MULTIPLE OPIATE RECEPTOR AFFINITIES OF KAPPA-ANALGESICS AND AGONIST ANTAGONIST ANALGESICS - INVIVO ASSESSMENT

  • 1 January 1983
    • journal article
    • research article
    • Vol. 226  (2) , 545-550
Abstract
The affinities of .kappa.- and agonist/antagonist (Ag/Ant) analgesics [dl-cyclazocine, l-cyclazocine, d-cyclazocine, l-butorphanol and d-butorphanol] for .mu. and .delta. opiate receptors were examined in vivo in the rat. In the case of .kappa.- agonists, these agents appear to be .mu. and .delta. antagonists in vivo. The .mu. antagonist activity appears to involve a specific isoreceptor population, namely .mu.-2 receptors. With Ag/Ant analgesics, a more complex pharmacology is evident such that at .mu. and .delta. receptor populations these agents can exhibit pure Ag, pure Ant or a combination of Ag and Ant actios. These activities vary with the neuronal localization of the receptor population being examined. Complex species differences are evident with Ag/Ant actions.