R. Kaufmann et al., TYPE-B CHOLECYSTOKININ RECEPTORS ON RAT GLIOMA C-6 CELLS - BINDING-STUDIES AND MEASUREMENT OF INTRACELLULAR CALCIUM MOBILIZATION, Brain research, 639(1), 1994, pp. 109-114
To our knowledge, no brain derived cell line has been shown as yet to
bear cholecystokinin(CCK)(B) receptors. In this paper, CCK binding sit
es were identified on rat C-6 glioma cells. Pharmacological characteri
zation demonstrated a single class of high affinity binding sites (K-d
= 1.7 +/- 0.3 x 10(-10) M) and a binding capacity of 6.1 +/- 1.8 fmol
/ mg protein. These CCK binding sites displayed a typical CCKB pharmac
ological profil as shown in competition studies by using several CCK-r
elated compounds and nonpeptide CCK antagonists discriminating between
CCKA and CCKB sites. In order to demonstrate that CCK binding sites c
onstitute a functional receptor CCK-8S induced mobilization of free in
tracellular calcium was investigated in single C-6 cells by using a la
ser scanning confocal imaging system. Since rise in [Ca2+](i) noted by
stimulation of C-6 cells with CCK-8S could be blocked by the CCKB rec
eptor antagonist L-365,260 (100 nM) but not by the CCKA receptor antag
onist L-364,718 (100 nM), CCK induced calcium signal is triggered by a
ctivation of CCKB receptors in C-6 cells. The rat C-6 glioma cell line
may serve as a useful model for studying CCKB receptor in brain.