Analysis of differential plaque depositions in the brains of Tg2576 and Tg-APPswe/PS1dE9 transgenic mouse models of Alzheimer disease

Adequate assessment of plaque deposition levels in the brain of mouse models of Alzheimer disease (AD) is required in many core issues of studies on AD, including studies on the mechanisms underlying plaque pathogenesis, identification of cellular factors modifying plaque pathology, and developments of anti-AD drugs. The present study was undertaken to quantitatively evaluate plaque deposition patterns in the brains of the two popular AD models, Tg2576 and Tg-APPswe/PS1dE9 mice. Coronally-cut brain sections of Tg2576 and Tg-APPswe/PS1dE9 mice were prepared and plaque depositions were visualized by staining with anti-amyloid beta peptides antibody. Microscopic images of plaque depositions in the prefrontal cortex, parietal cortex, piriform cortex and hippocampus were obtained and the number of plaques in each region was determined by a computer-aided image analysis method. A series of optical images representing a gradual increase of plaque deposition levels were selected in the four different brain regions and were assigned in each with a numerical grade of 1-6, where +1 was lowest and +6, highest, so that plaques per unit in mm2 increased "sigmoidally" over the grading scales. Analyzing plaque depositions using the photographic plaque reference panels and a computer-aid image analysis method, it was demonstrated that the brains of Tg2576 mice started to accumulate predominantly small plaques, while the brains of Tg-APPswe/PS1dE9 mice deposited relatively large plaques.

Rapid Disruption of Cellular Integrity of Zinc-treated Astroglia Is Regulated by p38 MAPK and Ca(2+)-dependent Mechanisms

Cultured cortical primary astroglia treated with zinc died while rapidly detached from culture plates, a distinct part of zinc-treated astroglia. In the present study, we investigated the mechanism underlying the rapid change in the morphologic integrity of zinc-treated astroglia. Among the early cellular events occurring in zinc-treated astroglia, strong activation of p38 MAPK and JNK was evident. Although inhibitors of p38 (SB203580 and SB202190) or JNK (SP600125) did not protect zinc-insulted astroglia from cell death, the p38 inhibitors, but not the JNK inhibitor, suppressed actin filament and cell morphology disruption. The Ca2+ ionophore, A23187, also suppressed actin filament and cell morphology disruption, but not cell death, of zinc-insulted astroglia. However, A23187 did not inhibit p38 MAPK activation in zinc-treated astroglia. Together these results suggest that zinc influx in astroglia results in rapid loss of the morphologic integrity via mechanisms regulated by p38 kinase and/or Ca2+ signaling.

Function of bcl-X proteins in Nitric Oxide-induced Apoptosis in RAW 264.7 Macrophages / 대한면역학회지

LPS and IFN-r induce nitric oxide synthase in macrophages and the resultant NO causes apoptotic cell death in the activated macrophages. NO production and apoptosis were inhibited by N-monomethyl L-arginine (NMMA), a competitive inhibitor of NO synthase. To study the role of BCL-X proteins, RAW 264.7 cells were transfected with the expression vectors with human bcl-Xl or bcl-Xs cDNAs, respectively. Stable transfectants were selected and confirmed by RT-PCR. NO production in response to LPS and IFN-r caused apoptosis in RAW 264.7 cells and vector transfected control cells within 24 hr. Both NO production and apoptosis were inhibited by N(G)-monomethyl L-arginine (NMMA). In contrast, bcl-Xs transfectant appeared slightly susceptible and bcl-X(L)< transfectant appeared slightly resistant, although NO production was similar to control cells. These results suggest that bcl-X proteins play roles in both positive and negative regulation of apoptosis induced by NO.