The p38 mitogen-activated protein kinase [p38(MAPK)] mediates responses to extracellular stressors. An increase in the phosphorylated form of p38(MAPK) [p-p38(MAPK)] has been associated with early events in Alzheimer disease (AD). Although most often associated with processes including apoptosis, inflammation and oxidative stress, p-p38(MAPK) also mediates beneficial physiological functions, such as cell growth, survival and phagocytosis of cellular pathogens. Amyloid plaques [β-amyloid aggregates] are a hallmark of AD-related pathology. As p38(MAPK) has been detected in the vicinity of senile plaques, we combined immunohistochemistry and stereological sampling to quantify the distribution of plaques and p-p38(MAPK)-immunoreactive (IR) cells in the sensorimotor cortex of 3-, 6- and 10-month-old TgCRND8 mice. This animal model expresses an aggressive nature of the AD-related human amyloid-β protein precursor (APP). It was confirmed by the appearance of both dense-core (thioflavin-S-positive) and diffuse plaques, even in the youngest mice. p-p38(MAPK)-IR cells were associated with both dense-core and diffuse plaques, but the expected age-dependent increase in the density of plaque-associated p-p38(MAPK)-IR cells was restricted to dense-core plaques. Furthermore, the density of dense-core plaque-associated p-p38(MAPK)-IR cells was inversely correlated with the size of the core within the given plaque, which supports a role for these microglia in restricting core growth. p-p38(MAPK)-IR cells were also observed throughout wildtype and TgCRND8 mouse cortical parenchyma, but the density of these non-plaque-associated cells remained constant, regardless of age or genotype. We conclude that the constitutive presence of p-p38(MAPK)-IR microglia in aging mouse brain is indicative of a longitudinal role for this kinase in normal brain physiology. Additionally, the majority of p-p38(MAPK)-IR cells were predominantly co-immunoreactive for the Macrophage-1 (CD11b/CD18) microglial marker, regardless of whether they were associated with plaques or localized to the parenchyma. We suggest that the facts that a pool of p-p38(MAPK)-IR microglia appears to restrict b-amyloid plaque core development and the non-pathological role of p-p38(MAPK) in parenchyma, needs to be considered when anticipating targeted p38(MAPK) therapeutics in the context of clinical AD.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:SSU.etd-08222011-135239 |
| Date | 22 September 2011 |
| Creators | ZHAO, TUO |
| Contributors | Li, Xinmin, Mousseau, Darrell, Chlan-Fourney, Jennifer, Walz, Wolfgang, Roesler, Bill |
| Publisher | University of Saskatchewan |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://library.usask.ca/theses/available/etd-08222011-135239/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Saskatchewan or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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