Changes In Hormone Concentrations Research Articles

Endocrine flexibility can facilitate or constrain the ability to cope with global change.

Global climate change has increased average environmental temperatures world-wide, simultaneously intensifying temperature variability and extremes. Growing numbers of studies have documented phenological, behavioural and morphological responses to climate change in wild populations. As systemic signals, hormones can contribute to orchestrating many of these phenotypic changes. Yet little is known about whether mechanisms like hormonal flexibility (reversible changes in hormone concentrations) facilitate or limit the ability of individuals, populations and species to cope with a changing climate. In this perspective, we discuss different mechanisms by which hormonal flexibility, primarily in glucocorticoids, could promote versus hinder evolutionary adaptation to changing temperature regimes. We focus on temperature because it is a key gradient influenced by climate change, it is easy to quantify, and its links to hormones are well established. We argue that reaction norm studies that connect individual responses to population-level and species-wide patterns will be critical for making progress in this field. We also develop a case study on urban heat islands, where several key questions regarding hormonal flexibility and adaptation to climate change can be addressed. Understanding the mechanisms that allow animals to cope when conditions become more challenging will help in predicting which populations are vulnerable to ongoing climate change. This article is part of the theme issue 'Endocrine responses to environmental variation: conceptual approaches and recent developments'.

Effect of Selenomethionine or Yeast Enriched with Selenium on Reproductive Performance, Progesterone and Estrogen Hormones in Iraqi Ewes

This study was conducted at the animal farm affiliated with the college of agriculture, university of anbar, ramadi, iraq, to investigate the effects of selenomethionine or selenium-enriched yeast on the reproductive performance and hormone levels (progesterone and estrogen) in Iraqi ewes. the study was carried out from July 26, 2022, to january 27, 2023. eighteen ewes with an average age of 2-3 years and an average body weight of 43 ± 2.5 kg were used. the ewes were randomly divided into three equal groups, with six ewes in each group. all ewes were fed the same ration. group 1 served as the control group and received no treatment, while group 2 was treated with selenomethionine at a dose of 0.03 g/kg/bw. group 3 was treated with selenium-enriched yeast (saccharomyces cerevisiae-selenium) at the same dose, following the guidelines of the national research council (nrc, 1980). the treatments were administered orally for 45 days by dissolving the samples in 30 ml of distilled water. blood samples were collected from the jugular vein to assess changes in hormone concentrations. the results showed a significant increase in progesterone levels during the second period for groups 1 and 2 compared to group 3 (p ≤ 0.01). group 1 exhibited a significant increase in the time of the first appearance of estrus and the average time for estrus compared to group 2. group 2 showed a significant increase in estrus rate compared to group 1 and group 3. both group 2 and group 3 exhibited a significant increase in fertility rate, fertilization rate, pregnancy rate, and lambing rate. group 2 and group 3 also showed a significant increase in fecundity, twinning rate, and litter size compared to group 1. In conclusion, the supplementation of Selenomethionine and Selenium-enriched yeast positively affected reproductive performance in Iraqi ewes, as evidenced by improved hormone levels, estrus characteristics, fertility rates, and lambing outcomes.

Salivary Testosterone and Cortisol Changes During a Game in Professional Male Basketball Players.

