Research led by William R. Thomas, PhD, alongside Professor Liliana M. Dávalos, PhD, at Stony Brook University has uncovered the molecular mechanisms that allow the Eurasian common shrew to alter its brain and body size throughout the year. Published in eLife, this study provides insights into how gene expression changes enable these small mammals to shrink their brains during winter and regrow them in spring. The findings could offer genetic clues relevant to neurological and metabolic health in mammals.
The study delves into Dehnel’s phenomenon, a unique adaptation where the shrew's brain and other organs shrink significantly to conserve energy during winter months. Unlike other small mammals that hibernate or migrate, the shrew remains active through these physiological changes.
Thomas' team focused on the hypothalamus, a crucial brain region for energy regulation. "We generated a unique data set," Thomas explained, "with which we were able to compare the shrew hypothalamus across seasons and species." They identified genes involved in energy homeostasis and cell death regulation that may be linked to seasonal brain size reduction.
Additionally, genes associated with maintaining the blood-brain barrier and calcium signaling were found to be upregulated in shrews compared to other mammals. These adaptations might help manage energy efficiently in response to high metabolic demands.
The research also explores potential connections between these findings and human neurological diseases. Genes like CCDC22, which are involved in protein recycling within cells—a process critical for preventing conditions such as ALS, Alzheimer’s disease, and Parkinson’s disease—showed significant seasonal variation in shrews.
Thomas highlighted that understanding how metabolic shifts influence brain size could eventually inform strategies for addressing similar changes related to aging in humans.
To identify key genes involved during this process, methods such as RNA extraction and sequencing were employed. The researchers plan further studies on physiological changes associated with brain size using an MRI atlas developed for shrews.
This international effort included contributions from institutions such as Max Planck Institute of Animal Behavior and University Medical Center Freiburg among others. Funding was partly provided by the Human Frontiers of Science Program along with a Presidential Innovation award granted to Dávalos from Stony Brook University.