Interaction of thiocolchicoside with [3H]strychnine binding sites in rat spinal cord and brainstem.
Radioreceptor binding assays and receptor autoradiography were used to investigate the activity of thiocolchicoside on strychnine-sensitive binding sites in rat brain and spinal cord using [3H]strychnine as a ligand. Thiocolchicoside displaced the binding of [3H]strychnine with an affinity similar to that of unlabeled glycine, and showed a Hill coefficient and proportionality parameter (P) less than unity. The activity of thiocolchicoside toward [3H]strychnine binding sites was confirmed in autoradiographic studies. The results suggest that thiocolchicoside behaves as an allosteric compound acting on the strychnine-sensitive glycine receptor in rat brainstem and spinal cord, and that this may provide a possible mechanism for the myorelaxant activity of this colchicoside derivative, the first clinically useful drug acting on this receptor.
Cimino
M
M
Institute of Pharmacology and Pharmacognosy, University of Urbino, Italy.
Marini
P
P
Cattabeni
F
F
D000818:Animals; D001345:Autoradiography; D001665:Binding Sites; D001933:Brain Stem / Q000187:drug effects / Q000378:metabolism*; D003078:Colchicine / Q000031:analogs & derivatives* / Q000494:pharmacology; D066298:In Vitro Techniques; D011869:Radioligand Assay; D051381:Rats; D018009:Receptors, Glycine / Q000378:metabolism; D013116:Spinal Cord / Q000187:drug effects / Q000378:metabolism*; D013331:Strychnine / Q000494:pharmacology*; D014316:Tritium
D018009:Receptors, Glycine; C027822:strychnine receptor; D014316:Tritium; D013331:Strychnine; D003078:Colchicine; C004280:thiocolchicoside