Original article

Scand J Work Environ Health 1986;12(4):435-437    pdf

Effect of local vibration on the brain monoamines of rats

by Ariizumi M, Yamaguchi Y, Okada A

The experimental study investigated the effect of local vibration on brain monoamines,and the effect wascompared with that of whole-body vibration. The hindlegsof rats wereexposed to localvibrationwithfrequencies of 20 and 120 Hz underconstantacceleration of 50 m/s2 for 240 min. The rats weredecapitated immediately thereafter. The levels of norepinephrine (NE), dopamine(DA), and serotonin(5-HT)in the wholebrain or its parts weredetected 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 aminesin the whole brain were not significantly affectedby localvibration(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 elevatedby whole-bodyvibration, but less elevated by local vibration. Thus the effects inducedin brain monoaminesby local vibration are considerably less than those induced by whole-body vibration.