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Background Many hormones display distinct circadian rhythms, driven by central regulators, hormonal bioavailability, and half-life. A set of 11-oxygenated C19 steroids (11-oxyandrogens) and pregnenolone sulfate (PregS) are elevated in congenital adrenal hyperplasia and other disorders, but their circadian patterns have not been characterized. Participants and methods Peripheral blood was collected every 2 h over 24 h from healthy volunteer men (10 young, 18–30 years, and 10 older, 60–80 years). We used mass spectrometry to quantify 15 steroids, including androstenedione (A4), testosterone (T), 11β-hydroxy- and 11-ketotestosterone (11OHT, 11KT),11β-hydroxy- and 11-ketoandrostenedione (11OHA4, 11KA4), and 4 ∆5-steroid sulfates. Diurnal models including mesor (rhythm adjusted median), peak, and nadir concentrations, acrophase, and amplitude were computed. Results 11OHA4 followed a rhythm similar to cortisol: acrophase 8:00 h, nadir 21:00 h and were similar in young and old men. 11KT had similar diurnal patterns, but the peak was lower in older than in young men, as was the case for A4. All four steroid sulfates were higher in young vs older men. PregS and 17-hydroxypregnenolone sulfate (17OHPregS) showed sustained elevations between 8:00 and 18:00 h, and nadirs around midnight, while DHEAS and AdiolS displayed minimal diurnal variations. All 4 11-oxyandrogens correlated tightly with cortisol (r from 0.54 for 11OHT to 0.81 for 11OHA4, P < 0.0001 for all), but very weakly with T, supporting their adrenal origin and ACTH governance. Conclusions 11-Oxyandrogens, PregS, and 17OHPregS display distinct circadian and age variations, which should be accounted for when used as clinical biomarkers.

AbstractContextInterleukin-2 (IL-2), a proinflammatory cytokine, has been used to treat malignancies. Increased cortisol and adrenocorticotropin (ACTH) were noted, but growth hormone (GH) secretion was not investigated in detail.ObjectiveWe quantified GH secretion after a single subcutaneous injection of IL-2 in 17 young and 18 older healthy men in relation to dose, age, and body composition.MethodsThis was a placebo-controlled, blinded, prospectively randomized, crossover study. At 20:00 hours IL-2 (3 or 6 million units/m2) or saline was injected subcutaneously. Lights were off between 23:00 and 07:00 hours. Blood was sampled at 10-minute intervals for 24 hours. Outcome measures included convolution analysis of GH secretion.ResultsGH profiles were pulsatile under both experimental conditions and lower in older than young volunteers. Since the effect of IL-2 might be time limited, GH analyses were performed on the complete 24-hour series and the 6 hours after IL-2 administration. Total and pulsatile 24-hour GH secretion decreased nonsignificantly. Pulsatile secretion fell over the first 6 hours after IL-2 (P = .03), with visceral fat as a covariate (P = .003), but not age (P = .10). Plots of cumulative 2-hour bins of GH pulse mass showed a distinction by treatment and age groups: A temporary GH decrease of 32% and 28% occurred in the first 2-hour bins after midnight (P = .02 and .04) in young participants, whereas in older individuals no differences were present at any time point.ConclusionThis study demonstrates that IL-2 temporarily diminishes GH secretion in young, but not older, men.

Abstract Context: Interleukin-2 (IL2), a proinflammatory cytokine, is used for treatment of malignancies. Increased cortisol and ACTH were noted, but GH secretion was not investigated in detail. This is the first study in healthy men which uses moderate high IL2 doses as used in cancer treatment. Objective: The goal of this study was to quantify GH secretion after a single sc injection of IL2 in young and older healthy men in relation to dose, age and body composition. Design: This was a placebo-controlled, blinded, prospectively randomized cross-over study in 17 young subjects (mean age 24.1 yr) and 18 older subjects (mean age 63.9 yr). The subjects underwent 24 h of blood sampling at 10-min intervals, starting at 1800 h. At 2000 h IL2 (3 or 6 million units per m2 body surface) or saline was injected sc. Lights were off between 2300 and 0700 h. Outcome Measures: Deconvolution analysis of GH. Abdominal visceral fat (AVF) was calculated from single slice CT. Results: GH secretion (pulsatile and total) was negatively related to AVF (R=0.67, P&lt;0.0001) and to age (R=0.56, P=0.001). These relations were maintained after IL2 administration. GH profiles were pulsatile under both experimental conditions. Since the effect of IL2 might be limited in time, GH deconvolution analyses were performed on the complete 24 h data series, the period with lights off and 6 h after IL2 administration. Total 24 h GH secretion decreased non-significantly from 74.6 ±10.2 to 67.5±7.4 µg/L (P=0.25) and pulsatile secretion from 69.4±9.8 to 62.2±7.4 µg/L (P=0.23). In the GLM procedure the effect of IL2 treatment was borderline significant (P=0.08), no interaction with age (P=0.28), but borderline with IL2 dose (P=0.07), and caused by decreased GH secretion (88 to 67 µg/L) at a low dose IL2. In a sub-analysis of the two age groups no effect on GH secretion in the older group was noted, in contrast to young subjects, especially on low dose IL2 (P=0.07). The analysis was refined further by calculating cumulative pulse masses in 2-h bins. By this approach it could be demonstrated that the cumulative GH pulse mass in older subjects across the 24 h was unchanged, while that in young subjects was temporarily inhibited in the bins between midnight and 0400 h (P=0.019 and 0.038). Conclusion: This study demonstrated that IL2 temporarily diminished GH secretion in young but not elderly volunteers. Pituitary hormone secretion by IL2 has not been studied as extensively as other cytokines, including IL1, IL6 and TNF. IL2 stimulates ACTH and TSH, inhibits LH and has no effect on GH secretion by rat pituitary (PNAS 58:185,1993). In patients with renal cancer IL2 infusion has no effect on GH levels (Anti-Cancer Res 10:753,1990. The present findings extend these observations to a large group of healthy volunteers, in whom we demonstrated previously suppression of the gonadal axis and activation of the HPA-axis (JCEM 101:539,2016, Endocr Connect 9:637,2010).

