The Biology Of Stress

We all feel stressed sometimes, but how often do we stop to think about the science behind stress? Well, a recent study induced stress in mice by having them interact with aggressive and bigger mice than themselves (1,2). The study created two groups of mice that underwent this stressor. There was the anhedonia presenting group. These mice preferred plain water over sugar water. Which makes sense as “anhedonia” is classified as decreased pursuit for rewards, similar to depressive symptoms. The other group of mice were called “resilient” which choose sugar water more often than plain water. The study look at the brain cells, or neurons, when the mice were making their choice of the different fluids to drink. They determined that anhedonia mice had less neuronal communication in brain regions that process emotions, while resilient mice had more. The scientists then took anhedonia mice and injected a chemical into the mice that increased activity in that brain region. This caused them to increase their preference for sugar water after stress, indicating that they became more similar to the resilient to stress mice. This study showcases that stress responses have a cellular and physiological basis, and highlights possible ways to biologically modulate stress responses.

1) Xia, F., Fascianelli, V., Vishwakarma, N., Ghinger, F. G., Kwon, A., Gergues, M. M., Lalani, L. K., Fusi, S., & Kheirbek, M. A. (2024). Understanding the neural code of stress to control anhedonia. Nature. https://doi.org/10.1038/s41586-024-08241-y

2) Kozlov, M. (2024). Stress can dull our capacity for joy: mouse brain patterns hint at why. Nature. https://doi.org/10.1038/d41586-024-03958-2