A novel GLP-1/GIP/Gcg triagonist reduces cognitive deficits and pathology in the 3xTg mouse model of Alzheimer's disease.

Type 2 diabetes mellitus (T2DM) is an important risk factor for Alzheimer's disease (AD). Glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) have been identified to be effective in T2DM treatment and neuroprotection. In this study, we further explored the effects of a novel unimolecular GLP-1/GIP/Gcg triagonist on the cognitive behavior and cerebral pathology in the 7-month-old triple transgenic mouse model of AD (3xTg-AD), and investigated its possible electrophysiological and molecular mechanisms. After chronic administration of the GLP-1/GIP/Gcg triagonist (10 nmol/kg bodyweight, once daily, i.p.) for 30 days, open field, Y maze and Morris water maze tests were performed, followed by in vivo electrophysiological recording, immunofluorescence and Western blotting experiments. We found that the chronic treatment with the triagonist could improve long-term spatial memory of 3xTg-AD mice in Morris water maze, as well as the working memory in Y maze task. The triagonist also alleviated the suppression of long-term potentiation (LTP) in the CA1 region of hippocampus. In addition, the triagonist significantly reduced hippocampal pathological damages, including amyloid-ß (Aß) and phosphorylated tau aggregates, and upregulated the expression levels of S133 p-CREB, T286 p-CAMKII and S9 p-GSK3ß in the hippocampus of the 3xTg-AD mice. These results demonstrate for the first time that the novel GLP-1/GIP/Gcg triagonist is efficacious in ameliorating cognitive deficits and pathological damages of 3xTg-AD mice, suggesting that the triagonist might be potentially beneficial in the treatment of AD.

[The improvement effect of scFv17 on the gait of triple-transgenic mice].

OBJECTIVE: To observe the gait changes of Alzheimer's disease PS1M146V/APPswe/tauP301L triple-transgenic (3xTg-AD) mice and to investigate the improvement effect of single chain variable domain antibody fragment 17 (scFv17) on the gait. METHODS: In the present study, a selection of 6-month-old 3xTg-AD mice (n=18) and C57BL/6 wild-type mice (n=24) was performed. First, we observed their gait changes and found that the gait of 12-month-old 3xTg-AD mice was severely damaged. Then, the two groups of mice were randomly divided into four groups:WT+PBS(n=12), WT+scFv17(n=12), 3xTg-AD+PBS(n=9) and 3xTg-AD+scFv17(n=9). The gait behavior test and pathological test were performed after 12 weeks'continuous administration of scFv17 (1.5 mg/kg) or an equal volume of PBS (0.01 mol/L) by nasal gavage twice a week. RESULTS: Compared with the same month old wild type mice, the rear track width of 12 month old 3xTg-AD mice was increased(P<0.01), swing time percent was decreased (P<0.01), stance time percent was increased(P<0.01), so the ability of movement coordination and balance was seriously damaged. ScFv17 could improve the coordination and balance ability of 12 month old 3xTg-AD mice(P<0.01). The morphological structure of 3xTg-AD mice cerebellar Purkinje cells was improved. The treatment of scFv17 increased the Nissl body number of the cerebellar Purkinje cells of 3xTg-AD mice (P<0.01). scFv17 reduced the amyloid ß protein (Aß) plaques in the cerebellar cortex of 3xTg-AD mice (P<0.01), and scFv17 reduced the intracellular neurofibrillary tangles (NFT) of the cerebellar Purkinje cells of the 3xTg-AD mice (P<0.01). CONCLUSIONS: The coordination and balance ability of 3xTg-AD mice was significantly impaired. ScFv17 can improve gait behaviour in the 3xTg-AD significantly.The mechanism may be related to the improvement of the structure and protein function of cerebellar Purkinje cells, and the eliminating of the Aß plaques and the neurofibrillary tangles.

[GLP-1/GIP/Gcg receptor Triagonist improves the cognitive behaviors in triple-transgenic mice of Alzheimer's disease].