Background: Interleukin-2 (IL-2), one of the proinflammatory cytokines, is used in the treatment of certain malignancies. In some studies, transient increases in cortisol and ACTH secretion occurred. Thus, this agent may be used as an experimental probe of adrenal cortisol secretion. Objective: This study quantifies the effects of low and moderate doses of IL-2 on cortisol secretion and assesses the modulation by age, dose and body composition. Site: Mayo Clinical Translational Research Unit. Subjects: Study comprised 35 healthy men, 17 young and 18 older. Methods: Randomized prospective double-blind saline-controlled study of IL-2 administration in two doses with concurrent 10-min blood sampling for 24 h. Outcome measures: Deconvolution analysis and approximate entropy of cortisol secretion. Results: Low-dose IL-2 administration increased nocturnal pulsatile cortisol secretion from 1460 ± 160 to 2120 ± 220 nmol/L/8 h in young subjects and from 1680 ± 105 to 1960 ± 125 nmol/L/8 h (treatment P < 0.0001, but more in young than older, P = 0.02). Comparable results were obtained for total cortisol secretion ( P treatment <0.0001, age effect P = 0.005). The higher IL-2 dose caused a large increase in young ( P < 0.0001), but not in older ( P = 0.90) subjects. This dose also increased approximate entropy from 0.877 ± 0.041 to 1.024 ± 0.049 ( P = 0.008), pointing to reduced secretory orderliness. Incremental cortisol (nocturnal) secretion correlated negatively with visceral fat mass ( R = −0.41, P = 0.019). Conclusion: In healthy men, IL-2 injection drives pulsatile cortisol secretion in a dose-dependent way in young, but not older, individuals and erodes cortisol secretory orderliness at a higher dose in young subjects. Cortisol responses are diminished with increasing abdominal visceral fat mass.

Abstract Introduction: In young men, sleep restriction decreases testosterone and increases afternoon cortisol, leading to anabolic-catabolic imbalance, insulin resistance and metabolic, neurocognitive, reproductive, and other adverse effects. Age-related differences in the hypothalamo-pituitary-testicular/adrenal response to sleep restriction could expose older individuals to greater or lesser risk, but this possibility has not been previously studied. Subjects and Methods: Thirty-five healthy young and older men aged 18-30y (n=17) and 60-80y (n=18), underwent blood sampling in the Mayo Clinic Center for Clinical and Translational Science every 10 minutes for 24 hours from 6PM-6PM under two conditions in random order spaced at least 3 weeks apart: awake (no sleep) or sleep (from 10PM to 6AM). Blood was assayed for LH, testosterone (T) and cortisol (F), and then analyzed by automated mathematical deconvolution and with cross approximate entropy statistics to determine hormone secretion and hormone synchrony, respectively. Statistical significance was construed by repeated measures ANOVA using a full factorial model that included age, sleep and the interaction. Results: Sleep deprivation had multiple effects on 24-hour (6PM-6PM) Te secretion with significant reductions in mean concentrations, basal, total and pulsatile secretion, and pulse frequency (each P&lt;0.05), in the absence of detectable changes in LH. These effects were most apparent in older men and differed according to age for some parameters: pulsatile Te secretion (P=0.03) and T pulse frequency (P=0.02). Time-of-day analyses revealed that sleep restriction significantly reduced Te in the morning (6AM-9AM) and afternoon (3PM-6PM), reduced LH in the morning, and increased F in the afternoon, particularly in older men. Cross-approximate entropy statistics showed that sleep restriction enforced greater LH-Te and Te-LH joint synchrony in the morning (P&lt;0.05 for each), but not in the afternoon. Conclusion: Sleep restriction decreases morning LH secretion, morning and afternoon Te secretion, and increases afternoon F secretion, especially in older men. This combination of findings could plausibly cause metabolic and reproductive ill-health when accumulated over decades of life, and may explain how chronic sleep loss contributes to metabolic and reproductive diseases that are more prevalent in older men. These preliminary data also suggest a time-of-day dependent uncoupling of the regulatory control of the testicular axis, and of cortisol secretion. Direct verification by interventions that manipulate hormones during the morning and late afternoon in appropriately matched cohorts of young and older men are now required.

