Whole body vibration enhances choline acetyltransferase-immunoreactivity in cortex and amygdala

Whole body vibration (WBV) is a form of physical stimulation brought about by mechanical vibrations transmitted to a subject. WBV can increase attention in cognitive tasks in mice and men. However, little is known about the mechanisms that underlie this improved brain functioning. We examined whether WBV affects the cholinergic forebrain system of mice. Male C57Bl/6J mice (2 months of age) received WBV in a cage attached to a small vibrating platform (30 Hz with peak-to-peak displacements ranging from 14 to 75mm). WBV was applied five days a week for a period of five weeks with daily sessions of ten minutes. Control mice (pseudo-WBV) were treated similarly, but did not receive the actual vibration. Mice were sacrificed 24 hours after the last session and their brains were processed immuno cyto chemically for the acetylcholine-synthesizing enzyme cholineacetyl transferase (ChAT). ChAT-immunoreactivity was measured in the nucleus basalis magnocellularis (NBM), the somatosensory cortex, and the basolateral amygdala (where the cholinergic fibers arising from the NBM terminate). ChAT-immunoreactivity was significantly increased due to WBV in layer 5 of the somatosensory cortex (by 23%; p< 0.01) and amygdala (by 21%; p<0.05), but not in the NBM as compared to pseudo-WBV. As increased ChAT-immunoreactivity indicates a higher cholinergic activity, these results reveal that the positive effects of WBV on attention are most likely (at least in part) mediated by an increased activity of the NBM cholinergic system. WBV could therefore be a suitable intervention strategy in conditions where a reduced cholinergic forebrain activity plays a role.