Changes in the pituitary-testicular system with age

Analysis of diurnal variation in serum testosterone levels in men with symptoms of testosterone deficiency

BACKGROUND

Testosterone (T) plays a crucial role in various physiological functions in men, and understanding the variations in T levels during the day is essential for diagnosing and treating testosterone deficiency (TD).

AIM

We sought to evaluate the reduction in serum total T (TT) levels throughout the day in men with symptoms of testosterone deficiency and to determine the variables having an impact on the extent of this decline.

METHODS

The study population consisted of a group of men who within 3 months of each other had all undergone both early morning and afternoon TT level measurements. We did not include patients with a history of a prior orchiectomy, testosterone levels below 100 ng/dL or above 1000 ng/dL, a history of androgen deprivation therapy, or patients on T therapy. Statistical analyses were conducted using descriptive statistics, t-tests, chi-square tests, and correlation calculations. Liquid chromatography-tandem mass spectrometry was used to measure TT, and a change in TT levels greater than 100 ng/dL was considered significant. Using multivariable and univariable analysis, we attempted to define predictors of a decrease in afternoon TT levels.

OUTCOMES

The majority of men showed no significant difference in T levels between morning and afternoon.

RESULTS

In total, 506 men with a median age of 65 years were analyzed. The most common comorbidities were hypertension and hyperlipidemia. Levels of TT were measured in the morning and afternoon, and no significant differences in mean T levels based on the time of the test were found. Age was not significantly associated with T levels.

CLINICAL IMPLICATIONS

There was a weak negative correlation between age and the difference between morning and afternoon T levels, with younger men showing more significant variations in T levels. The most considerable differences in T levels were observed in men younger than 30 years. There were no predictors of the magnitude of the T decrease in the afternoon.

STRENGTHS AND LIMITATIONS

Strengths of the study include the number of subjects and the use of liquid chromatography-tandem mass spectrometry for T measurement. Limitations include failure to measure morning and afternoon T levels on the same day, the retrospective nature of the study, and a smaller sample size of patients younger than 30 years.

CONCLUSION

In this study we found no strong link between age and daily T fluctuation, but we observed a decrease in the magnitude of variation with aging. The group experiencing the most significant decline in daily T had higher morning and consistently normal afternoon T levels.

Ameliorative effects of nano Moringa on fluoride-induced testicular damage via down regulation of the StAR gene and altered steroid hormones

Fluoride is a common environmental contaminant that has harmful effects on human health when it is present in high concentrations. Fluoride enters the bloodstream after being absorbed by the gastrointestinal system when fluoride-contaminated groundwater is consumed by people. The aim of the present study was to determine whether polyphenol-rich nano Moringa oleifera (NMO) could protect rat testicles from sodium fluoride (NaF) damage by evaluating sperm quality, sex hormones, testicular oxidative status, histopathology, and StAR gene expression. Twenty-eight adult Wistar rats were divided equally and randomly into four groups: group one received distilled water; group two received NMO at a dosage of 250 mg/kg/body weight; group three received NaF at a dosage of 10 mg/kg/body weight; and group four received NaF and NMO. The rats were orally administrated daily for a duration of eight weeks. The study's findings demonstrated that, in comparison to rats exposed to NaF alone, co-administration of NMO and NaF enhanced sperm motility and viability, decreased sperm morphological changes, restored the balance between oxidant and antioxidant status, improved testosterone and dehydroepiandrosterone, improved testicular histology, raised the Johnson score, and upregulated the StAR gene in testicular tissue. These findings show that NMO is promise as a prophylactic medication against sodium fluoride-induced testicular damage because administration of NMO had no adverse effects and enhanced reproductive health.

Frequent coexistence of early repolarization pattern, J-point elevation, and high Sokolow-Lyon voltage in young men

Background

Earlier studies have shown male dominance of an early repolarization (ER) pattern and frequent coexistence with high Sokolow-Lyon voltage. Although possible involvement of androgen is speculated, the underlying mechanism has not been clarified yet. Previous studies were conducted in adult populations or only in children, and there has been no study in which the ER pattern was investigated in a series of individuals ranging from children before puberty to adults.

Methods

We included 600 individuals comprising six groups according to age: 10-14 years old, 15-19 years old, twenties, thirties, forties, and fifties. Each group had 50 males and 50 females. The distribution of an ER pattern and related ECG parameters were assessed by age and gender.

Results

In early teenagers, there was no significant gender difference in the prevalence of an ER pattern (24% in men vs. 28% in women, p = .82). The prevalence of an ER pattern increased after puberty and reached a peak in men in their twenties (42%). With further advance of age, the prevalence of an ER pattern decreased. On the other hand, the prevalence of an ER pattern in women peaked at 28% in teenagers, and it decreased through twenties (20%) to thirties (10%). Similar male dominance after puberty was observed in Sokolow-Lyon voltage and J-point elevation but not in P-wave amplitude.

Conclusion

The prevalence of an ER pattern, Sokolow-Lyon voltage, and J-point elevation are all augmented after puberty and decrease with aging, leading to frequent coexistence of these ECG findings in young men.

It is all About the Chase: Neurosteroidogenesis in Male Rats is Driven by Control of Mating Pace

BACKGROUND

Masculine sexual behaviors are dependent on androstane-derived steroids; however, the modulatory effects of mating, and of mating control, on androstane neurosteroidogenesis remain largely unknown.

OBJECTIVE

Herein, we investigated the effects of mating control, prior sexual experience, and age on brain region specific neurosteroidogenic responses in male rats.

METHODS

Effects of acute sexual experience were tested in naïve male rats that either remained sexually- naïve, were exposed to a standard mating chamber, or were either given control of the mating pace in a standard mating chamber (male control) or mated wherein the female stimulus rat controlled the mating pace in a paced-mating chamber (female control). Aged (10-12 months) sexually responsive male rats were similarly euthanized from the homecage or engaged in male controlled or female controlled mating. All rats were euthanized immediately following exposure conditions for radioimmunoassay of steroids in midbrain, hypothalamus, hippocampus and cortex.

RESULTS

Consummatory sexual behavior in male vs. female-controlled mating paradigms was altered by age and prior sexual experience. Male-controlled mating increased androstane neurosteroid metabolism, such that complementary increases in the testosterone (T) metabolite 5α-androstane-3α-17β- diol (3α-diol) in the midbrain and hypothalamus of male rats corresponded to decreases in the prohormone, T. 3α-diol were increased in the hippocampus in response to the context alone, and to a lesser degree in response to mating. Mating diminished neurosteroidogenesis in the cortex. Neurosteroidogenesis was overall reduced in aged male rats compared to naïve controls, however, these effects were more prominent in sexually non-responsive aged male rats.

CONCLUSION

Extending previous findings, these results indicate differential production of androstane neurosteroids in a mating exposure, age and brain region dependent manner.

