[Show abstract][Hide abstract] ABSTRACT: Secondary hypogonadism is common in ageing men; its natural history and predisposing factors are unclear.
1) To identify factors which predispose eugonadal men (T ≥10.5nmol/L) to develop biochemical secondary hypogonadism (T<10.5nmol/L, LH≤9.4U/L) and secondary hypogonadal men to recover to eugonadism. 2) To characterize clinical features associated with these transitions.
Prospective observational general population cohort survey.
Clinical research centres.
3369 community-dwelling men aged 40-79 yr in eight European centres.
Observational follow-up of 4.3 years.
Subjects were categorised according to change/no change in biochemical gonadal status during follow-up into persistent eugonadal (n=1909), incident secondary hypogonadal (n=140), persistent secondary hypogonadal (n=123) and recovered from secondary hypogonadism to eugonadism (n=96). Baseline predictors and changes in clinical features associated with incident secondary hypogonadism and recovery from secondary hypogonadism were analysed by regression models.
The incidence of secondary hypogonadism was 155.9/10,000/year, while 42.9% of men with secondary hypogonadism recovered to eugonadism. Incident secondary hypogonadism was predicted by obesity [BMI≥30kg/m(2): odds ratio (OR)=2.86 (95% confidence interval 1.67;4.90); p<0.0001], weight gain [OR=1.79 (1.15;2.80);p=0.011] and increased waist circumference [OR=1.73 (1.07;2.81); p=0.026 and 2.64 (1.66;4.21);p<0.0001, for waist circumference 94-102 and ≥102 cm, respectively]. Incident secondary hypogonadal men experienced new/worsening sexual symptoms [low libido, erectile dysfunction and infrequent spontaneous erections]. Recovery from secondary hypogonadism was predicted by non-obesity [OR=2.28 (1.21;4.31); p=0.011], weight loss [OR=2.24 (1.04;4.85); p=0.042], normal waist circumference [OR=1.93 (1.01;3.70); p=0.048], younger age [<60yr OR=2.32 (1.12;4.82); p=0.024] and higher education [OR=2.11 (1.05;4.26); p=0.037], but symptoms did not show significant concurrent improvement.
Obesity-related metabolic and lifestyle factors predispose older men to the development of secondary hypogonadism, which is frequently reversible with weight loss.
The Journal of Clinical Endocrinology and Metabolism 05/2015; DOI:10.1210/jc.2015-1571 · 6.31 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The recent onslaught of mass spectrometry (MS) to measurements of steroid hormones, including demands that they should be the only acceptable method, has confused clinicians and scientists who have relied for more than 40 years on a variety of immunoassay (IA) methods in steroid hormone measurements. There is little doubt that MS methods with their superior specificity will be the future method of choice in many clinical and research applications of steroid hormone measurement. However, the majority of steroid measurements are currently, and will continue to be, carried out using various types of IAs for several reasons, including their technical ease, cost and availability of commercial reagents. Speedy replacement of all IAs with MS is an unrealistic and unnecessary goal, because the availability of MS measurements is limited by cost, need of expensive equipment, technical demands and lack of commercial applications. Furthermore, IAs have multiple well-known advantages that vindicate their continuing use. The purpose of this article is to elucidate the advantages and limitations of the MS and IA techniques from two angles, i.e. promotion of MS and defence of IA. The purpose of the text is to give the reader an unbiased view about the current state and future trends of steroid analysis and to helps him/her to chose the correct assay method to serve his/her diagnostic and research needs.
European Journal of Endocrinology 04/2015; 173(2). DOI:10.1530/EJE-15-0338 · 3.69 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The luteinizing hormone/chorionic gonadotropin receptor (LHCGR) is a G protein-coupled receptor (GPCR) that plays a central role in male sexual differentiation, regulation of ovarian follicular maturation, ovulation and maintenance of corpus luteum and pregnancy, as well as maintenance of testicular testosterone production. Mutations in the LHCGR gene are very rare. The aim of this work was to study the clinical and molecular characteristics of a rare familial LHCGR mutation.
A family with five affected members, including a phenotypically female, but genotypically male (46,XY) patient with Leydig cell hypoplasia type 1 and four genotypically female siblings with reproductive abnormalities were studied genetically. Cell trafficking studies as well as signaling studies of mutated receptor were performed.
The 5 affected patients were all homozygous for a novel mutation in the LHCGR gene, a deletion of guanine in position 1850 (1850delG). This resulted in a frame-shift affecting most of the C-terminal intracellular domain. In vitro studies showed that the 1850delG receptor was completely incapable of transit to the cell membrane, becoming trapped within the endoplasmic reticulum. This could not be rescued by small molecule agonist treatment or stimulated intracellularly by co-expression of a yoked-hCG.
This novel LHCGR mutation leads to complete inactivation of the LHCGR receptor due to trafficking and signalling abnormalities, which improves our understanding of the impact of the affected structural domain on receptor trafficking and function.
