The pituitary adenylate cyclase activating polypeptide type 1 receptor (PAC1-R) is expressed on gastric ECL cells: evidence by immunocytochemistry and RT-PCR.

The current study was undertaken to determine the presence and distribution of PAC1-Rs within the gastric mucosa. Polyclonal antibodies to the carboxyl terminus of the rat PAC1-R were generated and shown to be specific against the PAC1-R expressed in NIH 3T3 cells. Western blot analysis using isolated (approximately 85% pure) ECL cell membranes identified a 48 kD protein consistent with the calculated molecular mass of the cloned PAC1-R. RT/PCR performed using specific primers for the PAC1-R confirmed the presence of splice variants of the rat PAC1-R, but not VPAC1-R or VPAC2-R. These data provide the first direct evidence for the existence of functional PACAP Type I receptors on ECL cells of the gastric mucosa and suggest a potential role for PACAP in the stimulation of gastric acid secretion and in the regulation of the growth of ECL cells.