1,3-Di-o-tolylguanidine (DTG) differentially affects acute and tonic formalin pain: antagonism by rimcazole.
The role of the sigma receptor in prolonged pain was examined by assessing the effects of 1,3,di-o-tolylguanidine (DTG), a selective sigma receptor ligand, on the formalin test in mice. Formalin injected subcutaneously into the hindpaw produces a biphasic pain response: an acute phase of short duration followed by a longer-lasting tonic phase. DTG (10 mg/kg, i.p.) potently reduced pain behavior in the acute phase but increased pain behavior in the tonic phase. Rimcazole (5 and 10 mg/kg, i.p.), a selective sigma receptor antagonist, blocked both the DTG-induced decrease and increase in pain behavior observed in the acute and tonic phases, respectively. These data support previous findings indicating a modulatory role for the sigma receptor in nociceptive processes, and suggest that this receptor differentially modulates acute vs. tonic pain.
Kest
B
B
Department of Psychiatry and Biobehavioral Sciences, Neuropsychiatric Institute, UCLA 90024, USA.
Mogil
J S
JS
Sternberg
W F
WF
Pechnick
R N
RN
Liebeskind
J C
JC
D000818:Animals; D002227:Carbazoles / Q000494:pharmacology*; D005557:Formaldehyde; D006146:Guanidines / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D008297:Male; D051379:Mice; D010147:Pain Measurement / Q000187:drug effects*; D017480:Receptors, sigma / Q000037:antagonists & inhibitors
D002227:Carbazoles; D006146:Guanidines; D017480:Receptors, sigma; D005557:Formaldehyde; C034931:rimcazole; C050232:1,3-ditolylguanidine