Control of circadian and episodic variations of adrenal androgens secretion in man

Abstract

The 24-h profiles of plasma cortisol (F), 11-beta-hydroxyandrostenedione (11OHAD), androstenedione (AD), dehydroisoandrosterone (DHEA) and testosterone (T) were obtained simultaneously in 11 normal males sampled at 15-min intervals. The data were submitted to a detailed quantitative analysis including the estimation of the circadian rhythm and of the episodic variations as well as the evaluation of the concomitance of episodic pulses of different hormones. A bimodal circadian rhythm was detected in the various individual profiles. The major acrophase occurred in the morning earlier for T (around 04:00 h) than for the hormones of totally or partially adrenal origin (around 07:00 h); the secondary acrophase (around 17:00 h) and the main midnight nadir were common to all hormones. The amplitude of the rhythm was highest for purely adrenal hormones (F and 11OHAD), averaging 79 and 75%, respectively, lower for hormones of mixed origin (DHEA and AD), averaging 44 and 42%, respectively, and minimal for T (22%). The possible relationship between the circadian and pulsatile variations of the various steroids was estimated in each individual by calculating Pearson's standard coefficient of variation on all pairs of hormonal profiles. A very tight relationship (r greater than 0.75; p less than 0.001) was found between the 4 adrenal hormones in each individual; a looser but significant correlation (r greater than 0.30; p less than 0.001) was also detected between T and its partial precursors (AD and DHEA) and between T and the purely adrenal hormones: F and 11OHAD (r greater than 0.30; p less than 0.01). The pulsatility of the corticotrophic axis was readily transmitted to the secretory pattern of 11OHAD, DHEA and AD. Ninety-six percent of the F pulses were reflected in at least one other hormonal profile. Finally, we showed that concomitant pulses common to the five adrenal and gonadal patterns were more frequent than would be expected on the basis of chance. These results: demonstrate a total parallelism between the long-lasting secretory events and the episodic bursts of the 4 adrenal hormones showing that the reticular and fascicular zones of the adrenal respond to pituitary control as an homogeneous structure; demonstrate the existence of a partial synchronization of adrenal and testicular pulsatile variations; suggest that, throughout the afternoon, a common mechanism may influence the slow variations of adrenal hormones and of testicular testosterone.

Dehydroepiandrosterone secretion in dairy cattle is episodic and unaffected by ACTH stimulation

“…Cortisol and DHEA pulse frequency observed in cows was comparable with that observed in humans (Lejeune-Lenain et al 1987), where DHEA and cortisol episodic secretions showed a strong overall synchronisation (Rosenfeld et al 1975, Lejeune-Lenain et al 1987. In particular, both steroids showed a bi-modal circadian pattern with a major acrophase in early morning and a late evening nadir, and a high degree of correlation and concomitance of episodic pulses (Lejeune-Lenain et al 1987). In this study, frequent sampling was performed for 8 h from the morning to early afternoon, and this was not suitable to detect any circadian pattern of steroid release.…”

“…In humans, DHEA and DHEA-S display a diurnal rhythm in parallel to that of cortisol (Lejeune-Lenain et al 1987), and it was hypothesised that social activity and living habits may play a role in the synchronisation of diurnal DHEA/DHEA-S rhythms (Zhao et al 2003). In the human, adrenal DHEA secretion is episodic and it is synchronous with cortisol release, while DHEA-S seems to be less synchronous with both DHEA and cortisol (Rosenfeld et al 1975).…”

“…In the human, adrenal DHEA secretion is episodic and it is synchronous with cortisol release, while DHEA-S seems to be less synchronous with both DHEA and cortisol (Rosenfeld et al 1975). In the human male, it was observed that the pulsatility of the corticotropic axis was transmitted to the secretory pattern of DHEA, and a partial synchronisation between testicular and adrenal pulsatile secretion was hypothesised (Lejeune-Lenain et al 1987).…”

Regulation of Circadian Gene Expression in Liver by Systemic Signals and Hepatocyte Oscillators

“…The genome-wide mapping of genes whose cyclic expression in liver does not depend on functional hepatocyte oscillators unveiled putative signaling pathways that may participate in the phase entrainment of peripheral clocks. oscillate with a robust daily amplitude (Lejeune-Lenain et al 1987 and references therein). The transcription of another class of genes, perhaps best described as cellautonomously clock-controlled genes, may be driven by core components of local oscillators, such as BMAL1, CLOCK, CRYs, and PERs, or transcription factors such as the PAR basic leucine zipper (bZIP) proteins DBP, HLF, and TEF, whose circadian accumulation and/or activity depends on these factors.…”

Analysis of testosterone pulsatility in women with ovulatory menstrual cycles

“…A pulse is identified by an abrupt increase with a subsequent decrease in the hormone output, which reflects in its serum concentration (13). Although normal pulsatility of androgen secretion was demonstrated in men (14,15) as well as in some diseases (16), the normal pulsatile pattern of secretion and its variability among the different phases of the menstrual cycle have not been established yet.…”