|
pubmed:abstractText |
The expression of the messenger RNAs coding for glucagon-like peptide-I (GLP-I) receptor, VIP receptor, and pituitary adenylate cyclase-activating polypeptide (PACAP) receptor as well as the expression of the receptor proteins were demonstrated in the rat medullary carcinoma of thyroid cell line 6/23 by the following experiments: 1) RNA extraction, reverse transcriptase, and polymerase chain reaction with specific primers; 2) binding of the radiolabeled ligands [125I]GLP-I-(7-36)-NH2, [125I]PACAP-(1-27), and [125I]VIP and inhibition by, respectively, unlabeled GLP-I-(7-36)-NH2, PACAP-(1-27), and VIP; and 3) study of adenylate cyclase activation by the peptides and selective inhibition of the VIP/PACAP response by the antagonist [D-Phe2]VIP. Besides the highly selective GLP-I receptor, PACAP receptors of types I and II were present on the cell line and coupled to adenylate cyclase. PACAP stimulated the adenylate cyclase through type I and II receptors, whereas VIP interacted with type II receptors only. Messenger RNA analysis indicated that at least three splice variants of the PACAP type I receptor may be expressed in 6/23 cells.
|