European Journal of Endocrinology 03/2015; 172(6). DOI:10.1530/EJE-14-1095 · 3.69 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND Leydig cells (LC) are the sites of testicular androgen production. Development of LC occurs in the testes of most mammalian
species as two distinct growth phases, i.e. as fetal and pubertal/adult populations. In primates there are indications of
a third neonatal growth phase. LC androgen production begins in embryonic life and is crucial for the intrauterine masculinization
of the male fetal genital tract and brain, and continues until birth after which it rapidly declines. A short post-natal phase
of LC activity in primates (including human) termed ‘mini-puberty’ precedes the period of juvenile quiescence. The adult population
of LC evolves, depending on species, in mid- to late-prepuberty upon reawakening of the hypothalamic–pituitary–testicular
axis, and these cells are responsible for testicular androgen production in adult life, which continues with a slight gradual
decline until senescence. This review is an updated comparative analysis of the functional and morphological maturation of
LC in model species with special reference to rodents and primates.
Human Reproduction Update 02/2015; 21(3). DOI:10.1093/humupd/dmv008 · 8.66 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Context: Low testosterone (T) has been associated with incident metabolic syndrome (MetS), but it remains unclear if this association is independent of sex hormone binding globulin (SHBG). Estradiol (E2) may also be associated with MetS, but few studies have investigated this. Objective: To study the association between baseline sex steroids and the development of incident MetS and to investigate the influence of SHBG, BMI and insulin resistance on this risk. Methods: 3369 community-dwelling men aged 40-79 years were recruited for participation in EMAS. MetS was defined by the updated NCEP ATP III criteria. Testosterone and E2 levels were measured by liquid and gas chromatography/mass spectrometry respectively. Logistic regression was used to assess the association between sex steroids and incident MetS. Results: 1651 men without MetS at baseline were identified. During follow-up 289 men developed incident MetS, while 1362 men did not develop MetS. Men with lower baseline total T levels were at higher risk for developing MetS (Odds ratio (OR)=1.72, p<0.001), even after adjustment for SHBG (OR=1.43, p=0.001), BMI (OR=1.44, p<0.001) or HOMA-IR (OR=1.64, p<0.001). E2 was not associated with development of MetS (OR=1.04; p=0.56). However, a lower E2/T ratio was associated with a lower risk of incident MetS (OR=0.38; p<0.001), even after adjustment for SHBG (OR=0.48; p<0.001), BMI (OR=0.60; p=0.001) or HOMA-IR (OR=0.41; p<0.001). Conclusions: In men, lower T levels, but not E2, are linked with an increased risk of developing MetS, independent of SHBG, BMI or insulin resistance. A lower E2/T ratio may be protective against developing MetS.
[Show abstract][Hide abstract] ABSTRACT: The general interest in the availability of male contraceptives is on the increase across different cultures and ethnic backgrounds, due in part to the fact that men are now willing more than ever, to share the responsibility of family planning. Despite the expression of interest and tremendous advances in research however, a modern male hormonal contraceptive method has remained an elusive goal. Testosterone (T) alone, or in combination with a progestin currently provides the most promising lead to male hormonal contraception. The principle relies on enhanced negative feedback of exogenous T to suppress gonadotropins, thereby blocking the endocrine stimulus for the process of spermatogenesis. A serious drawback is the inconsistent suppression among men of different ethnic backgrounds. This has increased the quest for development to include other nonhormonal methods. In reality many obstacles still have to be overcome before an acceptable method is available. In this review, we highlight recent developments in male hormonal contraceptives methods. Based on our recent findings from animal experiment, we shed light on why the method is not achieving the intended results, and suggest possible ways forward.
Current molecular pharmacology 01/2015; 7(2). DOI:10.2174/1874467208666150126154732
[Show abstract][Hide abstract] ABSTRACT: Background:
G protein-coupled receptors (GPCRs) represent a physiologically and pharmacologically important family of receptors that upon coupling to GαS stimulate cAMP production catalyzed by adenylyl cyclase. Thus, developing assays to monitor cAMP production is crucial to screen for ligands in studies of GPCR signaling. Primary cell cultures represent a more robust model than cell lines to study GPCR signaling since they physiologically resemble the parent tissue. Current cAMP assays have two fundamental limitations: 1) absence of cAMP kinetics as competition-based assays require cell lysis and measure only a single time-point, and 2) high variation with separate samples needed to measure consecutive time points. The utility of real-time cAMP biosensors is also limited in primary cell cultures due to their poor transfection efficiency, variable expression levels and inability to select stable clones. We therefore, decided to develop an assay that can measure cAMP not only at a single time-point but the entire cAMP kinetics after GPCR activation in untransfected primary cells.
