Whole-brain mapping of neuronal activity in mice after social defeat stress

抄録

Neuronal communication between separate brain regions is a basis for higher brain function. Previous studies focusing on specific brain regions contribute to our understanding of stress-related behaviors in animal models, however, neuronal communication between separate brain regions involved in the stress-related behaviors remains obscure. Additionally, unidentified brain regions or functional features may be involved in the expression of the stress-related behaviors. Whole-brain mapping of neuronal activity with subcellular resolution is a powerful approach to detect candidate brain regions involved in a specific brain function and to integrate atomized information about neuronal communication. Here, we performed whole-brain mapping of immediate early gene-reporter mice subjected to a single social defeat stress using an automated imaging system with unprecedented speed, FAST (block-face serial microscopy tomography), which we recently developed. We exposed Arc-dVenus mice, which express destabilized Venus fluorescent protein in activated neurons, to a single social defeat stress induced by a CD1 aggressor mouse. Five hours after the defeat, brains were fixed, excised and subjected to whole-brain mapping by FAST system. After 3D reconstruction from the obtained images, distinct dVenus positive cells were automatically counted by the image processing and analysis software, TRI/FCS-NUC64. The data sets were analyzed using two computational methods, a single-layer perceptron and support vector machine. We found that a single defeat stress increased the number of dVenus-positive cells in the stress-related brain regions such as the amygdala and nucleus accumbens. In addition to the well-known stress-related brain regions, we detected the dVenus-positive cells in the claustrum, suggesting that the claustrum is a candidate brain region that regulates stress-related behaviors. Interestingly, the single layer perceptron analysis revealed that the activation changes in the claustrum contributed mostly to the discrimination between the defeated and control mice. Furthermore, the support vector machine also showed that the weighted coefficient of the claustrum for the discrimination of the defeated and control mice was the highest among all examined brain regions. These results suggest that the claustrum might be an important brain region for the stress response.