Cabarkapa, D, Eserhaut, DA, Cabarkapa, DV, Philipp, NM, and Fry, AC. Salivary testosterone and cortisol changes during a game in professional male basketball players. J Strength Cond Res 37(8): 1687-1691, 2023-The purpose of this study was to examine acute changes in salivary testosterone (T), cortisol (C), and testosterone-to-cortisol ratio (T/C) during a simulated 5-on-5 basketball game. Seven professional male basketball players volunteered to participate in this study. Repeated-measures analysis design was used to examine changes in hormonal concentrations across 8 testing time points: immediately upon arrival to the gymnasium-baseline (BS); post-warm-up (PW); post-first (P1Q), second (P2Q), third (P3Q), and fourth quarter (P4Q); and 30 (P30) and 60 minutes (P60) postgame. The findings of this study indicate that a simulated 5-on-5 basketball game provoked significant changes in salivary T, C, and T/C. When compared to the BS levels (x̄ ± SD [nmol·L-1]; 6.72 ± 2.53), salivary C concentration experienced a notable increase P3Q (16.20 ± 7.70) and remained elevated throughout the rest of the sampling periods, with values failing to return to BS levels P60 (11.88 ± 5.58). Conversely, a significant increase in salivary T occurred P1Q (0.76 ± 0.21) when compared to the BS levels (0.58 ± 0.12) and remained elevated up to P30 (0.75 ± 0.20), with values returning to BS levels P60 (0.63 ± 0.14). In addition, despite no significant intragame alterations, T/C exhibited a notable decrease P30 (0.06 ± 0.02) and P60 (0.07 ± 0.04), when compared to BS values (0.10 ± 0.04). Overall, these findings provide additional insight into the physiological stress that basketball players are exposed to during 5-on-5 competitive play and can be used to appropriately adjust and monitor training loads to optimize recovery and on-court basketball performance.

Hormonal imbalance in patients with chronic kidney disease in the pre-dialysis and dialysis periods (part 2)

In the previous article, we presented the results of literature review showing the changes in hormone concentrations (parathyroid hormone, insulin, growth factor, prolactin) in patients with chronic renal failure (CRF) at the pre-dialysis and dialysis stages, described pathological relationships between renal failure and serum hormones concentrations, as well as changes in their biological effects. In this article, that continues the general topic, we provide the results of literature review that shows changes in serum concentrations of thyroid, adrenal, sex hormones and the features of the functioning of hypothalamus-pituitary-peripheral glands axis in patients with CRF. The presence of close pathogenic interactions of renal functional condition with hormonal activity of the thyroid gland was evaluated, as well as the ability of thyroid gland to influence the CRF progression both during pre-dialysis and dialysis sta­ges of CRF. Most patients with CRF have low serum triiodothyronine and thyroxine levels. It means that CRF is a pathological condition associated with thyroid hypofunction that progressively worsening as glomerular filtration rate decreases. For patients receiving dialysis treatment, hypothyroidism is associated with higher mortality. Secondary adrenal insufficiency is usually progresses in patients on renal replacement therapy. Non-diagnosed chronic adrenal failure may be life-threating that’s why the analysis of adrenal function is especially actual for patients on both pre-­dialysis and dialysis stages of CRF. Secondary adrenal insufficiency caused by long-lasting treatment with corticoids is a diagnostic problem for patients on dialysis treatment, because many nephrological diseases are treated by corticoids, and immunosuppressive therapy protocols used after the kidney transplantation are usually include prednisone. As the endocrine dysfunction progresses in patients with CRF, sexual dysfunction develops due to sex hormone imbalance. Abnormal androgen concentration is a typical fin­ding in CRF. A negative correlation was found between endogenic testosterone concentration and CRF stages I–V that indicated an abnormal profile of male sex hormones. There are gender-specific features of the development and progression of clinical symptoms of hormonal imbalance. The number of experimental studies show that continuous estradiol treatment may prevent the development of glomerulosclerosis. The results of clinical trials concluded that lower CRF progression and the lower incidence of CRF observed in young females compared to males, as well as the absence of gender protection in post-menopausal period, shows the important role of female sex hormones.

Exercise-Induced Alternations of Adiponectin, Interleukin-8 and Indicators of Carbohydrate Metabolism in Males with Metabolic Syndrome.

