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. 2016 Jul 12:6:29396.
doi: 10.1038/srep29396.

Chronic hyperglycemia induced via the heterozygous knockout of Pdx1 worsens neuropathological lesion in an Alzheimer mouse model

Chuang Guo  1 , Shuai Zhang  1 , Jia-Yi Li  1 , Chen Ding  1 , Zhao-Hui Yang  1 , Rui Chai  1 , Xu Wang  2 , Zhan-You Wang  1   3
Affiliations

Chronic hyperglycemia induced via the heterozygous knockout of Pdx1 worsens neuropathological lesion in an Alzheimer mouse model

Chuang Guo et al. Sci Rep. .

Abstract

Compelling evidence has indicated that dysregulated glucose metabolism links Alzheimer's disease (AD) and diabetes mellitus (DM) via glucose metabolic products. Nevertheless, because of the lack of appropriate animal models, whether chronic hyperglycemia worsens AD pathologies in vivo remains to be confirmed. Here, we crossed diabetic mice (Pdx1(+/-) mice) with Alzheimer mice (APP/PS1 transgenic mice) to generate Pdx1(+/-)/APP/PS1. We identified robust increases in tau phosphorylation, the loss of the synaptic spine protein, amyloid-β (Aβ) deposition and plaque formation associated with increased microglial and astrocyte activation proliferation, which lead to exacerbated memory and cognition deficits. More importantly, we also observed increased glucose intolerance accompanied by Pdx1 reduction, the formation of advanced glycation end-products (AGEs), and the activation of the receptor for AGEs (RAGE) signaling pathways during AD progression; these changes are thought to contribute to the processing of Aβ precursor proteins and result in increased Aβ generation and decreased Aβ degradation. Protein glycation, increased oxidative stress and inflammation via hyperglycemia are the primary mechanisms involved in the pathophysiology of AD. These results indicate the pathological relationship between these diseases and provide novel insights suggesting that glycemic control may be beneficial for decreasing the incidence of AD in diabetic patients and delaying AD progression.