Aging and androgens: Physiology and clinical implications

In men >  ~35 years, aging is associated with perturbations in the hypothalamus-pituitary-testicular axis and declining serum testosterone concentrations. The major changes are decreased gonadotropin-releasing hormone (GnRH) outflow and decreased Leydig cell responsivity to stimulation by luteinizing hormone (LH). These physiologic changes increase the prevalence of biochemical secondary hypogonadism-a low serum testosterone concentration without an elevated serum LH concentration. Obesity, medications such as opioids or corticosteroids, and systemic disease further reduce GnRH and LH secretion and might result in biochemical or clinical secondary hypogonadism. Biochemical secondary hypogonadism related to aging often remits with weight reduction and avoidance or treatment of other factors that suppress GnRH and LH secretion. Starting at age ~65-70, progressive Leydig cell dysfunction increases the prevalence of biochemical primary hypogonadism-a low serum testosterone concentration with an elevated serum LH concentration. Unlike biochemical secondary hypogonadism in older men, biochemical primary hypogonadism is generally irreversible. The evaluation of low serum testosterone concentrations in older men requires a careful assessment for symptoms, signs and causes of male hypogonadism. In older men with a body mass index (BMI) ≥ 30, biochemical secondary hypogonadism and without an identifiable cause of hypothalamus or pituitary pathology, weight reduction and improvement of overall health might reverse biochemical hypogonadism. For older men with biochemical primary hypogonadism, testosterone replacement therapy might be beneficial. Because aging is associated with decreased metabolism of testosterone and increased tissue-specific androgen sensitivity, lower dosages of testosterone replacement therapy are often effective and safer in older men.

Hallmarks of Testicular Aging: The Challenge of Anti-Inflammatory and Antioxidant Therapies Using Natural and/or Pharmacological Compounds to Improve the Physiopathological Status of the Aged Male Gonad

The evolutionary theory of aging supports a trade-off relationship between reproduction and aging. Aging of the male reproductive system primarily affects the testes, leading to a decrease in the levels of sexual hormones, alterations in sperm quality and production, and a decline in fertility that does not necessarily involve a complete cessation of spermatogenesis. Inflammation, oxidation, and apoptosis are events considered as predictors of pathogenesis and the development of age-related diseases that are frequently observed in aged testes. Although the molecular mechanisms are still poorly understood, accumulating evidence points toward pro-inflammatory molecules and reactive oxygen species as primary contributing factors for testicular aging. However, the real impact of aging-related testicular alterations on fertility, reproductive health, and life span is far from being fully revealed. This work discusses the current knowledge on the impact of aging in the testis, particularly of aging-related dysregulated inflammation and oxidative damage on the functioning of its different cell populations. More interestingly, this review covers the potential benefits of anti-aging interventions and therapies using either pharmacological compounds (such as non-selective non-steroidal anti-inflammatory medication) or more natural alternatives (such as various nutraceuticals or even probiotics) that exhibit anti-inflammatory, antioxidant, and anti-apoptotic properties. Some of these are currently being investigated or are already in clinical use to delay or prevent testicular aging.

Androstenedione (a Natural Steroid and a Drug Supplement): A Comprehensive Review of Its Consumption, Metabolism, Health Effects, and Toxicity with Sex Differences

Androstenedione is a steroidal hormone produced in male and female gonads, as well as in the adrenal glands, and it is known for its key role in the production of estrogen and testosterone. Androstenedione is also sold as an oral supplement, that is being utilized to increase testosterone levels. Simply known as "andro" by athletes, it is commonly touted as a natural alternative to anabolic steroids. By boosting testosterone levels, it is thought to be an enhancer for athletic performance, build body muscles, reduce fats, increase energy, maintain healthy RBCs, and increase sexual performance. Nevertheless, several of these effects are not yet scientifically proven. Though commonly used as a supplement for body building, it is listed among performance-enhancing drugs (PEDs) which is banned by the World Anti-Doping Agency, as well as the International Olympic Committee. This review focuses on the action mechanism behind androstenedione's health effects, and further side effects including clinical features, populations at risk, pharmacokinetics, metabolism, and toxicokinetics. A review of androstenedione regulation in drug doping is also presented.

The European Academy of Andrology (EAA) ultrasound study on healthy, fertile men: Scrotal ultrasound reference ranges and associations with clinical, seminal, and biochemical characteristics

BACKGROUND

Scrotal color Doppler ultrasound (CDUS) still suffers from lack of standardization. Hence, the European Academy of Andrology (EAA) has promoted a multicenter study to assess the CDUS characteristics of healthy fertile men (HFM) to obtain normative parameters.

OBJECTIVES

To report and discuss the scrotal organs CDUS reference ranges and characteristics in HFM and their associations with clinical, seminal, and biochemical parameters.

METHODS

A cohort of 248 HFM (35.3 ± 5.9years) was studied, evaluating, on the same day, clinical, biochemical, seminal, and scrotal CDUS following Standard Operating Procedures.

RESULTS

The CDUS reference range and characteristics of the scrotal organs of HFM are reported here. CDUS showed a higher accuracy than physical examination in detecting scrotal abnormalities. Prader orchidometer (PO)- and US-measured testicular volume (TV) were closely related. The US-assessed TV with the ellipsoid formula showed the best correlation with the PO-TV. The mean TV of HFM was ~ 17 ml. The lowest reference limit for right and left testis was 12 and 11 ml, thresholds defining testicular hypotrophy. The highest reference limit for epididymal head, tail, and vas deferens was 12, 6, and 4.5 mm, respectively. Mean TV was associated positively with sperm concentration and total count and negatively with gonadotropins levels and pulse pressure. Subjects with testicular inhomogeneity or calcifications showed lower sperm vitality and concentration, respectively, than the rest of the sample. Sperm normal morphology and progressive motility were positively associated with epididymal head size/vascularization and vas deferens size, respectively. Increased epididymis and vas deferens sizes were associated with MAR test positivity. Decreased epididymal tail homogeneity/vascularization were positively associated with waistline, which was negatively associated with intratesticular vascularization. CDUS varicocele was detected in 37.2% of men and was not associated with seminal or hormonal parameters. Scrotal CDUS parameters were not associated with time to pregnancy, number of children, history of miscarriage.

CONCLUSIONS

The present findings will help in better understanding male infertility pathophysiology, improving its management.

Circadian Rhythms in Environmental Health Sciences

PURPOSE OF REVIEW

This review aims to explore how circadian rhythms influence disease susceptibility and potentially modify the effect of environmental exposures. We aimed to identify biomarkers commonly used in environmental health research that have also been the subject of chronobiology studies, in order to review circadian rhythms of relevance to environmental health and determine if time-of-day is an important factor to consider in environmental health studies. Moreover, we discuss opportunities for studying how environmental exposures may interact with circadian rhythms to structure disease pathology and etiology.

RECENT FINDINGS

In recent years, the study of circadian rhythms in mammals has flourished. Animal models revealed that all body tissues have circadian rhythms. In humans, circadian rhythms were also shown to exist at multiple levels of organization: molecular, cellular, and physiological processes, including responding to oxidative stress, cell trafficking, and sex hormone production, respectively. Together, these rhythms are an essential component of human physiology and can shape an individual's susceptibility and response to disease. Circadian rhythms are relatively unexplored in environmental health research. However, circadian clocks control many physiological and behavioral processes that impact exposure pathways and disease systems. We believe this review will motivate new studies of (i) the impact of exposures on circadian rhythms, (ii) how circadian rhythms modify the effect of environmental exposures, and (iii) how time-of-day impacts our ability to observe the body's response to exposure.

Possible link between FSH and RANKL release from adipocytes in men with impaired gonadal function including Klinefelter syndrome

INTRODUCTION

The FSH receptor (FSHR) has been found to be expressed in human bone cells and bone marrow-adipocytes, and highly-debated mouse studies have suggested extra-gonadal effects of gonadotropins on glucose, adipocyte and bone homeostasis. These putative effects could be direct or indirectly mediated by endocrine factors released from bone-cells or adipocytes. Here, we investigated whether gonadotropins are linked with glucose- and lipid-metabolism in hypergonadotropic men.

METHODS

Single centre, cross-sectional study of 307 men with idiopathic infertility and 28 men with Klinefelter syndrome (KS).

