Effects of C-terminal fragments of cholecystokinin on plasma insulin and glucagon concentrations in sheep.
The effects of three C-terminal fragments of cholecystokinin (CCK) (CCK-8-sulphated form [SF], CCK-8-non-sulphated form [NSF] and CCK-4) on insulin and glucagon secretion were examined in sheep in vivo. Each CCK fragment was injected intravenously at a wide range of doses (1 pmol to 3 x 10(5) pmol kg-1). CCK-8(SF) had the lowest threshold dose (10 pmol kg-1) and a maximal response dose of 10(3) pmol kg-1 for increasing plasma insulin concentration; the respective threshold doses of CCK-8(NSF) and CCK-8 for increasing plasma insulin were 30 and 100 times greater than that of CCK-8(SF). A maximal insulin response was not obtained at the highest doses of CCK-8(NSF) or CCK-4 tested (3 x 10(3) and 3 x 10(5) pmol kg-1, respectively). These results indicate that CCK-A type receptors rather than CCK-B receptors may be involved in CCK-induced insulin secretion in sheep. None of the CCK fragments affected plasma glucagon concentration. The lack of a glucagon response to exogenous CCK-fragments may be one of the characteristics of the endocrine pancreatic responses of ruminant species.
Mineo
H
H
Faculty of Veterinary Medicine, Rakuno Gakuen University, Hokkaido, Japan.
Kamita
H
H
Muto
H
H
Ito
M
M
Hyun
H S
HS
Onaga
T
T
Yanaihara
N
N
D000818:Animals; D002766:Cholecystokinin / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005934:Glucagon / Q000097:blood*; D007275:Injections, Intravenous / Q000662:veterinary; D007328:Insulin / Q000097:blood*; D008297:Male; D018377:Neurotransmitter Agents / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D010179:Pancreas / Q000737:chemistry / Q000378:metabolism / Q000502:physiology; D010446:Peptide Fragments / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology; D011863:Radioimmunoassay / Q000662:veterinary; D011949:Receptors, Cholecystokinin / Q000032:analysis / Q000502:physiology; D012756:Sheep / Q000097:blood*; D012844:Sincalide / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D013758:Tetragastrin / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*
D007328:Insulin; D018377:Neurotransmitter Agents; D010446:Peptide Fragments; D011949:Receptors, Cholecystokinin; D013758:Tetragastrin; D005934:Glucagon; D002766:Cholecystokinin; D012844:Sincalide