In the mouse, the corticoid stress response depends on lateralization

The influence of brain/behavioral lateralization on the neuroendocrine stress response was studied in the mouse. Using a paw preference test in a food reaching task, mice were classified as left-pawed, ambidextrous or right-pawed. Plasma levels of corticosterone (CS) were measured in basal conditions, 4 h after an intraperitoneal injection of lipopolysaccharide (LPS) or after a short period of restraint. In unstressed control mice, plasma levels of corticosterone were higher in left-pawed animals as compared to ambidextrous. LPS increased plasma levels of CS to similarly high levels, around 600 ng/ml, in the three experimental groups. By contrast after 1 h of restraint, the increased CS levels, lower to those observed after LPS injection, were higher in left-pawed mice as compared to right-pawed animals. These results are the first demonstration that activation of the hypothalamic-pituitary-adrenal axis observed during the stress response to a physical stimulus may be related to lateralization.