Immunoreactive gastrin (IRG) and cholecystokinin (IRCCK) in chickens before and after bombesin (BBS)

This study was conducted in chickens to measure IRG and IRCCK in gut and brain tissues and in plasma before and after stimulation with BBS. After 24 h fast, six chickens were sacrificed and regions of the GI tract, liver, pancreas, and brain were collected, extracted in boiling water or 0.5M acetic acid. Five chickens were infused IV with saline for 30 min. and then with 3 μg/Kg-hr of BBs for 1 h. Levels of IRG and IRCCK were measured by radioimmunoassays. IRG was 6 pmol/g in the ileum, 3.5 pmol/g in the gizzard and was less in other regions of the GI tract. IRG was 12 pmol/g in cortex, 8 pmol/g in cerebellum and smaller amount in the liver. The amounts of IRCCK measured in all the tissue extracts were in the range of 0.1 to 0.5 pmol/g. The highest concentration was in the duodenum. Before BBS, IRG and IRCCK levels in the plasma were 9 +/- 2, and 81 +/- 24 pmol/g, respectively. After BBS, IRG was 13 +/- 1 and IRCCK was 139 +/- 18 (p < 0.05). Integrated responses for IRG and for IRCCK during BBS were increased significantly above basal. Substances with immunogenic similarities to gastrin and cholecystokinin can be measured in extracts of GI tissues and in plasma of chickens. They can be released into circulation by bombesin