Antagonist effects of β-funaltrexamine and naloxonazine on alfentanil-induced antinociception and muscle rigidity in the rat Journal Article


Authors: Negus, S. S.; Pasternak, G. W.; Koob, G. F.; Weinger, M. B.
Article Title: Antagonist effects of β-funaltrexamine and naloxonazine on alfentanil-induced antinociception and muscle rigidity in the rat
Abstract: Alfentanil is a potent and short-acting mu opioid agonist that produces both antinociceptive effects and muscle rigidity. In the present study, the susceptibility of alfentanil-induced antinociception and rigidity to antagonism by the selective mu antagonist beta-funaltrexamine and the selective mu-1 antagonist naloxonazine was examined. Alfentanil (37.7-150.0 mug/kg) produced a dose-dependent increase both in antinociception as measured by the warm-water tail-dip assay and in rigidity as measured by electromyographic recording of the gastrocnemius muscle. Both beta-funaltrexamine (10.0 and 20.0 mg/kg) and naloxonazine (7.5 and 15.0 mg/kg) produced dose-dependent and parallel rightward shifts in the alfentanil dose-effect curves for both antinociception and rigidity. Furthermore. the alfentanil dose-effect curves for antinociception and rigidity were shifted to the right to a similar degree by any given pretreatment. These results suggest that alfentanil-induced antinociception in the warm-water tail-dip test and rigidity are mediated by pharmacologically similar populations of opioid receptors. More specifically, these results suggest that mu-1 opioid receptors mediate both alfentanil-induced antinociception and rigidity.
Keywords: morphine; analgesia; spinal-cord; involvement; agonists; opioid binding-sites; postural support mechanisms; mu-opiate receptors; brain membranes; haloperidol catalepsy
Journal Title: Journal of Pharmacology and Experimental Therapeutics
Volume: 264
Issue: 2
ISSN: 0022-3565
Publisher: American Society for Pharmacology and Experimental Therapeutics  
Date Published: 1993-02-01
Start Page: 739
End Page: 745
Language: English
ACCESSION: WOS:A1993KM43200031
PROVIDER: wos
PUBMED: 8437122
Notes: Article -- Source: Wos
Citation Impact
MSK Authors
  1. Gavril W Pasternak
    414 Pasternak