Neurotransmitter metabolism

An excellent description of the discovery of neurotransmitters is provided by Valenstein (2005). Only the essentials of neurotransmitter metabolism are covered here for more detailed information the reader is directed to textbooks of neurochemistry, e.g. Siegel et al. (1994). For a more advanced coverage of the topics discussed here as well as information on the electrical properties of the neurons involved, the interested reader is directed to Steriade McCarley (2005). 

Choi, I. Y., Lei, H. and Gruetter, R. Effect of deep pentobarbital anesthesia on neurotransmitter metabolism in vivo on the correlation of total glucose consumption with glutama-tergic action. /. Cereb. Blood Flow Metab. 22 1343-1351, 2002. 

Gruetter, R., Seaquist, E. R. and Ugurbil, K. A mathematical model of compartmentalized neurotransmitter metabolism in the human brain. Am. J. Physiol. 281, E100-112, 2001. 

Careful analyses of the pharmacologic properties of 3H-hailucinogen binding sites indicated that they may correspond to 5-HT receptors (in the case of 3H-LSD), sigma opiate receptors (in the case of 3H-PCP), or even GABA receptors (in the case of 3H-muscimol). Such data recall that hallucinogens should interfere markedly with the metabolism of neurotransmitters in the CNS. These hallucinogen-induced alterations of neurotransmitter metabolism and functions are summarized below. 

The only known change in neurotransmitter metabolism so far detected is a deficiency of acetylcholine in the brain. This has been shown in post-mortem studies on the brains of patients with Alzheimer s disease. Some success in reducing the symptoms of the disease has been obtained with drugs that inhibit the activity of acetylcholinesterase leading to an increase in the acetylcholine concentration, but the improvement is minimal so that its use is controversial. 

The biochemical basis nnderlying the normal fnnctioning of the brain is discussed above, where it is emphasised that of the two forms of communication, electrical and chemical, it is the latter that provides most flexibility. Not snrprisingly, therefore, there are more disorders dne to disturbances in neurotransmitter metabolism than there are due to disturbances in electrical commnnication. Nonetheless, damage to the structure of the myelin sheath aronnd the axon which interferes with electrical commnnication can lead to the severe disorder mnltiple sclerosis. 

Monamines are inactivated into aldehydes by amine oxidase (monoamine oxidase, MAO ) with deamination and simultaneous oxidation. MAO inhibitors therefore play an important role in pharmacological interventions in neurotransmitter metabolism. 

Jaeken J, Casaer P, de Cock P, Corbeel L, Eeckels R, Eggermont E, Schechter PJ, Brucher JM (1984) Gamma-aminobutyric acid-transaminase deficiency a newly recognized inborn error of neurotransmitter metabolism. Neuropediatrics 15 165-169... 

Tsai G, Passani LA, Slusher BS, Carter R, Baer L, et al. 1995. Abnormal excitatory neurotransmitter metabolism in schizophrenic brains. Arch Gen Psychiatry 52 829-836. 

Central nervous system and neuromuscular junction. A remarkable number of alkaloids interfere with the metabolism and activity of neurotransmitters in the brain and nerve cells, a fact known to man for a thousand years (Table IV). The cellular interactions have been discussed above. Disturbance of neurotransmitter metabolism impairs sensory faculties, smell, vision, or hearing, or they may produce euphoric or hallucinogenic effects. 

Freeman, G. B., Nielsen, P., Gibson, G. E. (1986). Monoamine neurotransmitter metabolism and locomotor activity during chemical hypoxia. Journal of Neurochemistry, 46, 733—738. 

Hutson SM, Lieth E, La Noue KF. 2001. Function of leucine in excitatory neurotransmitter metabolism in the central nervous system. J Nutr 131 846S-850S. 

SC7 shares a pattern with nestin and two splice variants of the neurotransmitter-metabolizing enzyme, GAD (glutamatic acid decarboxylase). Middle panel These genes are shown in a branch of the cluster tree for 112 genes expressed in the developing rat spinal cord. 

Impairment of large neutral amino acid (LNAA) transport across the blood-brain barrier (BBB) with disturbances in neurotransmitter metabolism [33, 37]... 

Fig. 1 Chromatograms of a standard solution of monoamine transmitters and their metabolites at (A) a poly(para-aminobenzoic acid) modified electrode and (B) a bare glassy carbon electrode. (1) Norepinephrine, (2) epinephrine, (3) dopamine, (4) 3,4-dihydroxyphenol acetic acid, (5) serotonin, (6) 5-hydroxyindole acetic acid, and (7) homovanillic acid. Source From Study on the effect of electromagnetic impulse on neurotransmitter metabolism in nerve cells by high performance liquid chromatography-electrochemical detection coupled with microdialysis, in Anal. Biochem. ...

Xu, F. Gao, M. Wang, L. Jin, L. Study on the effect of electromagnetic impulse on neurotransmitter metabolism in nerve cells by high performance hquid chromatography-electrochemical detection coupled with microdialysis. Anal. Biochem. 2002, 307, 33-39. 

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