Endogenous estradiol and testosterone levels are associated with cognitive performance in older women and men

Relatively few studies have investigated the relationship between endogenous sex steroid levels and cognition in older people and the reported results have been inconsistent. A number of experimental hormone replacement studies have suggested that estrogen replacement in older women enhances cognition, especially verbal memory. In contrast, little research has been done focusing on men. In the current study the association between endogenous sex steroids (estradiol and testosterone) and cognition was investigated in 38 healthy older women (mean age 68 years) and 30 healthy older men (mean age 69 years). Five cognitive tests measuring verbal memory, spatial memory, verbal fluency, mental rotation, and susceptibility to interference were administered. Results revealed that in women higher estradiol levels as well as testosterone levels were associated with better verbal memory (paired associates and estradiol; r =.38, P < 0.05; paired associates and testosterone; r =.33, P < 0.05;). Moreover estradiol, but not testosterone was associated with less susceptibility to interference (Stroop color word test; r = -0.34, P < 0.05). In men the only significant association was a negative correlation between testosterone and verbal fluency (r = -0.38, P < 0.05). The associations observed in this small study support the notion that estradiol is protecting verbal memory and possibly also frontal lobe mediated functions in older women. In contrast to the positive findings in women endogenous sex steroids do not appear to be closely linked to better cognition in older men.     

Menstrual cycle variation in spatial ability: relation to salivary cortisol levels

This study examined whether menstrual cycle phase was associated with performance on the Primary Mental Abilities Test of Spatial Relations, a test of mental rotation, in undergraduate students (N = 82). As cortisol levels also vary across the menstrual cycle under conditions of stress and influence cognitive performance, saliva samples were obtained before and after the test session to examine whether cortisol levels were related to between- and within-group differences in spatial performance. Men scored higher on the spatial test than all the groups of women, although the difference between men and women in the menstrual phase was not significant. Women in the luteal phase scored lower than the menstrual, follicular, and oral contraceptive user groups of women. There were no sex or menstrual cycle differences in cortisol levels, and no association between cortisol levels and spatial performance. The poorer performance of women in the luteal phase was not related to differences in ratings of perceived stress, perceived success on the test, or mood. Although menstrual cycle phase accounted for a significant proportion of the variance (15%) in performance on the spatial test, this does not explain why men outperformed women regardless of the phase of the cycle. Thus, there are clearly several other variables, sociocultural and physiological, involved in mediating individual differences in spatial performance.     

Androgens and eye movements in women and men during a test of mental rotation ability

Eye movements were monitored in 16 women and 20 men during completion of a standard diagram-based test of mental rotation ability to provide measures of cognitive function not requiring conscious, decisional processes. Overall, women and men allocated visual attention during task performance in very similar, systematic ways. However, consistent with previous suggestions that sex differences in attentional processes during completion of the mental rotation task may exist, eye movements in men compared to women indicated greater discrimination and longer processing of correct alternatives during task performance. Other findings suggested that androgens may enhance cognitive processes that are recruited differentially by women and men as a function of the task. Specifically, smaller (i.e., more masculine) digit ratios were associated with men's shorter fixations on distracters, suggesting that perinatal androgen action may influence brain systems that facilitate the identification of relevant task stimuli. In women, higher circulating testosterone levels appeared to contribute to more general processes engaged during task performance, for example higher levels of visual persistence. It is possible that variability in the relative contribution of such hormone sensitive cognitive processes to accuracy scores as a function of different sample characteristics or assessment methods may partially account for the inconsistent findings of previous research on hormonal factors in mental rotation ability.     

Cortisol and GH secretory dynamics, and their interrelationships, in healthy aged women and men