Adiponectin (ADIPO) and interleukin-8 (IL-8) are proteins that play a significant, albeit opposing, role in metabolic syndrome (MetS). The reported data on the effect of physical activity on the levels of these hormones in the population of people with MetS are conflicting. The aim of the study was to evaluate the changes in hormone concentrations, insulin-resistance indices and body composition after two types of training. The study included 62 men with MetS (age 36.6 ± 6.9 years, body fat [BF] = 37.53 ± 4.5%), randomly assigned to: an experimental group EG1 (n = 21) with aerobic exercise intervention, an experimental group EG2 (n = 21) with combined aerobic and resistance exercise intervention, both for 12 weeks, and a control group CG (n = 20) without interventions. Anthropometric measurements and body composition (fat-free mass [FFM], gynoid body fat [GYNOID]), as well as a biochemical blood analysis (adiponectin [ADIPO], interleukin-8 [IL-8], homeostatic model assessment-adiponectin (HOMA-AD) and homeostatic model assessment-triglycerides (HOMA-TG) were performed at baseline, and at 6 and 12 weeks of intervention and 4 weeks after the intervention (follow-up). Intergroup (between groups) and intragroup (within each group) changes were statistically evaluated. In the experimental groups EG1 and EG2, no significant changes were observed in the ADIPO concentration, but a decrease of GYNOID and insulin-resistance indices was confirmed. The aerobic training led to favorable changes in IL-8 concentration. The use of combined resistance and aerobic training led to improved body composition, decreased waist circumference and better insulin-resistance indices in men with MetS.

Studies of Thyroid Hormones (Propylthiouracil and L-Thyroxine) Interaction with Human Serum Albumin-Spectroscopic Approach

In this work, UV-absorption, fluorescence spectroscopy and Fourier transform infrared (FTIR) spectroscopy were used to investigate the relationship between Propylthiouracil and L-Thyroxine with human serum albumin. The binding constants of propylthiouracil and L-Thyroxine have been determined of both UV-absorption and fluorescence spectroscopy. The binding Constants values measured at 293k are 1.659×10³ M^-1 for propylthiouracil and 1.013×10⁴ M^-1 for L-Thyroxine. The constant values of the Stern–Volmer quenching were determined to be 2.144×10³ L mol^-1 for propylthiouracil and 1.937×10³ L mol^-1 L-for Thyroxine. The UV-absorption intensity of HSA- hormones complexes has increased with increasing of propylthiouracil and L-Thyroxine concentration. With the rise in propylthiouracil and L-thyroxine concentrations, the fluorescence results indicate a decrease in HSA- hormone emission intensity. To determine the effects of protein secondary structure and hormone binding mechanisms, we have used FTIR spectroscopy with Fourier self-deconvolution technique and second derivative resolution enhancement, as well as curve-fitting methods for the investigation of the amide I, II, and III regions. The peak positions within the three amide regions (amide I, amide II and amide III) were allocated and any results were explored due to changes in concentration. Due to variations in hormone concentrations, the measurements of the FTIR spectra indicate a difference in the intensity of absorption bands.. FTIR Spectra measurements reflect a difference in the strength of the absorption bands due to changes in hormone concentrations.

Thyroid hormones in canine pregnancy and lactation

It is believed that thyroid function has a significant effect on fertility and fetal development in mammals. So far, however, only few studies have been published about potential effects of the reproductive cycle stage on thyroid hormone concentrations in dogs. Therefore, over the course of 122 pregnant and non-pregnant cycles in healthy bitches, Thyroid stimulating hormone (TSH), free Thyroxine (fT4), total Thyroxine (tT4) and Progesterone (P4) were measured six times to assess the influence of the cycle stage and pregnancy on hormone concentrations. The aim was to evaluate established reference intervals for the thyroid hormones in a female study population. Of the 122 bitches, 98 became pregnant. Blood samples were collected during estrus, three times in pregnancy, during lactation and after weaning, or at equivalent times during and after estrus in non-pregnant dogs. No differences between pregnant and non-pregnant animals in any of the thyroid hormones were found. Hormone concentrations, however, differed significantly between the six samplings (p < .01). TSH initially declined during pregnancy, then rose again. The mean concentration of all dogs exceeded the overall upper reference limit of 0.70 ng/mL during lactation. Concentrations of tT4 and ft4 increased during the first third of pregnancy and then subsequently declined. The overall reference limits for tT4 were 0.47–3.20 μg/dL, and for fT4 4.86–29.60 pmol/L, but the reference intervals varied between the sampling dates. The observed patterns may reflect that maternal tT4 and fT4 seem to have important effects during early pregnancy, including a pronounced negative feedback effect on TSH. The initial increase and subsequent decline of tT4 and fT4 concentrations during the course of pregnancy is in accordance with findings in humans and may support the development of fetal thyroid function. The observed peak of TSH concentrations during lactation suggests that the demand for thyroid hormones in this phase is largest. Even if the underlying causes and mechanisms of thyroid regulation are not fully understood, the results of this study show relevant changes of hormone concentrations in the course of the sexual cycle and pregnancy. In that regard, cycle stage needs to be considered when assessing thyroid function in bitches.

