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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.
The stress-response
Published in Herman Staudenmayer, Environmental Illness, 2018
DA and its metabolites such as 3–4-dihydroxyphenylacetic acid and homovanillic acid substantially reflect events in the brain, whereas EPI and its metabolites tend to reflect the activity of the adrenal medulla. Stimulation with drugs which enhance DA (e.g., amphetamines and cocaine) may result in attentional hypervigilance and feelings of paranoia (Satel et al., 1991). Elevated DA metabolism may be an adaptive response to environmental stress (DeBellis et al., 1994b), but may also reflect hypervigilance, panic attacks, and other anxiety symptoms associated with stress-induced hyperactivity of central DA systems. DA levels below homeostasis are associated with reduction in activity and absence of pleasure. Extreme abnormalities in DA concentrations are associated with schizophrenia (high levels) and Parkinson’s disease (low levels) (Walker and Diforio, 1997).
Voltammetric Detection of Neurotransmitter Release
Published in Richard P. Buck, William E. Hatfield, Mirtha UmañA, Edmond F. Bowden, Biosensor Technology Fundamentals and Applications, 2017
Voltammetric electrodes meet many of these requirements and have been used for many years to sample chemicals in the brain. Leland Clark was the first to show that this approach could be used to measure oxygen levels and ascorbate concentrations in the mammalian brain (14). In early work, Adams’ group showed that the fate of species injected in the brain could be monitored (15), and that homovanillic acid could be monitored in the lateral ventricles following stimulation of dopaminergic pathways (16). Gonon showed that electrochemical surface modification could be used to resolve various compounds (17). However, some of the early work with carbon electrodes was flawed by problems in identification of the detected species (18). This has been the subject of a recent review and most of the problems are now clearly recognized (19).
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.
Thermodynamic and kinetic analysis of the reaction between biological catecholamines and chlorinated methylperoxy radicals
Published in Molecular Physics, 2018
Dušan S. Dimić, Dejan A. Milenković, Jasmina M. Dimitrić Marković, Zoran S. Marković
Dopamine, epinephrine and norepinephrine are hormones in the central nervous system, and they are involved in the movement control, mood modulation, emotions, sleeping and other important functions. They are produced from 3,4-dihydroxy-L-phenylalanine (L-DOPA). The common structural element for the mentioned molecules is the catechol moiety, and that is the reason why this molecule is included in the study. The catechol moiety is a significant structural element for the antiradical scavenging activity, as shown in our previous examination [13,14]. Dopamine is decomposed into several metabolites, which also have an extensive role in the human body, and some of them are included in this contribution: 3-methoxytyramine (3-MT), homovanillic acid (HVA), 3.4-dihydroxyphenylacetic acid (DOPAC).
Fatigue: Is it all neurochemistry?
Published in European Journal of Sport Science, 2018
There are three main pathways in the dopaminergic neurotransmitter system: the nigrostriatal tractus, ventral mesostriatal pathway and tubero-infundibular system (Frazer & Hensler, 1994). In regard to the synthesis of DA, the first step is the conversion of tyrosine or 4-hydroxyphenylalanine into l-3,4-dihydroxyphenylalanine (l-DOPA) by tyrosine hydroxylase. In the next step, l-DOPA is decarboxylated to DA by DOPA decarboxylase. Finally, DA is metabolized by monoamine oxidase to 3,4 dihydroxyphenylacetic acid (DOPAC), and homovanillic acid (HVA), or can be converted into NA by dopamine-b-hydroxylase (Roelands & Meeusen, 2010). DA is heavily implicated in increases of arousal, motivation, reinforcement, reward, the control of motor behaviour and addiction (Nestler, Hyman, & Malenka, 2001).