Quantitative analysis of substance P-immunoreactive boutons on physiologically characterized dorsal horn neurons in the cat lumbar spinal cord.
J Comp Neurol
; 376(1): 45-64, 1996 Dec 02.
Article
em En
| MEDLINE
| ID: mdl-8946283
ABSTRACT
A quantitative analysis of substance P (SP)-immunoreactive (IR) terminals contacting physiologically characterized dorsal horn neurons was performed. Three types of neuron were studied nociceptive specific (NS) from lamina I (n = 3), wide dynamic range (WDR) from laminae II-IV (n = 3), and nonnociceptive (NN) from lamina IV (n = 3). The nociceptive response of focus was a slow, prolonged depolarization to noxious stimuli, because this response was previously shown to be blocked by selective neurokinin-1 (NK-1) receptor antagonists. Ultrastructural immunocytochemistry was used to quantify the relative number of SP-IR boutons apposed to the intracellularly labeled cell per unit of length (density). Densities of the total population (SP immunoreactive+nonimmunoreactive) of apposed boutons were similar in all three regions (cell body, proximal and distal dendrites) for the three functional types of neuron. NS neurons received a significantly higher density of appositions from SP-IR boutons than NN cells in all three regions. However, compared to WDR cells, NS cells possessed a significantly higher density of appositions from SP-IR boutons only in the cell body and proximal dendrites. WDR cells had a higher density of appositions from SP-IR boutons than NN cells, but only in the proximal and distal dendrites. On average, 33.5% of the SP-IR boutons apposed to the cells displayed a synaptic contact. Finally, 30-45% of the SP-IR boutons apposed to the cells colocalized calcitonin gene-related protein (CGRP) immunoreactivity, indicating their primary sensory origin. The data indicate a direct correlation between the amount of SP-IR input and the nociceptive nature of the cells and suggest that SP acts on NK-1 receptors at a short distance from its release site.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Medula Espinal
/
Substância P
/
Neurônios
Limite:
Animals
Idioma:
En
Revista:
J Comp Neurol
Ano de publicação:
1996
Tipo de documento:
Article
País de afiliação:
Canadá