Influence of puberty on relationships between body composition and blood pressure: a cross-sectional study.

Fat mass (FM) and fat-free mass (FFM) are positively associated with blood pressure (BP) in youth. Yet, how puberty, independent of age, affects these relationships remains unclear. Given puberty may be a crucial period for cardiometabolic health, we examined how pubertal development moderates the associations of FM/FFM with BP. Pubertal development, resting BP, and body composition were assessed in a convenience sample of youth (5.5-17 years). General linear models were conducted to assess if pubertal development moderated the relationships between FM/FFM and systolic/diastolic BP standardized for age, sex, and height (SBPz/DBPz). Among participants (N = 1405; age: M = 13.3 ± 2.9 years; 65.4% female; 53.2% racial/ethnic minority), FM/FFM were positively associated with SBPz and DBPz (ps ≤ 0.02). Pubertal development moderated the associations between FFM and BPz (ps ≤ 0.01), but not FM (ps > 0.43). For early/mid and late pubertal participants, there were positive associations between FFM and BP (DBPz: βs = 0.10-0.18, ps ≤ 0.01; SBPz: βs = 0.33-0.43, ps < 0.001); however, these relationships were attenuated, especially for prepubertal DBPz (DBPz: β = 0.01, p = 0.91; SBPz: β = 0.24, p = 0.001). Puberty moderated the relationships between FFM and SBPz/DBPz in analyses that separately modeled the contributions of age and sex. These data suggest that the FFM-DBPz association may potentially be impacted by increasing sex hormone concentrations during puberty. Fat mass (FM) and blood pressure (BP) were positively associated throughout puberty. Fat-free mass (FFM) and BP were positively associated throughout puberty; however, puberty moderated the FFM-BP relationship, such that there was a positive relationship in early/mid and late puberty, but the relationship was attenuated for prepubertal children. These findings contribute further insight into physiological and cardiometabolic changes occurring during puberty. Changes in hormone concentrations may explain the impact puberty has on the FFM-BP relationship. Understanding predictors of BP are important as childhood BP is associated with future cardiometabolic outcomes.

The influence of manual semen collection in male trained dogs (Canis familiaris), in the presence or absence of a female in estrus, on the concentrations of cortisol, oxytocin, prolactin and testosterone.

Sex pheromones are chemical substances secreted into the environment that affect the physiology and behavior of recipients. Females use these compounds during oestrus to attract males, which leads to attempts of mating. This study evaluates the influence of manual semen collection in male dogs, in the presence or absence of a female in estrus, on the blood concentrations of cortisol (CRT), oxytocin (OXT), prolactin (PRL) and testosterone (T), as hormones involved both in the physiology of reproduction and stress. Ten male dogs were used in Experiment 1 to measure the serum and plasma concentrations of the aforementioned hormones in the absence of semen collection. Subsequently in the same animals, the concentrations of these hormones were evaluated before and after semen collection in the presence (Exp. 2) or in absence of a female in estrus (Exp. 3). No significant changes in hormone concentration caused by the semen collection were found, either with, or without the presence of female in estrus. Obtained results suggest that the procedure of manual semen collection in dogs, probably due to its passive character, does not stimulate endocrine glands to secrete hormones, and the process of ejaculation is probably controlled by neural pathway. The lack of effect of semiochemical stimulation to the CRT, PRL, OXT and T level, could be caused by a short contact with female during semen collection. Further studies on involvement of the hormones during the process of natural mating, especially preceded by long courtships, similar to that observed under natural conditions, should shed a light on the physiology of mating and the connection between the endocrine system and semiochemical stimulation in dogs.

