Testosterone Trajectories and Reference Ranges in a Large Longitudinal Sample of Male Adolescents

Pubertal dynamics plays an important role in physical and psychological development of children and adolescents. We aim to provide reference ranges of plasma testosterone in a large longitudinal sample. Furthermore, we describe a measure of testosterone trajectories during adolescence that can be used in future investigations of development.We carried out longitudinal measurements of plasma testosterone in 2,216 samples obtained from 513 males (9 to 17 years of age) from the Avon Longitudinal Study of Parents and Children. We used integration of a model fitted to each participant's testosterone trajectory to calculate a measure of average exposure to testosterone over adolescence. We pooled these data with corresponding values reported in the literature to provide a reference range of testosterone levels in males between the ages of 6 and 19 years.The average values of total testosterone in the ALSPAC sample range from 0.82 nmol/L (Standard Deviation [SD]: 0.09) at 9 years of age to 16.5 (SD: 2.65) nmol/L at 17 years of age; these values are congruent with other reports in the literature. The average exposure to testosterone is associated with different features of testosterone trajectories such as Peak Testosterone Change, Age at Peak Testosterone Change, and Testosterone at 17 years of age as well as the timing of the growth spurt during puberty.The average exposure to testosterone is a useful measure for future investigations using testosterone trajectories to examine pubertal dynamics

A time-resolved fluorescence immunoassay for the measurement of testosterone in saliva: Monitoring of testosterone replacement therapy with testosterone buciclate

Monitoring of testosterone replacement therapy requires a reliable method for testosterone measurement. Determination of salivary testosterone, which reflects the hormone's biologically active plasma fraction, is a superior technique for this purpose. The aim of the present study was to establish a new sensitive time-resolved fluorescence immunoassay for the accurate measurement of testosterone levels in saliva and to validate it by monitoring testosterone replacement therapy in eight hypogonadal men. A clinical phase I- study with the new ester testosterone buciclate was performed to search for new testosterone preparations to produce constant serum levels in the therapy of male hypogonadism. After two control examinations eight male patients with primary hypogonadism were randomly assigned to two treatment groups (n = 2x4) and given single doses of either 200 mg (group I) or 600 mg (group II) testosterone buciclate intramuscularly. Saliva and blood samples were obtained 1, 2, 3, 5 and 7 days post injection and then weekly for three months. The time-resolved fluorescence immunoassay for salivary testosterone shows a detection limit of 16 pmol/l, an intra-assay CV of 8.9% (at a testosterone concentration of 302 pmol/l), an inter-assay CV of 8.7% (at a testosterone concentration of 305 pmol/l) and a good correlation with an established radioimmunsassay of r = 0.89. The sample volume required by this method is only 180 mu l for extraction and duplicate determination. The assay procedure requires no more than three hours. In group I (200 mg) testosterone did not increase to normal levels either in saliva or in serum. However, in group II, androgen levels increased significantly and were maintained in the normal range for up to 12 weeks with maximal salivary testosterone levels of 303 +/- 18 pmol/l (mean+/-SE) and maximal testosterone levels of 13.1 +/- 0.9 nmol/l (mean+/-SE) in serum in study week 6 and 7. The time-resolved fluorescence immunoassay for salivary testosterone provides a useful tool for monitoring androgen status in men and women and is well suited for the follow-up of testosterone replacement therapy on an outpatient basis. The long-acting ester testosterone buciclate is a promising agent for substitution therapy of male hypogonadism and in combination with testosterone monitoring in saliva offers an interesting new perspective for male contraception

Testosterone insulin-like effects: an in vitro study on the short-term metabolic effects of testosterone in human skeletal muscle cells

Testosterone by promoting different metabolic pathways contributes to short-term homeostasis of skeletal muscle, the largest insulin-sensitive tissue and the primary site for insulin-stimulated glucose utilization. Despite evidences indicate a close relationship between testosterone and glucose metabolism, the molecular mechanisms responsible for a possible testosterone-mediated insulin-like effects on skeletal muscle are still unknown

Does the interaction between cortisol and testosterone predict men's facial attractiveness?

Although some researchers have suggested that the interaction between cortisol and testosterone predicts ratings of men’s facial attractiveness, evidence for this pattern of results is equivocal. Consequently, the current study tested for a correlation between men’s facial attractiveness and the interaction between their cortisol and testosterone levels. We also tested for corresponding relationships between the interaction between cortisol and testosterone and ratings of men’s facial health and dominance (perceived traits that are correlated with facial attractiveness in men). We found no evidence that ratings of either facial attractiveness or health were correlated with the interaction between cortisol and testosterone. Some analyses suggested that the interaction between cortisol and testosterone levels may predict ratings of men’s facial dominance, however, with testosterone being more closely related to facial dominance ratings among men with higher cortisol. Our results suggest that the relationship between men’s facial attractiveness and the interaction between cortisol and testosterone is not robust

Contribution of the adrenal gland to the production of androstenedione and testosterone during the first two years of life