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Figures

Figure 1
Figure 1. Metabolic features of Pdx1+/−/APP/PS1 mice.
(A,B) Ponderal growth and randomly blood glucose changes in 3- to 10-month-old WT, Pdx1+/−, APP/PS1 and Pdx1+/−/APP/PS1 mice. (C) Blood glucose levels at 41 weeks of age. (D) Glucose levels following intraperitoneal injection of 2 g/kg glucose at 12 weeks of age. (E) Blood glucose levels during an ITT (0.75 U/kg, 13-week-old mice). (F) Serum insulin concentrations at 41 weeks of age. (G–J) Pancreatic sections were stained with antisera against insulin/Pdx1/IAPP/Aβ in islets from 10-month-old APP/PS1 and Pdx1+/−/APP/PS1 mice for immunohistochemistry. Scale bar = 25 μm. (K–M) Western blot analysis showed that the Pdx1 levels were decreased, whereas the IAPP levels were markedly increased in the Pdx1+/−/APP/PS1 mouse brain compared with the APP/PS1 mouse brain. GAPDH was used as an internal control. (N,O) Immunohistochemistry and Western blot results showed that the Pdx1 protein had not been observed in the hippocampus of mice. Data represent the mean ± S.E. (n = 10). *p < 0.05, **p < 0.01 compared with the WT control group; #p < 0.05, ##p < 0.01 compared with the APP/PS1 group.
Figure 2
Figure 2. Morris water maze assessment of Pdx1+/−/APP/PS1 mice.
(A) The results of the hidden platform tests did not differ between the Pdx1+/− and WT control groups. The APP/PS1 mice exhibited a significantly longer escape latency than that of the control mice, and the Pdx1+/−/APP/PS1 mice exhibited a significantly poorer performance than that of the APP/PS1 mice at 40 weeks of age. (B) Memory test in the MWM probe trial without the platform. During the probe trial, the APP/PS1 and Pdx1+/−/APP/PS1 mice traveled to the center of the quadrant fewer times than did the WT mice. Note that the deficits in the Pdx1+/−/APP/PS1 mice were increased compared with those of the APP/PS1 mice. Data represent the mean ± S.E. (n = 10). *p < 0.05, **p < 0.01 compared with the WT control group; #p < 0.05, ##p < 0.01 compared with the APP/PS1 group.
Figure 3
Figure 3. Aβ deposition and synapse loss in Pdx1+/−/APP/PS1 mice.
(A) Immunohistochemical staining indicating the distribution of Aβ plaques in the cortex and hippocampus of the APP/PS1 and Pdx1+/−/APP/PS1 mouse brains. (B,C) Quantification revealed that hyperglycemia significantly increased the number and area of Aβ plaques in the cortex and hippocampus. Analysis was performed using Image-Pro Plus 6.0 software. (D,E) Western blot analysis demonstrated that the Aβ oligomer levels were markedly increased in the Pdx1+/−/APP/PS1 mouse brains compared with the APP/PS1 mouse brains. GAPDH was used as an internal control. (F) Immunofluorescence labeling and confocal microscopy analysis revealed the distribution and expression of anti-SYP and Aβ in the brain sections of the APP/PS1 mice. Negative stains for SYP indicated synaptic loss. Scale bar = 100 μm. Data represent the mean ± S.E. (n = 10). *p < 0.05, **p < 0.01 compared with the WT control group; #p < 0.05, ##p < 0.01 compared with the APP/PS1 group.
Figure 4
Figure 4. Analysis of the modulation of Aβ signaling mechanisms.
(A) Western blots showing the protein levels of APP695, p-APP668, ADAM-10, BACE-1, sAPPα, sAPPβ, CTFs, PS1, and IDE in the homogenized brain tissues of Pdx1+/−, APP/PS1, Pdx1+/−/APP/PS1, and WT littermate mice at 41 weeks of age. GAPDH was used as an internal control. (B–J) Quantitative analyses of the immunoreactivities to the antibodies presented in the previous panel. Data represent the mean ± S.E. (n = 10). *p < 0.05, **p < 0.01 compared with the WT control group; #p < 0.05, ##p < 0.01 compared with the APP/PS1 group.
Figure 5
Figure 5. Exacerbation of tau pathology in Pdx1+/−/APP/PS1 mouse brains.
(A) HE staining showing the location of the hippocampal CA3 subfield of the Pdx1+/−/APP/PS1 mouse brain. Representative immunohistochemical staining for p-Tau (Thr205)- and p-Tau (Ser396)-positive areas in the hippocampal CA3 subfield of WT, Pdx1+/−, APP/PS1, and Pdx1+/−/APP/PS1 mice. Scale bar = 60 μm. (B) Representative Western blots of total tau and tau phosphorylated at Ser396, Ser404, Thr205, and Thr231 in the homogenized brain tissues of Pdx1+/−, APP/PS1, Pdx1+/−/APP/PS1, and WT littermate mice at 41 weeks of age. GAPDH was used as an internal control. (C–F) Densitometric analyses of the immunoreactivities to the antibodies presented in the previous panel. Data represent the mean ± S.E. (n = 10). *p < 0.05, **p < 0.01 compared with the WT control group; #p < 0.05, ##p < 0.01 compared with the APP/PS1 group.
Figure 6
Figure 6. Analysis of the modulation of tau hyperphosphorylation signaling mechanisms.
(A) Western blots showing the protein levels of GSK3α/β, p-GSK3α/β, ERK1/2, p-ERK1/2, JNK1/2, p-JNK1/2, P38, p-P38, Cdk5, p35, p25 and PP2A in the homogenized brain tissues of Pdx1+/−, APP/PS1, Pdx1+/−/APP/PS1, and WT littermate mice at 41 weeks of age. GAPDH was used as an internal control. (B–K) Quantitative analyses of the immunoreactivities to the antibodies presented in the previous panel. Data represent the mean ± S.E. (n = 10). *p < 0.05, **p < 0.01 compared with the WT control group; #p < 0.05, ##p < 0.01 compared with the APP/PS1 group.
Figure 7
Figure 7. Upregulated AGE/RAGE signaling in Pdx1+/−/APP/PS1 mouse brains.
(A) Western blots demonstrating the protein levels of GLUT1, GLUT3, AGE, RAGE, and NF-κB in the brains of Pdx1+/−, APP/PS1, Pdx1+/−/APP/PS1, and WT littermate mice at 41 weeks of age. GAPDH was used as an internal control. (B–F) Quantitative analyses of the immunoreactivities to the antibodies presented in the previous panel. (G) ROS content was increased markedly in the hippocampus of Pdx1+/−/APP/PS1 mice compared with APP/PS1 mice. Data represent the mean ± S.E. (n = 10). *p < 0.05, **p < 0.01 compared with the WT control group; #p < 0.05, ##p < 0.01 compared with the APP/PS1 group.
Figure 8
Figure 8. Increased neuroinflammation in Pdx1+/−/APP/PS1 mouse brains.
(A) Western blots demonstrating the protein levels of GFAP, Iba1 and TNFα in the brains of Pdx1+/−, APP/PS1, Pdx1+/−/APP/PS1, and WT littermate mice at 41 weeks of age. GAPDH was used as an internal control. (B–D) Quantification revealed that the levels of GFAP, Iba1 and TNFα were significantly increased in the brains of the Pdx1+/−/APP/PS1 mice compared with the APP/PS1 mice. Immunofluorescence labeling and confocal microscopy analysis showing the distribution and expression of Aβ (a1-d1) and GFAP (E) and Iba1 (F) (a2-d2) in the cortex and hippocampus of the APP/PS1 and Pdx1+/−/APP/PS1 mouse brains. The images are representative of three independent experiments. Scale bar, 20 μm. Data represent the mean ± S.E. (n = 10). *p < 0.05, **p < 0.01 compared with the WT control group; #p < 0.05, ##p < 0.01 compared with the APP/PS1 group.
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References

    1. Xu W. et al. Mid- and late-life diabetes in relation to the risk of dementia: a population-based twin study. Diabetes 58, 71–77 (2009). - PMC - PubMed
    1. Xu W., Qiu C., Winblad B. & Fratiglioni L. The effect of borderline diabetes on the risk of dementia and Alzheimer’s disease. Diabetes 56, 211–216 (2007). - PubMed
    1. Alafuzoff I., Aho L., Helisalmi S., Mannermaa A. & Soininen H. Beta-amyloid deposition in brains of subjects with diabetes. Neuropathol Appl Neurobiol 35, 60–68 (2009). - PubMed
    1. Miklossy J. et al. Beta amyloid and hyperphosphorylated tau deposits in the pancreas in type 2 diabetes. Neurobiol Aging 31, 1503–1515 (2010). - PMC - PubMed
    1. Valente T., Gella A., Fernandez-Busquets X., Unzeta M. & Durany N. Immunohistochemical analysis of human brain suggests pathological synergism of Alzheimer’s disease and diabetes mellitus. in Neurobiol Dis, Vol. 37, 67–76 (2010). - PubMed

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