Изучение влияния пептидов продуктов пчеловодства на поведение крыс в условиях хронического стресса

Chronic stress is one of the causes of depression. Various daily factors, accumulating, can lead to the formation of a constant state of stress and anxiety. In this study, we measured the ability of peptides of royal jelly, drone brood, and bee honey up to 5 kDa to reduce anxiety under chronic stress conditions in male Wistar rats. To do this, the animals of the control and experimental groups were subjected to random stress factors for 14 days (2 factors per day), while simultaneously receiving 0.9% NaCl solution (control group) or aqueous solutions of the corresponding peptides intranasally at a concentration of 300 μg/kg of body weight (peptides were obtained by a combination of ultrafiltration, ion exchange chromatography and gel-filtration). After 14 days, the level of anxiety in animals of all groups was measured using such behavioral tests as “Open field”, “Forced swimming” and “Light-dark box”. It was found that in the OF test, animals treated with royal jelly and drone brood peptides show shorter freezing time, higher horizontal and vertical locomotor activity, spend more time on research activities and grooming; in the FST animals of the same groups spent more time actively swimming; in the LDB test animals of the same groups spent more time in the illuminated part of the experimental setup and crossed the border between the dark and light parts more times. The results indicate that rats treated with royal jelly and drone brood peptides have lower levels of stress and anxiety compared to animals that received 0.9% NaCl solution (control group) or a solution of bee honey peptides. After conducting behavioral tests, the animals were withdrawn from the experiment and the concentration of corticosterone and ACTH was determined in the blood serum. It was found that there is no any changes in hormone concentrations between rats from control or experimental groups. Probably, the peptides of drone brood and royal jelly have an anxiolytic effect, without affecting the work of the hypothalamic-pituitary-adrenal axis, but acting through intracerebral molecular targets.

The Impact of Heat Stress on Immune Status of Dairy Cattle and Strategies to Ameliorate the Negative Effects

Heat stress (HS) is well known to influence animal health and livestock productivity negatively. Heat stress is a multi-billion-dollar global problem. It impairs animal performance during summer when animals are exposed to high ambient temperatures, direct and indirect solar radiations, and humidity. While significant developments have been achieved over the last few decades to mitigate the negative impact of HS, such as physical modification of the environment to protect the animals from direct heat, HS remains a significant challenge for the dairy industry compromising dairy cattle health and welfare. In such a scenario, it is essential to have a thorough understanding of how the immune system of dairy cattle responds to HS and identify the variable responses among the animals. This understanding could help to identify heat-resilient dairy animals for breeding and may lead to the development of climate resilient breeds in the future to support sustainable dairy cattle production. There are sufficient data demonstrating the impact of increased temperature and humidity on endocrine responses to HS in dairy cattle, especially changes in concentration of hormones like prolactin and cortisol, which also provide an indication of the likely im-pact on the immune system. In this paper, we review the recent research on the impact of HS on immunity of calves during early life to adult lactating and dry cows. Additionally, different strategies for amelioration of negative effects of HS have been presented.

UV-B Radiation as a Novel Tool to Modulate the Architecture of In Vitro Grown Mentha spicata (L.)

In vitro culturing can generate plants with a distorted morphology. Some distortions affect the plant’s survival after transfer to an ex vitro environment, while others can affect the aesthetic value. Therefore, exogenous hormones are often applied in in vitro cultures to modulate plant architecture. In this study, it was hypothesised that regulatory effects of UV-B radiation on plant morphology can be exploited under in vitro conditions, and that UV exposure will result in sturdier, less elongated plants with more branches and smaller leaves, mediated by changes in plant hormones. Plants were grown in tissue-culture containers and exposed to ~0.22 W m−2 UV-B for 8 days. Subsequently, plants were transferred to soil and monitored for a further 7 days. Results show that UV induced a marked change in architecture with a significant increase in axillary branches, and reductions in leaf area, plant height and root weight. These changes were associated with significant alterations in concentrations of hormones, including IAA, GA7, GA3 and iP–9–G. Changes in hormone concentrations suggest a regulatory, rather than a stress response to UV-B. Therefore, it is proposed that the application of UV in in vitro culture can be an innovative approach to manipulate plant architecture.