Abstract Context. Interleukin-2 (IL2), a proinflammatory cytokine, is used for treatment of malignancies. Increased cortisol and ACTH were noted, but not investigated in detail. This is the first study in healthy men which uses moderate high IL2 doses as used in cancer treatment. Objective. The goal of this study was to quantify cortisol secretion after a single sc injection of IL2 at 1900 h in young and older healthy men in relation to dose, age and body composition. Design. This was a placebo-controlled, blinded, prospectively randomized cross-over study in 17 young subjects (mean age 24.1 yr, range 19–30 yr) and 18 older subjects (mean age 63.9 yr, range 60–75 yr). The subjects underwent 24 h of blood sampling at 10-min intervals, starting at 1800 h. At 2000 h IL2 (3 or 6 million units per m2 body surface) or saline was injected sc. Lights were off between 2300 and 0700 h. Setting. The study was performed in a Clinical Translational Research Unit. Outcome measures. Mean concentrations of cortisol, deconvolution analysis, and approximate entropy. Abdominal visceral fat (AVF) and total abdominal fat (TAF) were calculated from single slice CT. Results. Cortisol concentrations started to rise at 2300 h. The AUC’s during the lights-on periods were unchanged by IL2. Therefore, most analyses were restricted to the 8 h lights-off period. In young volunteers pulsatile cortisol secretion increased from 52.9±5.8 to 77.0±8.0 µg/L/8h and in older subjects from 60.6±3.8 to 70.6±4.6 µg/L/8h (GLM: treatment P &lt;0.0001, treatment x age: P=0.02, mean ± SEM). Thus, the effect was smaller in older subjects. Increasing the IL2 dose increased cortisol secretion in young subjects (P= 0.001), but not in older subjects (P=0.90). In addition, the slopes (mean ± SE) of the linear part of the concentration curves after IL-2 were steeper than after placebo, pointing to accelerated release (young 1.40±0.13 to 3.76±0.11, P&lt;0.0001, in older 1.27±0.04 to 3.28±0.15, P&lt;0.0001).The incremental nocturnal pulsatile cortisol secretion after IL2 was negatively related to body composition (AVF: R= ̶ 0.41, P=0.019; TAF R= ̶ 0.41, P=0.043). Nocturnal ApEn-cortisol did not increase after low dose IL2 (0.981± 0.099 to 0.991±0.046, P=0.92). After high-dose, ApEn increased from 0.877±0.041 to 1.024±0.049, P=0.008, not correlated with body composition, nor with age. The ApEn increase points to decreased secretory regularity imposed by enhanced CRF signaling, rather than diminished cortisol feedback, which leads to greater secretory regularity. Conclusion. Il2, a paradigm for inflammation, increased pulsatile cortisol secretion, more in young than in older subjects. Higher IL2 doses in young subjects amplified cortisol secretion, but not in older subjects. Cortisol secretion exhibited an advance (earlier) time shift, accompanied by accelerated secretion. Incremental nocturnal cortisol secretion was negatively related to fat mass.