OUTCOME

associations between serum LH and FSH with soluble-RANKL (sRANKL), osteoprotegerin (OPG), osteocalcin, fasting glucose and insulin, sex steroids, and body composition. Expression of FSHR was studied in human-derived adipocyte-cell-models (hMADS, TERT-hWA) and FSH stimulation of RANKL expression and secretion in hMADS in vitro.

RESULTS

Serum FSH was not directly linked with glucose- and lipid-metabolism. However, FSH was inversely associated with sRANKL in both infertile men and KS men (p = .023 and p = .012). Infertile men with elevated FSH (>11 U/L) had significantly lower sRANKL (p = .015). sRANKL was positively associated with fat percentage, fasting insulin, and glucose (all p < .05). Men with prediabetes had higher sRANKL (p = .021), but lower testosterone (p < .0001) and Inhibin B (p = .005). The FSHR was expressed in the investigated human derived adipocytes, and 3-6 h treatment with FSH markedly increased RANKL release (p < .05).

CONCLUSION

KS and infertile men with prediabetes have low Inhibin B, and testosterone but elevated RANKL compared with non-prediabetic men despite comparable levels of serum gonadotropins. Serum FSH and sRANKL was inversely associated in both infertile and KS men, but the increased release of RANKL from FSH treated adipocytes suggest a direct effect of FSH on RANKL production in some tissues. Further studies are required to clarify whether FSH targets RANKL in the skeleton. ClinicalTrial_ID:NCT01304927.

Quantitative (stereological) study of the epididymis and seminal vesicle in the rat from young to old

There is a scarcity of morphometric data on the developmental and ageing changes in the epididymis and seminal vesicle in young and old rats. Eighty-six normal male Sprague-Dawley rats were randomly sampled from a cohort of animals aged 1-36 months (7-9 animals each age group). The epididymis and seminal vesicle (with the closely attached coagulating gland) were removed, and methacrylate resin-embedded sections were prepared for quantitative study of key histological structures by light microscopy. Stereological methods (point counting and optical disector) were used to estimate the total volumes of sperm mass, secretion (glandular lumen) and other structures and the number of spermatozoa. The results showed that the rapid growth of the reproductive organs was between 1 and 4 months of age. The epididymis stored the largest volume of sperm mass or number of spermatozoa at 12 months of age, but thereafter until 36 months of age, the sperm storage did not markedly diminish. The volume of secretion stored in the seminal vesicular gland declined by more than 35% from a plateau at 12-18 months until 36 months of age while that in the coagulating gland declined by more than 30% from a plateau at 18-24 months until 36 months of age.

Protocol for systematic review and meta-analysis of sex hormones and diabetes risk in ageing men and women of African ancestry

AIM

To present the protocol of a systematic review and meta-analysis of the available evidence examining the association between sex hormones and type 2 diabetes risk in ageing men and women of African descent.

METHODS

We shall conduct a comprehensive search of published studies that examined the association between sex hormones and type 2 diabetes risk in men and women aged ≥40 years from 01/01/1980 to 31/03/2018 with no language restriction. Databases to be searched include: PubMed, Scopus, Cochrane Library, Cumulative Index to Nursing and Allied Health, ISI Web of Science, Clinical Trial registries, Google Scholar and institutional websites such as the WHO, American Diabetes Association, International Diabetes Federation, World Diabetes Foundation, European Association for the Study of Diabetes, African Journal Online and ProQuest databases. This protocol is developed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols guidelines. Independent screening for eligible studies using defined criteria and data extraction, will be completed in duplicate. Discrepancies will be resolved by consensus or consultation with a third researcher. Risk of bias of included studies will be assessed by the appropriate Cochrane risk of bias tool. The overall association estimates will be pooled using appropriate meta-analytic techniques. Heterogeneity will be assessed using Cochrane Q statistic and the inconsistency index (I2). The random effects model will be used to calculate a pooled estimate.

ETHICS AND DISSEMINATION

No ethics clearance is required as no primary data will be collected. The systematic review and meta-analysis are part of a PhD project at WITS University (Johannesburg, South Africa) and results will be presented at conferences and published in a peer-review journal. The results will guide future population specific interventions.

PROSPERO REGISTRATION NUMBER

CRD42017074581.

Progressive impairment of testicular endocrine function in ageing men: Testosterone and dihydrotestosterone decrease, and luteinizing hormone increases, in men transitioning from the 8th to 9th decades of life

CONTEXT

Sex hormone trajectories in ageing men and their health implications remain unclear. We examined longitudinal trajectories and associations of testosterone (T), dihydrotestosterone (DHT), oestradiol (E2), luteinizing hormone (LH) and sex hormone-binding globulin (SHBG) in oldest old men.

DESIGN

Prospective cohort study.

PARTICIPANTS

We studied 1025 community-dwelling men median age 75.1 years at baseline with 8.6 years of follow-up.

MEASUREMENTS

Baseline and follow-up T, DHT and E2 were assayed using mass spectrometry. Physical performance was assessed at follow-up. Correlations and covariate-adjusted P-values were determined.

RESULTS

Longitudinal change in T was -2.0%/year, DHT -7.2%/year, LH +7.5%/year, SHBG +5.6%/year while E2 remained stable. Annualized increases in LH correlated with decreases in T and DHT (r = -.20, P < .0001 and r = -.12, P = .0035, respectively). Higher baseline T correlated with better physical performance at follow-up (eg, Step test r = .07, P = .03), as did higher baseline DHT (eg, time to sit-stand [TSS] r = -.07, P = .01). Larger annualized increases in LH predicted poorer physical performance at follow-up (eg, TSS r = .14, P = .001). Higher T at follow-up was associated with better physical performance (eg, TSS r = -.07, P = .04), as were higher DHT and lower LH. At baseline, 24 men (2.4%) had abnormally high LH (>16 IU/L); at follow-up, 175 (17.4%) had high LH of whom 70 had low T (<6.4 nmol/L).

CONCLUSIONS

Annualized increases in LH are associated with declines in T and DHT, and predict poorer subsequent physical performance in oldest old men. Men transitioning from 8th to 9th decades exhibit biochemical evidence of progressively impaired testicular endocrine function, warranting further evaluation.

Larger Testicular Volume Is Independently Associated with Favorable Indices of Lung Function

BACKGROUND

Men with chronic obstructive pulmonary disease, have reduced endogenous testosterone levels, but the relationship between pulmonary function and endogenous testosterone levels, is inconsistent. Testicular volume is a known indicator of endogenous testosterone levels, male fertility, and male potency. In the present study, the authors investigated the relationship, between testicular volume and lung function.

METHODS

One hundred and eighty-one South Korean men age 40-70, hospitalized for urological surgery, were retrospectively enrolled, irrespective of the presence of respiratory disease. Study subjects underwent pulmonary function testing, prior to procedures, and testicular volumes were measured by orchidometry. Testosterone levels of patients in blood samples collected between 7 AM and 11 AM, were measured by a direct chemiluminescent immunoassay.

