Circadian variations and extraadrenal effect of ACTH on insulinemia in rabbit.
The present experiment was designed to study the action of ACTH1-24 on insulin secretion during the circadian cycle in normal rabbits and to provide evidence that ACTH1-24 has an extra-adrenal effect on this secretion. In normal rabbits intravenous administration of three doses of ACTH1-24 (1, 10, 100 micrograms/kg) at 10 a. m. increased plasma insulin levels. Hyperglycemia only occurred with doses of 10 and 100 micrograms/kg. A maximum insulin response was already obtained at 1 micrograms/kg. The same experiment performed at 12 p. m. also induced hyperinsulinemia which was only noted at 10 and 100 micrograms/kg; hyperglycemia was only observed after stimulation by the highest dose (100 micrograms/kg). ACTH was therefore more effective during the day; however, at 12 p. m. plasma insulin levels were the highest, but only with the maximum dose of ACTH (100 micrograms/kg). The effect of ACTH1-24 was evaluated throughout the day on normal and adrenalectomized rabbits. In normal animals injection of ACTH1-24 increased plasma glucose and insulin levels both together. In the contrary, in rabbits deprived of adrenal glands, ACTH1-24 induced high insulinemia along with hypoglycemia. We could, therefore, reasonably conclude that ACTH stimulates directly the pancreatic secretion of insulin.
Lesault
A
A
UFR des Sciences, Laboratoire de Physiologie Animale, Limoges, France.
Elchinger
B
B
Desbals
B
B
D000315:Adrenalectomy; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D002940:Circadian Rhythm; D003366:Cosyntropin / Q000494:pharmacology*; D007328:Insulin / Q000097:blood* / Q000378:metabolism; D000078790:Insulin Secretion; D007700:Kinetics; D008297:Male; D011817:Rabbits
D001786:Blood Glucose; D007328:Insulin; D003366:Cosyntropin