ACTH-Dependent Ultradian Rhythm of Corticosterone Secretion

• DOI: 10.1210/en.2010-1209
• Publication Date: 2011-02-09T03:05:55Z
• Authors: Francesca Spiga; Eleanor J. Waite; Ying Liu; Yvonne M. Kershaw; Greti Aguilera; Stafford L. Lightman
• Keywords: Corticosterone; Pulsatile flow; ACTH receptor

Abstract The activity of the hypothalamic-pituitary-adrenal axis is characterized by an ultradian pulsatile pattern glucocorticoid secretion. Despite increasing evidence for importance pulsatility in regulating glucocorticoid-responsive gene transcription, little known about mechanism underlying synthesis and release. We tested hypothesis that ACTH release critical optimal adrenocortical function. Hypothalamic-pituitary-adrenal was suppressed oral methylprednisolone, (4 ng/h) infused 24h either as a constant infusion or 5-min pulses at hourly intervals. Control methylprednisolone-treated rats had very low plasma corticosterone (CORT) levels with undetectable also steroidogenic acute regulatory protein (StAR) cytochrome P450 side-chain cleavage (P450scc) heteronuclear RNA reduced to approximately 50% seen untreated animals. Pulsatile but not restored CORT secretion, this accompanied parallel rises StAR P450scc during rising phase pulse, which then fell falling phase. paralleled transcription melanocortin 2 receptor accessory protein. activation adrenal cortex only secretion induces episodic rate-limiting enzymes necessary physiological responses. Because identical amounts did activate provides more effective signaling system activity.