Adverse Outcome Pathways for Chronic Copper Toxicity to Fish and Amphibians.

In the present review, we synthesize information on the mechanisms of chronic copper (Cu) toxicity using an adverse outcome pathway framework and identify three primary pathways for chronic Cu toxicity: disruption of sodium homeostasis, effects on bioenergetics, and oxidative stress. Unlike acute Cu toxicity, disruption of sodium homeostasis is not a driving mechanism of chronic toxicity, but compensatory responses in this pathway contribute to effects on organism bioenergetics. Effects on bioenergetics clearly contribute to chronic Cu toxicity with impacts at multiple lower levels of biological organization. However, quantitatively translating these impacts into effects on apical endpoints such as growth, amphibian metamorphosis, and reproduction remains elusive and requires further study. Copper-induced oxidative stress occurs in most tissues of aquatic vertebrates and is clearly a significant driver of chronic Cu toxicity. Although antioxidant responses and capacities differ among tissues, there is no clear indication that specific tissues are more sensitive than others to oxidative stress. Oxidative stress leads to increased apoptosis and cellular damage in multiple tissues, including some that contribute to bioenergetic effects. This also includes oxidative damage to tissues involved in neuroendocrine axes and this damage likely alters the normal function of these tissues. Importantly, Cu-induced changes in hormone concentrations and gene expression in endocrine-mediated pathways such as reproductive steroidogenesis and amphibian metamorphosis are likely the result of oxidative stress-induced tissue damage and not endocrine disruption. Overall, we conclude that oxidative stress is likely the primary driver of chronic Cu toxicity in aquatic vertebrates, with bioenergetic effects and compensatory response to disruption of sodium homeostasis contributing to some degree to observed effects on apical endpoints. Environ Toxicol Chem 2022;41:2911-2927. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Dairy Buffalo Behavior: Calving, Imprinting and Allosuckling.

Maternal behavior, in water buffalo and other ruminants, is a set of patterns of a determined species, including calving, imprinting, and suckling. This behavior is mainly triggered by hormone concentration changes and their interactions with their respective receptors in the brain, particularly oxytocin. These chemical signals also influence mother-young bonding, a critical process for neonatal survival that develops during the first postpartum hours. Currently, dairy buffalo behavior during parturition has rarely been studied. For this reason, this review aims to analyze the existing scientific evidence regarding maternal behavior in water buffalo during calving. It will address the mechanisms of imprinting, maternal care, and allosuckling strategies that may influence the survival and health of calves.

Numerical characterization of 1D-Photonic crystal waveguide for female reproductive hormones sensing applications

The current work investigates the detection of a wide range of estradiol and progesterone hormone concentrations by the use of a defective 1D photonic crystal. The suggested structure consists of repeating layers of PbS and SiO2, with a central cavity layer. The transfer matrix technique is manipulated to examine the transmission spectrum of the proposed structure. The mainstay of the present work is to analyse the shift in the wavelength of the defect mode concerning the changes in different concentrations of hormones that are infiltrated into the cavity layer. In the course of a simulation, various geometrical parameters such as the thickness of the cavity layer and incident angle are properly optimized to envisage high performance. The colour map plot is investigated to convey a clear view of the shift of defect mode position concerning the change in incident angle. Moreover, all the sensing parameters like sensitivity, figure of merit, quality factor, signal-to-noise ratio, sensor resolution, and limit of detection are evaluated for each hormone at different incident angles. The main application behind this study is that it is important to sense the levels of estradiol and progesterone hormones for balanced needs in a women's reproductive system as well as to monitor the overall health systems. This proposed structure is suitable for bio-sensing applications due to their cost-effective fabrication and high performance.

