AUTORADIOGRAPHIC DISTRIBUTION OF BOMBESIN GASTRIN-RELEASING PEPTIDE RECEPTORS IN FETAL CORTEX TRANSPLANTS/

Bombesin/gastrin-releasing peptide (BB/GRP) receptors were characteriz ed in fetal cortex transplants in the rat. Using in vitro autoradiogra phy techniques, the density of (I-125-Tyr(4))BB grains was low 2 weeks after transplantation but increased 4 weeks after cortex transplantat ion into the adult rat fourth ventricle. Densitometry analysis of the autoradiograms indicated that (I-125-Tyr(4))BB bound with high affinit y (K-d = 5 nM) to a single class of sites in the transplant tissue. Sp ecific (I-125-Tyr(4))BB binding was inhibited with high affinity by (T yr(4))BB but not by NMB (IC50 values of 3 and 100 nM, respectively). T hese data suggest that GRP may act as a novel growth factor and play a regulatory role in the development of fetal cortex transplants. (C) 1 996 Academic Press, Inc.