Glucose-induced secretion of ACTH-like products by rat pancreatic islets.
This work was performed to study the release of proopiomelanocortin (POMC)-derived peptides from isolated pancreatic islets and the effect of ACTH--a member of that peptide family--on insulin secretion. Islets were incubated with 3,3 and 16.6 mM glucose and insulin and ACTH-like products (ACTH-LP) were measured by radioimmunoassay. Glucose stimulated the simultaneous release of insulin and ACTH-LP, the ACTH-LP concentration being higher when assayed with an antibody reacting with the N-terminus of ACTH. However, the increment in this release in the presence of the higher glucose concentration was larger when measured with an antibody against the ACTH mid-portion. Thus, although the islets would release more of a smaller ACTH-LP, 16.6 mM glucose would selectively increase the release of peptides of larger molecular size. Islets incubated with different concentrations of synthetic ACTH (50-500 pg/ml) increased the release of insulin in a dose-dependent manner. These results suggest that the release of endogenous ACTH-LP could contribute to the paracrine regulation of insulin secretion.
Borelli
M I
MI
CENEXA-Centro de Endocrinologia Experimental y Aplicada (UNLP-CONICET), Facultad de Ciencias Médicas, UNLP, La Plata, Argentina.
Morano
M I
MI
Estivariz
F E
FE
Gagliardino
J J
JJ
D000324:Adrenocorticotropic Hormone / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D005947:Glucose / Q000494:pharmacology*; D066298:In Vitro Techniques; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
D007328:Insulin; D000324:Adrenocorticotropic Hormone; D005947:Glucose