Attenuation of tolerance to opioid-induced antinociception and protection against morphine-induced decrease of neurofilament proteins by idazoxan and other I_2-imidazoline ligands

摘要

Agmatie, the proposed endogenous ligand for imidazoline receptors, has been shown to attenuate tolerance to morphine-induced antinociception(Kolesnikov et al., 1996). The main aim of this study was to assess if idazoxan, an α_2-adrenoceptor antagonist that also interacts with imidazoline receptors, could also modulate opioid tolerance in rats and to establish which type of imidazoline receptors (or other receptors) are involved. Antinociceptive responses to opioid drugs were determined by the tail-flick test. The acute Administration of morphine(10 mg kg~-1, i.p., 30 min) or pentazocine (10 mg kg~-1), i.p., 30 min) resulted In marked increases in tail-flick latencies (TFLs).