Pharmacological characterisation of two tachykinin binding sites in the rat cerebral cortex.
The pharmacological properties of two types of tachykinin receptor were characterised on rat cortical synaptosomes using 125I-Bolton Hunter substance P (125I-BHSP) or with 125I-Bolton Hunter eledoisin (125I-BHE). Shorter SP C-terminal fragments, such as SP (6-11) or (pGlu)-SP (6-11), were more potent than SP itself or longer SP C-terminal fragments in competing for 125I-BHE binding; their efficacy was comparable to that of eledoisin. In contrast, longer SP C-terminal fragments exhibited a higher affinity than shorter ones for the 125I-BHSP binding sites as previously reported. SP N-terminal fragments were devoid of activity on either type of binding sites. SP methyl ester inhibited 125I-BHSP binding but was without effect on 125I-BHE binding whilst, DiMe-C7, a metabolically stable tachykinin analog, had the opposite selectivity. Eledoisin related peptide (ERP) was less effective than either SP or eledoisin on 125I-BHSP and 125I-BHE binding sites respectively. Finally, the undecapeptide or octapeptide SP antagonists, which are weak inhibitors of 125I-BHSP binding, had negligable activity on 125I-BHE binding sites.
Torrens
Y
Y
Beaujouan
J C
JC
Glowinski
J
J
D000818:Animals; D001665:Binding Sites; D002540:Cerebral Cortex / Q000378:metabolism*; D004600:Eledoisin / Q000031:analogs & derivatives / Q000494:pharmacology; D066298:In Vitro Techniques; D007457:Iodine Radioisotopes; D008297:Male; D009419:Nerve Tissue Proteins / Q000494:pharmacology; D015288:Neurokinin A; D051381:Rats; D011919:Rats, Inbred Strains; D017981:Receptors, Neurotransmitter / Q000378:metabolism*; D018039:Receptors, Tachykinin; D013373:Substance P / Q000494:pharmacology; D013388:Succinimides; D013574:Synaptosomes / Q000378:metabolism
D007457:Iodine Radioisotopes; D009419:Nerve Tissue Proteins; D017981:Receptors, Neurotransmitter; D018039:Receptors, Tachykinin; D013388:Succinimides; D013373:Substance P; C022581:Bolton-Hunter reagent; D004600:Eledoisin; D015288:Neurokinin A