Exploring Age-Related Changes in Rat Brain Networks

Published on May 13, 2022

Just like the human brain, the aging process affects the structural and metabolic properties of rat brains. In this study, researchers examined the topological characteristics of individual brain metabolic networks in rats to better understand how age impacts these networks. Using a method called Jensen-Shannon Divergence Similarity Estimation (JSSE), they constructed individual metabolic networks for young and aged rats. The findings revealed that aging in rats is associated with decreased clustering coefficient and local efficiency in the whole-brain metabolic network. Specific regions of the brain, such as the left posterior dorsal hippocampus and left olfactory tubercle, showed higher degrees and nodal efficiency in aged rats compared to young rats. The study also discovered the existence of a rich-club organization in rat brain networks and found that these connections are susceptible to aging, with a decrease in overall strength. These findings contribute to our understanding of how the brain reorganizes during aging. To dive deeper into the research, read the full article!

Normal aging causes profound changes of structural degeneration and glucose hypometabolism in the human brain, even in the absence of disease. In recent years, with the extensive exploration of the topological characteristics of the human brain, related studies in rats have begun to investigate. However, age-related alterations of topological properties in individual brain metabolic network of rats remain unknown. In this study, a total of 48 healthy female Sprague–Dawley (SD) rats were used, including 24 young rats and 24 aged rats. We used Jensen-Shannon Divergence Similarity Estimation (JSSE) method for constructing individual metabolic networks to explore age-related topological properties and rich-club organization changes. Compared with the young rats, the aged rats showed significantly decreased clustering coefficient (Cp) and local efficiency (Eloc) across the whole-brain metabolic network. In terms of changes in local network measures, degree (D) and nodal efficiency (Enod) of left posterior dorsal hippocampus, and Enod of left olfactory tubercle were higher in the aged rats than in the young rats. About the rich-club analysis, the existence of rich-club organization in individual brain metabolic networks of rats was demonstrated. In addition, our findings further confirmed that rich-club connections were susceptible to aging. Relative to the young rats, the overall strength of rich-club connections was significantly reduced in the aged rats, while the overall strength of feeder and local connections was significantly increased. These findings demonstrated the age-related reorganization principle of the brain structure and improved our understanding of brain alternations during aging.

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