Micro‐iontophoretic studies on neurones in the cuneate nucleus
TLDR
Cuneate cells in anaesthetized cats were strongly excited by L‐glutamate, and somewhat less by D‐ glutamate; cells which receive afferents from hair receptors were particularly sensitive.Abstract:
1. Cuneate cells in anaesthetized cats were strongly excited by L-glutamate, and somewhat less by D-glutamate; cells which receive afferents from hair receptors were particularly sensitive.
2. Glutamate could be used to demonstrate post-synaptic inhibitory inputs from the dorsal column, the medial lemniscus and the frontal cortex.
3. Many cuneate cells were also strongly excited by adenosinetriphosphate (ATP); this was probably due to the chelating action of ATP, as citric acid was also quite effective.
4. γ-Aminobutyric acid (GABA) readily blocked all forms of spontaneous and evoked activity, except antidromic invasion of cuneothalamic neurones; cells which receive proprioceptive afferents were particularly sensitive to GABA. Glycine had a comparable effect.
5. Acetylcholine (ACh), catecholamines, histamine, 5-hydroxytryptamine (5-HT) and an extract containing substance P mostly had only weak depressant actions. Cholinergic and mono-aminergic mechanisms are probably not very significant in the cuneate.
6. These results are consistent with the possibility that glutamate and GABA (or glycine), or some closely related compounds, are the main excitatory and inhibitory transmitters in the cuneate nucleus.
7. If ATP is released from afferent nerve endings, it could also play a significant role in excitation.read more
Citations
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Amino acid transmitters in the mammalian central nervous system
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Cellular distribution and functions of P2 receptor subtypes in different systems.
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The role of adenosine and its nucleotides in central synaptic transmission.
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The physiological role of adenosine in the central nervous system.
TL;DR: This chapter's attention is directed to the actions of adenosine and related purines in the CNS, and the receptors and biochemical actions that underlie these functional responses and behavioral responses to purinergic drugs are considered.
References
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The action of calcium on the electrical properties of squid axons
B. Frankenhaeuser,A. L. Hodgkin +1 more
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An unidentified depressor substance in certain tissue extracts
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The excitation and depression of spinal neurones by structurally related amino acids.
David R. Curtis,J. C. Watkins +1 more
TL;DR: A survey of the activity of compounds structurally related to both series of amino acids finds that one of them or a related substance may have excitatory transmitter function within the nervous system.
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