Physiologically identified 5-HT sub(2)-like receptors at the crayfish neuromuscular junction

The model synaptic preparation of the crayfish opener neuromuscular junction is known to be responsive to exogenous application of 5-HT. The primary effect of 5-HT is an enhancement of vesicular release from the presynaptic motor nerve terminal. 5-HT is known to act through an IP sub(3) cascade whic...

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Bibliographic Details
Published in:Brain research 2002-04, Vol.932 (1-2), p.91-98
Main Authors: Tabor, J N, Cooper, R L
Format: Article
Language:English
Subjects:
Freshwater
Procambaridae
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Summary:The model synaptic preparation of the crayfish opener neuromuscular junction is known to be responsive to exogenous application of 5-HT. The primary effect of 5-HT is an enhancement of vesicular release from the presynaptic motor nerve terminal. 5-HT is known to act through an IP sub(3) cascade which suggests the presence of a 5-HT sub(2) receptor subtype; however, this is based on vertebrate 5-HT receptor classification. We examined this possibility by using a selective agonist and two antagonists of the vertebrate 5-HT sub(2) receptor subtypes. The antagonist ketanserin and spiperone reduce the responsiveness of 5-HT in a dose-dependent manner. The broad 5-HT sub(2) receptor agonist, alpha -methyl-5-hydroxytryptamine ( alpha -Me-5-HT) enhances synaptic transmission, in a concentration-dependent manner, but it is not as potent as 5-HT. These results support the notion that a 5-HT sub(2) receptor subtype is present presynaptically on the crayfish motor nerve terminals. By knowing the types of 5-HT receptors present on the presynaptic motor nerve terminals in this model synaptic preparation, a better understanding of the mechanisms of action of 5-HT on vesicular release will be forthcoming.
ISSN:0006-8993