TY - JOUR
T1 - Electrophysiological properties of neurones with CGRP-like immunoreactivity in rat dorsal root ganglia
AU - Lawson, S. N.
AU - Mccarthy, P. W.
AU - Prabhakar, E.
PY - 1996/2/12
Y1 - 1996/2/12
N2 - Intracellular voltage recordings and fluorescent dye injections were made in vitro in 107 neurons in lumbar dorsal root ganglia (DRGs) of 6- to 8- week-old rats. Calcitonin gene-related, peptide-like immunoreactivity (CGRP- LI) was examined in these neurones, which were divided into C-, Aδ-, and Aα/β-fibre neurones on the basis of their conduction velocities (CVs). A- fibre neurones with CGRP-LI had significantly longer mean action potential (AP) and afterhyperpolarisation (AHP) durations than those without CGRP-LI. Aδ neurones with CGRP-LI had significantly longer AHP durations, slower CVs, and slower maximal fibre following frequencies than those without CGRP-LI. They also had longer AP durations (not significant). The largest Aδ neurones were CGRP-LI negative, whereas the smaller cells were either positive or negative. Aα/β neurones with CGRP-LI also had longer mean APs (not significant) and AHPs (significant) than those without CGRP-LI, and the cell size distributions were similar for positive and negative neurones. Most A- fibre neurones with CGRP-LI had inflections on the falling phase of the somatic AP. Of the A-fibre neurones with such inflections (A(i) neurones), those with CGRP-LI had longer AP durations (not significant) and longer AHP durations (significant) than A(i) neurones without CGRP-LI, pointing to a functionally distinct subgroup of A(i) neurones. There were no significant differences in electrophysiological properties or cell size measurements between C-fibre neurones with and without detectable CGRP-LI. The patterns of electrophysiological properties of Aδ neuronal somata with CGRP-LI and of most, but not all, Aα/β neuronal somata with CGRP-LI are similar to those reported for cutaneous nociceptors with A fibres in rat (Ritter and Mendell [1992] J. Neurophysiol. 68:2033-2041). Because rat DRG neurones that express CGRP normally also express trkA (Averill et al. [1995] Eur. J. Neurosci. 7:1484-1494), the properties described here of neurones with CGRP-LI are probably the same as those of DRG neurones with trkA.
AB - Intracellular voltage recordings and fluorescent dye injections were made in vitro in 107 neurons in lumbar dorsal root ganglia (DRGs) of 6- to 8- week-old rats. Calcitonin gene-related, peptide-like immunoreactivity (CGRP- LI) was examined in these neurones, which were divided into C-, Aδ-, and Aα/β-fibre neurones on the basis of their conduction velocities (CVs). A- fibre neurones with CGRP-LI had significantly longer mean action potential (AP) and afterhyperpolarisation (AHP) durations than those without CGRP-LI. Aδ neurones with CGRP-LI had significantly longer AHP durations, slower CVs, and slower maximal fibre following frequencies than those without CGRP-LI. They also had longer AP durations (not significant). The largest Aδ neurones were CGRP-LI negative, whereas the smaller cells were either positive or negative. Aα/β neurones with CGRP-LI also had longer mean APs (not significant) and AHPs (significant) than those without CGRP-LI, and the cell size distributions were similar for positive and negative neurones. Most A- fibre neurones with CGRP-LI had inflections on the falling phase of the somatic AP. Of the A-fibre neurones with such inflections (A(i) neurones), those with CGRP-LI had longer AP durations (not significant) and longer AHP durations (significant) than A(i) neurones without CGRP-LI, pointing to a functionally distinct subgroup of A(i) neurones. There were no significant differences in electrophysiological properties or cell size measurements between C-fibre neurones with and without detectable CGRP-LI. The patterns of electrophysiological properties of Aδ neuronal somata with CGRP-LI and of most, but not all, Aα/β neuronal somata with CGRP-LI are similar to those reported for cutaneous nociceptors with A fibres in rat (Ritter and Mendell [1992] J. Neurophysiol. 68:2033-2041). Because rat DRG neurones that express CGRP normally also express trkA (Averill et al. [1995] Eur. J. Neurosci. 7:1484-1494), the properties described here of neurones with CGRP-LI are probably the same as those of DRG neurones with trkA.
KW - calcitonin gone-related peptide
KW - CGRP intracellular recording
KW - conduction velocity
KW - electrophysiology
KW - sensory neurone
KW - trkA
U2 - 10.1002/(SICI)1096-9861(19960212)365:3<355::AID-CNE2>3.0.CO;2-3
DO - 10.1002/(SICI)1096-9861(19960212)365:3<355::AID-CNE2>3.0.CO;2-3
M3 - Article
C2 - 8822175
AN - SCOPUS:0030064620
SN - 0021-9967
VL - 365
SP - 355
EP - 366
JO - Journal of Comparative Neurology
JF - Journal of Comparative Neurology
IS - 3
ER -