A comparison of the effects of morphine, enkephalin, kyotorphin and D-phenylalanine on rat central neurones.
1 Morphine, Met-enkephalin, kyotorphin and D-phenylalanine have been applied by microiontophoresis to neurones in the globus pallidus and cerebral cortex of rats anaesthetized with urethane. 2 In the pallidum, most cells were inhibited by all the agonists, with a high correspondence between cells inhibited by Met-enkephalin and D-phenylalanine and by Met-enkephalin and kyotorphin. Whereas responses to Met-enkephalin were readily antagonized by naloxone, responses to kyotorphin and D-phenylalanine were not. 3 In the cerebral cortex a high proportion of cells was excited by all four agonists and antagonism by naloxone was less consistent than in pallidum. 4 It is concluded that the naloxone-reversible analgesic effects of kyotorphin and D-phenylalanine may be mediated indirectly, rather through an activation of opiate receptors.
D000818:Animals; D001921:Brain / Q000187:drug effects*; D002540:Cerebral Cortex / Q000187:drug effects; D004723:Endorphins / Q000494:pharmacology*; D004744:Enkephalin, Methionine / Q000494:pharmacology*; D005917:Globus Pallidus / Q000187:drug effects; D007478:Iontophoresis; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects*; D010649:Phenylalanine / Q000494:pharmacology*; D051381:Rats
D004723:Endorphins; C019448:kyotorphin; D009270:Naloxone; D010649:Phenylalanine; D004744:Enkephalin, Methionine; D009020:Morphine