AMPA and NMDA glutamate receptors are found in both peptidergic and non-peptidergic primary afferent neurons in the rat

• Published in: Cell and tissue research Vol. 334; no. 1; pp. 17 - 23
• Main Authors: Willcockson, Helen, Valtschanoff, Juli
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.10.2008; Springer Nature B.V
• Subjects: Animals; Biomedical and Life Sciences; Biomedicine; Cellular biology; Ganglia, Spinal - cytology; Ganglia, Spinal - metabolism; Human Genetics; Molecular Medicine; Neurology; Neurons, Afferent - cytology; Neurons, Afferent - metabolism; Pain management; Peptides; Proteomics; Rats; Rats, Sprague-Dawley; Receptors, AMPA - metabolism; Receptors, N-Methyl-D-Aspartate - metabolism; Receptors, Purinergic P2 - metabolism; Receptors, Purinergic P2X3; Regular Article; Rodents; Substance P - metabolism; Glutamate receptor; Rat (Sprague Dawley); Dorsal root ganglion; Substance P; P2X
• ISSN: 0302-766X; 1432-0878
• DOI: 10.1007/s00441-008-0662-0

Two distinct classes of nociceptive primary afferents, peptidergic and non-peptidergic, respond similarly to acute noxious stimulation; however the peptidergic afferents are more likely to play a role in inflammatory pain, while the non-peptidergic afferents may be more characteristically involved in neuropathic pain. Using multiple immunofluorescence, we determined the proportions of neurons in the rat L4 dorsal root ganglion (DRG) that co-express AMPA or NMDA glutamate receptors and markers for the peptidergic and non-peptidergic classes of primary afferents, substance P and P2X 3 , respectively. The fraction of DRG neurons immunostained for the NR1 subunit of the NMDA receptor (40%) was significantly higher than that of DRG neurons immunostained for the GluR2/3 (27%) or the GluR4 (34%) subunits of the AMPA receptor. Of all DRG neurons double-immunostained for glutamate receptor subunits and either marker for peptidergic and non-peptidergic afferents, a significantly larger proportion expressed GluR4 than GluR2/3 or NR1 and in a significantly larger proportion of P2X 3 - than SP-positive DRG neurons. These observations support the idea that nociceptors, involved primarily in the mediation of neuropathic pain, may be presynaptically modulated by GluR4-containing AMPA receptors.