Alzheimer's disease (AD) is a progressively neurodegenerative disorder, which seriously affects human health but is still irreversible up to now. Recent studies indicate that type 2 diabetes mellitus (T2DM) is an important risk factor for AD, and the drugs used for treatment of T2DM have shown some neuroprotective effects in the treatment of AD. Glucagon-like peptide-1 (GLP-1)/ glucose-dependent insulinotropic polypeptide (GIP)/glucagon (Gcg) receptor Triagonist is a new monomeric polypeptide equally activating the GLP-1/GIP/Gcg receptors, which is built on the basis of GLP-1/Gcg receptor coagonist core sequence, and incorporated with partial amino acids of GIP. Recently, the Triagonist has been reported to be effective in alleviating diabetic complications in rodent models of obesity. The present study observed for the first time the cognitive improvement effects of the Triagonist in the triple-transgenic AD mice (3xTg-AD) by using multiple behavioral techniques, and explored its probable molecular mechanisms using ELISA and Western blot. The results showed that the chronic treatment with the Triagonist (i.p.) significantly reversed the impairments in working memory of 3xTg-AD mice, with an obvious increase in the percentage of correct spontaneous alternation in the Y maze; the Triagonist treatment also improved long-term spatial memory and re-learning ability of 3xTg-AD mice in classical Morris water maze and reverse water maze tests, with decreased escape latency in under water platform tests and increased swimming time in probe tests. ELISA and Western blot experiments showed that the Triagonist up-regulated the levels of cAMP, PKA and p-CREB in the hippocampus of 3xTg-AD mice. These results indicate that GLP-1/GIP/Gcg receptor Triagonist can improve the cognitive behaviors in 3xTg-AD mice, and the up-regulation of hippocampal cAMP/PKA/CREB signal pathway may mediate the neuroprotection of the Triagonist, suggesting that the GLP-1/GIP/Gcg receptor Triagonist may be a novel therapeutic strategy for the treatment of AD.

[Effects of adiponectin on the anxiety and memory impairment in triple transgenic Alzheimer's disease model mice].

OBJECTIVE: To investigate the effects of adiponectin (APN) on anxiety and memory impairment of 9-month-old triple transgenic Alzheimer's disease (3xTg-AD) model mice. METHODS: The 9-month-old 3xTg-AD mice and C57BL/6J mice were randomly divided into four groups (n=8 for each group):Wild type(WT)+Saline, 3xTg-AD +Saline, WT+APN and 3xTg-AD +APN group. All mice were implanted cannula in lateral ventricle and each mouse was intracerebroventricular injected with adiponectin or saline under free moving condition after 7 days recovery. The anxiety and memory ability of each mouse were observed by using open field test, object recognition task and Y-maze test. RESULTS: ①In the open field test, compared to WT+Saline group, the time of 3xTg-AD +Saline mice spent in center was significantly decreased, and the time spent in periphery was obviously increased. However, APN treatment effectively reversed the phenomenon appeared in 3xTg-AD mice, indicating that APN could alleviate the anxiety observed in 3xTg-AD mice. ②In novel object recognition task, the discrimination index of 3xTg-AD+Saline group was (-16.7±10.1)%, significantly lower than (18.0±8.2)% in WT+Saline group (P<0.01) and (15.7±8.8)% in 3xTg-AD+APN group (P<0.01), which indicated that APN could effectively prevent the recognition memory impairment in 3xTg mice. ③In Y-maze test, the spontaneous alternation rate of 3xTg-AD +Saline group was (40.0±1.7)%,significantly lower than (56.6±4.6)% in WT+Saline group and (53.9±5.6)% in 3xTg-AD +APN group (P<0.01), which indicated that APN could prevent working memory impairment in 3xTg-AD mice. CONCLUSIONS: Adiponectin could effectively alleviate the anxiety and reverse the impairment of recognition memory and working memory of 9-month-old 3xTg-AD mice, and might play an important role in the prevention and treatment of AD.

[Expressions of synaptophysin and BDNF/Trk-B in cerebellum of APPswe/PS1dE9 transgenic mice].

OBJECTIVE: To observe the expressions of synaptophysin and BDNF/Trk-B in cerebellum of APPswe/PS1dE9 transgenic mice. METHODS: The healthy 9-month old APP/PS1 male mice (n1) and the same wild type male mice(n2) were divided into two groups, APP/PS1 group and wild-type(WT) group. The expressions of synaptophysin and brain-derived neurotrophic factor/tyrosine kinase B (BDNF/Trk-B) in cerebellum were determined by Western blot (n1=6; n2=6) and immunohistochemical(n1=4; n2=4).The possible synaptic changes in APP/PS1 group were observed by using electron microscopy. RESULTS: Compared with WT group, the expressions of synaptophsin and BDNF/Trk-B in cerebellum were decreased in APP/PS1 group. Increased width of the synaptic cleft and decreased thickness of postsynaptic density were also observed. CONCLUSIONS: In APP/PS1 group, expressions of synaptophsin and BDNF/Trk-B in cerebellum were decreased; changes in ultrastructure of synapses seemed to be widespread alterations. These findings suggest a possible association between expression of BDNF/TrkB and synaptic plasticity in AD cerebellum.