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Cerebral T2-weighted signal decrease during aging in the mouse lemur primate reflects iron accumulation
M Dhenain1, C Duyckaerts, J L Michot
1Institut National de la Santé et de la Recherche Médicale U 324, Paris, France. dhenain@broca.inserm.fr
Abstract:
4.7 Tesla T2-weighted magnetic resonance images showed a highly significant signal decrease in the pallidum, substantia nigra, putamen, and a less significant decrease in the thalamus and the caudate of aging mouse lemurs (Microcebus murinus). We evaluated the contribution of iron deposits to the signal decrease comparing Perls' stained histological sections of six mouse lemurs brains aged 1 to 10 years to magnetic resonance images. In young animals, none of the brain structures was stained. A large number of iron deposits were visible in the pallidum and substantia nigra of aged animals and a moderate number in the middle aged ones. In the putamen, few iron deposits were visible in aged and middle-aged animals. The thalamus and the caudate appeared unstained with Perls' technique; iron was too low to be detected. The intensification of the reaction by diaminobenzidine revealed iron deposits in the thalamus of aging animals. This study suggests that in mouse lemurs, iron deposits are responsible for T2-weighted signal decrease in the central gray nuclei.
Insights
Iron accumulation in aging mouse lemurs
Area of Science:
- Neuroscience
- Comparative Anatomy
- Magnetic Resonance Imaging
Background:
- Aging is associated with changes in brain structure and function.
- Iron is a metal that plays a role in various biological processes but can be toxic in excess.
- Mouse lemurs (Microcebus murinus) are a valuable model for studying aging due to their natural lifespan.
Purpose of the Study:
- To investigate the relationship between iron deposits and T2-weighted magnetic resonance imaging (MRI) signal changes in the aging brains of mouse lemurs.
- To determine if increased iron accumulation contributes to observed signal alterations in specific brain regions.
Main Methods:
- Acquisition of 4.7 Tesla T2-weighted MRI scans from aging mouse lemurs.
- Histological examination of brain sections using Perls' Prussian blue staining to detect iron deposits.
- Correlation of MRI signal intensity with iron staining in various brain nuclei (pallidum, substantia nigra, putamen, thalamus, caudate).
Main Results:
- Significant T2-weighted signal decrease observed in the pallidum and substantia nigra of aging mouse lemurs.
- Age-dependent iron deposition was confirmed, with higher concentrations in aged animals, particularly in the pallidum and substantia nigra.
- Iron deposits were found to correlate with signal reduction in these nuclei, while thalamus and caudate showed minimal iron and less signal change.
Conclusions:
- Iron accumulation in central gray nuclei is a key factor contributing to T2-weighted MRI signal decrease in aging mouse lemurs.
- This finding highlights the role of iron in age-related neuroimaging alterations.
- Mouse lemurs serve as a relevant model for understanding iron-mediated brain changes during aging.