Afferent sensillar inputs to the Retzius cell of the leech Hirudo medicinalis.
Research article published in Archives italiennes de biologie (1987)
Abstract
Water-wave and photic stimulation of the sensilla elicits synaptic potentials identical to those elicited by electrical stimulation of the segmental roots. Mechanical stimulation elicits a localized IPSP and a generalized EPSP in the RCs and an IPSP in the AE motoneurons. Photic stimulation gives rise to a generalized EPSP in the RCs alone. The impulse discharges elicited in the afferent fibers by the two kinds of stimuli is transmitted along the cord both anteriorly and posteriorly to the stimulated segment. This implies that the afferent impulses excite a pool of intersegmental neurons in each ganglion, which distribute their discharges to the adjacent ganglia. The evidence for occlusion between cordal and photically elicited volleys indicates that it shares with the sensillar input a common pool of interneurons. The possible functional significance of the inhibitory and excitatory inputs is discussed.
Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.
Summary
Water-wave and photic stimulation of the sensilla elicits synaptic potentials identical to those elicited by electrical stimulation of the segmental roots. Mechanical stimulation elicits a localized IPSP and a generalized EPSP in the RCs and an IPSP in the AE motoneurons.
Why This Matters for Hirudotherapy
This study examined how water-wave, photic, and mechanical stimulation of sensilla activates afferent pathways to Retzius cells and motoneurons in the leech central nervous system. The researchers found that mechanical stimulation produces both inhibitory and excitatory responses in Retzius cells while photic stimulation selectively excites them, and that afferent impulses travel bidirectionally along the nerve cord through shared interneuron pools. This work contributes to understanding the fundamental neurophysiology of the medicinal leech, including the Retzius cell, a primary serotonergic neuron in leech biology. However, this is basic neuroscience research with no direct bearing on hirudotherapy practice or the therapeutic leech secretome.
Citation
Afferent sensillar inputs to the Retzius cell of the leech Hirudo medicinalis.
Carretta et al. · Archives italiennes de biologie, 1987
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