CIRCULATING POLYMORPHIC FORMS OF ACTH AND RELATED PEPTIDES: AGE—DEPENDENT NATURE OF DEXAMETHASONE SUPPRESSION IN MALE RATS

Abstract

Proopiomelanocortin(POMC) through post-translational processes gives rise to a series of structural related peptides. These include MSHs, ACTHs, CLIPs, LPHs,and endorphins. In this study we have examined various molecular forms of ACTH-like immunoreactivity(ACTH-LI) present in systemic blood of male rats by chromatofocusing. To gain further insight into the physiological basis of the release of ACTH-LI peptides and its age-dependent nature, we have studied various molecular forms of ACTH-LI under dexamethasone(DX), which is expected to inhibit the release of endogenous CRF. Resolution of circulating ACTH-LI peptides utilizing chromatofocusing revealed 6 heterogenous components having isoelectric points between 4.7 and 3.29. The results demonstrated entirely different patterns of ACTH-LI peptides seen in the prepubertal group and the adult group. While the prepubertal pattern showed a relative shift to less acidic components, the adult animals had more acidic components. Under DX less acidic components in the prepubertal group were diminished and acidic components were increased. In the adults the less acidic components did not show any alterations, while the more acidic component (peak VI) was greatly enhanced. With these studies as a baseline, it convincingly demonstrates that the alterations in the ACTH-LI components with maturation are perhaps involved in the biopotency of a hormone, and inhibition of CRF by DX modulates the shift of the components from less acidic to more acidic forms.

Log in or create a free account to read this content

Gain free access to this article, as well as selected content from this journal and more on nature.com

Access through your institution

or

Sign in or create an account

Continue with Google

Continue with ORCiD