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Murine trisomy 16 model of Down's syndrome: central nervous system electron microscopic observations
1Surrey Place Centre, Toronto, Ontario, Canada.
Abstract:
Murine trisomy 16 is an excellent model for the human Down's syndrome (DS). Electron microscopic (EM) observations were made of the cortical plate within the developing telencephalic vesicle at the gestational age of E17. The EM observations revealed: (A) microtubular profiles which were more coiled and curved in the trisomic condition; (B) poor cell-to-cell apposition and increased cellular membrane fragmentation in trisomy 16; (C) increased nuclear contour irregularity in trisomic neurons; (D) significant decrease in the cross-sectional area of neuronal nuclei in trisomy 16 (p less than 0.01). The microtubular observations lend credence to the hypothesis that abnormal cytoskeletal interactions may underlie the mental deficiency seen in DS and may predispose to the eventual development of Alzheimer's disease (AD) in DS individuals. The cellular membrane findings may be related to reported CNS membrane lipid abnormalities in DS. The nuclear morphologic observations may be related to the reported differences in chromatin and nuclear histone expression in AD. These results strengthen the role of the trisomy 16 mouse as a model for DS and potentially for AD.
Insights
Murine trisomy 16, a model for Down
Area of Science:
- Neuroscience
- Genetics
- Developmental Biology
Background:
- Murine trisomy 16 closely models human Down's syndrome (DS).
- Understanding DS pathogenesis is crucial for developing effective interventions.
Purpose of the Study:
- To investigate cellular and subcellular alterations in the developing brain of trisomy 16 mice using electron microscopy.
- To correlate these findings with known features of Down's syndrome and Alzheimer's disease.
Main Methods:
- Electron microscopy (EM) was employed to examine the cortical plate of E17 trisomy 16 mouse embryos.
- Specific focus was placed on microtubule structure, cell-to-cell apposition, membrane integrity, and nuclear morphology.
Main Results:
- Trisomy 16 neurons exhibited more coiled/curved microtubules, poorer cell apposition, and increased membrane fragmentation.
- Neuronal nuclei showed increased contour irregularity and a significant decrease in cross-sectional area (p < 0.01).
Conclusions:
- Abnormal cytoskeletal interactions in trisomy 16 may contribute to cognitive deficits in Down's syndrome and Alzheimer's disease risk.
- Observed cellular and nuclear changes may relate to known lipid and chromatin abnormalities in DS and AD.
- The trisomy 16 mouse remains a valuable model for studying Down's syndrome and potentially Alzheimer's disease.