Localization of N-methyl-D-aspartate NR2B subunits on primary sensory neurons that give rise to small-caliber sciatic nerve fibers in rats.
In the present study we have used immunohistochemical staining and retrograde tracing techniques to investigate the relationship between the N-methyl-D-aspartate receptor NR2B subunits and small-diameter primary afferent dorsal root ganglion neurons that give rise to the sciatic nerve fibers. Three days after an intra-sciatic nerve injection of tetramethyl rhodamine isothiocyanate-conjugated wheat germ agglutinin which labels small-diameter primary afferents, many NR2B and wheat germ agglutinin-double-labeled cells ( approximately 70% of wheat germ agglutinin-labeled neurons) were observed in the L5 dorsal root ganglia. Three days after an intra-sciatic nerve injection of fluorescein isothiocyanate-conjugated Bandeiraea simplicifolia agglutinin isolectin B4 which labels predominantly non-peptidergic C-fiber primary afferents, NR2B and Bandeiraea simplicifolia agglutinin isolectin B4 double-labeled neurons ( approximately 90% of Bandeiraea simplicifolia agglutinin isolectin B4-labeled neurons) were also observed in the L5 dorsal root ganglion. Three days after an intra-sciatic nerve injection of fluorescein isothiocyanate-conjugated cholera toxin B subunit, only approximately 40% of cholera toxin B subunit-labeled neurons were NR2B positive and those labeled neurons tended to be small-sized. When calcitonin gene-related peptide and NR2B were labeled by a double immunofluorescent staining technique, we found that the majority of calcitonin gene-related peptide-positive neurons was NR2B immunoreactive (>90% of calcitonin gene-related peptide-positive neurons, and approximately 60% of NR2B-positive neurons) as well. Size frequency analysis also demonstrated that NR2B subunits were predominantly localized on the small and medium-sized neurons. These results suggest that NR2B subunits are predominantly expressed on small diameter primary afferents, and these NR2B containing N-methyl-D-aspartate receptors may play a role in the modulation of neurotransmitter release from primary afferent terminals.
Ma
Q P
QP
Department of Pharmacology, Merck Sharp & Dohme Research Laboratories, Neuroscience Research Centre, Terlings Park, CM20 2QR, Harlow, UK. qingping_ma@merck.com
Hargreaves
R J
RJ
D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism; D002452:Cell Count; D048429:Cell Size / Q000502:physiology; D002772:Cholera Toxin / Q000494:pharmacology; D016650:Fluorescein-5-isothiocyanate; D037102:Lectins; D009412:Nerve Fibers / Q000378:metabolism* / Q000648:ultrastructure; D009475:Neurons, Afferent / Q000378:metabolism* / Q000648:ultrastructure; D009619:Nociceptors / Q000378:metabolism / Q000648:ultrastructure; D010146:Pain / Q000378:metabolism*; D037121:Plant Lectins; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism*; D012584:Sciatic Nerve / Q000378:metabolism* / Q000648:ultrastructure; D014909:Wheat Germ Agglutinins
C045475:Griffonia simplicifolia lectins; D037102:Lectins; C121001:NR2B NMDA receptor; D037121:Plant Lectins; D016194:Receptors, N-Methyl-D-Aspartate; D014909:Wheat Germ Agglutinins; D002772:Cholera Toxin; D016650:Fluorescein-5-isothiocyanate; D015740:Calcitonin Gene-Related Peptide