RT Journal Article
SR Electronic
T1 Spinal Substance P Receptor Expression and Internalization in Acute, Short-Term, and Long-Term Inflammatory Pain States
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 7670
OP 7678
DO 10.1523/JNEUROSCI.19-17-07670.1999
VO 19
IS 17
A1 Prisca Honoré
A1 Patrick M. Menning
A1 Scott D. Rogers
A1 Michael L. Nichols
A1 Allan I. Basbaum
A1 Jean-Marie Besson
A1 Patrick W. Mantyh
YR 1999
UL http://www.jneurosci.org/content/19/17/7670.abstract
AB Inflammatory pain involves the sensitization of both primary afferent and spinal cord neurons. To explore the neurochemical changes that contribute to inflammatory pain, we have examined the expression and ligand-induced internalization of the substance P receptor (SPR) in the spinal cord in acute, short-term, and long-term inflammatory pain states. These inflammatory models included unilateral injection of formalin (8–60 min), carrageenan (3 hr), and complete Freund’s adjuvant (CFA; 3 d) into the rat hindpaw as well as adjuvant-induced polyarthritis (21 d). In acute inflammatory pain there is ongoing release of substance P (SP) as measured by SPR internalization in lamina I neurons at both 8 and 60 min after formalin injection. Although there is no tonic release of SP in short-term inflammatory pain, at 3 hr after carrageenan injection, SP is released in response to both noxious and non-noxious somatosensory stimulation with SPR internalization being observed in neurons located in both laminae I and III-IV. In long-term inflammatory pain models (CFA and polyarthritis) the same pattern of SP release and SPR activation occurs as is observed in short-term inflammation with the addition that there is a significant upregulation of the SPR in lamina I neurons. These results suggest that SPR internalization might serve as a marker of the contribution of ongoing primary afferent input in acute and persistent pain states. These stereotypical neurochemical changes suggest that there are unique neurochemical signatures for acute, short-term, and long-term inflammatory pain.