RESULTS

The 181 study subjects were divided into two groups, by testicular volume (≥35 mL vs. <35 mL), the larger testes group, had better lung functions (forced vital capacity [FVC]: 3.87±0.65 L vs. 3.66±0.65 L, p=0.037; forced expiratory volume in 1 second [FEV₁]: 2.92±0.57 L vs. 2.65±0.61 L, p=0.002; FVC % predicted: 98.2±15.2% vs. 93.8±13.1%, p=0.040; FEV₁ % predicted: 105.4±19.5% vs. 95.9±21.2%, p=0.002). In addition, the proportion of patients with a FEV₁/FVC of <70%, was lower in the larger testes group. Univariate analysis conducted using linear regression models, revealed that testicular volume was correlated with FVC (r=0.162, p=0.029), FEV₁ (r=0.218, p=0.003), FEV₁/FVC (r=0.149, p=0.046), and FEV₁ % predicted (r=0.178, p=0.017), and multivariate analysis using linear regression models, revealed that testicular volume was a significant predictive factor for FEV₁ % predicted (β=0.159, p=0.041).

CONCLUSION

Larger testicular volume was independently associated, with favorable indices of lung function. These results suggest that androgens, may contribute to better lung function.

Aging and sex hormones in males

Several large cohort studies have disclosed the trajectories of sex steroids changes overtime in men and their clinical significance. In men the slow, physiological decline of serum testosterone (T) with advancing age overlaps with the clinical condition of overt, pathological hypogonadism. In addition, the increasing number of comorbidities, together with the high prevalence of chronic diseases, all further contribute to the decrease of serum T concentrations in the aging male. For all these reasons both the diagnosis of late-onset hypogonadism (LOH) in men and the decision about starting or not T replacement treatment remain challenging. At present, the biochemical finding of T deficiency alone is not sufficient for diagnosing hypogonadism in older men. Coupling hypogonadal symptoms with documented low serum T represents the best strategy to refine the diagnosis of hypogonadism in older men and to avoid unnecessary treatments.

Assessment of the 2D:4D ratio in aggression-related injuries in children attending a paediatric emergency department

BACKGROUND

The 2D:4D ratio is a sexually dimorphic trait. A lower ratio is correlated with sporting prowess, successful financial trading, risk taking behaviour, aggression, and aggression-related injuries, such as the fifth metacarpal fractures.

AIMS

We aimed to assess if the ratio correlates to skeletally immature patient aggression.

METHODS

Radiology reports were searched for the terms "5th metacarpal" or "boxer". Of 537 X-rays, 142 had fractures. The mechanism of injury was recorded in 102 patients, differentiating aggressive and non-aggressive injury groups. Bone age and chronological age were recorded.

RESULTS

A clear male preponderance for aggression was identified with only 60% of non-aggressive injuries occurring in males compared to 95% in the aggression group (p < 0.001). Patients with aggression injuries were older chronologically (14.6 vs 12.7, p < 0.001) and by bone age (14.5 vs 13.0, p < 0.001). For male patients, there was no difference in the 2D:4D ratio (p = 0.94); however, for females, the difference was significant (p = 0.04).

CONCLUSIONS

Aggression injuries occur at an older age and are more common in males. In the female cohort, there was a distinct difference in digit ratio.

Current opinion on the role of testosterone in the development of prostate cancer: a dynamic model

BACKGROUND

Since the landmark study conducted by Huggins and Hodges in 1941, a failure to distinguish between the role of testosterone in prostate cancer development and progression has led to the prevailing opinion that high levels of testosterone increase the risk of prostate cancer. To date, this claim remains unproven.

PRESENTATION OF THE HYPOTHESIS

We present a novel dynamic mode of the relationship between testosterone and prostate cancer by hypothesizing that the magnitude of age-related declines in testosterone, rather than a static level of testosterone measured at a single point, may trigger and promote the development of prostate cancer.

TESTING THE HYPOTHESIS

Although not easily testable currently, prospective cohort studies with population-representative samples and repeated measurements of testosterone or retrospective cohorts with stored blood samples from different ages are warranted in future to test the hypothesis.

IMPLICATIONS OF THE HYPOTHESIS

Our dynamic model can satisfactorily explain the observed age patterns of prostate cancer incidence, the apparent conflicts in epidemiological findings on testosterone and risk of prostate cancer, racial disparities in prostate cancer incidence, risk factors associated with prostate cancer, and the role of testosterone in prostate cancer progression. Our dynamic model may also have implications for testosterone replacement therapy.

Serum Testosterone (T) Level Variability in T Gel-Treated Older Hypogonadal Men: Treatment Monitoring Implications

CONTEXT

The optimal frequency for on-treatment serum T measurement used for dose adjustment after transdermal T gel application is unknown, especially in older men with thinner skin and slower metabolic clearance.

OBJECTIVES

The objectives of the study was to determine the variability of postgel application serum T concentrations and assess whether single levels are reflective of average serum T concentrations over 24 hours (Cavg0-24).

DESIGN

This was a double-blinded, placebo-controlled randomized trial.

SETTING

The study was conducted at five academic centers.

PARTICIPANTS

Forty-seven symptomatic men 65 years old or older with an average of two morning T concentration less than 275 ng/dL participated in the study.

INTERVENTION(S)

Transdermal T or placebo gel was applied for 120 ± 14 days. Monthly dose adjustments were made if necessary to target serum T between 400 and 500 to 800 ng/dL.

MAIN OUTCOME MEASURES

Variability of serum T 2 hours after the gel application on two outpatient visits and at multiple time points over 24 hours during the inpatient day was measured.

RESULTS

On-treatment T levels varied substantially on the 2 ambulatory days and over 24 hours during the inpatient day. Ambulatory 2-hour postapplication T levels did not correlate significantly with either 2-hour postapplication serum T or Cavg0-24 measured during the inpatient day. Only 22.2% of men receiving T had a Cavg0-24 within the target range of 500-800 ng/dL; 81.5% had a Cavg0-24 within the broader 300-1000 ng/dL range.

CONCLUSION

Large within-individual variations in serum T after T gel application render ambulatory 2-hour postapplication T level a poor indicator of average serum T on another day. Our data point out the limitations of dose adjustments based on a single postapplication serum T measurement.

Could androgens maintain specific domains of mental health in aging men by preserving hippocampal neurogenesis?

Interest surrounds the role of sex-hormones in regulating brain function outside of reproductive behaviour. Declining androgen production in aging males has been associated with cognitive impairment, depression and increased risk of developing Alzheimer's disease. Indication for testosterone replacement therapy is based on biochemically determined low circulating testosterone combined with manifest symptoms. However, which aspects of age-related cognitive decline are attributable to low circulating testosterone remain ambiguous. Studies examining cognition in aging men receiving testosterone replacement therapy have yielded equivocal results. The exact role of testosterone in maintaining cognitive function and the underlying neural mechanisms are largely unknown, though it would appear to be domain specific. Clarity in this area will provide clinical direction toward addressing an increasing healthcare burden of mental health decline coincident with increasing longevity. The premise that androgens contribute to maintaining aspects of mental health in aging men by preserving hippocampal neurogenesis will be used as a forum in this review to discuss current knowledge and the need for further studies to better define testosterone replacement strategies for aging male health.

Effects of seasonal differences in testosterone and cortisol levels on pain responses under resting and anxiety conditions

PURPOSE

This study investigated whether hormones and pain perception are associated with exam anxiety, and also whether exam anxiety is affected by seasonal differences in testosterone and cortisol levels.

MATERIALS AND METHODS

Forty-six healthy males were recruited from a medical college. Anxiety was induced by having participants perform the Objective Structured Clinical Examination. Pressure was applied to the participants to induce pain. Pain thresholds, pain ratings, anxiety ratings, blood pressure, heart rate, salivary testosterone and cortisol levels were measured under resting and anxiety conditions in the spring and summer. Data were collected from 46 participants during the spring (n=25) and summer (n=21).