We studied 130 healthy aged women (n = 57) and men (n = 73), age 65-88 yr, with age-related reductions in insulin-like growth factor I and gonadal steroid levels to assess the interrelationships between cortisol and growth hormone (GH) secretion and whether these relationships differ by sex. Blood was sampled every 20 min from 8:00 PM to 8:00 AM; cortisol was measured by RIA and GH by immunoradiometric assay, followed by deconvolution analyses of hormone secretory parameters and assessment of approximate entropy (ApEn) and cross-ApEn. Cortisol mass/burst, cortisol production rate, and mean and integrated serum cortisol concentrations (P < 0.0005), and overnight basal GH secretion (P < 0.05), were elevated in women vs. men. Integrated cortisol concentrations were directly related to most measures of GH secretion in women (P < 0.01) and with mean and integrated GH concentrations in men (P < 0.05). Integrated GH concentrations were directly related to mean and integrated cortisol levels in women (P < 0.005) and men (P < 0.05), with no sex differences. There were no sex differences in cortisol or GH ApEn values; however, the cross-ApEn score was greater in women (P < 0.05), indicating reduced GH-cortisol pattern synchrony in aged women vs. men. There were no significant relationships of integrated cortisol secretion with GH ApEn, or vice versa, in either sex. Thus postmenopausal women appear to maintain elevated cortisol production in patterns that are relatively uncoupled from those of GH, whereas mean hormone outputs remain correlated.     

Gender dimorphism in skeletal muscle leptin receptors, serum leptin and insulin sensitivity

To determine if there is a gender dimorphism in the expression of leptin receptors (OB-R170, OB-R128 and OB-R98) and the protein suppressor of cytokine signaling 3 (SOCS3) in human skeletal muscle, the protein expression of OB-R, perilipin A, SOCS3 and alpha-tubulin was assessed by Western blot in muscle biopsies obtained from the m. vastus lateralis in thirty-four men (age = 27.1+/-6.8 yr) and thirty-three women (age = 26.7+/-6.7 yr). Basal serum insulin concentration and HOMA were similar in both genders. Serum leptin concentration was 3.4 times higher in women compared to men (P<0.05) and this difference remained significant after accounting for the differences in percentage of body fat or soluble leptin receptor. OB-R protein was 41% (OB-R170, P<0.05) and 163% (OB-R128, P<0.05) greater in women than men. There was no relationship between OB-R expression and the serum concentrations of leptin or 17beta-estradiol. In men, muscle OB-R128 protein was inversely related to serum free testosterone. In women, OB-R98 and OB-R128 were inversely related to total serum testosterone concentration, and OB-R128 to serum free testosterone concentration. SOCS3 protein expression was similar in men and women and was not related to OB-R. In women, there was an inverse relationship between the logarithm of free testosterone and SCOS3 protein content in skeletal muscle (r = -0.46, P<0.05). In summary, there is a gender dimorphism in skeletal muscle leptin receptors expression, which can be partly explained by the influence of testosterone. SOCS3 expression in skeletal muscle is not up-regulated in women, despite very high serum leptin concentrations compared to men. The circulating form of the leptin receptor can not be used as a surrogate measure of the amount of leptin receptors expressed in skeletal muscles.     

Serum bisphenol a concentrations showed gender differences, possibly linked to androgen levels

To investigate human exposure to bisphenol A (BPA), a widely used endocrine disruptor, we measured serum BPA concentrations and analyzed the interrelation of BPA with sex-related hormones. BPA was detected in all human sera by a novel enzyme-linked immunosorbent assay. Serum BPA concentrations were significantly higher in normal men (1.49 +/- 0.11 ng/ml; P < 0.01) and in women with polycystic ovary syndrome (1.04 +/- 0.10 ng/ml; P < 0.05) compared with normal women (0.64 +/- 0.10 ng/ml). There were significant positive correlations between serum BPA and total testosterone (r = 0.595, P < 0.001) and free testosterone (r = 0.609, P < 0.001) concentrations in all subjects and likewise between serum BPA and total testosterone (r = 0.559, P < 0.01) and free testosterone (r = 0.598, P < 0.001) concentrations in all female subjects, but not between serum BPA and other sex-related hormone concentrations in any group. These findings showed that there are gender differences in serum BPA concentrations, possibly due to differences in the androgen-related metabolism of BPA.     

