Expression and cell-specific localization of the cholecystokinin B/gastrinreceptor in the human stomach

Gastrin stimulates gastric acid secretion by acting on the cholecystokinin B/gastrin receptor (CCK-BR). The localization of this receptor at the cellu lar level showed conflicting results in animal studies and has not been des cribed in man by immunohistochemistry. The aim of the present study is to c haracterize the precise cellular location of the CCK-BR in the human stomac h. Polyclonal antisera were raised against different epitopes of the CCK-BR molecule and used for immunohistochemical investigations. CCK-BR mRNA was detected in paraffin tissue sections by the highly sensitive method of in s itu reverse transcriptase-polymerase chain reaction (RT-PCR). Using immunoh istochemistry, CCK-BR could successfully be localized in gastric parietal c ells. In the majority of parietal cells, CCK-BR immunoreactivity was presen t at the basolateral cell membrane domain. In some parietal cells, a granul ar pattern of immunoreactivity was exclusively confined to the cytoplasm of the cells. CCK-BR mRNA was found in parietal cells and in enterochromaffin -like (ECL) cells by means of in situ RT-PCR. No expression of CCK-BR was f ound in the gastric antral mucosa. Our data support the concept that gastri n stimulates gastric acid secretion directly via CCK-B receptors on parieta l cells and indirectly by inducing histamine release from histamine-contain ing ECL cells, which contributes to acid secretion by parietal cells.