Muscarinic M2-receptors in rat thoracic dorsal root ganglia.
The occurrence and distribution of the muscarinic M2-receptor subtype (M2R) was investigated in rat thoracic dorsal root ganglia (DRG). Messenger RNA for M2R was demonstrated by RT-PCR in total RNA from DRG. Immunoreactivity to M2R-protein was localized to 26% of sensory neurons, the majority of them (85%) belonging to the size class of 25-40 microm in diameter. Double-labeling (immuno)histochemistry revealed that all M2R-immunoreactive neurons bind the lectin, I-B4, whereas they are generally devoid of substance P-immunoreactivity. These data show the presence of M2R on a subpopulation of presumably nociceptive primary afferent neurons, thereby extending previous pharmacological and electrophysiological studies that indicated a role of M2R and/or M4R in inhibition of calcium channel currents in rat sensory neurons (Wanke, E., Bianchi, L., Mantegazza, M., Guatteo, E., Macinelli, E. and Ferroni, A., Muscarinic regulation of Ca2+ currents in rat sensory neurons: channel and receptor types, dose-response relationships and cross-talk pathways. Eur. J. Neurosci., 6 (1994) 381-391).
Haberberger
R
R
Institute for Anatomy and Cell Biology, Justus-Liebig-University, Giessen, Germany. rainer.v.haberberger@anatomie.med.uni-giessen.de
Henrich
M
M
Couraud
J Y
JY
Kummer
W
W
D000818:Animals; D005727:Ganglia, Spinal / Q000737:chemistry* / Q000166:cytology; D007150:Immunohistochemistry; D008297:Male; D009474:Neurons / Q000737:chemistry; D051381:Rats; D017208:Rats, Wistar; D011976:Receptors, Muscarinic / Q000032:analysis*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013909:Thorax / Q000294:innervation*
D011976:Receptors, Muscarinic