RESULTS

Pain thresholds and testosterone levels were significantly lower under anxiety than at rest for all participants (n=46), while cortisol levels, pain ratings, and anxiety ratings were significantly higher under anxiety than at rest. In the spring (n=25), testosterone levels were significantly higher at rest than under anxiety, while there was no difference in cortisol levels between resting and anxiety conditions. In the summer (n=21), cortisol levels were significantly higher under anxiety than at rest, while there was no difference in testosterone levels between resting and anxiety conditions. There were no significant seasonal differences in pain and anxiety ratings and pain threshold.

CONCLUSION

These results indicate that seasonal differences in testosterone and cortisol levels under anxiety and at rest may affect pain responses. These results also suggest that acute clinical pain may be relieved by managing anxiety that is related to a decrease of testosterone in spring and a large increase of cortisol in summer.

Puberty dysregulation and increased risk of disease in adult life: possible modes of action

Puberty is the developmental window when the final maturation of body systems is orchestrated by hormones; lifelong sex-related differences and capacity to interact with the environment are defined during this life stage. Increased incidence in a number of chronic, multifactorial diseases could be related to environmental exposures during puberty: however, insight on the susceptibility of the peripubertal period is still limited. The estrogen/androgen balance is a crucial axis in harmonizing the whole pubertal development, pointing out the significance of exposures to endocrine disruptors. Besides the reproductive system, endocrine-related perturbations may affect the maturation of skeleton, adipose tissues, brain, immune system, as well as cancer predisposition. Thus, risk assessment of environmental stressors should duly consider specific aspects of the pubertal window. Besides endocrine-related mechanisms, suggested research priorities include signaling molecules (e.g., kisspeptins, dopamine) as xenobiotic targets and disturbances of specific pubertal methylation processes potentially involved in neurobehavioral disorders and cancer risk in adulthood.

Sex and gonadal hormones in mouse models of Alzheimer's disease: what is relevant to the human condition?

Biologic sex and gonadal hormones matter in human aging and diseases of aging such as Alzheimer's - and the importance of studying their influences relates directly to human health. The goal of this article is to review the literature to date on sex and hormones in mouse models of Alzheimer's disease (AD) with an exclusive focus on interpreting the relevance of findings to the human condition. To this end, we highlight advances in AD and in sex and hormone biology, discuss what these advances mean for merging the two fields, review the current mouse model literature, raise major unresolved questions, and offer a research framework that incorporates human reproductive aging for future studies aimed at translational discoveries in this important area. Unraveling human relevant pathways in sex and hormone-based biology may ultimately pave the way to novel and urgently needed treatments for AD and other neurodegenerative diseases.

Testosterone and cardiovascular disease in men

Despite regional variations in the prevalence of coronary artery disease (CAD), men are consistently more at risk of developing and dying from CAD than women, and the gender-specific effects of sex hormones are implicated in this inequality. This 'Perspectives' article reviews the current evidence regarding the cardiovascular effects of testosterone in men including an examination of the age-related decline in testosterone, the relationship between testosterone levels and coronary disease, coronary risk factors and mortality. We also review the vaso-active effects of testosterone, and discuss how these have been used in men with heart failure and angina. We discuss the 'cause' versus 'effect' controversy, regarding low testosterone levels in men with coronary heart disease, as well as concerns over the use of testosterone replacement therapy in middle aged and elderly men. The article concludes with a discussion regarding the future direction for work in this interesting area, including the relative merits of screening for, and treating hypogonadism with testosterone replacement therapy in men with heart disease.

The effect of circulating estradiol concentrations on gonadotropin secretion in young and old castrated male-to-female transsexuals

CONTEXT

In aging men, circulating testosterone (T) declines which is associated with an increase in the levels of luteinizing hormone (LH) and follicle stimulating hormone (FSH) , albeit insufficient to maintain T at its original level. It has been speculated that a higher sensitivity of the hypothalamus and/or pituitary for the feedback effect of circulating sex hormones in older men is responsible.

OBJECTIVE

To compare the effect of experimentally varied plasma levels of estradiol on the LH and FSH secretion in young and old castrated male-to-female transsexuals, in almost absence of T. DESIGN, SUBJECTS, AND INTERVENTIONS: In 10 healthy, young (mean age 37.6 ± 6.2 years) and 11 healthy, old (mean age 68.1 ± 7.0) male-to-female transsexuals after gonadectomy plasma estradiol levels were experimentally varied with estradiol patches (the first week 100 μg/day patches, the second week 50 μg/day, the third week 25 μg/day and the fourth week no patch was applied) and plasma levels of LH and FSH were monitored after every week.

RESULTS

Mean plasma bioavailable estradiol (E2) levels in the two groups ranged between 13.6 and 104 pmol/l. LH and FSH were inversely related to peripheral estradiol levels, were lower in the old group at all time points reaching statistical significance in the last week of the study when no patch was applied and estradiol levels were extremely low.

CONCLUSIONS

The results of this study do not support the hypothesis of an age related increasing sensitivity of the hypothalamo-pituitary compartment for the negative feedback of E2, but suggest a deficient feed-forward drive in older male-to-female transsexuals.

Aging Men and Lipids

Many theories aim at explaining the mechanisms of aging and death in humans. Decreased levels of androgens, growth hormone, and insulin-like growth factor accompany natural aging in men. Androgens influence the growth and maturation of men in various stages of their life. The action of androgens is performed by binding or not binding to androgen receptors. However, various actions of androgens were clarified after the discovery and genotyping of the androgen receptor. The influence of androgens on the lipid profile was reported by several researchers. This negative influence of androgens in men and the positive influence of estrogens in women are responsible for the higher impact of atherogenesis in men compared with women. In aging men, this negative influence of androgens on the lipid profile is more pronounced. This review considers the influence of age on lipid metabolism in men.

Determinants of male health: the interaction of biological and social factors

This review discusses the social and biological factors that may influence male development from conception to adulthood and also underlie the development of health disorders. It will provide assistance to those who may be considering the formulation of a male health policy. It aims to emphasize that social determinants function on a biological background that is profoundly influenced by a male's genome, inherited from his parents. The importance of the male-specific reproductive disorders is emphasized, but these also affect somatic structures through the secretion of androgens secreted from the testes. In turn, the function of the cardiovascular and nervous systems can significantly influence reproductive processes such as erectile dysfunction.

Seasonal and circadian variation in salivary testosterone in rural Bolivian men

Testosterone (T) plays a key role in the increase and maintenance of muscle mass and bone density in adult men. Life history theory predicts that environmental stress may prompt a reallocation of such investments to those functions critical to survival. We tested this hypothesis in two studies of rural Bolivian adult men by comparing free T levels and circadian rhythms during late winter, which is especially severe, to those in less arduous seasons. For each pair of salivary T(AM)/T(PM) samples (collected in a approximately 12-h period), circadian rhythm was considered classic (C(CLASSIC)) if T(AM) > 110%T(PM), reverse (C(REVERSE)) if T(PM) > 110%T(AM), and flat (C(FLAT)) otherwise. We tested the hypotheses that mean T(AM) > mean T(PM) and that mean T(LW) < mean T(OTHER) (LW = late winter, OTHER = other seasons). In Study A, of 115 T(PM)-T(AM) pairs, 51% = C(CLASSIC), 39% = C(REVERSE), 10% = C(FLAT); in Study B, of 184 T(AM)-T(PM) pairs, 55% = C(CLASSIC), 33% = C(REVERSE), 12% = C(FLAT). Based on fitting linear mixed models, in both studies T(OTHER-AM) > T(OTHER-PM) (A: P = 0.035, B: P = 0.0005) and T(OTHER-AM) > T(LW-AM) (A: P = 0.054, B: P = 0.007); T(PM) did not vary seasonally, and T diurnality was not significant during late winter. T diurnality varied substantially between days within an individual, between individuals and between seasons, but neither T levels nor diurnality varied with age. These patterns may reflect the seasonally varying but unscheduled, life-long, strenuous physical labor that typifies many non-industrialized economies. These results also suggest that single morning samples may substantially underestimate peak circulating T for an individual and, most importantly, that exogenous signals may moderate diurnality and the trajectory of age-related change in the male gonadal axis.