Effects of Phytohormone-Producing Rhizobacteria on Casparian Band Formation, Ion Homeostasis and Salt Tolerance of Durum Wheat

Inoculation with plant growth-promoting rhizobacteria can increase plant salt resistance. We aimed to reveal bacterial effects on the formation of apoplastic barriers and hormone concentration in relation to maintaining ion homeostasis and growth of salt-stressed plants. The rhizosphere of a durum wheat variety was inoculated with cytokinin-producing Bacillus subtilis and auxin-producing Pseudomonas mandelii strains. Plant growth, deposition of lignin and suberin and concentrations of sodium, potassium, phosphorus and hormones were studied in the plants exposed to salinity. Accumulation of sodium inhibited plant growth accompanied by a decline in potassium in roots and phosphorus in shoots of the salt-stressed plants. Inoculation with both bacterial strains resulted in faster appearance of Casparian bands in root endodermis and an increased growth of salt-stressed plants. B. subtilis prevented the decline in both potassium and phosphorus concentrations and increased concentration of cytokinins in salt-stressed plants. P. mandelii decreased the level of sodium accumulation and increased the concentration of auxin. Growth promotion was greater in plants inoculated with B. subtilis. Increased ion homeostasis may be related to the capacity of bacteria to accelerate the formation of Casparian bands preventing uncontrolled diffusion of solutes through the apoplast. We discuss the relative impacts of the decline in Na accumulation and maintenance of K and P content for growth improvement of salt-stressed plants and their possible relation to the changes in hormone concentration in plants.

Longitudinal changes in serum testosterone and sex hormone-binding globulin in men aged 40-69 years from the UK Biobank.

Testosterone and sex hormone-binding globulin (SHBG) concentrations are reported to decline during male ageing, but whether these changes reflect physiological ageing or age-related comorbidities remains uncertain. We examined longitudinal changes in serum testosterone and SHBG concentrations in middle-aged to older men, concordance between baseline and follow-up valuesand relationships with concomitant changes in lifestyle and medical factors. Population-based longitudinal cohort study. Community-dwelling men aged 40-69 years. Immunoassay serum total testosterone (n = 7812) and SHBG (n = 6491) at baseline (2006-2010) and follow-up (2012-2013). Free testosterone (cFT) was calculated. Bland-Altman analyses and concordance correlation of repeated measurements were conducted. Associations of changes in hormone concentrations with lifestyle and medical factors were explored using Spearman's rank correlation. Over 4.3 years follow-up, there was a negligible mean change (±SE) in serum total testosterone concentration (+0.06 ± 0.03 nmol/L), whereas mean SHBG concentration increased (+3.69 ± 0.12 nmol/L) and cFT decreased (-10.7 ± 0.7 pmol/L). Concordance estimates were 0.67 (95% confidence interval [CI]: 0.66-0.69) for total testosterone, 0.83 (CI = 0.82-0.84) for SHBG and 0.56 (CI = 0.54-0.58) for cFT. Changes in serum total testosterone correlated with changes in SHBG (Spearman's rank ρ = 0.33, CI = 0.30-0.35), and inversely with changes in body mass index (BMI) (ρ = -0.18, CI = -0.20 to -0.16)and waist circumference (ρ = -0.13, CI = -0.15 to -0.11) and in SHBG with changes in BMI (ρ = -0.34, CI = -0.36 to -0.32) and waist circumference (ρ = -0.21, CI = -0.24 to -0.19). In relatively healthy middle-aged to older men, mean serum total testosterone concentration is stable with ageing, while mean SHBG concentration increases. Both total testosterone and SHBG concentrations were highly concordant over time.

Repeatability of daily profiles of baseline glucocorticoid metabolites measured in the urine and faeces of eastern rock sengis (Elephantulus myurus)

