Abstract.
Objective: The interactions of α-adrenoceptors with the antinociceptive effects of non-steroidal anti-inflammatory drugs (NSAIDs) were assessed in acute thermal nociception in mice.¶Materials and methods: The analgesic effect was analyzed by the tail-flick test.¶Results: The pretreatment with yohimbine (1 mg/kg i.p.), 30 min prior to the intraperitoneal injection of ketoprofen (50 mg/kg), diclofenac (30 mg/kg) and piroxicam (50 mg/kg) antagonized the antinociception induced by these NSAIDs, significantly reducing the tail-flick latency. Yohimbine did not affect paracetamol (125 mg/kg) induced antinociception. Prazosin (1 mg/kg i.p.) antagonized only the effect of paracetamol, without affecting the latency of the other drugs. When NSAIDs were administered i.t. (ketoprofen 2 m/kg; diclofenac 0.9 mg/kg; piroxicam 1.5 mg/kg; paracetamol 3.75 mg/kg), the same results were obtained after i.p. pretreatment with yohimbine and prazosin. The pretreatment of phenoxybenzamine (1 mg/kg i.p.) antagonized all antinociceptive effects.¶Conclusions: NSAIDs induced antinociception in an acute thermal pain model without inflammation. The mechanism of antinociception induced by ketoprofen, diclofenac and piroxicam involves an activation of α2-adrenoceptors at spinal and supraspinal levels, while paracetamol-induced antinociception is probably due mainly to central activation of the descending noradrenergic inhibitory system by α1-adrenoceptors.
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Received 11 September 2001; returned for revision 4 December 2001; accepted by G. Geisslinger 17 January 2002
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Pinardi, G., Sierralta, F. & Miranda, H. Adrenergic mechanisms in antinociceptive effects of non steroidal anti-inflammatory drugs in acute thermal nociception in mice. Inflamm. res. 51, 219–222 (2002). https://doi.org/10.1007/PL00000296
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DOI: https://doi.org/10.1007/PL00000296