Testosterone's short-term positive effect on luteinizing-hormone secretory-burst mass and its negative effect on secretory-burst frequency are attenuated in middle-aged men

BACKGROUND

Testosterone (T) production declines and LH pulses become smaller and more frequent in middle-aged men. The mechanisms underlying these changes are not known.

RATIONALE

Small frequent LH pulses in middle-aged men could reflect impaired feedback by systemic T.

HYPOTHESIS

Middle age disrupts negative feedback by T on selected facets of LH secretion.

SUBJECTS AND SETTING

Healthy men were studied at an academic medical center.

METHODS

The protocol comprised blockade of gonadal steroidogenesis and graded transdermal addback of T doses of 0, 2.5, 5, or 7.5 mg/d designed to span the castrate to physiological range of T concentrations in each of 23 healthy men ages 19-71 yr (interquartile range, 28-53 yr). We quantified 12-h basal and pulsatile LH secretion (92 time series) using a mathematically justified deconvolution method.

RESULTS

Stepwise T supplementation from the hypogonadal through the eugonadal range repressed mean (12-h) LH concentrations (P = 0.001). By regression analysis, age attenuated the capabilities of increasing T concentrations to 1) increase LH secretory-burst mass (P < 0.0001); and 2) decrease LH secretory-burst frequency (P = 0.025). Age did not alter T's feedback on basal LH secretion, interpulse regularity, the waveform of LH secretory bursts, or the slow half-life of LH.

CONCLUSION

Middle age impairs both the positive and negative actions of systemic T on pulsatile LH secretion in healthy men, thus potentially explaining earlier inconsistencies in feedback studies based upon single-sample mean LH concentrations. Longitudinal studies will be required to elucidate the precise age dependence of inferred dual feedback failure.

Demographic, physical and lifestyle factors associated with androgen status: the Florey Adelaide Male Ageing Study (FAMAS)

OBJECTIVE

Plasma androgen levels are inversely associated with health in men, the age-related decline of which may result from factors other than ageing per se. This study aimed to determine the effects of demographic, physical and lifestyle factors on age-related androgen status in men.

DESIGN

An observational survey of a regionally representative male population residing in the North West regions of Adelaide, Australia.

PARTICIPANTS

Study sample includes 1195 men aged 35-81 years with a response rate of 45.1%.

MEASUREMENTS

Plasma levels of total testosterone (TT), bioavailable testosterone (BT), SHBG, insulin-like peptide 3 (INSL3), and gonadotrophins were measured along with an extensive list of demographic, physical and lifestyle factors including body composition, muscle strength and biomarkers of chronic diseases, physical activity, nutrition and smoking behaviour.

RESULTS

Low TT was mostly associated with high abdominal fat and triglycerides and low muscle strength rather than ageing per se. Low BT was associated with increased age followed by high whole body fat percentage. BT and TT levels were higher in unmarried men and smokers. SHBG levels increased with age, but were also inversely associated with insulin and triglycerides. The Leydig cell specific factor INSL3 was the strongest biomarker associated with both TT and BT.

CONCLUSIONS

Factors associated with low androgen status variably include high body fat percentage, low muscle strength and biomarkers of the metabolic syndrome. Reducing exposure to factors that adversely affect androgen status may improve the general health of ageing men by mechanisms yet to be defined.

Effects of aromatase inhibition in hypogonadal older men: a randomized, double-blind, placebo-controlled trial

OBJECTIVE

To assess the effects of sustained aromatase inhibition in older hypogonadal men.

DESIGN AND PATIENTS

In a 1-year randomized, double-blind, placebo-controlled trial, 88 men, aged 60 and older with testosterone levels between 5.2 and 10.4 nmol/L on a single measure or between 10.4 and 12.1 nmol/L on two consecutive measures, and symptoms of hypogonadism were recruited. Subjects received either anastrozole 1 mg daily or placebo.

MEASUREMENTS

Changes in gonadal steroid hormone levels, body composition (by computerized tomography (CT) and dual x-ray absorptiometry (DXA)), strength, prostate specific antigen (PSA), symptoms of benign prostatic hypertrophy (BPH), hematocrit and lipid levels were assessed.

RESULTS

Testosterone levels increased from 11.2 +/- 3.3 nmol/L at baseline to 18.2 +/- 4.8 nmol/L at month 3 (p < 0.0001 vs. placebo) while bioavailable testosterone levels increased from 2.7 +/- 0.8 nmol/L at baseline to 5.4 +/- 1.7 nmol/L at month 3 (p < 0.0001 vs. placebo). Testosterone and biotestosterone levels peaked at month 3 and then declined by month 12 (though they remained significantly higher than baseline and greater than placebo). Estradiol levels decreased from 55.8 +/- 15.4 pmol/L at baseline to 42.2 +/- 13.6 pmol/L at month 3 and then remained stable (p < 0.0001). Body composition and strength did not change, nor did PSA, BPH symptoms, hematocrit or lipid levels.

CONCLUSIONS

Anastrozole administration normalized androgen production in older hypogonadal men and decreased estradiol production modestly. These alterations did not improve body composition or strength.

Estrogen-regulated development and differentiation of the prostate

Both androgens and estrogens play a significant role in the prostate and are critical for normal prostate growth and development, as well as the maintenance of adult prostatic homeostasis throughout life. It is the balance of these two hormones, rather than each individually, that is important for prostatic development and differentiation. Estrogen action is mediated by the estrogen receptors, ERalpha and ERbeta. ERalpha is expressed throughout the prostatic tissue during fetal and early neonatal life, and if activated inappropriately, produces late-life disease, including inflammation and emergence of pre-malignant pathologies. In contrast, ERbeta expression is initiated after ERalpha, is localized primarily to the epithelium, and appears to be important during later periods of development such as puberty and adulthood, acting to regulate cellular proliferation and differentiation in the adult tissue. Therefore, there is also a spatial and temporal balance between ERalpha and ERbeta that is critical for development. Together with the shifting balance between androgens and estrogens themselves, the subtle, yet critical, balance between the activity of ERalpha and ERbeta is what ultimately determines the response of the prostate to estrogen, and is crucial for prostate health.

Association of bioavailable estradiol levels and testosterone levels with serum albumin levels in elderly men

Estrogens are reported to be the essential sex steroid acting on some male physiological functions, and bioavailable estrogens comprise the free and albumin-bound fractions. Moreover, most of the bioavailable sex steroid is made up of albumin-bound fraction. We examined the age-related change in serum free, albumin-bound and bioavailable estradiol levels in comparison with each fraction of testosterone and its relationship with serum albumin level in elderly men. Albumin-bound as well as bioavailable estradiol levels declined with age, and their decreases were associated much more with the decrease of albumin level than the increase of sex-hormone binding globulin (SHBG) level in sixties and seventies, and similar results were recognized in the level of each fraction of testosterone, suggesting albumin levels have an important role for maintaining bioavailable sex steroid levels in males aged over sixty. Moreover, our study showed that SHBG levels associated inversely with bioavailable sex steroid levels particularly when serum albumin level was low. It seems likely that the decrease of bioavailable estradiol as well as testosterone is induced by the decrease of albumin-bound fractions in combination with the increase of SHBG-bound fractions in males aged over sixty, and that their physical characteristics of aging could be induced by the decrease of albumin-bound fractions caused by the decrease of serum albumin regardless of total sex steroid levels.

