Gene expression comparisons between captive and wild shrew brains reveal captivity effects

Compared to their free-ranging counterparts, wild animals in captivity
experience different conditions with lasting physiological and behavioral
effects. Although shifts in gene expression are expected to occur upstream
of these phenotypes, we found no previous gene expression comparisons of
captive vs. free-ranging mammals. We assessed gene expression profiles of
three brain regions (cortex, olfactory bulb, and hippocampus) of wild
shrews (Sorex araneus) compared to shrews kept in captivity for two months
and undertook sample drop-out to examine robustness given limited sample
sizes. Consistent with captivity effects, we found hundreds of
differentially expressed genes in all three brain regions, 104 overlapping
across all three, that enriched pathways associated with neurodegenerative
disease, oxidative phosphorylation, and genes encoding ribosomal proteins.
In the shrew, transcriptomic changes detected under captivity resemble
responses in several human pathologies, including major depressive
disorder and neurodegeneration. While interpretations of individual genes
are tempered by small sample sizes, we propose captivity influences brain
gene expression and function and can confound analyses of natural
processes in wild individuals under captive conditions.