Plasma epinephrine levels in hypertension and across gender and ethnicity

Epinephrine (E) infusions raise blood pressure and there is an excess incidence of hypertension among males and blacks. However, reports of E levels by ethnicity, gender, and blood pressure status are inconsistent. Insensitive assays, variability in plasma E levels within individuals, and the small size of most studies have contributed to these conflicting reports. We measured plasma E levels in a large diverse sample of subjects, using a highly sensitive assay. A total of 361 individuals participated in the study: 61% were men and 39% women, 74% were normotensive and 26% hypertensive, 59% were white and 41% were black. Except for difference in blood pressure and body mass index between the normotensives and hypertensives, subjects had similar baseline characteristics and took no antihypertensive medications for at least five days prior to sampling. All blood samples were collected after resting for a least 30 minutes following the insertion of an indwelling i.v. catheter. Catecholamine levels were determined using a radioenzymatic assay (assay sensitivities for E and norepinephrine were 6 pg/ml and 10 pg/ml, respectively). An ethnicity by gender interaction was found (F(1,315) = 5.126, p = .024). Subsequent analysis revealed that white women had significantly lower basal plasma E levels than white men (p <0.001) and black women (p = 0.036). There were no significant differences in E levels between black men and women or between white men and black men. Uncorrected E levels were lower in normotensive than hypertensive subjects (p = .009) but this difference was not significant when corrected for body mass index (BMI). Uncorrected norepinephrine levels were higher in women than men (p = .03) but the difference was no longer significant when corrected for BMI. Plasma E levels were significantly lower among white women than men or black women. In contrast to prior studies, E levels were lower in hypertensives, but this may reflect obesity among hypertensives.     

Leptin responses to physical inactivity induced by simulated weightlessness

Physical inactivity induced by head-down bed rest (HDBR) affects body composition (BC). Leptin is involved in BC regulation by acting on fuel homeostasis. We investigated whether leptin and counterregulatory hormone levels are affected by a 7-day HDBR. Fasting blood was sampled daily (0700) in males (n = 8) and on alternating days in females (n = 8) for measurements of leptin, insulin, norepinephrine (NE), epinephrine (Epi), growth hormone (GH), cortisol, nonesterified fatty acid (NEFA), and glucose. BC was measured by H(2)(18)O dilution. Energy intake (men 10.5 +/- 0.2 MJ/day, women 7.9 +/- 0.3 MJ/day) and BC were unchanged by HDBR. Increased levels of leptin (men 40%, P = 0.003; women 20%, P = 0. 050), insulin (men 34%, P = 0.018; women 25%, P = 0.022), and the insulin-to-glucose ratio (men 30%, P = 0.049; women 25%, P = 0.031) were noted. GH, NE, Epi, and cortisol levels were unaltered. NEFA dropped in both sexes, but glucose decreased only in women. In conclusion, HDBR increased leptin levels independently of stress response, changes in fat mass, energy intake, or gender. These changes were correlated to the insulin-resistance development in men. Further analyses are required, but the results have to be considered for longer HDBR periods with 1) the well-described drop in energy intake and 2) the BC changes.     

Gender and ethnic differences in urinary stress hormones: the population-based Chicago Health, Aging, and Social Relations Study.

Gender and ethnic disparities in cardiovascular disease and mortality have spurred interest in the epidemiology of stress hormone production. Greater disease burden among men and blacks raises the possibility of gender and ethnic differences in stress hormone production. The purpose of this study was to determine whether urinary stress hormones were higher among men and blacks in a population-based sample. Urinary hormone analysis permits a time-integrated assessment of the stress response system. However, differences in collection and standardization strategies have led to inconsistent findings. Subjects were an ethnically diverse population-based sample of 229 men and women aged 50-67 yr who provided an overnight urine specimen. Urine concentration was standardized using a traditional creatinine-based approach as well as a new method that accounts for muscle mass. With the use of creatinine standardization, no gender or ethnic differences were noted in epinephrine or cortisol production. Norepinephrine levels were higher among women compared with men (P = 0.001), however. After accounting for muscle mass, we found that both epinephrine (P = 0.018) and norepinephrine (P = 0.033) levels were higher among men compared with women. No significant differences in cortisol production were found by gender or ethnicity. The consistency of these results with previous studies of 24-h urine samples suggests muscle mass should be accounted for when comparing overnight urinary hormone values across gender and ethnicity.     

