title: Ontogeny of benzomorphan-selective (kappa) sites: a computerized analysis.
abstract: In an investigation of the postnatal development of kappa opiate receptors, the affinity and capacity of 0.5 nM [3H]-ethylketocyclazocine (EKC) binding in crude rat brain homogenates was measured by displacement with unlabeled EKC, morphine, or D-ala2-D-leu5-enkephalin (DADL). Displacement curves were analyzed using a weighted, non-linear regression, curve fitting computer program. At all stages of development, [3H]-EKC binding fit a two site model significantly better than a one site model. Affinities of EKC, morphine, or DADL for the high affinity [3H]-EKC binding site did not change during the postnatal period. The density of the high affinity [3H]-EKC binding site increased linearly with age, whereas the levels of the low affinity site rose more rapidly during the second week.
mesh_terms: D000375:Aging; D000701:Analgesics, Opioid / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000254:growth & development* / Q000378:metabolism; D003496:Cyclazocine / Q000031:analogs & derivatives* / Q000378:metabolism; D016314:Ethylketocyclazocine; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000378:metabolism*; D017473:Receptors, Opioid, kappa
chemical_list: D000701:Analgesics, Opioid; D011957:Receptors, Opioid; D017473:Receptors, Opioid, kappa; D016314:Ethylketocyclazocine; D003496:Cyclazocine