Astrocyte properties in cetacean cortices

Cetacean neurons are far more extensively studied in the scientific literature than the other principal cell type of the central nervous system-glia. To help address this knowledge gap, the current study profiled astrocytes in five cetacean species-Tursiops truncatus (Tt), Orcinus orca (Oo), Ziphius cavirostris (Zc), Pseudorca crassidens (Pc), and Kogia breviceps (Kb) with brain masses ranging from 596 g in Kb to 6215 g for Oo. Using formalin-fixed brain tissues stained with anti-glial fibrillary acidic protein antibodies, astrocyte distributions across cortical regions were profiled for each animal, including measurements of astrocyte diameter. Results showed statistically significant (p < 0.003) effects for cortical layer and species in addition to astrocyte size (cell body) between the animals. The largest astrocytes were found in the larger cetaceans (Pc), although average astrocyte size did not statistically differ from the control (Mus musculus). The results of this investigation advance our knowledge of cetacean astrocyte biology, with translational implications for human conditions such as dementia and traumatic brain injury. Collectively, these findings illustrate a quantitative approach to better understand neuroanatomical variations across cetacean species.