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.

[Real-time measurement of Ca2+ flux in hippocampal slice with non-invasive micro-test technique].

The deposition of amyloid-ß protein (Aß) in the brain is the most important pathological feature of Alzheimer's disease (AD). The mechanism of Aß neurotoxicity may be closely related to the disturbance of intracellular Ca2+ homeostasis. Non-invasive micro-test technique (NMT) is a novel technique developed in recent years, which can be used to directly record transmembrane ion influx and efflux in a non-contact way by detecting the diffusion potentials outside of the membrane. The present study examined the effects of Aß31-35 pretreatment on glutamate (Glu)-induced Ca2+ influx and low [Ca2+] solution-induced Ca2+ efflux in the hippocampal slices of C57BL/6 mice using NMT. The results showed that: (1) acute administration of Glu (2.5, 5, 10 mmol/L) evoked a persistent transmembrane Ca2+ influx in hippocampal CA1 neurons, with a rapid onset and subsequent decay; (2) pretreatment with Aß dose-dependently increased the average rate of Ca2+ influx induced by Glu during the initial 5 min, which was blocked by NMDA receptor antagonist D-APV; (3) perfusion with low [Ca2+] artificial cerebrospinal fluid (aCSF) induced a continuous Ca2+ efflux, which was mostly blocked by KB-R7943, a specific antagonist of Na+/Ca2+ exchanger; (4) Aß31-35 pretreatment partially inhibited the low [Ca2+] aCSF-induced Ca2+ efflux. These results indicate that Aß not only facilitates Ca2+ influx but also inhibits Ca2+ efflux, which jointly contribute to the Aß-induced intracellular Ca2+ overload; the potentiation of Aß on Glu excitotoxicity is mainly mediated by NMDA receptors, while the target for Aß to affect Ca2+ efflux was mainly Na+/Ca2+ exchanger. NMT showed multiple advantages in detecting transmembrane Ca2+ flux in brain slices, such as non-invasiveness to target cells, fast, convenient and real-time acquisition of Ca2+ flux. Therefore, this study provided new experimental evidence for Aß-induced Ca2+ overload, as well as a novel application for NMT in measuring transmembrane Ca2+ flux of neurons in the brain.

[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.

Anisomycin alleviates cognitive impairments and pathological features in 3xTg-AD mice.

Neuroinflammation plays a pivotal role in the pathogenesis of Alzheimer's disease (AD). Anisomycin is a pyrrolidine antibiotic isolated from Streptomyces griseolus, which is an efficient anti-inflammatory agent that functions both in vivo and in vitro. However, it is not clear whether anisomycin can exert neuroprotective effect in AD. In the present study, anisomycin was intragastrically administrated to female triple-transgenic AD (3xTg-AD) model mice, then Morris water maze test was used to observe the long-term spatial memory of mice, the in vivo hippocampal field potential recording was performed to evaluate the synaptic plasticity, the Western blot and immunofluorescence were employed to detect pathological changes, and the bioinformatics analysis was used to predict the potential target of anisomycin exerting effects in AD. The results showed that anisomycin ameliorated the long-term spatial memory deficits, improved LTP depression and increased the expression of PSD-95, reduced the Aß and tau pathologies, and alleviated the activation of microglia and astrocytes in the brains of 3xTg-AD mice. In addition, the results from bioinformatics analysis showed that the potential target of anisomycin focused on inflammatory pathway. These results indicated that anisomycin exerts neuroprotective effects in 3xTg-AD mice by alleviating neuroinflammation, but the potential mechanism of anisomycin exerting neuroprotective effects needs to be further investigated.

Selective Orexin 2 Receptor Blockade Alleviates Cognitive Impairments and the Pathological Progression of Alzheimer's Disease in 3xTg-AD Mice.

The orexin system is closely related to the pathogenesis of Alzheimer's disease (AD). Orexin-A aggravates cognitive dysfunction and increases amyloid ß (Aß) deposition in AD model mice, but studies of different dual orexin receptor (OXR) antagonists in AD have shown inconsistent results. Our previous study revealed that OX1R blockade aggravates cognitive deficits and pathological progression in 3xTg-AD mice, but the effects of OX2R and its potential mechanism in AD have not been reported. In the present study, OX2R was blocked by oral administration of the selective OX2R antagonist MK-1064, and the effects of OX2R blockade on cognitive dysfunction and neuropsychiatric symptoms in 3xTg-AD mice were evaluated via behavioral tests. Then, immunohistochemistry, western blotting, and ELISA were used to detect Aß deposition, tau phosphorylation, and neuroinflammation, and electrophysiological and wheel-running activity recording were recorded to observe hippocampal synaptic plasticity and circadian rhythm. The results showed that OX2R blockade ameliorated cognitive dysfunction, improved LTP depression, increased the expression of PSD-95, alleviated anxiety- and depression-like behaviors and circadian rhythm disturbances in 3xTg-AD mice, and reduced Aß pathology, tau phosphorylation, and neuroinflammation in the brains of 3xTg-AD mice. These results indicated that chronic OX2R blockade exerts neuroprotective effects in 3xTg-AD mice by reducing AD pathology at least partly through improving circadian rhythm disturbance and the sleep-wake cycle and that OX2R might be a potential target for the prevention and treatment of AD; however, the potential mechanism by which OX2R exerts neuroprotective effects on AD needs to be further investigated.