Increases in serum estrogen levels during major illness are caused by increased peripheral aromatization

Although serum testosterone levels decrease acutely in critically ill patients, estrogen levels rise. We hypothesized that increased rates of aromatization of androgens to estrogens underlie the increase in serum estrogen levels. Eleven men and three women (age 42-69 yr) were prospectively studied before and again after elective coronary artery bypass graft surgery (CABG). Each patient received priming doses of [(14)C]androgen and [(3)H]estrogen that were immediately followed by peripheral infusions for 210 min. Eight men and three women received androstenedione (A(4))/estrone (E(1)) and three men received testosterone (T)/estradiol (E(2)). Adipose tissue biopsies were obtained in another six men before and after CABG to evaluate levels of P450 aromatase mRNA. Serum T levels decreased postoperatively in all 17 men (P < 0.001), whereas E(1) levels rose (P = 0.004), with a trend toward a rise in E(2) (P = 0.23). Peripheral aromatization rates of androgens to estrogens rose markedly in all 14 patients (P < 0.0001). Estrogen clearance rates rose (P < 0.002). Mean serum A(4) levels increased slightly postoperatively (P = 0.04), although no increase in A(4) production rates (PRs) was observed. T PRs decreased in two of three men, whereas clearance rates increased in all three. Adipose tissue P450 aromatase mRNA content increased postoperatively (P < 0.001). We conclude that the primary cause of increased estrogen levels in acute illness is increased aromatase P450 gene expression, resulting in enhanced aromatization of androgens to estrogens, a previously undescribed endocrine response to acute illness. Both increased T clearance and decreased T production contribute to decreased serum T levels. Animal studies suggest that these opposing changes in circulating estrogen and androgen levels may be important to reduce morbidity and mortality in critical illness.     

Predictors of depressive symptoms post-acute coronary syndrome

Objective: We examined the influence of gender on the prevalence of acute coronary syndrome (ACS) and the severity of depressive symptoms post-ACS.Methods: Patients received a Zung self-assessment questionnaire at hospital discharge for unstable angina (UA) or acute myocardial infarction (AMI) and returned it by mail. Major depressive symptoms were diagnosed based on a summed depressive symptoms (SDS) score of >50. Depressive symptomatology was modeled by stepwise multivariable logistic regression with the following predictors: gender, age, hypertension, diabetes mellitus, history of smoking, hypercholesterolemia, peripheral vascular disease, prior stroke, prior myocardial infarction (MI), and prior percutaneous coronary intervention or coronary artery bypass graft surgery. We also modeled severity of depressive symptoms via stepwise multiple linear regression with the same predictor variables.Results: A total of 944 patients were surveyed: 716 men and 228 women, mean (SD) age, 67 (13) years and 71 (12) years, respectively. Of these patients, 250 (35%) men and 103 (45%) women had depressive symptoms (P = 0.005). No significant difference was observed between men and women in rates of cardiac catheterization; severity of coronary artery disease; treatment with antiplatelet agents, β-blockers, angiotensin-converting enzyme inhibitors, or statins; or percutaneous or surgical revascularization rates during or post-ACS. Significant predictors of the presence of depressive symptoms were female gender (odds ratio [OR] = 1.64; 95% CI, 1.19-1.28), diabetes mellitus (OR = 1.42; 95% CI, 1.03-1.97), prior MI (OR = 1.56; 95% CI, 1.15-2.20), and smoking (OR = 1.41; 95% CI, 1.01-1.97). Variables significantly associated with a higher severity of depressive symptoms were female gender, prior MI, smoking, and stroke. Men with prior MI had significantly higher mean (SD) SDS scores than did men without prior MI in all age groups (48.4 [11] vs 44.6 [11], respectively; P < 0.001). In addition, significantly more men with prior MI had depressive symptoms compared with those without prior MI (45% vs 32%; P = 0.001). However, prior MI did not appear to affect SDS scores in women (49.1 [12] for prior MI vs 48.5 [12] for no prior MI; P = NS), and there was no significant difference in the percentage of women who had depressive symptoms with or without a history of prior MI. Depressive symptoms were much more severe in women with UA (SDS = 49.0 [12]) compared with women with AMI (SDS = 45.0 [12]; P = NS), or men with AMI (45.0 [12]; P = 0.004) or UA (46.0 [11]; P = 0.007) (analysis of variance, P = 0.003).Conclusions: Female gender is a significant independent predictor of depressive symptoms and their severity post-UA and post-AMI. History of prior MI is associated with a higher frequency and severity of depressive symptoms in men. These findings call for routine screening for depressive symptoms in men with prior MI and in women who present with ACS.     

