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The studies on 3 Albino rats (230±30g.) on the rotenone model of Parkinson's disease has been conducted. The extracellular on-line recording of spike activity of 110 single neurons of the Locus coeruleus at high frequency stimulation (HFS) of Periaqueductal gray had produced. According to programmed mathematical analysis the frequencies of excitatory poststimulus effects of LC neurons activity exceeded above 100 Hz. Tetanic potentiation in two sequences exceeded the prestimulus level (7.03- and 3.76-times). The prestimulus frequency of activity, preceding to depressor sequences, reduced to be (7.03- and 3.76-times). The prestimulus frequency of activity, preceding to excitatory sequences, reached the values 53.67 and 22.01. The poststimulus frequency of activity, accompanied by two depressor sequences, reached the values 3.68 and 2.73, accompanied by two excitatory sequences - 115.35 and 44.58. Thus, the powerful excitotoxicity has been revealed, testifying about serious neurodegenerative defeat of the important antinociceptive structure LC. [ABSTRACT FROM AUTHOR]

The effect of horizontal mechanical vibration 4Hz, 30dB of 10 minutes duration on pain threshold and hydration rate of brain cortex and cardiac tissues samples has been examined on rats. The experiments were performed in vivo and in vitro on the intact and experimental groups of the animals to check the changes in cell metabolic regulation. Additional the changes in the rats' fecal pH gradient have been assessed. For in vitro experiments the studied tissue samples were incubated to 30 minutes in Tirode physiological solution. Also for estimation of the number of the membrane receptors [Na+/K+ ATPases] the studied tissues were incubated in the Na+/K+ exchange pump specific inhibitor [3+H]-ouabain of 10-9 and 10-4 M solutions for 30 minutes. Obtained results revealed that treatment with mechanical vibration (4Hz, 30dB, 10min) resulted in a 105% increase in pain threshold value, which is the reduction in pain sensitivity, directly correlating with the rate of hydration changes, in particular of 14.6% dehydration. The experimental data revealed certain orderliness between the changes in cell hydration level and pain threshold in brain studied tissues and cardiac tissue, which is set in between the functional activity of the hydration of the nervous and muscular systems. This can be considered as the basis for the hypothesis according to which the cell volume can be used as a cell marker to characterize the functional state of the different tissue cells. [ABSTRACT FROM AUTHOR]

The aim of the study was investigation the ratio of excitatory and depressor post-stimulus manifestations of Periaqueductal gray (PAG) single neuron activity during Locus coeruleus (LC) stimulation in a Parkinson's disease (PD) model to identify excitotoxicity in neurodegeneration and the formation of persistent pain, which is poorly treatable. The electrophysiological studies were performed on 6 Albino rats (230±30g.): intact (n=3) and on the rotenone model of Parkinson's disease (PD) induced by unilateral injection of rotenone for 4 weeks holding of animals (n=3). The extracellular on-line registration of spike activity of 236 single neurons of the Periaqueductal gray (PAG) at high frequency stimulation (HFS) of Locus coeruleus (LC) in intact animals (116 neurons) and on the model of PD (120 neurons) was produced. According to programmed mathematical analyses were detected changes in depressor and excitatory responses (TD and TP), accompanied by post-tetanic depression and potentiation. In the neurons PAG at HFS LC on the model of PD the full suppression of synaptic depressor poststimulus manifestations of activity, accompanied by posttetanic and the prevalence of such excitatory has been revealed. Was the conclusion about serious neurodegenerative damage of the important antinociceptive structure - PAG, that promotes resistant chronic pain in parkinsonian patients.

This study aimed to investigate the ratio of excitatory and depressor post-stimulus manifestations of SI single neuron activity during VPL stimulation of the thalamic nucleus in a PD model to identify excitotoxicity in neurodegeneration and the formation of persistent pain, which is poorly treatable. Electrophysiological studies were performed on 6 albino rats (230±30 g): intact (n=3) and rotenone model (n=3) of Parkinson's disease (PD) induced by unilateral administration of rotenone for 4 weeks (n=3). We performed extracellular recordings of spike activity of 207 single neurons in the primary somatosensory cortex (SI) of the ventral posterolateral thalamic nucleus (VPL). Changes in depressor and excitatory responses (TD and TP), accompanied by post-tetanic depression and potentiation, were detected using the analysis. A significant excess in the frequency of the prestimulus (background) activity of SI neurons in a PD model was revealed as a result of the inevitable development of excitotoxicity. At the post-stimulus level, excitotoxicity under pathological conditions should also be recognized. In conclusion, the PD model revealed excitotoxicity in the SI neurons with the emergence of persistent chronic pain.

The activation of Na/ 40 Ca exchange in reverse (R) mode leading to neuronal swelling and muscle contraction has been suggested as a mechanism for generation of pain signals. However, the activation of R Na/ 45 Ca exchange, having higher rate than R Na/ 40 Ca exchange, brings to depression of pain sensation, the mechanism of which is not clear. The previous data that the 4 Hz mechanical vibration (MV) has pain-relieving effects by activation of cGMP-dependent Na/Ca exchange in forward (F) mode, which leads to muscle hydration and neuronal dehydration, as in case of R Na/ 45 Ca exchange activation, allow us to suggest that the comparative study of the effects of 4 Hz MV and R Na/ 45 Ca exchange on thermal pain thresholds, tissue hydrations in different experimental conductions will make it possible to evaluate the mechanisms of R Na/ 45 Ca exchange-induced inhibition of pain sensation. The obtained data show that the R Na/ 45 Ca exchange-induced depression of pain sensation is due to high [Ca 2+ ] i- inactivation of Na/K pump which brings to further increase of [Ca 2+ ] i , while 4 Hz MV-activated F Na/Ca exchange-induced pain-relieving effect is due to Na/K pump activation by low [Ca 2+ ] i . It is suggested that the R Na/ 45 Ca exchange inhibits pain sensation, which is due to high [Ca 2+ ] i- induced depression inhibition of muscle contractility, while the 4 Hz MV-induced pain-relieving effect is due to activation of Na/K pump by cGMP-dependent decrease of [Ca 2+ ] i leading to muscle relaxation and neuronal dehydration. Therefore, the 4 Hz MV has been suggested as a novel quantum-mechanical sensitive target for pain therapy.