Characterisation of kappa-opioid binding sites in rat and guinea-pig spinal cord.
The binding of radiolabelled ligands with high affinity for kappa-opioid binding sites has been studied in homogenates of lumbo-sacral spinal cord from the rat. The unselective ligands [3H]bremazocine and [3H]diprenorphine labelled a large number of sites which could not be fully resolved in terms of mu-, delta- and kappa-types by displacement assays. In particular binding at the kappa-site appeared anomalous in that sites which could be identified as high affinity kappa-type represented only 40% of total kappa-binding, defined using the unselective [3H]ligands. This was confirmed by the low levels of binding seen with the kappa-agonists [3H]dynorphin A(1-9) and [3H]U-69593. In guinea-pig cord, under conditions in which binding to mu- and delta-sites was suppressed, [3H]dynorphin A(1-9) and [3H]U-69593 labelled only 60% of the kappa population, defined by the [3H]unselective ligands. The reasons for the observed discrepancies are discussed.
Wood
M S
MS
Department of Chemistry, University of Technology, Loughborough, Leics, U.K.
Rodriguez
F D
FD
Traynor
J R
JR
D000818:Animals; D044482:Benzeneacetamides; D001575:Benzomorphans / Q000378:metabolism; D002216:Captopril / Q000494:pharmacology; D004174:Diprenorphine / Q000378:metabolism; D004399:Dynorphins / Q000378:metabolism; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007930:Leucine / Q000494:pharmacology / Q000031:analogs & derivatives; D008024:Ligands; D008297:Male; D010446:Peptide Fragments / Q000378:metabolism; D011759:Pyrrolidines / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000378:metabolism*; D017473:Receptors, Opioid, kappa; D013116:Spinal Cord / Q000378:metabolism*
D044482:Benzeneacetamides; D001575:Benzomorphans; D008024:Ligands; D010446:Peptide Fragments; D011759:Pyrrolidines; D011957:Receptors, Opioid; D017473:Receptors, Opioid, kappa; D004174:Diprenorphine; D004399:Dynorphins; C040238:dynorphin A (1-9); D002216:Captopril; D007930:Leucine; C012211:ubenimex; C027248:bremazocine; C045444:U 69593