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Title: GABA-ergic neurons in the leach central nervous system

Abstract

GABA is a candidate for an inhibitory neurotransmitter in the leech central nervous system because of the well-documented inhibitory action of GABA in other invertebrates. To demonstrate that GABA meets the criteria used to identify a substance as a neurotransmitter, the author examined GABA metabolism and synaptic interactions of inhibitory motor neurons in two leech species, Hirudo medicinalis and Haementeria ghilianii. Segmental ganglia of the leech ventral nerve cord and identified inhibitors have the capacity to synthesize GABA when incubated in the presence of the precursor glutamate. Application of GABA to cell bodies of excitatory motor neurons or muscle fibers innervated by the inhibitors hyperpolarizes the membrane potential of the target cell and activates a chloride ion conductance channel, similar to the inhibitory membrane response following intracellular stimulation of the inhibitor. Bicuculline methiodide (5 x 10/sup -5/M), GABA receptor antagonist, blocks reversibly the response to applied GABA and the inhibitory synaptic inputs onto the postsynaptic neurons or muscle fibers without interfering with their excitatory inputs. Furthermore, the inhibitors are included among approximately 25 neurons per segmental ganglion that take up GABA by a high affinity uptake system, as revealed by /sup 3/H-GABA-autoradiography. The development of the capacities to synthesize andmore » to take up GABA were examined in leech embryos. The embryos are able to synthesize GABA at early stages of the development of the nervous system, before any neurons have extended neutrites.« less

Authors:
Publication Date:
Research Org.:
California Univ., Berkeley (USA)
OSTI Identifier:
5887200
Resource Type:
Thesis/Dissertation
Resource Relation:
Other Information: Thesis (Ph. D.)
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; ANNELIDS; BIOELECTRICITY; ANTIHYPERTENSIVE AGENTS; AUTORADIOGRAPHY; METABOLISM; CENTRAL NERVOUS SYSTEM; EMBRYOS; NERVE CELLS; TRACER TECHNIQUES; TRITIUM COMPOUNDS; ANIMAL CELLS; ANIMALS; CARDIOVASCULAR AGENTS; DRUGS; ELECTRICITY; INVERTEBRATES; ISOTOPE APPLICATIONS; LABELLED COMPOUNDS; NERVOUS SYSTEM; SOMATIC CELLS; 550201* - Biochemistry- Tracer Techniques

Citation Formats

Cline, H T. GABA-ergic neurons in the leach central nervous system. United States: N. p., 1985. Web.
Cline, H T. GABA-ergic neurons in the leach central nervous system. United States.
Cline, H T. Tue . "GABA-ergic neurons in the leach central nervous system". United States.
@article{osti_5887200,
title = {GABA-ergic neurons in the leach central nervous system},
author = {Cline, H T},
abstractNote = {GABA is a candidate for an inhibitory neurotransmitter in the leech central nervous system because of the well-documented inhibitory action of GABA in other invertebrates. To demonstrate that GABA meets the criteria used to identify a substance as a neurotransmitter, the author examined GABA metabolism and synaptic interactions of inhibitory motor neurons in two leech species, Hirudo medicinalis and Haementeria ghilianii. Segmental ganglia of the leech ventral nerve cord and identified inhibitors have the capacity to synthesize GABA when incubated in the presence of the precursor glutamate. Application of GABA to cell bodies of excitatory motor neurons or muscle fibers innervated by the inhibitors hyperpolarizes the membrane potential of the target cell and activates a chloride ion conductance channel, similar to the inhibitory membrane response following intracellular stimulation of the inhibitor. Bicuculline methiodide (5 x 10/sup -5/M), GABA receptor antagonist, blocks reversibly the response to applied GABA and the inhibitory synaptic inputs onto the postsynaptic neurons or muscle fibers without interfering with their excitatory inputs. Furthermore, the inhibitors are included among approximately 25 neurons per segmental ganglion that take up GABA by a high affinity uptake system, as revealed by /sup 3/H-GABA-autoradiography. The development of the capacities to synthesize and to take up GABA were examined in leech embryos. The embryos are able to synthesize GABA at early stages of the development of the nervous system, before any neurons have extended neutrites.},
doi = {},
url = {https://www.osti.gov/biblio/5887200}, journal = {},
number = ,
volume = ,
place = {United States},
year = {1985},
month = {1}
}

Thesis/Dissertation:
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