T. Pelissier et al., Antinociceptive effect of clomipramine in monoarthritic rats as revealed by the paw pressure test and the C-fiber-evoked reflex, EUR J PHARM, 416(1-2), 2001, pp. 51-57
The antinociceptive effect of clomipramine was studied in monoarthritic rat
s by using the paw pressure test and the C-fiber-evoked reflex. Monoarthrit
is was produced by intra-articular injection of complete Freund's adjuvant
into the tibio-tarsal joint. Joint circumference as well as vocalization th
reshold to graded paw pressure were evaluated weekly during a 14-week perio
d after the intra-articular injection. At week 8, monoarthritic and vehicle
-injected control rats were given either clomipramine or saline and both th
e paw pressure threshold and inhibition of the C-fiber-evoked reflex respon
se were evaluated. Results showed that (i) 1.5, 3.0, and 6.0 mg/kg, i.v. of
clomipramine induced significantly greater dose-dependent antinociception
to paw pressure testing in the monoarthritic group, as compared to the cont
rol one; and (ii) 0.75, 1.5, 3.0, and 6.0 mg/kg, i.v. of clomipramine exert
ed significantly higher dose-dependent inhibition of the C-reflex activity
in monoarthritic rats than in controls. Results suggest that the higher sen
sitivity to clomipramine in monoarthritic rats could be related to adaptive
changes occurring in monoamine metabolism or in other neurotransmitter sys
tems during chronic pain. (C) 2001 Published by Elsevier Science B.V.