Orexinergic bouton density is lower in the cerebral cortex of cetaceans compared to artiodactyls

This study provides a comparison of orexinergic bouton density in the cerebral cortex of twelve cetartiodactyl species (ten artiodactyls and two cetaceans) by means of immunohistochemical staining and stereological analysis. It was found that the morphology of the axonal projections of the orexinergic system to the cerebral cortex was similar across all species, as the presence, size and proportion of large and small orexinergic boutons were similar. Despite this, orexinergic bouton density was lower in the cerebral cortex of the cetaceans studied compared to the artiodactyls studied, even when corrected for brain mass, neuron density, glial density and glial: neuron ratio. Results from correlational and principal component analyses indicate that glial density is a major determinant of the observed differences between artiodactyl and cetacean cortical orexinergic bouton density.
Source: Journal of Chemical Neuroanatomy - Category: Neuroscience Source Type: research