CANDLES (Cyclic AMP iNdirect Detection by Light Emission from Sensor cells) assay for monitoring cAMP kinetics in cell cultures, particularly in primary cultures was developed. The assay requires co-culturing of primary cells with sensor cells that stably express a luminescent cAMP sensor. Upon GPCR activation in primary cells, cAMP is transferred to sensor cells via gap junction channels, thereby evoking a luminescent read-out. GPCR activation using primary cultures of rat cortical neurons and mouse granulosa cells was measured. Kinetic responses of different agonists to adrenergic receptors were also compared using rat cortical neurons. The assay optimization was done by varying sensor-test cell ratio, using phosphodiesterase inhibitors and testing cell-cell contact requirement.
Here we present CANDLES assay based on co-culturing test cells with cAMP-detecting sensor cells. This co-culture setup allows kinetic measurements, eliminates primary cell transfections and reduces variability. A variety of cell types (rat cortical neurons, mouse granulosa cells and established cell lines) and receptors (adrenergic, follicle stimulating hormone and luteinizing hormone/chorionic gonadotropin receptors) were tested for use with CANDLES. The assay is best applied while comparing cAMP generation curves upon different drug treatments to untransfected primary cells.
Cell Communication and Signaling 11/2014; 12(1):70. DOI:10.1186/PREACCEPT-2584811211316350 · 4.67 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: During epididymal sperm maturation, the lipid content of the sperm membrane is modified, which facilitates sperm motility and fertility. However, little is known about the mechanisms regulating the maturation process. By generating a conditional knockout (cKO) of Dicer1 in the proximal part of the mouse epididymis, we studied the role of RNA interference in epididymal functions. The Dicer1 cKO epididymis displayed an altered lipid homeostasis associated with a 0.6-fold reduction in the expression of the gene elongation of very long chain fatty acids-like 2, an enzyme needed for production of long-chain polyunsaturated fatty acids (PUFAs). Furthermore, the expression of several factors involved in cholesterol synthesis was up-regulated. Accordingly, the Dicer1 cKO sperm membrane showed a 0.7-fold decrease in long-chain PUFAs, whereas the amount of cholesterol in acrosome-reacted sperm displayed a 1.7-fold increase. The increased cholesterol:PUFA ratio of the sperm membrane caused breakage of the neck and acrosome region and immotility of sperm. Dicer1 cKO mice sperm also displayed reduced ability to bind to and fertilize the oocyte in vitro. This study thus shows that Dicer1 is critical for lipid synthesis in the epididymis, which directly affects sperm membrane integrity and male fertility.-Björkgren, I., Gylling, H., Turunen, H., Huhtaniemi, I., Strauss, L., Poutanen, M., Sipilä, P. Imbalanced lipid homeostasis in the conditional Dicer1 knockout mouse epididymis causes instability of the sperm membrane.
The FASEB Journal 11/2014; 29(2). DOI:10.1096/fj.14-259382 · 5.48 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Background: Social and lifestyle influences on age-related changes in body morphology are complex because lifestyle and physiological response to social stress can affect body fat differently. Objective: We examined the associations of socioeconomic status (SES) and lifestyle factors with body mass index (BMI) and waist circumference (WC) in middle-aged and elderly European men. Design and setting: Cross-sectional study of 3,319 men aged 40-79 recruited from eight European centres. Outcomes: We estimated relative risk ratios (RRRs) of overweight/obesity associated with unfavourable SES and lifestyles. Results: The prevalence of BMI30kg/m2 or WC102cm rose linearly with age, except in the 8th decade when high BMI, but not high WC, declined. Among men aged 40-59y, compared to non-smokers or most active men, centre and BMI adjusted RRRs for having a WC between 94-101.9cm increased by 1.6-fold in current smokers, and 2.7-fold in least active men, maximal at 2.8-fold in least active men who smoked. Similar patterns but greater RRRs were observed for men with WC≥102cm, notably 8.4-fold greater in least active men who smoked. Compared to men in employment, those who were not in employment had increased risk of having a high WC by 1.4-fold in the 40-65y group and by 1.3-fold in the 40-75y group. These relationships were weaker among elderly men. Conclusion: Unfavourable SES and lifestyles associate with increased risk of obesity, especially in middle-aged men. The combination of inactivity and smoking was the strongest predictor of high WC, providing a focus for health promotion and prevention at an early age.
European Journal of Endocrinology 10/2014; 172(1). DOI:10.1530/EJE-14-0739 · 3.69 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The advent of technologies to genetically manipulate the mouse genome has revolutionised research approaches, providing a unique platform to study the causality of reproductive disorders in vivo. With the relative ease of generating genetically modified mouse models, the last two decades have yielded multiple loss-of-function and gain-of-function mutation mouse models to explore the role of gonadotrophins and their receptors in reproductive pathologies. This work has provided key insights into the molecular mechanisms underlying reproductive disorders with altered gonadotrophin action, revealing the fundamental roles of these pituitary hormones and their receptors in the hypothalamic-pituitary-gonadal axis. This review will describe genetically modified mouse models of gonadotrophins and their receptors with enhanced or diminished actions, specifically focussing on the male. We will discuss the mechanistic insights gained from these models into male reproductive disorders, and discuss the relationship and understanding provided into male human reproductive disorders originating from altered gonadotrophin action.