Glucocorticoids and the circadian clock

Abstract

Glucocorticoids, hormones produced by the adrenal gland cortex, perform numerous functions in body homeostasis and the response of the organism to external stressors. One striking feature of their regulation is a diurnal release pattern, with peak levels linked to the start of the activity phase. This release is under control of the circadian clock, an endogenous biological timekeeper that acts to prepare the organism for daily changes in its environment. Circadian control of glucocorticoid production and secretion involves a central pacemaker in the hypothalamus, the suprachiasmatic nucleus, as well as a circadian clock in the adrenal gland itself. Central circadian regulation is mediated via the hypothalamic-pituitary-adrenal axis and the autonomic nervous system, while the adrenal gland clock appears to control sensitivity of the gland to the adrenocorticopic hormone (ACTH). The rhythmically released glucocorticoids in turn might contribute to synchronisation of the cell-autonomous clocks in the body and interact with them to time physiological dynamics in their target tissues around the day.

Cortisol and anxiety response to a relaxing intervention on pregnant women awaiting amniocentesis

“…Cortisol tended to decrease between 8:30 and 15 h ( p < 0.001), in agreement with its well-known circadian rhythm (Weitzman et al, 1971;Veldhuis et al, 1989;Dickmeis, 2009), and tended to increase with gestational age ( p = 0.002). From the coefficients of regression analysis, we found that, on average, 2.7 additional gestation days corresponded to more 3.4 nmol/L in the plasma cortisol, assuming everything else remains equal.…”

High testosterone levels and sensitivity to acute stress in perpetrators of domestic violence with low cognitive flexibility and impairments in their emotional decoding process: A preliminary study

“…In the first session participants were interviewed in order to identify (and subsequently reject) participants who suffered from organic or psychological diseases. The second session took place between 4 pm and 7 pm in order to control diurnal variations of C secretion (Dickmeis, 2009). Participants were instructed to abstain from eating or brushing their teeth, as well as caffeine, alcohol, or exercise, and any drug 2 hr before arriving at the laboratory.…”

Glucocorticoids and circadian clock control of cell proliferation: At the interface between three dynamic systems

“…Glucocorticoids have long been recognised to show diurnal rhythms of release (reviewed in [81,[87][88][89]). In diurnal animals, peak levels of glucocorticoids are encountered in the early morning, whereas nocturnal animals show a peak in the early night.…”

“…The splanchnic nerve also seems to mediate changes in the sensitivity of the adrenal gland to ACTH, which modulate corticosterone production and release in a circadian fashion even when ACTH levels do not change (reviewed in [89,97,104]). …”

“…Furthermore, glucocorticoids interact with other circadian outputs, one of which is the cell cycle [89].…”