Effects of whole body vibration on biogenic amines in rat brain.

Abstract

The effects of whole body vibration on the concentrations of noradrenaline (NA), dopamine (DA), and serotonin (5-HT) in the whole brain and brain regions of rats were investigated. Compared with control rats, vibration with 20 Hz frequency decreased the brain concentration of NA only when the acceleration (intensity) was increased to 5.0 G (p less than 0.05). The concentration of DA in the whole brain was not affected by acceleration. When acceleration was kept at a constant 0.4 G level and rats were exposed for the same 240 minute period to 5, 20, or 30 Hz vibration, neither NA nor DA concentrations changed in the whole brain. Regional changes in the concentration of biogenic amines in the brain of rats exposed to vibration of 20 Hz and 5.0 G showed few significant differences. Thus NA significantly decreased only in the hypothalamus (p less than 0.01), although in the hippocampus the decrease was nearly significant (p less than 0.10). The concentration of 5-HT significantly increased in the hypothalamus and cerebellum (p less than 0.05). DA tended to increase in the cortex and decrease in the striatum (p less than 0.10). These experiments seem to indicate that NA in the whole brain and especially in the hypothalamus is a better indicator of vibration exposure than 5-HT, and that NA is affected by the intensity but not by the frequency of vibration. NA and 5-HT in the hypothalamus change in the opposite direction. DA concentrations in the brain are basically unaffected by vibration.

Modifications of neuronal activity in the rat hypothalamic supraoptic nucleus after long-lasting vibrational stimulation

“…According to some data [27], serotonin can exert direct excitatory effects via serotonin receptors of different subtypes localized on the surface of the neurons; at the same time, this agent realizes its inhibitory effects indirectly, by activation of local inhibitory GABA-ergic interneurons. Based on these data, we can suppose that the predominance of excitatory vibrational stimulation-induced effects in the hypothalamus (an increase in the mean discharge frequency, the respective shifts in the distribution of neurons within different frequency ranges, and alteration of the mean frequency of impulsation within separate frequency subgroups), which are clearly pronounced after 5 days of vibration sessions, is related to an increase in the concentration of serotonin in the hypothalamus [6].…”

“…Activation of the cerebral GABA system is considered a modulatory mechanism that limits potentially dangerous excitation of the stress-realizing systems of the organism. It was demonstrated that vibrational stimulation provides generalized excitation of cerebral neuromodulatory systems [5,6,22]. Monoaminergic systems are known to regulate stress-induced neuroendocrine, autonomic, and behavioral reactions of the organism by controlling the information flow to neuronal networks [23].…”

“…The hypothalamus is one of the crucial central structures fulfilling these functions [3]. There were some reports on vibration-caused changes in the functional state of hypothalamic structures [1,[4][5][6]. Such modifications are to a considerable extent determined by the existence of functional connections between the hypothalamic nuclei and vestibular system [7], as well as of excitatory nociceptive synaptic inputs to cells of the hypothalamic supraoptic nucleus [8].…”

Background activity of neurons of the supraoptic hypothalamic nucleus in rats under conditions of vibrational stimulation and electromagnetic extrahigh-frequency irradiation

“…All stress influences induce significant changes in the activity of the noradrenaline-, serotonin-, and dopaminergic systems in most subdivisions of the brain [3][4][5]15], which correlate with a significant rise in the corticosterone level in the blood plasma [2]. In different structural/functional cerebral systems, including the hypothalamus, reception of corticosterone undergoes considerable modifications after long-lasting vibrational stimulation.…”

“…A number of studies demonstrated that the action of general vibration is a stressor factor intensely influencing the organism of humans [1][2][3][4]. Vibration induces an imbalance of homeostasis, with the subsequent development of disorders of the functions of the nervous and endocrine systems and changes in the emotional state [5].…”