A short version of the ADAM Questionnaire for androgen deficiency in Chinese men

BACKGROUND

A 10-question screening questionnaire for androgen deficiency in aging men (ADAM) was reported in previous white but not Chinese populations. We therefore investigated the validity of a Chinese version of the Saint Louis University ADAM questionnaire to screen for androgen deficiency in Chinese men.

METHODS

This was a cross-sectional study. Seven hundred ninety-six ambulatory community-based Chinese men, 18-89 years old, were recruited from October 2003 through June 2006. Self-administered Chinese ADAM questionnaire and morning blood samples for serum total testosterone (TT) and bioavailable testosterone (BT) levels were collected from all participants. Low serum BT levels (androgen deficiency) were defined as <5th percentile of serum BT levels in young healthy Chinese men (18-29 years).

RESULTS

The Chinese ADAM questionnaire had good internal consistency (Cronbach alpha = 0.74) and test-retest reliability (Pearson correlation coefficient, r = 0.86; p <.001, two-tailed). As a screening test for low serum BT levels, the Chinese ADAM questionnaire has a high sensitivity of 88% but low specificity of 32%. In 6 of the 10 questions, the mean serum BT levels were significantly lower in those who answered positively than in those who answered negatively. Using a cut-off score of > or =2, a six-question short Chinese ADAM questionnaire demonstrated sensitivity, specificity, and positive and negative predictive values of 86%, 40%, 46%, and 82%, respectively.

CONCLUSION

We have validated a full Chinese version and developed a shortened version of the ADAM questionnaire, and demonstrated that they are sensitive but not specific screening tests for androgen deficiency in Chinese men.

Bioavailable testosterone is associated with a reduced risk of amnestic mild cognitive impairment in older men

OBJECTIVE

We investigated the risk of amnestic mild cognitive impairment (aMCI) in relation to serum bioavailable (BT) and total testosterone (TT) levels in older men.

DESIGN, SETTING AND SUBJECTS

A cross-sectional study in an ambulatory setting, with older men aged 55-93 years with normal cognition, aMCI and Alzheimer's disease (AD).

MEASUREMENTS

Morning serum BT and TT levels were determined. AD was diagnosed by the Neurological and Communicative Disorders and Stroke/Alzheimer's Disease and Related Disorders Association (NINCDS-ADRDA) criteria for probable AD and aMCI by the Petersen criteria.

RESULTS

We recruited 203 Chinese older men (48 aMCI, 66 AD and 89 with normal cognition). Mean serum BT, but not TT, levels were significantly lower in the aMCI (mean BT +/- SEM 1.06 +/- 0.10 nmol/l) and AD (0.99 +/- 0.08 nmol/l) groups than in the normal controls (1.82 +/- 0.12 nmol/l) (P < 0.001, one-way anova) with no significant difference between the aMCI and AD groups. After adjustment for education, age and apolipoprotein E (apoE) genotype, logistic regression analyses showed that the serum BT level [adjusted odds ratio (OR) = 0.52, 95% confidence interval (CI) 0.32-0.85] was an independent protective factor for aMCI. For the combined outcome of aMCI and AD, the serum BT level was an independent protective factor but age and apoE epsilon4 were independent risk factors. There was no interaction between BT and age.

CONCLUSIONS

In older men, serum BT, but not TT, levels were associated with a lower risk of aMCI and AD.

Age-related alterations in pituitary and testicular functions in long-lived growth hormone receptor gene-disrupted mice

The somatotropic axis, GH, and IGF-I interact with the hypothalamic-pituitary-gonadal axis in health and disease. GH-resistant GH receptor-disrupted knockout (GHRKO) male mice are fertile but exhibit delayed puberty and decreases in plasma FSH levels, testicular content of LH, and prolactin (PRL) receptors, whereas PRL levels are elevated. Because the lifespan of GHRKO mice is much greater than the lifespan of their normal siblings, it was of interest to compare age-related changes in the hypothalamic-pituitary-gonadal axis in GHRKO and normal animals. Plasma IGF-I, insulin, PRL, LH, FSH, androstenedione and testosterone levels, and acute responses to GnRH and LH were measured in young (2-4 and 5-6 months of age) and old (18-19 and 23-26 months of age) male GHRKO mice and their normal siblings. Plasma IGF-I was not detectable in GHRKO mice. Plasma PRL levels increased with age in normal mice but declined in GHRKO males, and did not differ in old GHRKO and normal animals. Plasma LH responses to acute GnRH stimulation were attenuated in GHRKO mice but increased with age only in normal mice. Plasma FSH levels were decreased in GHRKO mice regardless of age. Plasma testosterone responses to LH stimulation were attenuated in old mice regardless of genotype, whereas plasma androstenedione responses were reduced with age only in GHRKO mice. Testicular IGF-I mRNA levels were normal in young and increased in old GHRKO mice, whereas testicular concentrations and total IGF-I levels were decreased in these animals. These findings indicate that GH resistance due to targeted disruption of the GH receptor gene in mice leads to suppression of testicular IGF-I levels, and modifies the effects of aging on plasma PRL levels and responses of the pituitary and testes to GnRH and LH stimulation. Plasma testosterone levels declined during aging in normal but not in GHRKO mice, and the age-related increase in the LH responses to exogenous GnRH was absent in GHRKO mice, perhaps reflecting a delay of aging in these remarkably long-lived animals.

Lack of seasonal variation in serum sex hormone levels in middle-aged to older men in the Boston area

CONTEXT

Previous studies of seasonal variation of testosterone and other hormones in men have produced mixed results regarding the number and timing of peaks and nadirs and whether hormones vary seasonally at all. Wide variation in study designs, sample sizes, analytical methods, and characteristics of the study populations may account for the heterogeneity of results.

OBJECTIVE

The objective of the study was to determine whether serum total, free, and bioavailable testosterone, dihydrotestosterone, SHBG, LH, dehydroepiandrosterone, dehydroepiandrosterone sulfate, estrone, estradiol, and cortisol vary seasonally in men.

DESIGN

Two blood samples were drawn 1-3 d apart at study entry and again 3 and 6 months later (maximum six samples per subject). Hormone levels 1-3 d apart were averaged to reduce short-term intrasubject variation.

SETTING

The study population consisted of a community-dwelling population (Boston, MA).

STUDY PARTICIPANTS

One hundred thirty-four men 30-79 yr old were randomly selected from the respondents to the Boston Area Community Health Survey. One hundred twenty-one men who completed all six visits were included in the analysis.

MAIN OUTCOME MEASURES

In a repeated-measures analysis, 3-month change in hormone levels, measured twice per subject, and in a sinusoidal nonlinear regression with random subject effects, average hormone level in samples 1-3 d apart were measured.

RESULTS

Aside from cortisol, no evidence of seasonal variation in hormone levels was found. The amplitude of seasonal variation was much smaller than total intraindividual variation for all hormones considered.

CONCLUSIONS

Seasonal variation is likely an unimportant source of variation clinically and in epidemiological studies of hormone levels.

