PMC:3724972 / 2150-3110 JSONTXT

{"project":"2_test","denotations":[{"id":"23673515-165214-63233577","span":{"begin":422,"end":423},"obj":"165214"},{"id":"23673515-3031116-63233577","span":{"begin":422,"end":423},"obj":"3031116"},{"id":"23673515-9467594-63233577","span":{"begin":422,"end":423},"obj":"9467594"},{"id":"23673515-165214-63233578","span":{"begin":553,"end":554},"obj":"165214"},{"id":"23673515-3031116-63233578","span":{"begin":553,"end":554},"obj":"3031116"},{"id":"23673515-9467594-63233578","span":{"begin":553,"end":554},"obj":"9467594"},{"id":"23673515-219007-63233578","span":{"begin":553,"end":554},"obj":"219007"},{"id":"23673515-3017037-63233578","span":{"begin":553,"end":554},"obj":"3017037"},{"id":"23673515-9150699-63233578","span":{"begin":553,"end":554},"obj":"9150699"},{"id":"23673515-9467594-63233579","span":{"begin":930,"end":931},"obj":"9467594"}],"text":"Pituitary secretion of ACTH is normally regulated by hypothalamic and paracrine signals, and through negative feedback by glucocorticoids [4]. Systemic ACTH levels also exhibit a circadian rhythm, controlled by the suprachiasmatic nucleus and entrained by light–dark cycles [4]. Superimposed on this circadian rhythm is an ultradian cycle of pulsatile ACTH release, which is closely mimicked by cortisol levels (Fig. 1a) [5–7]. In patients with CD, both basal and peak ACTH levels are elevated (Fig. 1b), and ACTH and cortisol levels are uncoordinated [5–10].\nFig. 1 24-hour plasma levels of ACTH (dotted line) and cortisol (solid line) in a normal female (a) and a female patient with Cushing’s disease (b). Note that in CD, both basal and peak cortisol levels are elevated, and cortisol secretion is less synchronized to ACTH levels. From Roelfsema F, Pincus SM, Veldhuis JD (1998) J Clin Endocrinol Metab, volume 83, page 690 [7]. Reproduced with permission"}