5-Hydroxytryptamine serotonin

Hoyer D, Clarke DE, Fozard JR et al (1994) International Union of Pharmacology classification of receptors for 5-hydroxytryptamine (Serotonin). Pharmacol Rev 46 157-204... 

Important products derived from amino acids include heme, purines, pyrimidines, hormones, neurotransmitters, and biologically active peptides. In addition, many proteins contain amino acids that have been modified for a specific function such as binding calcium or as intermediates that serve to stabilize proteins—generally structural proteins—by subsequent covalent cross-hnk-ing. The amino acid residues in those proteins serve as precursors for these modified residues. Small peptides or peptide-like molecules not synthesized on ribosomes fulfill specific functions in cells. Histamine plays a central role in many allergic reactions. Neurotransmitters derived from amino acids include y-aminobutyrate, 5-hydroxytryptamine (serotonin), dopamine, norepinephrine, and epinephrine. Many drugs used to treat neurologic and psychiatric conditions affect the metabolism of these neurotransmitters. 

Rat serosal strips Tryptaminergic 5-Hydroxytryptamine (serotonin)/dibenzyline or lysergic acid dibromide Lin and Yeoh, 1965... 

Binds to DNA and prevents separation of the helical strands Affects neuronal transmissions Binds to opiate receptors and blocks pain pathway Acts as central nervous system depressant Inhibits Na/K/ATPase, increases intracellular calcium, and increases ventricular contractibility Blocks the actions of histamine on Hi receptor Blocks ai-adrenergic receptor, resulting in decreased blood pressure Inhibits reuptake of 5-hydroxytryptamine (serotonin) into central nervous system neurons Inhibits cyclooxygenase, inhibition of inflammatory mediators Inhibits replication of viruses or tumor cells Inhibits HIV reverse transcriptase and DNA polymerase Antagonizes histamine effects... 

Serotonin is an indolamine neurotransmitter, derived from the amino acid L-tryptophan. Tryptophan is converted to 5-hydroxytryptophan (5-HTP) by tryptophan hydroxylase. 5-HTP is converted to 5-hydroxytryptamine (serotonin, 5-HT) by aromatic amino acid decarboxylase. In the pineal gland, 5-HT may be further converted to /V-acetyl serotonin by 5-HT /V-acetyltransferase and then to melatonin by 5-hyroxyindole-O-methyltransferase. 5-HT is catabolized by monoamine oxidase, and the primary end metabolite is 5-hydroxyindoleacetic acid (5-HIAA). 

The pathways for synthesis of the monoamine neurotransmitters are not, at least in some neurones, saturated with precursor amino acids (tyrosine for formation of noradrenaline plus dopamine tryptophan for formation of 5-hydroxytryptamine (serotonin)). Marked increases in the blood level of these amino acids can increase their concentrations in neurones which can influence the concentration of the respective neurotransmitters in some neurones in the brain. This may result in changes in behaviour. 

Hoyer D, Qarke DE, Eozard JR, et al. International union of pharmacology classification of receptors for 5-hydroxytryptamine (serotonin). Pharmacol Rev 1994 46 157-203. 

Reserpine also interferes with the neuronal storage of a variety of central transmitter amines such that significant depletion of norepinephrine, dopamine, and 5-hydroxytryptamine (serotonin) occurs. This central transmitter depletion is responsible for the sedation and other CNS side effects associated with reserpine therapy. The depletion of brain amines also may contribute to the antihypertensive effects of reserpine. 

It is a potent alpha-adrenergic blocking agent and only haloalkylamine used clinically. It effectively prevents the responses mediated by alpha receptors and diastolic blood pressure tends to decrease. It interferes with the reflex adjustment of blood pressure and produces postural hypotension. It increases the cardiac output and decreases the total peripheral resistance. It also antagonizes cardiac arrhythmias provoked by catecholamines. Apart from these effects, phenoxybenzamine has other actions also e.g. antagonism of acetylcholine, histamine, 5-hydroxytryptamine (serotonin). However, the vasodilatation produced by phenoxybenzamine is because of alpha blockage. Adverse reactions are miosis, dryness of mouth, inhibition of ejaculation, palpitation, nasal stuffiness and in higher doses, postural hypotension and reflex bradycardia. 

It is an alkaloid obtained from the roots of Ramvolfia serpentina. It is known to deplete the catecholamines - adrenaline, noradrenaline and dopamine from the various sites in the body. It also depletes 5-hydroxytryptamine (serotonin). 

Neuronal systems that contain one of the monoamines—norepinephrine, dopamine, or 5-hydroxytryptamine (serotonin)— provide examples in this category. Certain other pathways emanating from the reticular formation and possibly some peptide-containing pathways also fall into this category. These systems differ in fundamental ways from the hierarchical systems, and the noradrenergic systems serve to illustrate the differences. 

Hydroxytryptamine (serotonin) Cell bodies in midbrain and pons project to all levels 5-HT1A LSD Metergoline, spiperone Inhibitory t K+ conductance, CAMP... 

At present, in addition to acetylcholine, glutamate, and y-aminobutyrate (GABA), glycine, noradrenaline (norepinephrine), and dopamine and 5-hydroxytryptamine (serotonin) are regarded as established transmitters. Other probable (putative) or possible candidate transmitters are also known. Aspartate, taurine, and a large number of peptides (Tables 30-1,30-4) are under consideration. 

Fig. 1. Occurrence of H3 receptors inhibiting release of acetylcholine, of amino acid and monoamine neurotransmitters in the mammalian CNS in vitro. The schematic drawing represents a midsagittal section of the human brain three areas with a more lateral position are shown by broken line (substantia nigra and part of the hippocampus and of the striatum). For each of the six regions of the CNS (subregions given in brackets), in which H3 heteroreceptors have been identified, the neurotransmitter(s) and the species are indicated. The superscripts refer to the numbers of the papers as listed under References. Own unpublished data suggest that an H3 receptor-mediated inhibition of noradrenaline release also occurs in the human cerebral cortex and hippocampus and in the guinea-pig cerebral cortex. Note that a presynaptic location has not been verified for each of the H3 heteroreceptors or has been even excluded (for details, see Table 1). Abbreviations ACh, acetylcholine DA, dopamine GABA, y-aminobutyric acid Glu, glutamate 5-HT, 5-hydroxytryptamine, serotonin NA, noradrenaline...

Fig. 9.4. Diagrammatic representation of the major elements in the integrated immunophysiological response to the host aimed at detecting, destroying and eradicating cestode infections (Th2, T helper type 2 cell AB, antibody 5-HT, 5-hydroxytryptamine (serotonin) APC, antigen presenting cell).

It appears that depression is related to a disturbance in CNS neurotransmission involving certain chemicals know as amine neurotransmitters. These transmitters include 5-hydroxytryptamine (serotonin), norepi-... 

Tryptamine and its Al-methyl and A/Al-dimethyl derivatives (Figure 6.70) are widely distributed in plants, as are simple hydroxylated derivatives such as 5-hydroxytryptamine (serotonin). These are formed (Figure 6.70) by a series of decarboxylation, methylation, and hydroxylation reactions, though the sequences of these reactions are found to vary according to final product and/or... 

Hydroxytryptamine (serotonin, 5HT) is metabolized according to the following scheme ... 

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