Age attenuates testosterone secretion driven by amplitude-varying pulses of recombinant human luteinizing hormone during acute gonadotrope inhibition in healthy men

CONTEXT

Whether testosterone (Te) depletion in aging men reflects deficits in the testis, hypothalamus, and/or pituitary gland is unknown.

OBJECTIVE

Our objective was to quantify the impact of age on gonadal Te secretion driven by amplitude-varying pulses of recombinant human LH (rhLH) in the absence of confounding by endogenous hypothalamo-pituitary signals.

DESIGN

This was a double-blind, placebo-controlled study.

SETTING

The setting was an academic medical center.

SUBJECTS

Fifteen healthy community-dwelling men ages 22-78 yr were included in the study.

INTERVENTION

Saline or four separate rhLH doses were each infused twice iv in randomized order as one pulse every 2 h over 20 h to stimulate Te secretion, after LH secretion was suppressed by a GnRH-receptor antagonist, ganirelix.

MAIN OUTCOME

LH and Te concentrations were determined in blood samples collected every 5 min. Maximal and minimal (as well as mean) Te responses were regressed linearly on age to reflect LH peak and nadir (and average) effects, respectively.

RESULTS

The ganirelix/rhLH paradigm yielded serum LH concentrations of 4.6 +/- 0.22 IU/liter (normal range 1-9). By regression analysis, age was associated with declines in rhLH pulse-stimulated peak and nadir (and mean) concentrations of total Te (P = 0.0068), bioavailable Te (P = 0.0096), and free Te (P = 0.013), as well as lower Te/LH concentration ratios (P < 0.005). Deconvolution analysis suggested that the half-life of infused LH increases by 12%/decade (P = 0.044; R(2) = 0.28).

CONCLUSIONS

Infusion of amplitude-varying pulses of rhLH during gonadal-axis suppression in healthy men unmasks prominent age-related deficits in stimulated total (39%), bioavailable (66%), and free (63%) Te concentrations, and a smaller age-associated increase in LH half-life. These data suggest that age-associated factors reduce the efficacy of LH pulses.

Transient neonatal estrogen exposure to estrogen-deficient mice (aromatase knockout) reduces prostate weight and induces inflammation in late life

Exposure of newborn male mice to estrogens is associated with age-related changes in prostate size and induction of epithelial hyperplasia and dysplasia. Whether these changes directly result from systemic estrogen administration or indirect effects of estrogens on systemic testosterone levels is unclear. We have addressed this question using aromatase-knockout (ArKO) mice that are estrogen-deficient during their lifespan but have elevated androgen levels and develop prostate enlargement and hyperplasia (McPherson SJ, Wang H, Jones ME, Pedersen J, Iismaa TP, Wreford N, Simpson ER, Risbridger GP: Endocrinology 2001, 142:2458-2467). Circulating testosterone and dihydrotestosterone levels were significantly decreased by neonatal diethylstilbestrol treatment, remained suppressed in adult wild-type mice, but rapidly returned to control levels in ArKO animals. However, adult prostate weight and luminal size were reduced in both wild-type and ArKO animals. Because both wild-type and ArKO mice developed epithelial hyperplasia and inflammation following neonatal diethylstilbestrol treatment, this validates that estrogens directly cause prostatic inflammation and epithelial hyperplasia. Furthermore, because ArKO mice are estrogen-deficient, this study demonstrates the sensitivity of the neonatal period to estrogen exposure and the long range and permanent nature of the prostatic responses that occur. Finally, this study establishes the ArKO mouse model of estrogen deficiency as a unique approach to study the effects of estrogens, estrogenic factors, and endocrine disruptors on prostate development.

Management of the cardinal features of andropause

There are several problems facing aging men, especially sexual dysfunction, hypogonadism, and psychologic changes. This constellation of changes is sometimes referred to as "manopause" or "andropause." Unlike the dramatic changes in the hormonal milieu occurring during menopause in women, the age-related changes in reproductive hormones of men are subtle and occur gradually throughout the years of mature life. It has been estimated that circulating testosterone (T) declines longitudinally from age 19 at an average rate of 1% per year. The free or dialyzable fraction of serum T and the bioavailable (the sum of free fraction and loosely bound to albumin fraction) T decline more rapidly with age. Although the essential role of androgens in reproductive tissue development and emergence of secondary sex characteristics is well known, their role in adult sexual function seems to be primarily facultative. The effect of T on the central nervous system extends beyond sexual behavior. T has been shown to alter mood, memory, ability to concentrate, and the overall sense of vigor and well being that may interact with a host of other psychologic changes associated with aging. Disordered erectile function is not generally an endocrine problem but rather vascular, neurologic, and psychogenic in origin. It also may be the first sign of systemic vascular disease. The clinical management of andropause requires an individualized approach. In some men, the main problem may be psychologic, whereas in others, hypogonadism may play an important role. Many with erectile failure, suffer silently regardless of its etiology. In this review, we suggest some practical guidelines for the management of these conditions.

The sensitivity of the child to sex steroids: possible impact of exogenous estrogens

The current trends of increasing incidences of testis, breast and prostate cancers are poorly understood, although it is assumed that sex hormones play a role. Disrupted sex hormone action is also believed to be involved in the increased occurrence of genital abnormalities among newborn boys and precocious puberty in girls. In this article, recent literature on sex steroid levels and their physiological roles during childhood is reviewed. It is concluded that (i) circulating levels of estradiol in prepubertal children are lower than originally claimed; (ii) children are extremely sensitive to estradiol and may respond with increased growth and/or breast development even at serum levels below the current detection limits; (iii) no threshold has been established, below which no hormonal effects can be seen in children exposed to exogenous steroids or endocrine disruptors; (iv) changes in hormone levels during fetal and prepubertal development may have severe effects in adult life and (v) the daily production rates of sex steroids in children estimated by the Food and Drug Administration in 1999 and still used in risk assessments are highly overestimated and should be revised. Because no lower threshold for estrogenic action has been established, caution should be taken to avoid unnecessary exposure of fetuses and children to exogenous sex steroids and endocrine disruptors, even at very low levels.

Androgens, aging, and Alzheimer's disease

Testosterone depletion is a normal consequence of aging in men that is associated with senescent effects in androgen- responsive tissues. We discuss new evidence that one consequence of testosterone depletion in men is an increased risk for the development of Alzheimer's disease (AD). Furthermore, we discuss two candidate mechanisms by which testosterone may affect AD pathogenesis. First, testosterone has been identified as an endogenous regulator of beta-amyloid, a protein that abnormally accumulates in AD brain and is implicated as a causal factor in the disease. Second, findings from several different paradigms indicate that testosterone has both neurotrophic and neuroprotective functions. These new findings support the clinical evaluation of androgen-based therapies for the prevention and treatment of AD.

Age-related patterns of urinary gonadotropins (FSH and LH) and E-3-G as measures of reproductive function among Turkana males of northern Kenya

To determine age-related patterns of gonadotropins and their relationship to energetic status in a subsistence population we analyzed urinary FSH, LH, and estrone-3-glucuronide (E-3-G) along with anthropometric measures among Turkana males of northern Kenya. Subjects were 134 nomadic and 109 settled males ages 20 to 80+. FSH, LH and E-3-G were significantly higher among the settled, compared to nomadic, males. LH, but not FSH, showed a significant increase across 10 year age groups among all the men. E-3-G increased across age groups only among the settled males. Controlled for age, FSH was inversely related to measures of fat free and body mass among the settled men. These findings suggest an unusual age profile of gonadotropins and estrogen metabolites that may reflect the impact of fluctuating food availability. More research is needed to address the impact of energetic and social factors on the male reproductive axis among energetically stressed populations.