Biochemical investigation neurotransmitter

L-Tyrosine metabohsm and catecholamine biosynthesis occur largely in the brain, central nervous tissue, and endocrine system, which have large pools of L-ascorbic acid (128). Catecholamine, a neurotransmitter, is the precursor in the formation of dopamine, which is converted to noradrenaline and adrenaline. The precise role of ascorbic acid has not been completely understood. Ascorbic acid has important biochemical functions with various hydroxylase enzymes in steroid, dmg, andhpid metabohsm. The cytochrome P-450 oxidase catalyzes the conversion of cholesterol to bUe acids and the detoxification process of aromatic dmgs and other xenobiotics, eg, carcinogens, poUutants, and pesticides, in the body (129). The effects of L-ascorbic acid on histamine metabohsm related to scurvy and anaphylactic shock have been investigated (130). Another ceUular reaction involving ascorbic acid is the conversion of folate to tetrahydrofolate. Ascorbic acid has many biochemical functions which affect the immune system of the body (131). 

A variety of different methodologies has been employed to investigate the neurotransmitter systems involved in control of behavioral states. Biochemical experiments have elucidated the pathways and enzymes involved in the synthesis, degradation, release and reuptake of different neurotransmitters. Immuno-histochemical techniques have allowed the visualization of their cellular and sub-cellular distribution throughout the nervous system as well as the distribution of their receptors and uptake systems. Chemical sampling techniques, including... 

This diversity of mental retardation, in both cause and phenotype, carries important implications for consideration of the biochemistry of consciousness. On the one hand, because this is an investigation of multiple causalities—including, for example, inborn errors of metabolism, each of which has its own unique biochemical profile (Cook Leventhal, 1996), it may not prove possible to identify specific neurotransmitter abnormalities which are common to mental retardation as such. On the other hand common themes concerning key neurotransmitters may be identified from studies of mental retardation. Altered neurotransmitter functioning associated with the severity of mental retardation is open to different interpretations, either reflecting fundamentally impaired development of cerebral structure or a more general impairment of central transmitter activity and functioning. 

In conclusion, data from biochemical, physiological/pharmacological and immunocyto-chemical studies concur in supporting Glu as a primary afferent neurotransmitter. Although it cannot be excluded that a subpopulation of primary afferent terminals that have escaped investigation transmit their signals by other means, the available evidence speaks strongly in favor of Glu as a transmitter in most, if not all, primary afferent terminals (Fig. 4). This of course does not exclude that other compounds, e.g. peptides, are co-released with Glu from selected populations of primary afferent terminals. 

Effect. No reliable biomarkers of manganese effect are known. Biochemical changes such as altered blood or urinary levels of steroids, neurotransmitters, or their metabolites are plausible biomarkers of exposure, but this possibility has not been thoroughly investigated. Although methods exist for the analysis of these biochemicals, further work to improve the analyses does not seem warranted unless the utility of this approach is established. 

The diverse physiological actions of capsaicin described in the previous sections have motivated numerous, equally diverse, in vivo and in vitro studies in search of biochemical correlates. The most attention, however, has been focused on the sensory system since a direct effect of capsaicin on sensory nerves has been suspected for a long time. More recent observations of capsaicin-induced sensory neuron degeneration in neonatal animals have added further impetus to determine the resultant neurochemical deficits of this lesion. It is perhaps fortunate that the small type B neurons of dorsal root ganglia which appear anatomically to succumb to capsaicin after both neonatal and adult treatment are also among the neurons for which putative neurotransmitter markers have been identified. Accordingly, these markers, two of which are the peptides somatostatin and substance P, have provided both a means to assess the neurotoxic potential of capsaicin, and to some extent relate anatomical with neurochemical investigations. For the sake of coherence the biochemical aspects of some reports cited in the previous sections are discussed here. The major conclusions in these reports will be summarized in Section 13. 

In a search for possible structural and biochemical correlates of the impaired mental development reported in children with PEM it seemed important to investigate synaptic development and the synthesis of neurotransmitters. Gangliosides are located in high... 

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