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ACTH-induced lipolysis in rat adipocytes: structure-activity relationships
Naunyn-Schmiedeberg'S Archives of Pharmacology
|March 16, 1978
Summary
Adrenocorticotropic hormone (ACTH) fragments were tested for lipolytic activity in rat adipocytes. ACTH1(-24) showed full activity, while shorter fragments had reduced affinity, suggesting specific sequences are crucial for hormone function.
Area of Science:
- Endocrinology
- Molecular Biology
- Biochemistry
Background:
- Adrenocorticotropic hormone (ACTH) regulates lipolysis.
- The precise structure-activity relationship of ACTH fragments is not fully elucidated.
Purpose of the Study:
- To investigate the lipolytic activity of natural porcine ACTH1(-39) and synthetic ACTH fragments.
- To determine the minimal active sequences and their binding affinities.
Main Methods:
- Utilized rat adipocytes for lipolysis assays.
- Administered natural and synthetic ACTH peptide fragments.
- Performed dose-response curve analysis to determine potency and affinity.
Main Results:
- ACTH1(-24) demonstrated full lipolytic activity, matching intrinsic activity and affinity.
- Shorter ACTH fragments acted as full agonists but exhibited lower affinity.
- ACTH5(-10) and ACTH7(-10) fragments were inactive.
- No antagonistic effects were observed with substimulatory doses of various ACTH fragments.
Conclusions:
- ACTH1(-24) is a key fragment for full lipolytic action.
- Specific sequences within ACTH are critical for maintaining high affinity and intrinsic activity.
- A refined model of ACTH active centers is proposed based on fragment potency.