Androstenedione and testosterone were measured in whole adrenal glands of 56 previously healthy boys who died suddenly between birth and 2 yr of age. In each adrenal gland, the concentration of androstenedione considerably exceeded that of testosterone. The highest concentrations were found during the first week of life (median, 295 ng/g; range, 98- 320 ng/g). Thereafter, values decreased rapidly until the end of the first year of life (median, 10 ng/g; range, 4.4-22.7 ng/g). Adrenal testosterone concentrations averaged 15% of those of androstenedione in the same gland and similarly decreased until the end of the first year. The decrease of adrenal androgen concentrations paralleled the involution of the fetal adrenal zone. A close correlation existed between the concentration of androstenedione in adrenal tissue and plasma. However, no correlation existed between adrenal and plasma testosterone. When the adrenals and testes of the same infant were compared, there was 10 times more androstenedione in the adrenals than in the testes during the first 2 yr of life. The testes contained more testosterone than the adrenals only during the first 4 months. Thus, in infant boys the adrenals are the main source of androstenedione during the first 2 yr. After the sixth month of life, they also are the main source of testosterone

Testosterone responses to competition in men are related to facial masculinity

Relationships between androgens and the size of sexually dimorphic male traits have been demonstrated in several non-human species. It is often assumed that a similar relationship exists for human male faces, but clear evidence of an association between circulating testosterone levels and the size of masculine facial traits in adulthood is absent. Here we demonstrate that, after experimentally determined success in a competitive task, men with more a masculine facial structure show higher levels of circulating testosterone than men with less masculine faces. In participants randomly allocated to a 'winning' condition, testosterone was elevated relative to pre-task levels at 5 and 20 min post-task. In a control group of participants allocated to a 'losing' condition there were no significant differences between pre- and post-task testosterone. An index of facial masculinity based on the measurement of sexually dimorphic facial traits was not associated with pre-task (baseline) testosterone levels, but was associated with testosterone levels 5 and 20 min after success in the competitive task. These findings indicate that a man's facial structure may afford important information about the functioning of his endocrine system

High Glucose, But Not Testosterone, Increases Platelet Aggregation Mediated by Endothelial Cells

Endothelial cells inhibit platelet aggregation by releasing thromboregulators, such as prostacyclin and nitric oxide. Male subject is a traditional risk factor for cardiovascular diseases. Platelet hyperreactivity has been frequently found in patient with diabetes mellitus. To examine whether testosterone and high glucose modify platelet aggregation through endothelial cells, we did an in vitro study using endothelial cells culture from human umbilical vein (HUVEC). Treatments were performed in HUVEC sub culture as either normoglucose (5.6 mM) or high glucose (22.4 mM) medium, with or without testosterone (0, 1, 10, 100 nM), for 24 hours. HUVEC were trypsinized, resuspended, and then incubated with platelet rich plasma from healthy male donors with ratio 1:104 for 3 minutes. Platelet aggregation measured by turbidimetry methode. This study showed that testosterone did not significantly influence platelet aggregation through endothelial cells in normoglucose (p = 0.144) or high glucose (p = 0.916) medium. There was no main effect of testosterone (p = 0.73) as well as no interaction between testosterone and glucose (p = 0.69), but there was a main effect of glucose (p = 0.004), to platelet aggregation through endothelial cells. In conclusion, high glucose, but not testosterone, inhibits platelet aggregation mediated by endothelial cells

Testicular endocrine activity is upregulated by D-Aspartic acid in the green frog Rana esculenta

This study investigated the involvement of D-aspartic acid (D-Asp) in testicular steroidogenesis of the green frog Rana esculenta and its effect on stimulation of thumb pad morphology and glandular activity, a typical testosterone-dependent secondary sexual characteristic in this amphibian species. In the testis, D-Asp concentrations vary significantly during the reproductive cycle: they are low in pre- and post-reproductive periods, but reach peak levels in the reproductive period (140-236 nmol/g wet tissue). Moreover, the concentrations of D-Asp in the testis through the sexual cycle positively match the testosterone levels in the gonad and the plasma. The racemase activity evaluated during the cycle expresses its peak when D-Asp and testosterone levels are highest, that is, during the reproductive period, confirming the synthesis of D-Asp from L-Asp by an aspartate racemase. Short-term in vivo experiments consisting of a single injection of D-Asp (2.0 micro mol/g body weight) demonstrated that this amino acid accumulates significantly in the testis, and after 3 h its uptake is coupled with a testosterone increase in both testis and plasma. Moreover, within 18 h of amino acid administration, the D-Asp concentration in the testis decreased along with the testosterone titer to prestimulation levels. Other amino acids (L-Asp, D-Glu and L-Glu) used instead of D-Asp were ineffective, confirming that the significant increase in testicular testosterone was a specific feature of this amino acid. In long-term experiments, D-Asp had been administered chronically to frogs caught during the three phases of the reproductive cycle, inducing testosterone increase and 17beta-estradiol decrease in the gonad during the pre- and post-reproductive period, and vice versa during the reproductive period

Wearing colored glasses can influence the exercise performance and testosterone concentration

Perception of red color is associated with higher testosterone concentration and better human performance. Thus, we evaluated the acute effects of wearing colored-lens glasses on the YoYo intermittent endurance exercise test 2 (YoYoIE2) performance indicators and testosterone concentration. Ten soccer players performed three YoYoIE2 (counterbalanced crossover) wearing colorless (control), blue- or red-lensed glasses (2–4 days of rest in between). YoYoIE2 performance did not differ among the trials (p>0.05), but blood testosterone increased post-exercise in red compared to red baseline (red=14%, effect size=0.75). Analysis showed faster heart rate recovery (p0.05) among the trials. Wearing red-colored lenses during high-intensity intermittent exercise increased testosterone concentration, but do not influence performance