2025-09-01 マックス・プランク研究所
3D reconstruction of a summer brain (left) and a winter brain (right), of the same individual of common shrew, imaged with in vivo MRI. © Dominik von Elverfeldt / University of Freiburg
<関連情報>
- https://www.mpg.de/25258209/0827-ornr-rare-seasonal-brain-shrinkage-in-shrews-is-driven-by-water-loss-not-cell-death-987453-x
- https://www.cell.com/current-biology/fulltext/S0960-9822(25)01081-4
細胞死を伴わない水分喪失によるコノハツリガネネズミの季節的脳萎縮のプログラム化 Programmed seasonal brain shrinkage in the common shrew via water loss without cell death
Cecilia Baldoni ∙ Marco Reisert ∙ Bethany Smith ∙ … ∙ John Nieland ∙ Dina K.N. Dechmann ∙ Dominik von Elverfeldt
Current Biology Published:September 1, 2025
DOI:https://doi.org/10.1016/j.cub.2025.08.015
Highlights
- Seasonal brain shrinkage in shrews occurs via cell shrinkage, not cell death
- Brain intracellular water decreases and extracellular water increases in winter
- Neuronal and glial numbers remain stable across seasons, preserving brain function
- Aquaporin-4 expression declines in cortex and hippocampus in winter
Summary
Brain plasticity, the brain’s inherent ability to adapt its structure and function, is crucial for responding to environmental challenges but is usually not linked to a significant change in size. A striking exception to this is Dehnel’s phenomenon, where seasonal reversible brain-size reduction occurs in some small mammals to decrease metabolic demands during resource-scarce winter months. Despite these volumetric changes being well documented, the specific microstructural alterations that facilitate this adaptation remain poorly understood. Our study employed diffusion microstructure imaging (DMI) to explore these changes in common shrews, revealing significant alterations in water diffusion properties such as increased mean diffusivity and decreased fractional anisotropy, leading to decreased water content inside brain cells during winter. These findings confirm that brain-size reduction correlates with a decrease in cell size, as our data indicate no reduction in cell numbers, showcasing a reorganization of brain tissue that supports survival without compromising brain function. These findings extend our understanding of neuronal resilience and may inform future research on regenerative mechanisms, particularly during the spring regrowth phase, offering potential strategies relevant to neurodegenerative disease.
