ACTH-Induced lipolysis in rat adipocytes: Structure-activity relationships

Abstract
The lipolytic action of natural porcine ACTH1–39 and of a number of highly purified synthetic ACTH peptide fragments was studied using rat adipocytes. Of the analogues tested, only ACTH1–24 exhibited full lipolytic activity with respect to intrinsic activity and affinity. Several shorter fragments appeared to be full agonists but had lower affinity. Fragments ACTH5–10 and ACTH7–10 were inactive. No antagonistic effects against the lipolytic action of ACTH could be demonstrated with substimulatory doses of ACTH1–16, ACTH1–10, ACTH7–24 and ACTH11–24. Based on the relative potency derived from dose-response curves, a more refined model with respect to the active centers being encoded in various sequences of the hormone, is proposed.