American Society of Hirudotherapy

Central and peripheral 5-HT receptors in the leech (Hirudo medicinalis) redefined.

Research article published in General pharmacology (1995)

Last Updated: June 18, 2026Reviewed by: ASH Editorial Board
Research article — evidence reviewArticle reference
Evidence: In vitro / laboratoryGenomics & ProteomicsSalivary PharmacologyLeake et al. · General pharmacology, 1995

Abstract

1. 5-Hydroxytryptamine (5-HT) receptors in the Retzius neurones (R cells) and longitudinal body wall muscle strips of the leech H. medicinalis were studied using a range of selective agonists developed for mammalian receptors. 2. All agonists induced hyperpolarisation of R cells: the order of their potency was 5-HT > 5-CT > 2-Me 5HT > alpha-Me-5-HT > > CGS-12066B = 5MeOT > PAPP > Buspirone. This receptor is most like a mammalian 5-HT1C/2 receptor. 3. 5-HT induces relaxation of body wall strips, preceded at higher doses by contraction or an increase in spontaneous contractions. The relaxing effect was best mimicked by 5-CT and alpha-Me-5-HT, suggesting a 5-HT1C/2 receptor. The contractile effect was best mimicked by 5-MeOT suggesting a 5-HT4-like receptor. The overall potency of agonists on the body wall muscle was 5-MeOT > 5-CT > 5-HT > alpha-Me-5-HT > 2-Me 5-HT > PAPP > Buspirone > > CGS-12066B. 4. Results suggest that either the sites of 5-HT action possess several different receptors or the receptors themselves are more complex with multiple properties.

Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.

Publication typeJournal ArticleResearch Support, Non-U.S. Gov't
Indexed MeSH termsAnimalsIn Vitro TechniquesLeechesMuscle ContractionNeuronsReceptors, SerotoninSerotoninSerotonin Receptor Agonists

Summary

1. 5-Hydroxytryptamine (5-HT) receptors in the Retzius neurones (R cells) and longitudinal body wall muscle strips of the leech H.

Why This Matters for Hirudotherapy

This in vitro study characterized serotonin (5-HT) receptors on Retzius neurons and longitudinal body wall muscle strips of *Hirudo medicinalis* using a range of mammalian-selective agonists. The researchers found that the receptor on Retzius cells most resembles a mammalian 5-HT1C/2 receptor, while body wall muscle shows evidence of both 5-HT1C/2-like and 5-HT4-like receptors mediating relaxation and contraction respectively, suggesting either multiple receptor types or receptors with complex properties. This pharmacological characterization is relevant to understanding the serotonergic physiology of the medicinal leech, including components of the leech secretome. However, this is basic in vitro pharmacology with no direct connection to hirudotherapy or the therapeutic use of leech-derived substances.

Citation

Central and peripheral 5-HT receptors in the leech (Hirudo medicinalis) redefined.

Leake et al. · General pharmacology, 1995

DOI

Added to ASH library: May 28, 2026 · Site last updated: June 18, 2026

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