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Transcranial Magnetic and Electric Stimulation
Published in Ben Greenebaum, Frank Barnes, Biological and Medical Aspects of Electromagnetic Fields, 2018
Shoogo Ueno, Masaki Sekino, Tsukasa Shigemitsu
Using microdialysis in anesthetized adult male Wistar rats, Keck et al. (2000a) monitored the intrahypothalamic release of arginine vasopressin (AVP) and amino acids (glutamate, glutamine, aspartate, swerine, arginine, taurine, γ-aminobutyric acid) and the intrahippocampal release of monoamines (dopamine, noradrenaline, serotonin) and their metabolites (homovanillic acid, 3,4-dihydroxyphenylacetic acid, 5-hydroxyindoleacetic acid) after the treatment of acute high-frequency (20 Hz) TMS (20 trains of 2.5 s). In response to rTMS, a continuous reduction in AVP release of up to 50% within the hypothalamic paraventricular nucleus was observed. Within this nucleus, the release of taurine, aspartate and serine were selectively stimulated by rTMS. In addition, in the dorsal hippocampus the extracellular concentration of dopamine was elevated in response to rTMS. They concluded this was the first in vivo evidence that acute rTMS of frontal brain regions has a differentiated modulatory effect on neurotransmitters/neuromodulator systems in distinct brain areas.
Carbon Monoxide-Induced Impairment of Learning, Memory, and Neuronal Dysfunction
Published in David G. Penney, Carbon Monoxide, 2019
Masayuki Hiramatsu, Tsutomu Kameyama, Toshitaka Nabeshima
It is reported that not only the massive increase in excitatory amino acids but also catecholamines play a very important role in the pathogenesis of hypoxic cell damage, because depletion of catecholamine by the administration of α-methyl-p-tyrosine protects dopamine and glutamate nerve terminals from ischemia-induced injury (Weinberger et al., 1985). A few studies have examined the possible effects of CO exposure on cerebral biogenic amines (Akiyama et al., 1991; Hiramatsu et al., 1994d). It has been reported that exposure to hypoxia (8-15% O2 in N2) increased dopamine levels in striatal dialysate in rats (Akiyama et al., 1991). Similarly, during CO exposure, dopamine levels rise dramatically in the extracellular fluid of the rat striatum, whereas its metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid decreased about 20-25% (Hiramatsu et al., 1994d). In contrast, the increase of serotonin release after CO exposure was much less compared to that of dopamine release and there was no significant difference in 5-hydroxyindoleacetic acid levels in rats (Hiramatsu et al., 1994d). Newby et al. (1978) found that striatal dopamine levels in rats are increased after 2 h of exposure to 0.15% CO, but not following 2 h of low oxygen. Dopamine levels in the striatum in the rats exposed to CO and low oxygen remained higher than in the control rats after treatment with a catecholamine synthesis inhibitor, indicating a decreased dopamine turnover. Akiyama et al. (1991) have suggested that exocytotic release of dopamine from nerve terminals is unaffected by hypoxia and that the hypoxia-induced increase in the extracellular dopamine levels is mainly the result of inhibition of the dopamine re-uptake mechanism by hypoxia. The effect of CO on dopamine turnover persisted for several weeks after a single 5 h CO exposure of 8-day-old rats (Newby et al., 1978).
Evaluation of potential health effects associated with occupational and environmental exposure to styrene – an update
Published in Journal of Toxicology and Environmental Health, Part B, 2019
M.I. Banton, J.S. Bus, J.J. Collins, E. Delzell, H.-P. Gelbke, J.E. Kester, M.M. Moore, R. Waites, S.S. Sarang
Kishi et al. (1992) investigated reproductive effects in pregnant rats and neurochemistry in CNS, at styrene concentrations of 0 (n = 14), 50 (n = 3), and 300 ppm (n = 7) from gestation days 7 to 21 administered 6 h/day. The study found no effects on maternal weight (but there was a dose-related numerical decrease not attaining statistical significance), length of gestation, or number of offspring. Body weight of offspring on postnatal day 1 was significantly decreased for both exposure groups without a dose–response relationship. A significant decrease was found in concentrations of serotonin, dopamine, 5-hydroxyindoleacetic acid, and homovanillic acid in the cerebrum and of serotonin in the cerebellum. A clear interpretation of the results is compromised due to the low number of litters and lack of historical control data for the neurotransmitters that are not part of routine toxicological investigations.