A. Appelgren et al., SUBSTANCE P-ASSOCIATED INCREASE OF INTRAARTICULAR TEMPERATURE AND PAIN THRESHOLD IN THE ARTHRITIC TMJ, Journal of orofacial pain, 12(2), 1998, pp. 101-107
Neuropeptides are considered mediators and modulators of inflammatory
joint disease. Substance P (SP) has been proposed as a mediator of pai
n, and Its vasoactive properties are well documented. In this study, t
he presence of SP-like immunoreactivity in the synovial fluid was corr
elated to intra-articular temperature (IAT) and pain from the arthriti
c temporomandibular joint (TMJ) 3 to 5 weeks after one intra-articular
injection of glucocorticosteroids. Eighteen TMJs were investigated fo
r IAT and the presence of SP-like immunoreactivity in the synovial flu
id in 12 patients with systemic inflammatory joint disease. After arth
rocentesis, the aspirates were analyzed for SP-like immunoreactivity b
y means of competitive radio immunoassay. A visual analogue scale and
an algometer determining the pressure pain threshold and tolerance lev
el assessed arthritic pain and hyperalgesia in the TMJ. Our results in
dicate that SP-like immunoreactivity is associated with IAT and that i
ncreased concentrations of joint fluid SP-like immunoreactivity corres
pond to increased pain threshold and tolerance and a concomitantly: de
creased visual analogue scale. These findings suggest that SP is impli
cated in the vascular and nonciceptive response of the arthritic joint
anti that SP, possibly assisted by the antinociceptive effect of loca
l corticosteroids, has a modulatory role in arthritic pain and hyperal
gesia.