title: N-terminal cyclization of a nonsulfated CCK analogue exhibits opioid antagonist activity in vitro.
mesh_terms: D000818:Animals; D002766:Cholecystokinin / Q000031:analogs & derivatives* / Q000494:pharmacology; D003500:Cyclization; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D009292:Narcotic Antagonists; D010456:Peptides, Cyclic / Q000494:pharmacology*
chemical_list: D009292:Narcotic Antagonists; D010456:Peptides, Cyclic; C053617:cyclo(cysteinyl-tyrosyl-norleucyl-glycyl-tryptophyl-cysteinyl)-aspartyl-phenylalaninamide; D002766:Cholecystokinin