Extracellular Ca2+ changes during transmitter application in the leech central nervous system
Research article published in Neuroscience letters (1996)
Abstract
Changes in extracellular Ca2+ concentration ([Ca2+]e) evoked by transmitters and transmitter agonists, respectively, and by elevation of bath K+ concentration were recorded in isolated segmental ganglia of the leech Hirudo medicinalis using Ca(2+)-selective microelectrodes. A 1-min bath application of kainate (10 microM), glutamate (1 mM), aspartate (1 mM), or carbachol (200 microM) decreased [Ca2+]e by up to 1 mM, whereas the inhibitory transmitters gamma-amino butyric acid (GABA, 100 microM) and serotonin (5-HT, 100 microM) did not change [Ca2+]e. The amplitude of the kainate-induced changes in [Ca2+]e increased with repetitive applications, and changes were blocked by 6-cyano-7-dinitroquinozaline-2,3-dione (CNQX). Elevation of bath K+ concentration from 4 to 40 mM led to a Ni(2+)-sensitive decrease in [Ca2+]e by 0.9 mM. Our results suggest that excitatory transmission in the leech central nervous system might be accompanied by substantial decreases in [Ca2+]e.
Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.
Summary
Changes in extracellular Ca2+ concentration ([Ca2+]e) evoked by transmitters and transmitter agonists, respectively, and by elevation of bath K+ concentration were recorded in isolated segmental ganglia of the leech Hirudo medicinalis using Ca(2+)-selective microelectrodes.
Why This Matters for Hirudotherapy
This study used Ca2+-selective microelectrodes to record changes in extracellular calcium concentration in isolated segmental ganglia of Hirudo medicinalis during bath application of neurotransmitters and agonists, finding that excitatory transmitters (kainate, glutamate, aspartate, carbachol) decreased extracellular Ca2+ by up to 1 mM, while inhibitory transmitters (GABA, serotonin) did not. The work contributes to fundamental neurophysiological understanding of the medicinal leech, the primary species employed in hirudotherapy, illuminating basic cellular signaling mechanisms in this organism. However, this is an in vitro study of isolated ganglia that does not investigate leech therapy, the salivary secretome, or any clinical application; its relevance to hirudotherapy is indirect, confined to basic leech neurobiology.
Citation
Extracellular Ca2+ changes during transmitter application in the leech central nervous system.
Lohr C, Rose C, Deitmer J · Neuroscience letters, 1996
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