The anomalous effect of some ACTH‐fragments missing the amino acid sequence 1–10 on the corticosteroidogenesis in purified isolated rat adrenal cells

The corticosteroidogenicity of ACTH-derived peptides was tested in a purified isolated rat adrenal cell system. The activity was related to the activity of standard ACTH (synthetic hACTH; potency fixed at 100). The peptides ACTH NH2 and ACTH showed steroidogenicity at pharmacological doses (potencies: 0.00067 and 0.00032, respectively). None of the peptides tested inhibited or potentiated the ACTH-induced steroidogenesis at low doses (0.5-50 000 pg). The results suggest the presence of a second center within the ACTH molecule capable of inducing steroidogenesis.