Two bidirectional nerve cord systems converging with electrical and chemical synapses on the Retzius cells of the leech Hirudo Medicinalis.
Research article published in Archives italiennes de biologie (1981)
Abstract
Electrical stimulation of the ventral cord of H. medicinalis elicits in both Retzius' cells of each segmental ganglion an EPSP which is composed by an early and a late component. The early EPSP is electrical in nature, since it is unaffected by displacements of the membrane potential and by high Mg2+, whereas the late one is chemical, being reversed in sign by membrane depolarization and suppressed by high Mg2+. Latency measurements show that the electrical and chemical EPSP components are mediated by two different pathways characterized by conduction velocities of 0.5 and 0.3 m/sec respectively. Both pathways run in each of the lateral connectives and propagate impulses in anterior and posterior direction. Collision experiments show that ascending and descending impulses along the pathway mediating the electrical EPSP travel along the same fibres. Separate stimulation of the lateral connectives and selective inactivation of one Retzius' cell show that both pathways converge onto each Retzius' cell show that both pathways converge onto each Retzius cell. The possible functional significance of the two excitatory pathways is discussed.
Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.
Resumen
Electrical stimulation of the ventral cord of H. medicinalis elicits in both Retzius' cells of each segmental ganglion an EPSP which is composed by an early and a late component.
Por qué esto importa para la hirudoterapia
This study examined neural signaling in the leech Hirudo medicinalis, showing that ventral-cord stimulation elicited Retzius-cell EPSPs with an early electrical component and a late chemical component mediated by pathways with conduction velocities of about 0.5 and 0.3 m/sec, respectively. Both pathways ran in the lateral connectives, propagated anteriorly and posteriorly, and converged on each Retzius cell. The abstract concerns fundamental leech neurobiology and synaptic circuitry. It does not address hirudotherapy, the leech secretome, therapeutic mechanisms, or clinical applications, so it provides no direct evidence relevant to leech therapy despite involving a leech species.
Citación
Two bidirectional nerve cord systems converging with electrical and chemical synapses on the Retzius cells of the leech Hirudo Medicinalis.
Carretta et al. · Archives italiennes de biologie, 1981
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Añadido a la biblioteca ASH: May 28, 2026 · Última actualización del sitio: June 18, 2026