Age-dependent alterations of the hippocampal cell composition and proliferative potential in the hAβPPSwInd-J20 mouse.
The J20 mouse expresses human mutant amyloid-β protein precursor (hAβPPSwInd) and is an established transgenic model of Alzheimer's disease (AD). From the age of 5 months, amyloid-β (Aβ) deposits appear in the hippocampus with concomitant increase of AD-associated features. Although changes occurring after the appearance of Aβ deposits have been extensively studied, very little is known about alterations that occur prior to 5 months. The present study aimed to identify changes in the cellular composition and proliferative potential of the J20 hippocampus using 1-18-month-old mice. Neuronal, non-neuronal, Ki-67+, and TUNEL+ cell numbers were counted with the isotropic fractionator method. Age-dependent changes of the expression of microglia-, astrocyte-, and neurogenesis-specific markers were sought in the entire hippocampus. Several transgene-associated changes were revealed before the appearance of Aβ deposits. The number of proliferating cells decreased whereas the number of microglia clusters increased as early as 4 weeks of age. The neurogenesis was also impaired in the dentate gyrus of 7-11-week-old J20 mice. A statistically significant negative correlation was found between the number of proliferating cells and age in both populations, but the time course of the age-dependence was steeper in wild-type than in J20 mice. Negative age-dependence was noted when the number of cells committed to apoptosis was examined. Our results indicate that overexpression of mutant hAβPP initiates a cascade of pathologic events well before the appearance of visible Aβ plaques. Accordingly, early signs of AD include reduced cell proliferation, impaired neurogenesis, and increased activity of microglia in the hippocampus.
Neuroscience Research Australia, Sydney, NSW, Australia School of Medical Science, The University of New South Wales, Sydney, NSW, Australia.
YuHong
Y
Fu
Neuroscience Research Australia, Sydney, NSW, Australia.
Zoltán
Z
Rusznák
Neuroscience Research Australia, Sydney, NSW, Australia School of Medical Science, The University of New South Wales, Sydney, NSW, Australia.
John B J
JB
Kwok
Neuroscience Research Australia, Sydney, NSW, Australia School of Medical Science, The University of New South Wales, Sydney, NSW, Australia.
Woojin Scott
WS
Kim
Neuroscience Research Australia, Sydney, NSW, Australia School of Medical Science, The University of New South Wales, Sydney, NSW, Australia.
George
G
Paxinos
D000367:Age Factors; D000375:Aging / Q000473:pathology*; D000544:Alzheimer Disease / Q000235:genetics* / Q000473:pathology; D016564:Amyloid beta-Protein Precursor / Q000235:genetics*; D000818:Animals; D016923:Cell Death; D049109:Cell Proliferation / Q000235:genetics*; D004195:Disease Models, Animal; D000089622:Doublecortin Domain Proteins; D006624:Hippocampus / Q000378:metabolism* / Q000473:pathology*; D006801:Humans; D020287:In Situ Nick-End Labeling; D019394:Ki-67 Antigen / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009457:Neuroglia / Q000473:pathology; D009479:Neuropeptides / Q000378:metabolism
D016564:Amyloid beta-Protein Precursor; D000089622:Doublecortin Domain Proteins; D019394:Ki-67 Antigen; D008869:Microtubule-Associated Proteins; D009419:Nerve Tissue Proteins; D009479:Neuropeptides
Alzheimer's disease; J20; cellular constituents; hippocampus; microglia; neurogenesis; proliferation