Integrated analysis of the lncRNA-associated ceRNA network in Alzheimer's disease.

Alzheimer's disease (AD) is a progressive neurodegenerative disease that worsens with age. Long non-coding RNAs (lncRNAs) dysregulation and its associated competing endogenous RNA (ceRNA) network have a potential connection with the occurrence and development of AD. A total of 358 differentially expressed genes (DEGs) were screened via RNA sequencing, including 302 differentially expressed mRNAs (DEmRNAs) and 56 differential expressed lncRNAs (DElncRNAs). Anti-sense lncRNA is the main type of DElncRNA, which plays a major role in the cis and trans regulation. The constructed ceRNA network consisted of 4 lncRNAs (NEAT1, LINC00365, FBXL19-AS1, RAI1-AS1719) and 4 microRNAs (miRNAs) (HSA-Mir-27a-3p, HSA-Mir-20b-5p, HSA-Mir-17-5p, HSA-Mir-125b-5p), and 2 mRNAs (MKNK2, F3). Functional enrichment analysis revealed that DEmRNAs are involved in related biological functions of AD. The co-expressed DEmRNAs (DNAH11, HGFAC, TJP3, TAC1, SPTSSB, SOWAHB, RGS4, ADCYAP1) of humans and mice were screened and verified by real-time quantitative polymerase chain reaction (qRT-PCR). In this study, we analyzed the expression profile of human AD-related lncRNA genes, constructed a ceRNA network, and performed functional enrichment analysis of DEmRNAs between human and mice. The obtained gene regulatory networks and target genes can be used to further analyze AD-related pathological mechanisms to optimize AD diagnosis and treatment.

Role of psoriatic keratinocytes in the metabolic reprogramming of dermal mesenchymal stem cells.

BACKGROUND: Psoriasis is an immune-mediated inflammatory skin disease, featured by epidermal hyperproliferation. Psoriasis exhibits metabolic abnormalities, which can further aggravate the condition of psoriasis. The present study aimed to investigate the role of psoriatic keratinocytes (KCs) in the metabolic reprogramming of dermal mesenchymal stem cells (DMSCs). METHODS: Dermal mesenchymal stem cells were cocultured with primary KCs either from psoriatic lesions or from normal subjects using Transwell plate. Glycolysis and mitochondrial metabolism of DMSCs were detected by Seahorse Metabolic Analyzer. Expression levels of proteins were analyzed by Western blotting. DMSCs proliferation was assessed using 5-ethynyl-2'-deoxyuridine assay and Cell Counting Kit-8. RESULTS: In comparison with normal KCs, coculture of psoriatic KCs with DMSCs dramatically increased glycolytic and mitochondrial metabolism, and expression levels of stem cell factor, epidermal growth factor, glucose transporter 1, and c-Myc. Moreover, psoriatic KCs were more potent than normal KCs in the stimulation of DMSC proliferation. CONCLUSIONS: In conclusion, psoriatic KCs display a higher potency in metabolic reprogramming and stimulation of DMSC proliferation, possibly contributing to the pathogenesis of psoriasis. However, whether the intervention of metabolic reprogramming of DMSCs can alleviate psoriasis remains to be determined.

A GLP-1/GIP/Gcg receptor triagonist improves memory behavior, as well as synaptic transmission, neuronal excitability and Ca2+ homeostasis in 3xTg-AD mice.

Alzheimer's disease (AD) is a progressively neurodegenerative disorder, which seriously affects human health and cannot be stopped by current treatments. Type 2 diabetes mellitus (T2DM) is a risk factor for AD. Our recent studies reported the neuroprotective effects of a GLP-1/GIP/Glucagon receptor triagonist (Triagonist), a novel unimolecular anti-diabetic drug, in cognitive and pathological improvements of 3xTg-AD mice. However, the detailed electrophysiological and molecular mechanisms underlying neuroprotection remain unexplored. The present study investigated the underlying electrophysiological and molecular mechanisms further by using whole-cell patch clamp techniques. Our results revealed that chronic Triagonist treatment effectively reduced working memory and reference memory errors of 3xTg-AD mice in a radial maze test. In addition, the Triagonist increased spontaneous excitatory synaptic activities, differentially modulated voltage- and chemically-gated Ca2+ flux, and reduced the over-excitation of pyramidal neurons in hippocampal slices of 3xTg-AD mice. In addition, chronic Triagonist treatment also up-regulated the expression levels of synaptophysin and PSD-95 in the hippocampus of 3xTg-AD mice. These results indicate that the Triagonist could improve memory formation, as well as synaptic transmission, Ca2+ balance, and neuronal excitability in 3xTg-AD mice. These neuroprotective effects of Triagonist may be involved in the up-regulation of synaptophysin and PSD-95. Therefore, the study suggests that multi-receptor agonists might be a novel therapeutic strategy for the 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.

[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.