Effects of a supraphysiological dose of testosterone on physical function, muscle performance, mood, and fatigue in men with HIV-associated weight loss

Testosterone increases fat-free mass (FFM) in men infected with human immunodeficiency virus (HIV), but its effects on muscle performance, physical function, mood, and quality of life are poorly understood. Sixty-one HIV-infected men with weight loss were randomized to receive weekly intramuscular injections of 300 mg of testosterone enanthate or placebo for 16 wk. The primary outcome of interest was physical function (walking speed, stair-climbing power, and load-carrying ability). Secondary outcome measures included body weight and composition, muscle performance, sexual function, mood, and quality of life. Serum nadir free and total testosterone levels increased (+188.0 +/- 29.6 and +720 +/- 86 ng/dl) in the testosterone, but not placebo, group. Testosterone administration was associated with increased FFM (2.8 +/- 0.5 kg), which was significantly greater than in the placebo group (P < 0.0001). Leg press strength increased significantly in testosterone-treated (P = 0.027), but not placebo-treated, men; the difference between groups was not significant. Other measures of muscle performance and physical function did not change significantly in either group. Men receiving testosterone demonstrated significantly greater improvements in mental health and quality-of-life scores than those receiving placebo and improvements in fatigue/energy and mood scores that were not significantly different from those receiving placebo. Sexual function scores did not change in either group. In HIV-infected men with weight loss, a supraphysiological dose of testosterone significantly increased FFM but did not improve self-reported or performance-based measures of physical function. Improvements in mood, fatigue, and quality-of-life measures in the testosterone group, although clinically important, need further confirmation.     

Gender as a determinant of responses to a self-screening questionnaire on anxiety and depression by patients with coronary artery disease

Background: Because patients with coronary artery disease (CAD) could benefit from interventions to decrease psychological distress, it is important to identify these individuals. Both salivary cortisol level and the Hospital Anxiety and Depression Scale (HADS) are recognized measures of stress/anxiety and depression.Objectives: This study was designed to determine whether there is an association between anxiety and depression, as measured by the HADS, and salivary cortisol levels among patients with CAD, and whether this association is affected by gender.Methods: All adult residents of Alberta, Canada, undergoing their first cardiac catheterization for CAD (≥50% occlusion of ≥2 coronary arteries) were eligible for participation in this study. A 14-question survey (the HADS) and 3 saliva-collection devices (a 1-day supply) were sent to the participants' home within 1 week of their initial cardiac catheterization. Participants were asked to take saliva samples for determination of cortisol levels on waking and at 30 and 60 minutes after waking, and then return the completed questionnaire and saliva samples using a prepaid express mailing envelope.Results: Seventy-one adults (52 men and 19 women) participated in the study. Mean (SD) ages were 68.4 (4.6) years for men and 69.1 (4.4) years for women. Among the women, significant negative correlations were found between the HADS anxiety score and the wake-up and 30-minute cortisol levels (higher HADS scores were associated with lower cortisol levels) (all, P < 0.05). Also among women, negative correlations were found between the HADS depression score and the salivary cortisol values, but the differences were not statistically significant. Conversely, among the men, nonsignificant positive correlations were found between the HADS anxiety scores and the salivary cortisol levels (higher HADS scores were associated with higher cortisol levels), and statistically significant positive correlations were observed between the HADS depression scores and all 3 salivary cortisol values (all, P < 0.05).Conclusions: Our findings suggest that the HADS is an appropriate screening instrument for anxiety and depression in patients with CAD. In particular, the scale appears to be sensitive for measuring anxiety in women and depression in men. When the HADS is used clinically as a screening tool, it should be examined through a “gender-based lens.”.     

Is testosterone influencing explosive performance?

The primary objective of this study was to analyze the relationship between testosterone levels and vertical jumping performance in elite men and women athletes. The secondary objective was to verify whether testosterone levels and vertical jumping performance were different in men and women athletes and if those measurements were different between different athletic groups. Seventy (22 women and 48 men) elite athletes in track and field (sprinters), handball, volleyball, and soccer competing at national and international levels participated in the study. After 10 hours of fasting and 1 day of rest, blood samples were drawn from the antecubital vein for determining testosterone levels. Vertical jumping tests consisted of countermovement jumps conducted on a resistive platform connected to a digital timer. Resting testosterone levels in women were 9.5% of those of the men (respectively 0.62 +/- 0.06 ng.ml(-1) and 6.49 +/- 0.37 ng.ml(-1); p < 0.001). Countermovement jump performance was significantly different between women and men athletes, with women's jumping ability 86.3% of that of men (p < 0.001). A significant positive relationship was identified between testosterone levels and vertical jump performance when all data where considered (r = 0.61, p < 0.001, n = 70).     

