Neuronal responses to amino acid iontophoresis in the deafferented spinal trigeminal nucleus
| Autor: | James B. Macon |
|---|---|
| Rok vydání: | 1978 |
| Předmět: |
Denervation
education.field_of_study Neurotransmitter Agents Chemistry Population Spinal trigeminal nucleus Iontophoresis medicine.disease Inhibitory postsynaptic potential medicine.anatomical_structure Developmental Neuroscience Neurology Spinal Cord Trigeminal neuralgia medicine Excitatory postsynaptic potential Cats Anesthesia dolorosa Animals Neurons Afferent Trigeminal Nerve Amino Acids education Nucleus Neuroscience |
| Zdroj: | Experimental neurology. 60(3) |
| ISSN: | 0014-4886 |
| Popis: | Facial paresthesias or anesthesia dolorosa occurring after retrogasserian trigeminal rhizotomy for trigeminal neuralgia have been attributed to neuronal hyperactivity in the deafferented spinal trigeminal complex. To gain insight into the mechanism of the deafferentation hyperactivity, the responses of spinal trigeminal neurons to amino acid iontophoresis via multibarrel micropipets were studied in 20 cats 2 to 4 weeks after unilateral retrogasserian trigeminal rhizotomy. A population of spontaneously hyperactive neurons (type 2) had markedly decreased sensitivity to the exogenous amino acid transmitters. Amino acid hyposensitivity was nonspecific for both excitatory and inhibitory agents, except in a small subgroup (type 2B) which was selectively hyposensitive to γ-aminobutyric acid. Some type 2 neurons were identified as trigeminothalamic projection neurons. Silent (type 1) neurons had normal responses to amino acids compared to those of controls. Endogenous corticofugal inhibition remained intact for all neuronal groups in the deafferented nucleus. The data do not support Cannon's law of denervation hypersensitivity as the mechanism of postrhizotomy hyperactivity, but seem more consistent with transneuronal atrophy in the deafferented spinal trigeminal nucleus. |
| Databáze: | OpenAIRE |
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