Our data suggest that IKVAV-PA may serve as a potential therapeutic intervention for the learning and memory losses in AD.

Yang H ，Qu T ，Yang H ，Wei L ，Xie Z ，Wang P ，Bi J ... -  《-》

Self-assembling nanofibers alter the processing of amyloid precursor protein in a transgenic mouse model of Alzheimer's disease.

Yang H ，Yang H ，Xie Z ，Wang P ，Bi J ... -  《-》

Soluble Aβ levels correlate with cognitive deficits in the 12-month-old APPswe/PS1dE9 mouse model of Alzheimer's disease.

Amyloid-beta peptide (Aβ) is believed to be central in the pathogenesis of Alzheimer's disease (AD) characterized by cognitive deficits. However, it remains uncertain which form(s) of Aβ pathology is responsible for the cognitive deficits in AD. In the present study, the cognitive deficits and the profiles of Aβ pathology were characterized in the 12-month-old APPswe/PS1dE9 double transgenic mice, and their correlations were examined. Compared with non-transgenic littermates, the middle-aged APPswe/PS1dE9 mice exhibited spatial learning and memory deficits in the water maze test and long-term contextual memory deficits in the step-down passive avoidance test. Among the middle-aged APPswe/PS1dE9 mice, hippocampal soluble Aβ1-40 and Aβ1-42 levels were highly correlated with spatial learning deficits and long-term contextual memory deficits, as well as cortical and hippocampal soluble Aβ1-40 and Aβ1-42 levels were strongly correlated with spatial memory deficits. By contrast, no significant correlations were observed between three measures of cognitive functions and amyloid plaque burden (total Aβ plaque load and fibrillar Aβ plaque load), total Aβ levels (Aβ1-40 and Aβ1-42), as well as insoluble Aβ levels (Aβ1-40 and Aβ1-42). Stepwise multiple regression analysis identified hippocampal soluble Aβ1-40 and Aβ1-42 levels as independent factors for predicting the spatial learning deficits and the long-term contextual memory deficits, as well as hippocampal and cortical soluble Aβ1-40 and Aβ1-42 levels as independent factors for predicting the spatial memory deficits in transgenic mice. These results demonstrate that cognitive deficits are highly related to the levels of soluble Aβ in middle-aged APPswe/PS1dE9 mice, in which soluble Aβ levels are only a tiny fraction of the amount of total Aβ levels. Consequently, our findings provide further evidence that soluble Aβ might primarily contribute to cognitive deficits in AD, suggesting that reducing the levels of soluble Aβ species would be a therapeutic intervention for AD patients even with large deposits of aggregated, insoluble Aβ.

Zhang W ，Hao J ，Liu R ，Zhang Z ，Lei G ，Su C ，Miao J ，Li Z ... -  《-》

Intrahippocampal injection of Aβ1-42 inhibits neurogenesis and down-regulates IFN-γ and NF-κB expression in hippocampus of adult mouse brain.

Zheng M ，Liu J ，Ruan Z ，Tian S ，Ma Y ，Zhu J ，Li G ... -  《-》

Effect of Tong Luo Jiu Nao on Aβ-degrading enzymes in AD rat brains.

Tong Luo Jiu Nao (TLJN) is a modern Chinese formula based on Traditional Chinese Medicine theory that has been used to treat ischemic cerebral stroke and vascular dementia. TLJN belongs to the ethnopharmacological family of medicines. In this study, we investigated the mechanism of the TLJN effect on Alzheimer's disease (AD). To investigate the effect of TLJN on β-amyloid-degrading enzymes and learning and memory in the AD rat brain. AD rats whose disease was induced by Aβ(25-35) injection into the bilateral hippocampus CA1 region were subjected to intragastric administration of various preparations. The experimental animals were healthy male Sprague-Dawley rats which were randomly divided into normal, sham, model, TLJN min, TLJN max and donepezil hydrochloride groups. Spontaneous alternation and passive avoidance behavior, which are regarded as measures of spatial learning and memory, were investigated using Y-maze testing. Western blotting and immunohistochemistry were used to observe the therapeutic effect of TLJN on the deposits of amyloid plaque and on the expression of synaptophysin, insulin-degrading enzyme and neprilysin. Y-maze results showed that the AD model group presented with spatial learning and memory impairments. Hematoxylin-eosin and Congo red staining indicated neuronal impairment and deposits of amyloid plaque in the model group and these results were consistent with their learning and memory deficits in the Y-maze. The TLJN-treated groups exhibited prolonged a cavity delitescence, decreased arm entries and improvement in learning and memory. Moreover, the structure of the neurons of the treated groups was restored and the expression of synaptophysin increased in both the hippocampus and cortex. In addition, their levels of insulin-degrading enzyme and neprilysin in the cortex and hippocampus were upregulated and the amyloid plaque was decreased. TLJN can improve learning and memory, up-regulate insulin-degrading enzyme and neprilysin levels, promote the degrading of Aβ and clear amyloid plaque from the AD rat brain. In future, TLJN may have significant therapeutic potential in the treatment of AD patients.

Liu Y ，Hua Q ，Lei H ，Li P ... -  《-》