Suffolk Reporter

New research from Stony Brook University has shed light on the unique ability of the Eurasian common shrew to alter its brain and body size with seasonal changes. Led by William R. Thomas, PhD, and Professor Liliana M. Dávalos, PhD, the study was published in eLife and explores the molecular mechanisms behind this phenomenon known as Dehnel’s phenomenon.

The study reveals that these small mammals can shrink their brains during winter and regrow them in spring. This adaptation helps conserve energy when food is scarce and temperatures are low. Unlike other small mammals that hibernate or migrate, shrews remain active through these size changes while maintaining a high metabolism.

The researchers focused on the hypothalamus, a part of the brain responsible for regulating energy balance. They examined gene expression shifts both seasonally in shrews and across various mammalian species, including humans.

“We generated a unique data set, with which we were able to compare the shrew hypothalamus across seasons and species,” says 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.”

Their findings suggest that certain genes linked to human neurological diseases could offer insights into potential treatments. Genes such as CCDC22, which plays a role in protein recycling within cells, were observed to vary by season in shrews. Improper protein recycling is associated with neurological diseases like ALS, Alzheimer’s disease, and Parkinson’s disease.

Thomas noted that chronic metabolic dysfunction is often related to neurological diseases in humans. By studying how shrews' brains adapt seasonally, researchers hope to gain insights into reversing similar changes in aging human brains.

The research team used methods like RNA extraction and sequencing to identify relevant genes during the brain-shrinking process. Their ongoing work includes developing an MRI and gene expression atlas for shrews and investigating evolutionary changes compared to other mammals.

This international collaboration involved researchers from institutions such as the Max Planck Institute of Animal Behavior and Aalborg University in Denmark. The project received funding from sources including the Human Frontiers of Science Program.