Effect of Local Vibration on the Brain Monoamines of Rats

The experimental study investigated the effect of local vibration on brain monoamines, and the effect was compared with that of whole-body vibration. The hind legs of rats were exposed to local vibration with frequencies of 20 and 120 Hz under constant acceleration of 50 m/s² for 240 min. The rats were decapitated immediately thereafter. The levels of norepinephrine (NE), dopamine (DA), and serotonin (5-HT) in the whole brain or its parts were detected by fluorometric methods. In the whole brain, the NE level showed a tendency to decrease at 120 Hz. The levels of DA and 5-HT showed no changes at either frequency. NE showed a significant decrease at 120 Hz in the hypothalamus and the hippocampus. 5-HT showed significant increases in the hypothalamus at both 20 and 120 Hz. The amines in the whole brain were not significantly affected by local vibration (20 Hz, 50 m/s²), but were by whole-body vibration (20 Hz, 50 m/s²). The NE level was significantly decreased by whole-body vibration (20 Hz, 50 m/s²) and showed a tendency to decrease due to exposure to local vibration (120 Hz, 50 m/s²). 5-HT was remarkably elevated by whole-body vibration, but less elevated by local vibration. Thus the effects induced in brain monoamines by local vibration are considerably less than those induced by whole-body vibration.