title: Characterisation of CCKB receptors on GH3 pituitary cells: receptor activation is linked to Ca2+ mobilisation.
abstract: Cholecystokinin receptors on GH3 rat anterior pituitary cells have been characterised using radioligand binding and Ca2+ mobilisation. [125I]Bolton Hunter CCK-8s (BHCCK) bound dose dependently to GH3 cells (Kd 85 pM, Bmax 23 fmol/mg protein). Competition curves with CCK-8s (IC50 2.4 nM), pentagastrin (IC50 25 nM) and devazepide (IC50 820 nM), were consistent with a population predominantly of CCKB receptors. Binding of [125I]BHCCK to lysed cells was inhibited by 10 microM GTP-gamma-S and 10 microM GppNHp, suggesting the receptor was linked to a guanine nucleotide binding protein. Intracellular Ca2+ mobilisation was a functional consequence of CCKB receptor activation in GH3 cells using the fluorescent dye fura-2. CCK-8s (0.1 nM-1 microM) and the selective CCKB receptor agonist, pentagastrin, (0.1 nM-100 microM) dose dependently increased intracellular Ca2+ with a similar maximal increase of 2.85-fold and 2.77-fold respectively. Response to a submaximal dose of the CCKB receptor agonist pentagastrin (100 nM) was dose dependently blocked by the CCKB receptor antagonist L-365,260. GH3 cells may therefore provide a useful model to study CCKB receptor coupling in a pituitary cell line.
authors.affiliation: Merck, Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Harlow, Essex, UK.
authors.forename: A J
authors.initials: AJ
authors.lastname: Smith
authors.forename: S
authors.initials: S
authors.lastname: Patel
authors.forename: S B
authors.initials: SB
authors.lastname: Freedman
mesh_terms: D000818:Animals; D001570:Benzodiazepinones / Q000494:pharmacology; D001711:Biotransformation / Q000502:physiology; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D020109:Devazepide; D006150:Guanine Nucleotides / Q000378:metabolism; D007457:Iodine Radioisotopes; D007700:Kinetics; D010179:Pancreas / Q000187:drug effects / Q000378:metabolism; D010418:Pentagastrin / Q000494:pharmacology; D010671:Phenylurea Compounds; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D011869:Radioligand Assay; D051381:Rats; D011949:Receptors, Cholecystokinin / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism*; D015290:Second Messenger Systems / Q000187:drug effects; D012844:Sincalide / Q000031:analogs & derivatives; D013388:Succinimides
chemical_list: D001570:Benzodiazepinones; C044758:Bolton Hunter-cholecystokinin octapeptide; D006150:Guanine Nucleotides; D007457:Iodine Radioisotopes; D010671:Phenylurea Compounds; D011949:Receptors, Cholecystokinin; D013388:Succinimides; C058121:L 365260; D010418:Pentagastrin; D020109:Devazepide; D012844:Sincalide; D002118:Calcium