title: Circadian cortisol secretion and circadian adrenal responses to ACTH are maintained in dexamethasone suppressed capuchin monkeys (Cebus apella).
abstract: We tested the hypothesis that the capuchin monkey adrenal (Cebus apella) gland has oscillatory properties that are independent of adrenocorticotropic hormone (ACTH) by exploring under ACTH suppression by dexamethasone: (i) maintenance of a circadian rhythm of plasma cortisol and (ii) clock time dependency of plasma cortisol response to exogenous ACTH. The capuchin monkey had a clear ACTH and plasma cortisol rhythm. Dexamethasone treatment resulted in low non-rhythmic ACTH levels and decreased cortisol to 1/10 of control values; nevertheless, the circadian rhythm of plasma cortisol persisted. We found that cortisol response to exogenous ACTH was clock time-dependent. The maximal response to ACTH occurred at the acrophase of the cortisol rhythm (0800 h). These results suggest that the capuchin monkey adrenal cortex may possess intrinsic oscillatory properties that participate in the circadian rhythm of adrenal cortisol secretion and in the circadian cortisol response to ACTH.
authors.affiliation: Departamento de Ciencias Fisiológicas, Pontificia Universidad Católica de Chile Santiago, Chile.
authors.forename: Claudia
authors.initials: C
authors.lastname: Torres-Farfan
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Valenzuela
authors.forename: Renato
authors.initials: R
authors.lastname: Ebensperger
authors.forename: Natalia
authors.initials: N
authors.lastname: Méndez
authors.forename: Carmen
authors.initials: C
authors.lastname: Campino
authors.forename: Hans G
authors.initials: HG
authors.lastname: Richter
authors.forename: Guillermo J
authors.initials: GJ
authors.lastname: Valenzuela
authors.forename: María
authors.initials: M
authors.lastname: Serón-Ferré
mesh_terms: D000311:Adrenal Glands / Q000187:drug effects / Q000378:metabolism*; D000324:Adrenocorticotropic Hormone / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D002428:Cebus / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology*; D003907:Dexamethasone / Q000494:pharmacology*; D005260:Female; D006854:Hydrocortisone / Q000378:metabolism*; D008297:Male; D013997:Time Factors
chemical_list: D003907:Dexamethasone; D000324:Adrenocorticotropic Hormone; D006854:Hydrocortisone