Repeatability of hormone concentrations is of great interest for studies investigating the evolution of hormonal traits. Particularly the repeatability of glucocorticoids (GCs) in response to a stressor is frequently investigated, but often only point (initial and/or response value), or single measures are used. A new method takes into account the entire individual hormone profile and generates an individual profile repeatability (PR) score. The method was developed for response profiles, but it may also be valuable for baseline values in species with diurnal changes in hormone concentrations. GCs are determined in a variety of matrices, and repeatability can vary considerably depending on the matrix. We investigated the repeatability of baseline GC metabolite (GCM) concentrations measured in urine (uGCM) and faeces (fGCM) of captive eastern rock sengis (Elephantulus myurus) using the more traditional linear mixed model approach and the PR method. GCMs were assessed over 24 h and measurements were repeated twice with two weeks between replicates. A diurnal rhythm in GCM concentrations associated with the activity period of the sengis was found in urine, but not in the faeces. Urinary GCM concentrations exhibited a moderate repeatability, whereas the repeatability of fGCM concentrations was low. Urinary GCM concentrations and their repeatability differed between the sexes; with higher concentrations and lower PR scores in females. No such sex differences were apparent for fGCM concentrations and the PR score was not able to characterise repeatability of fGCM concentrations, which were lacking a distinct profile. The PR score enabled a successful quantification of the repeatability of the diurnal uGCM profiles. Hormone profile, sex and sample matrix can affect hormonal traits considerably and the results may be obscured if these factors are not carefully considered.

Physical activity in relation to circulating hormone concentrations in 117,100 men in UK Biobank

PurposePhysical activity may reduce the risk of some types of cancer in men. Biological mechanisms may involve changes in hormone concentrations; however, this relationship is not well established. Therefore, we aimed to investigate the associations of physical activity with circulating insulin-like growth factor-I (IGF-I), sex hormone-binding globulin (SHBG, which modifies sex hormone activity), and total and free testosterone concentrations, and the extent these associations might be mediated by body mass index (BMI).MethodsCirculating concentrations of these hormones and anthropometric measurements and self-reported physical activity data were available for 117,100 healthy male UK Biobank participants at recruitment. Objectively measured accelerometer physical activity levels were also collected on average 5.7 years after recruitment in 28,000 men. Geometric means of hormone concentrations were estimated using multivariable-adjusted analysis of variance, with and without adjustment for BMI.ResultsThe associations between physical activity and hormones were modest and similar for objectively measured (accelerometer) and self-reported physical activity. Compared to men with the lowest objectively measured physical activity, men with high physical activity levels had 14% and 8% higher concentrations of SHBG and total testosterone, respectively, and these differences were attenuated to 6% and 3% following adjustment for BMI.ConclusionOur results suggest that the associations of physical activity with the hormones investigated are, at most, modest; and following adjustment for BMI, the small associations with SHBG and total testosterone were largely attenuated. Therefore, it is unlikely that changes in these circulating hormones explain the associations of physical activity with risk of cancer either independently or via BMI.

Endocrine and Body Composition Changes Across a Competitive Season in Collegiate Speed-Power Track and Field Athletes.

Mangine, GT, Eggerth, A, Gough, J, Stratton, MT, Feito, Y, and VanDusseldorp, TA. Endocrine and body composition changes across a competitive season in collegiate speed-power track and field athletes. J Strength Cond Res 35(8): 2067-2074, 2021-Maintaining lean mass is important for track and field (TF) athletes who compete in speed-power events, but little is known about how lean mass and related hormones might change over an 8- to 10-month collegiate season. Therefore, to monitor changes in free testosterone (T), cortisol (C), and body composition in TF athletes across their entire competitive season, 9 female (20.3 ± 1.2 years, 169 ± 5 cm, and 67.6 ± 8.5 kg) and 7 male (21.1 ± 2.0 years, 181 ± 9 cm, and 77.3 ± 5.9 kg) Division I TF athletes provided resting and fasted blood samples at the onset of their indoor season (baseline), before and on returning from the indoor conference championships (ICCs), at the beginning and end of a heavy midseason training week (HVY), and before leaving for the National Collegiate Athletic Association (NCAA) Championships. Body composition was also assessed at each of these periods using a 4-compartment model. Except for a 20% reduction (p = 0.030) from ICCs to the onset of HVY in men only, linear mixed models with repeated measures did not reveal any changes in hormone concentrations. Compared with baseline, an overall increase in fat-free mass was observed at HVY (∼2.74%, p = 0.023) before it reduced by 3.81% before the NCAA Championships (p = 0.022). Despite variations in training and competition, resting concentrations of hormones indicative of anabolic status remained relatively consistent over the course of an entire season in speed-power TF athletes. Coaches and athletes may consider monitoring these variables to assess the athlete's response to the changing demands of a competitive season.