Differences in cortisol, aldosterone and testosterone responses to ACTH 1-17 administered at two different times of day

The effects of 100 micrograms, i.m. of the analog ACTH 1-17 administered at 0800 and 1800 on the secretion of cortisol, aldosterone and testosterone have been studied in normal subjects: 8 male and 8 female. The group as a whole and the males had significantly greater absolute and percent increments in plasma cortisol after administration at 1800. In the females, there was only a greater percent increment in cortisol after the evening administration. The heptadecapeptide always significantly stimulated serum aldosterone, with no difference between the two times of administration. In the females, ACTH 1-17 significantly stimulated testosterone, with a more protracted secretion after the evening administration. In the males, there was always a significant testosterone decrease after the administration of the drug, with no difference between morning and evening. In conclusion, 100 micrograms i.m. of the analog ACTH 1-17 stimulates cortisol secretion more when given during the circadian nadir of plasma cortisol, but only in men. ACTH 1-17 increases testosterone in women and decreases it in men, whereas it seems to increase aldosterone secretion in both sexes.     

Preliminary evidence that acute stress moderates basal testosterone's association with retaliatory behavior

A contribution to a special issue on Hormones and Human Competition.Testosterone is theorized to increase retaliation after social provocation. However, empirical evidence in support of these theories is mixed. The present research investigated whether acute stress causally suppresses testosterone's association with retaliation. We also explored sex differences in behavioral responses to acute stress. Thirty-nine participants (51.28% male) were randomly assigned to a high- or low-stress condition. Then participants engaged in 20 one-shot rounds of the ultimatum game, which was used to assess retaliatory behavioral responses to unfair treatment. Participants provided two saliva samples to measure testosterone and cortisol concentrations - one sample before the stress manipulation, and the second after the ultimatum game (20 minutes post-stressor). Results revealed a positive association between basal testosterone and retaliation in the low-stress condition, but not in the high-stress condition. Further, cortisol concentrations increased in the high- compared to the low-stress condition, and these cortisol changes moderated the association between basal testosterone and retaliation. The associations between basal testosterone and retaliation under varying levels of stress were similar in men and women. However, there was a sex difference in behavioral responses to the stress manipulation that was independent of testosterone. In women, the high-stress condition reduced retaliation compared to the low-stress condition, whereas in men the opposite pattern emerged. Collectively, this study (i) provides preliminary evidence that experimentally manipulated stress blocks basal testosterone's association with retaliation, and (ii) reveals a sex difference in retaliation under varying levels of stress. Discussion focuses on mechanisms, limitations, and the need for follow-up studies with larger sample sizes.     

Daytime napping after a night of sleep loss decreases sleepiness, improves performance, and causes beneficial changes in cortisol and interleukin-6 secretion

Sleep loss has been associated with increased sleepiness, decreased performance, elevations in inflammatory cytokines, and insulin resistance. Daytime napping has been promoted as a countermeasure to sleep loss. To assess the effects of a 2-h midafternoon nap following a night of sleep loss on postnap sleepiness, performance, cortisol, and IL-6, 41 young healthy individuals (20 men, 21 women) participated in a 7-day sleep deprivation experiment (4 consecutive nights followed by a night of sleep loss and 2 recovery nights). One-half of the subjects were randomly assigned to take a midafternoon nap (1400-1600) the day following the night of total sleep loss. Serial 24-h blood sampling, multiple sleep latency test (MSLT), subjective levels of sleepiness, and psychomotor vigilance task (PVT) were completed on the fourth (predeprivation) and sixth days (postdeprivation). During the nap, subjects had a significant drop in cortisol and IL-6 levels (P < 0.05). After the nap they experienced significantly less sleepiness (MSLT and subjective, P < 0.05) and a smaller improvement on the PVT (P < 0.1). At that time, they had a significant transient increase in their cortisol levels (P < 0.05). In contrast, the levels of IL-6 tended to remain decreased for approximately 8 h (P = 0.1). We conclude that a 2-h midafternoon nap improves alertness, and to a lesser degree performance, and reverses the effects of one night of sleep loss on cortisol and IL-6. The redistribution of cortisol secretion and the prolonged suppression of IL-6 secretion are beneficial, as they improve alertness and performance.     

