Chapter

5-HT<sub>3</sub> receptor antagonists and their potential in psychiatric disorders

Michael G. Palfreyman, Stephen M. Sorensen, Albert A. Carr, Hsien C. Cheng and Mark W. Dudley

in 5-Hydroxytryptamine in Psychiatry

Published in print February 1991 | ISBN: 9780192620118
Published online March 2012 | e-ISBN: 9780191724725 | DOI: http://dx.doi.org/10.1093/acprof:oso/9780192620118.003.0023
5-HT3 receptor antagonists and their potential in psychiatric disorders

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Classification of 5-hydroxytryptamine (5-HT, serotonin) receptors in the guinea pig ileum into ‘D’ receptors located on smooth muscle cells and those located on intramural cholinergic neurones of the myenteric plexus (M type) has been superseded by the classification into ‘5-HT1-like’, 5-HT2, and 5-HT3. Pharmacological analysis of the 5-HT2 receptor suggested that it was identical to Gaddum's ‘D’ receptor. The 5-HT3 receptor appears to be the acceptor component of a ligand-gated cation channel which bears comparison with the nicotinic acetylcholine-operated ion channel. Serotonergic activation causes a rapid depolarizing response associated with an increase in the membrane conductance to Na+ and K+ ions. The explosion of interest in this receptor subtype and the plethora of new and very selective 5-HT3 antagonists owe much of their origin to pioneer studies undertaken in the late 1970s. 2-Methyl-5-HT is a potent agonist at 5-HT3 receptors, but it also has high affinity for 5-HT1D receptors and appreciable affinity for 5-HT1A and 5-HTlc sites. Phenylbiguanide, on the other hand, appears to be a much more selective 5-HT3 agonist. However, phenylbiguanide does cause carrier-mediated release of dopamine from slices of rat caudate which bodes caution in interpretation of its effects in intact tissues.

Keywords: 5-hydroxytryptamine receptors; intramural cholinergic neurones; myenteric plexus; ligand-gated cation channel; phenylbiguanide; psychiatric disorders

Chapter.  2652 words.  Illustrated.

Subjects: Neuroscience

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