Cell-specific localization of the cholecystokininA receptor in the porcine pancreas.
Cholecystokinin (CCK) produced in the mucosa of the upper small intestine exerts several biological functions. Its secretion in physiological amounts is modulated by the interaction of extracellular regulators and by binding to intracellular receptors of the target cells. The relative affinity of CCK to its receptor has been characterized in various biological and pharmacological studies and it is now well established that CCK has a higher affinity to the CCKA than to the CCKB receptor. Furthermore CCK influences the secretion of pancreatic enzymes in several species but very little is known about the relationship between CCK and the islet hormone-producing cells in the pig pancreas. The localization of this receptor at the cellular level showed conflicting results in animal studies and has not been described in pigs. The aim of the present study was to characterize the precise cellular location of the CCKA receptor in the porcine pancreas. Polyclonal antiserum was raised against the N-terminal epitope of the CCKA receptor molecule and used for localization studies. Using immunohistochemistry on methanol/acetic acid-fixed, paraffin-embedded pancreas, the CCKA receptor could successfully be localized in islet cells. Parallel staining of serial sections with antibodies directed against insulin and glucagon revealed colocalization with glucagon in alpha cells. No immunoreaction was found in the exocrine pancreas. Our results support the concept that in the porcine species the stimulation of the exocrine pancreas is mediated by the CCKB rather than the CCKA receptor, as it is known for the rat species.
Schweiger
M
M
Institute of Anatomy and Physiology, University of Hohenheim, Fruwirthstr. 35, D-70599 Stuttgart, Germany.
Erhard
M H
MH
Amselgruber
W M
WM
D000818:Animals; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000378:metabolism; D007515:Islets of Langerhans / Q000033:anatomy & histology* / Q000502:physiology; D010179:Pancreas / Q000033:anatomy & histology* / Q000378:metabolism; D043886:Receptor, Cholecystokinin A; D011949:Receptors, Cholecystokinin / Q000302:isolation & purification* / Q000502:physiology; D013194:Staining and Labeling; D013552:Swine
D043886:Receptor, Cholecystokinin A; D011949:Receptors, Cholecystokinin