A systems model of training responses and its relationship to hormonal responses in elite weight-lifters

A systems model, providing an estimation of fatigue and fitness levels was applied to a 1-year training period of six elite weight-lifters. The model parameters were individually determined by fitting the predicted performance (calculated as the difference between fitness and fatigue) to the actual one. The purpose of this study was to validate the systems model by comparing the estimated levels of fatigue and fitness with biological parameters external to the model calculation. The predicted and the actual performances were significantly correlated in each subject. The calculated fitness and fatigue levels were related to serum testosterone concentration, testosterone: cortisol and testosterone: sex hormone binding globulin ratios. The best results were obtained by the comparison between fitness and testosterone levels, which varied in parallel in each subject. In two subjects this correlation was significant (r = 0.91, P less than 0.05, and r = 0.92, P less than 0.01). The fitness changes calculated in each subject between the 15th and the 51st weeks of training were significantly correlated with the changes in serum testosterone concentration measured in the same period (r = 0.99, P less than 0.001). For the whole group testosterone and fitness variations were also significantly intercorrelated (r = 0.73, P less than 0.001). Correlations, less homogeneous and less significant, were calculated also for other hormones and ratios. These results suggest that (1) the relationships between training and performance can be described by the systems model, (2) the estimated index of fitness has a physiological meaning. The fatigue index remains to be clarified.     

Sex difference in the relationship between the hypothalamic-pituitary-adrenal axis and sex hormones in obesity

Objective: This study was carried out to investigate the role of sex in the regulation of the hypothalamic‐pituitary‐adrenal (HPA) axis and its relationship with testosterone levels in male and female obesity. Research Methods and Procedures: Twenty‐two obese men (OB‐M) and 29 obese women (OB‐W) participated in the study. Two groups of normal weight men (NW‐M) and women (NW‐W), respectively, served as controls. In basal conditions, blood concentrations of major androgens, sex hormone—binding protein, and gonadotropins were assessed, and the free androgen index (testosterone ×100/ sex hormone‐binding globulin) was calculated. All subjects underwent a combined corticotropin‐releasing hormone plus arginine‐vasopressin stimulation test. Results: OB‐M and NW‐M had higher basal adrenal cortical tropic hormone (ACTH) and cortisol levels than their female counterparts. In addition, ACTH, but not cortisol basal, levels were significantly higher in obese than in normal weight controls in both sexes. OB‐W had a higher response than OB‐M to the combined corticotropin‐releasing hormone plus arginine‐vasopressin test of both ACTH and cortisol [expressed as incremental percentage of area under the curve (AUC%)]. The same finding was present between NW‐W and NW‐M. Basal luteinizing hormone levels were negatively correlated to ACTH_AUC% in both OB‐W and OB‐M. In the OB‐W, however, a positive correlation was found between cortisol_AUC% and testosterone (r = 0.48; p = 0.002), whereas a tendency toward a negative correlation was present in OB‐M. Discussion: In conclusion, we have shown a significant positive relationship between the activity of the HPA axis and testosterone in obese women, which suggests a partial responsibility of increased HPA axis activity in determining testosterone levels. In addition, it clearly seems that, as reported in normal weight subjects, a sex difference in the HPA axis activity still persists even in the presence of obesity.     

Maternal testosterone and fetal sex

To investigate the influence of fetal sex on maternal testosterone levels throughout pregnancy, blood was sampled from 37 healthy pregnant women from week 14 until term and at 6 weeks postpartum. Testosterone concentrations were measured with a highly specific RIA after chromatographic purification. Mean (+/- SD) testosterone at the end of gestation was significantly higher compared to non-pregnant values (3.10 +/- 2.38 mM/l, n = 32 vs 1.14 +/- 1.06 nM/l, n = 35). It appeared that in women carrying a male fetus testosterone levels gradually increased during pregnancy up to 3.99 +/- 2.72 nM/l. In women carrying a female fetus the levels decreased after the first trimester from 2.44 nM/l to 1.80 nM/l. A statistically significant difference (P less than 0.01) existed in maternal testosterone concentrations between both groups during the second half of pregnancy.