Ingestive behaviour and physiology of the medicinal leech
Physiology study published in Journal of Experimental Biology (1988)
Abstract
Ingestion lasts 25 min in Hirudo medicinalis and is characterized by pharyngeal peristalsis which fills the crop. This peristalsis has an initial rate of 2.4 Hz which decays smoothly to 1.2 Hz at termination of ingestion. During ingestion, the leech body wall undergoes peristalsis which appears to aid in filling the crop diverticula. Body peristalsis begins at a rate of 10 min-1 and decreases linearly to 2 min-1 at termination. The body also undergoes dorsoventral flexions when blood flow is occluded. Blood meal size increases slightly with leech size: 8.4 g for 1-g leeches and 9.7 g for 2-g leeches. However, relative meal size decreases markedly with increasing animal size; from 8.15 times body mass for 1-g to 4.80 times for 2-g leeches. When intact leeches were exposed to micromolar concentrations of serotonin, there was an increase in the rate of pharyngeal peristalsis and the size of the blood meals. Leeches excrete the plasma from their ingested blood meals. Excretion is activated during ingestion, which increases feeding efficiency by increasing the proportion of blood cells in the ingestate. Excretion continues for 4-6 days following ingestion, removing all the remaining plasma from the ingestate. Leech ingestion comprises stereotyped muscular movements, secretion of saliva and excretion of plasma. A strikingly similar feeding physiology is seen in the blood-sucking insect Rhodnius, and we suggest that efficient sanguivory may require the convergent evolution of similar ingestive mechanisms.
Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.
Zusammenfassung
Definitive description of Hirudo medicinalis ingestion physiology: 25 min pharyngeal peristalsis filling crop diverticula, plasma excretion during ingestion, blood meal 8.4-9.7 g (4.8-8.15x body mass), serotonin modulation of pharyngeal rate and meal size.
Warum dies für die Hirudotherapie relevant ist
This study characterized the ingestive physiology of Hirudo medicinalis, reporting that blood-meal ingestion lasts about 25 minutes and involves pharyngeal peristalsis, body-wall peristalsis, and concurrent excretion of plasma that increases the proportion of blood cells in the ingestate. Blood-meal size increased slightly with leech size—8.4 g for 1-g leeches and 9.7 g for 2-g leeches—while relative meal size decreased, and micromolar serotonin increased peristalsis rate and meal size. The abstract notes that ingestion includes secretion of saliva, but it does not identify specific salivary components or their actions. Caveat: this is basic comparative physiology with no clinical data, no secretome characterization, and no direct evidence regarding therapeutic effects of leech therapy.
Zitation
Ingestive behaviour and physiology of the medicinal leech.
Lent CM et al. · Journal of Experimental Biology, 1988
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