Regulation of IGF-I receptors by corticotropin and angiotensin-II in cultured bovine adrenocortical cells.
The effects of angiotensin II (A-II) and corticotropin (ACTH) on insulin-like growth factor-I (IGF-I) receptors of bovine adrenocortical cells were investigated. Pretreatment of cells for 48 h with ACTH or A-II induced in a dose-dependent manner an increase in [125I]IGF-I binding (ED50 congruent to 10(-11)M, Vmax = 10(-10) M with ACTH; ED50 congruent to 3.10(-9) M, Vmax = 10(-7) M with A-II). This resulted from an increase in the number of binding sites without modification of the binding affinity. Pretreatment with 8-Bromo-cAMP (10(-3) M), a phorbol ester (PMA 10(-7) M) + ionophore A23187 (10(-7) M) produced a positive regulation of IGF-I receptors. Glucocorticoids did not mediate the effect of A-II and ACTH on IGF-I receptors. Since previous studies have shown that IGF-I increased ACTH and A-II receptors the present data indicate the existence of a reciprocal positive trophic effect between IGF-I and the two hormones on the regulation of their specific membrane-bound receptors.
Louveau
I
I
INSERM U 307, Hôpital Debrousse, Lyon, France.
Penhoat
A
A
Saez
J M
JM
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000302:Adrenal Cortex / Q000166:cytology / Q000502:physiology*; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology*; D000616:Aminoglutethimide / Q000494:pharmacology; D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D003907:Dexamethasone / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D007334:Insulin-Like Growth Factor I / Q000502:physiology*; D011956:Receptors, Cell Surface / Q000502:physiology*; D017451:Receptors, Somatomedin; D013002:Somatomedins / Q000502:physiology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D011956:Receptors, Cell Surface; D017451:Receptors, Somatomedin; D013002:Somatomedins; D000616:Aminoglutethimide; D000804:Angiotensin II; D015124:8-Bromo Cyclic Adenosine Monophosphate; D007334:Insulin-Like Growth Factor I; D003907:Dexamethasone; D000324:Adrenocorticotropic Hormone; D013755:Tetradecanoylphorbol Acetate