Research conducted by Stony Brook University has uncovered the seasonal changes in brain and body size of the Eurasian common shrew. Led by Postdoctoral Associate William Thomas and Professor Liliana Dávalos, the study reveals how gene expression allows these mammals to shrink their brains during winter and regrow them in spring. The findings, published in eLife, provide insights into neurological and metabolic health.
The study investigates Dehnel’s phenomenon, where the shrew's organs reduce by up to 30% to conserve energy during winter. Unlike other small mammals that hibernate or migrate, shrews remain active through this adaptation. The research focused on the hypothalamus, a brain region crucial for energy regulation.
“We generated a unique data set, with which we were able to compare the shrew hypothalamus across seasons and species,” said Thomas. “We found a suite of genes that change across the seasons involved in the regulation of energy homeostasis, as well as genes that regulate cell death that we propose may be associated with reductions in brain size.”
The study identified genes responsible for maintaining the blood-brain barrier and calcium signaling as being more expressed in shrews compared to other mammals. These changes might help manage energy demands efficiently.
Thomas and Dávalos suggest that these findings could aid understanding human neurological diseases. Genes like CCDC22 showed seasonal variation and were upregulated in shrews; this gene is linked with protein recycling issues seen in diseases such as ALS, Alzheimer’s, and Parkinson’s.
For humans, chronic metabolic dysfunction often relates to neurological disease progression. By examining how shrews' brains shrink and regrow, researchers hope to inform strategies against similar age-related changes in humans.
The team used RNA extraction and sequencing among other methods to identify relevant genes throughout this process. Future research will focus on studying physiological changes associated with brain size using an MRI atlas developed for shrews.
This international collaboration includes institutions like Max Planck Institute of Animal Behavior and University Medical Center Freiburg. Funding came from sources including Human Frontiers of Science Program and a Presidential Innovation award at Stony Brook University.