RESUMO
In Cushing's syndrome, the cortisol rhythm is impaired and can be associated with the disruption in the rhythmic expression of clock genes. In this study, we evaluated the expression of CLOCK, BMAL1, CRY1, CRY2, PER1, PER2, PER3 genes in peripheral blood leukocytes of healthy individuals (n = 13) and Cushing's disease (CD) patients (n = 12). Participants underwent salivary cortisol measurement at 0900 h and 2300 h. Peripheral blood samples were obtained at 0900 h, 1300 h, 1700 h, and 2300 h for assessing clock gene expression by qPCR. Gene expression circadian variations were evaluated by the Cosinor method. In healthy controls, a circadian variation in the expression of CLOCK, BMAL1, CRY1, PER2, and PER3 was observed, whereas the expression of PER1 and CRY2 followed no specific pattern. The expression of PER2 and PER3 in healthy leukocytes presented a late afternoon acrophase, similarly to CLOCK, whereas CRY1 showed night acrophase, similarly to BMAL1. In CD patients, the circadian variation in the expression of clock genes was lost, along with the abolition of cortisol circadian rhythm. However, CRY2 exhibited a circadian variation with acrophase during the dark phase in patients. In conclusion, our data suggest that Cushing's disease, which is characterized by hypercortisolism, is associated with abnormalities in the circadian pattern of clock genes. Higher expression of CRY2 at night outlines its putative role in the cortisol circadian rhythm disruption.
Assuntos
Relógios Circadianos , Hipersecreção Hipofisária de ACTH , Proteínas CLOCK/genética , Relógios Circadianos/genética , Ritmo Circadiano , Expressão Gênica , Humanos , Hidrocortisona , LeucócitosRESUMO
The postnatal synchronization of the circadian variation of the adrenal clock genes in mammals remains unknown. We evaluated the postnatal ontogeny of daily variation of clock genes (Clock/Bmal1/Per1/Per2/Per3/Cry1/Cry2/Rorα/Rev-Erbα) and steroidogenesis-related genes (Star and Mc2r) in rat adrenals and its relationship with the emergence of plasma corticosterone rhythm using cosinor analysis. Plasma corticosterone circadian rhythm was detected from postnatal day (P)1, with morning acrophase, between zeitgeber time (ZT)0 and ZT2. From P14, there was a nocturnal acrophase of corticosterone at ZT20, which was associated with pups' eye opening. From P3 there was a circadian variation of the mRNA expression of Bmal1, Per2, Per3, and Cry1 genes with morning acrophase, whereas Rev-Erbα had nocturnal acrophase. From P14, Bmal1, Per2, Per3, and Cry1 acrophases advanced by approximately 10 hours, as compared with early neonatal days, becoming vespertine-nocturnal. In all postnatal ages, Per2 and Cry1 circadian profiles were synchronized in phase with the circadian rhythm of plasma corticosterone, whereas Bmal1 was in antiphase. An adult-like Star circadian rhythm profile was observed only from P21. In conclusion, our original data demonstrated a progressive postnatal maturation of the circadian variation of the adrenal clock genes in synchrony with the development of the corticosterone circadian rhythm in rats.
Assuntos
Glândulas Suprarrenais/crescimento & desenvolvimento , Glândulas Suprarrenais/metabolismo , Proteínas CLOCK/genética , Ritmo Circadiano/fisiologia , Corticosterona/metabolismo , Corticosteroides/genética , Corticosteroides/metabolismo , Animais , Animais Recém-Nascidos , Proteínas CLOCK/metabolismo , Ritmo Circadiano/genética , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Masculino , Gravidez , Ratos , Ratos WistarRESUMO
INTRODUCTION: Cortisol awakening response (CAR) is a rapid increase of cortisol levels within 30-45 min after awakening. OBJECTIVE: This study evaluates CAR compared with cortisol circadian rhythm in active and in remission Cushing's disease (CD). MATERIALS AND METHODS: We evaluated healthy controls (HC, n=19), obese (OB, n=10), in remission (n=08), and active CD patients (n=10). Salivary free cortisol (SF) was determined at 0800, 1100, 1700, 2000, and 2300 h on the first day. CAR was obtained the next morning immediately upon awakening and at 15, 30, 45, and 60-min post-wake up. RESULTS: We observed differences in SF levels throughout the day in HC, OB, and in remission CD (ANOVA P=0.0001) but not in active CD (P=0.2). We demonstrated SF increment after awakening in HC, OB, and in remission CD (ANOVA P=0.007), with no effect of time on SF in active CD. The relative increment of SF obtained at the peak after awakening (CARi%) in the active CD (67±57%) was lower than in HC (154±107%), OB (240±188%), and in remission CD (186±184%) patients (P=0.009). There was a negative correlation between the SF at awakening and the CARi% in HC (r=-0.8), OB (r=-0.78), and in remission CD (r=-0.74) but not in active CD (r=-0.35; P=0.31). CONCLUSION: This study originally described a blunted CAR in active CD in contrast to its presence in HC, OB, and in remission CD. This subtle dysfunction of the hypothalamus-pituitary-adrenal axis may represent a distinct and additional physiopathological phenomenon superimposing the dysregulated cortisol circadian rhythm in this disease.