US EPA

1513357 

Journal Article 

Ruthenium red and capsazepine antinociceptive effect in formalin and capsaicin models of pain in mice 

Santos, ARS; Calixto, JB 

1997 

1 

Neuroscience Letters
ISSN: 0304-3940
EISSN: 1872-7972 

235 

1-2 

73-76 

English 

9389599 

10.1016/s0304-3940(97)00722-2 

WOS:A1997YE13300019 

http://linkinghub.elsevier.com/retrieve/pii/S0304394097007222
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This study investigates the antinociception caused by
intradermal (i.d) or intracerebroventricular (i.c.v.) injection of the capsaicin receptor
antagonist capsazepine (CPZ), and ruthenium red (RR) (a cation-selective antagonist coupled to
vanilloid receptor of capsaicin), on the chemical nociception caused by i.d. injection of
formalin (FM) and capsaicin (CAP) into the mouse paw. The i.d. injection of either CPZ or RR in
association with FM or CAP, inhibited the early phase, and to a lesser extent the late phase, of
the FM, as well as CAP-induced nociception. Given i.c.v., both CPZ and RR caused discrete
antinociception in the FM (both phases), while producing graded inhibition of CAP. The actions of
CPZ and RR were insensitive to i.p. injection of naloxone (5 mg/kg). These results indicate that
i.d. injection of CPZ and RR produce marked antinociception in chemical models of neurogenic pain
induced by CAP and FM in mice. However, administered by supraspinal site, both CPZ and RR were
inactive in inhibiting FM, but prevented, in a graded manner, CAP-induced algesic response,
suggesting the participation of distinct mechanisms in the nociception induced by FM and CAP.
Thus, vanilloid selective antagonists seem to be useful tools for investigating the nociception
elicited by CAP and FM. (C) 1997 Elsevier Science Ireland Ltd. 

capsazepine; ruthenium red; formalin and capsaicin test; neurogenic pain; vanilloid receptor; naloxone; mice