Binding characteristics of mu and kappa agonists in rat brain subcellular fractions.
Scatchard analysis of 3H-dihydromorphine (3H-DHM) binding to rat brain subcellular fractions gave a curvilinear plot in the microsomal (P3) and a linear plot in the mitochondrial (P2) fraction, respectively. In contrast, plots of 3H-ethylketocyclazocine (3H-EK) binding were linear in the P3 and curvilinear in the P2 fraction. No differences were seen in the potency of morphine and ketazocine in displacing either 3H-DHM or 3H-EK in the P2 fraction. In the P3 fraction, however, morphine was more potent than ketazocine in displacing 3H-DHM, but the reverse was true when 3H-EK was used as the ligand. Isolation of the P3 fraction may facilitate the demonstration of a kappa receptor in the rat brain.
D000701:Analgesics, Opioid / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D001921:Brain / Q000378:metabolism*; D003496:Cyclazocine / Q000031:analogs & derivatives* / Q000378:metabolism; D004090:Dihydromorphine / Q000378:metabolism*; D016314:Ethylketocyclazocine; D008297:Male; D009022:Morphine Derivatives / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000378:metabolism*; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu; D013347:Subcellular Fractions / Q000378:metabolism; D014316:Tritium
D000701:Analgesics, Opioid; D009022:Morphine Derivatives; D011957:Receptors, Opioid; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu; D014316:Tritium; D016314:Ethylketocyclazocine; D004090:Dihydromorphine; D003496:Cyclazocine