Abstract Context. Aging is associated with diminished testosterone (Te) secretion, which could be attributed to Leydig cell dysfunction, decreased pituitary stimulation and altered Te feedback. Objective. The goal was to quantify all three regulatory nodes of the GnRH-LH-Leydig cell- axis in the same cohort of healthy men, by measuring (1) indirectly the strength of the endogenous GnRH signal on the gonadotrope, (2) the strength of Te feedback on LH by ketoconazole (KTCZ), and (3) the effect of LH infusions on Te secretion, in relation to age and body composition. Design. This was a placebo-controlled, blinded, prospectively randomized cross-over study in 40 men, age 19–73 yr, BMI 20–34.3 kg/m2. A submaximal dose of ganirelix (GnRH antagonist) was used to assess outflow of GnRH, by calculating the difference between LH output during the control and ganirelix arm. Ketoconazole (steroidogenic inhibitor) was used to estimate feedback, by the difference in LH output during ketoconazole and control arm. High-dose ganirelix and repeated 6-min LH (18.75 IU) infusions were used to measure testicular responsivity. Blood sampling was at 10-min intervals. The 4 sessions were concluded with, a single submaximally GnRH stimulus to assess the responsiveness of the gonadotrope during ganirelix inhibition. Setting. The study was performed in a Clinical Translational Research Unit. Interventions. In 3 of the 4 experiments subjects underwent 5 h of blood sampling at 10-min intervals, starting at 0800 h. At 1100 h GnRH was injected and sampling was continued for another 2 h. Admission was at 1700 h the day before. At 2000 h they received KTCZ, dexamethasone or ganirelix and/or placebo. KTCZ and dexamethasone (or placebo) were administered again at 0700 when the IV catheter was placed. High-dose ganirelix was used to test the testicular responsiveness, and 7 LH pulses (90 min intervals) were given., with blood sampling from 1500 till 1300 h next day. Outcome measures. Mean concentrations of LH and (bio)Te, deconvolution analysis, endogenous dose-response LH-bioTe relation, and approximate entropy. Abdominal visceral fat (AVF) was calculated from single slice CT. Results. There were age-, but not body composition-related decreases in estimated endogenous GnRH secretion, Te’s feedback strength on LH, and Leydig cell responsivity to LH, accompanied by changes in approximate entropy. Bioavailable Te levels were negatively related to both age and AVF, without interaction between these variables. The LH response to a submaximal dose of GnRH was independent of age and AVF. Conclusion. Advancing age is associated with 1) attenuated bioavailable Te secretion caused by diminished GnRH outflow and not by decreased GnRH responsivity of the gonadotrope, 2) diminished testicular responsivity to infused LH pulses, and 3) partial compensation by diminished Te feedback on central gonadotropic regulation.

Abstract Study Objectives In young men, sleep restriction decreases testosterone (Te) and increases afternoon cortisol (F), leading to anabolic–catabolic imbalance, insulin resistance, and other andrological health consequences. Age-related differences in the hypothalamo–pituitary–testicular/adrenal response to sleep restriction could expose older individuals to greater or lesser risk. We aimed to evaluate and compare the 24-h and time-of-day effect of sleep restriction on F, luteinizing hormone (LH), and Te in young and older men. Methods Thirty-five healthy men, aged 18–30 (n = 17) and 60–80 (n =18) years, underwent overnight sleep deprivation (complete nighttime wakefulness) or nighttime sleep (10 pm to 6 am) with concurrent 10-min blood sampling in a prospectively randomized crossover study. F, LH, and Te secretion were calculated by deconvolution analysis. Results Sleep deprivation had multiple effects on 24-h Te secretion with significant reductions in mean concentrations, basal, total and pulsatile secretion, and pulse frequency (each p &lt; 0.05), in the absence of detectable changes in LH. These effects were most apparent in older men and differed according to age for some parameters: pulsatile Te secretion (p = 0.03) and Te pulse frequency (p = 0.02). Time-of-day analyses revealed that sleep restriction significantly reduced Te in the morning and afternoon, reduced LH in the morning in both age groups, and increased F in the afternoon in older men. Conclusions These data suggest a time-of-day dependent uncoupling of the regulatory control of the testicular axis and of F secretion. Future studies will need to directly verify these regulatory possibilities specifically and separately in young and older men. Clinical Trial Not applicable.

Abstract Background Aging is associated with diminished testosterone (Te) secretion, which may be attributed to Leydig cell dysfunction, decreased pituitary stimulation, and altered Te feedback. Objective To study all regulatory nodes—gonadotropin-releasing hormone (GnRH), luteinizing hormone (LH) and Leydig cell—in the same cohort of healthy men. Study Design This was a placebo-controlled, blinded, prospectively randomized cross-over study in 40 men, age range 19 to 73 years, and body mass index (BMI) range 20 to 34.3 kg/m2. A submaximal dose of the GnRH antagonist ganirelix was used to assess outflow of GnRH, by calculating the difference between LH output during the control arm and ganirelix arm. Ketoconazole (a steroidogenic inhibitor) was used to estimate feedback, by the difference in LH output during the ketoconazole and control arm. High-dose ganirelix and repeated LH infusions were used to measure testicular responsivity. Blood sampling was performed at 10-minute intervals. Results There were age-related, but not body composition–related decreases in estimated GnRH secretion, the feedback strength of Te on LH, and Leydig cell responsivity to LH, accompanied by changes in approximate entropy. Bioavailable Te levels were negatively related to both age and computed tomography (CT)–estimated abdominal visceral mass (AVF), without interaction between these variables. The LH response to a submaximal dose of GnRH was independent of age and AVF. Conclusion Advancing age is associated with (1) attenuated bioavailable Te secretion caused by diminished GnRH outflow and not by decreased GnRH responsivity of the gonadotrope, (2) diminished testicular responsivity to infused LH pulses, and (3) partial compensation by diminished Te feedback on central gonadotropic regulation.