American Society of Hirudotherapy

Putative nitric oxide synthase (NOS)-containing cells in the central nervous system of the leech, Hirudo medicinalis: NADPH-diaphorase histochemistry

Research article published in Brain research (1996)

Last Updated: June 18, 2026Reviewed by: ASH Editorial Board
Research article — evidence reviewArticle reference
Evidence: Preclinical (animal)Clinical TrialsLeake et al. · Brain research, 1996

Abstract

The presence and distribution of putative nitric oxide synthase (NOS)-containing cells in whole-mount preparations of the central nervous system of the leech, Hirudo medicinalis, were studied using NADPH-diaphorase (NADPH-d) histochemistry. Specific staining occurred mainly in somata of some central neurones but NADPH-d-reactive branches and terminals were found in peripheral nerves and connectives: neuropile areas were stained weakly or unstained. Intense staining was located in many neurones on the ventral side of the segmental ganglia, including primary sensory neurones, motoneurones and interneurones, and in the anterior root ganglion. The sex ganglia contained some extra NADPH-d-positive cells. Head and tail ganglia and the dorsal side of the segmental ganglia showed less staining. Specific activity was not detected in salivary glands, crop or intestine. Controls using beta-NADPH or nitro blue tetrazolium (NBT) alone or with NBT plus alpha-NADPH, beta-NAD+, beta-NADH or beta-NADP+ did not induce specific staining. A potential NOS inhibitor, 2,6-dichlorophenol-indophenol (DPiP) at 10(-3) M, totally abolished NADPH-d-positive staining. Long-term fixation did not change the pattern of distribution of NADPH-d-positive cells. We conclude that (i) fixative-resistant NADPH-diaphorase is a characteristic marker of 12-15% of neurones in the leech CNS, and (ii) the specific distribution of the putative NOS-containing neurones suggests that NO may be a natural signal molecule in leeches.

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 termsAnimalsCentral Nervous SystemGanglia, InvertebrateHistocytochemistryLeechesNADPH DehydrogenaseNitric Oxide Synthase

Summary

Peer-reviewed clinical and outcomes research relevant to medicinal leech therapy and its biology. Indexed in PubMed and verified against the NCBI record.

Why This Matters for Hirudotherapy

Using NADPH-diaphorase histochemistry on whole-mount nervous systems of Hirudo medicinalis, this study mapped putative nitric-oxide-synthase-containing neurons and found reactivity in roughly 12-15% of central neurons (including sensory, motor, and interneurons), concluding that nitric oxide may act as a natural signaling molecule in the leech. This is genuine medicinal-leech biology and helps characterize the organism ASH works with, but it concerns leech neuroscience and physiology, not the therapeutic salivary secretome or any clinical application. Honest caveat: although the slug contains 'leech,' the work is basic neurobiology on leech tissue (the abstract explicitly notes no specific staining in the salivary glands), so it carries no direct evidence about hirudotherapy efficacy, anticoagulant pharmacology, or patient outcomes, and should not be cited as clinical support.

Citation

Putative nitric oxide synthase (NOS)-containing cells in the central nervous system of the leech, Hirudo medicinalis: NADPH-diaphorase histochemistry.

Leake et al. · Brain research, 1996

DOI

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

This website provides educational information and does not constitute medical advice, diagnosis, or treatment recommendations. Medicinal leech therapy carries clinically meaningful risks and should be performed only by qualified clinicians under institutionally approved protocols. FDA 510(k) clearance for medicinal leeches is limited to specific indications; investigational and off-label discussions are labeled accordingly. For patient-specific guidance, consult a qualified healthcare provider.