Accumulation of Peroxidase-Positive Granules with Ageing in SAMP10 and SAMR1 Mouse Brains / 대한해부학회지

ABSTRACT

The microscopic and quantitative study reported here examined peroxidase-positive granules in the senescenceacceleration prone mouse (SAMP10) brain and the senescence-resistant mouse (SAMR1) brain. Three-month-old and 14-month-old SAMP10 and SAMR1 mice were used in this stusy. Coronal brain sections were made, and then incubated with medium containing 0.05% 3, 3'-diaminobenzidine and 0.003% H2O2 in 0.1 M PB to visualize endogenous peroxidase activity. Peroxidase-positive granules were rarely found in the three-month-old SAMR1, whereas a few positive granules were observed in the young SAMP10 brains. Forteen-month-old animals showed frequent labelling for endogenous peroxidase. This labelling was distributed exclusively in periventricular regions such as the periventricular and arcuate hypothalamic nuclei surrounding the third ventricle, and the periventricular portion of the caudate-putamen and lateral septal nuclei surrounding the lateral ventricle. Double labelling with GFAP antiserum indicated that most DAB-positive granules in these regions were located within astrocytes. Image analysis showed that significantly more peroxidase-positive granules occurred with advancing age in both the SAMP10 and SAMR1 brains. However, the amount of these inclusions was significantly greater in the young as well as the aged SAMP10 brain than in the age-matched SAMR1 controls. Electron microscopic examination of the aged SAMP10 brain showed localization of endogenous peroxidase in astrocytes. They appeared as accumulated granules or inclusion bodies with homogeneously high electron density, rather than as diffusely scattered small particles. In summary, DAB-stained granules indicating the presence of peroxidase activity accumulated with ageing in both SAMP10 and SAMR1 brains, mainly in astrocytes of the periventricular brain regions. Further, the accumulation was more accelerated from younger ages and more extensively in the SAMP10 brain. These results suggest that astroglial changes might occur from young period in the periventricular region of the SAMP10, which might be associated with the neurological senescence in the SAMP10.