Fluctuations In Testosterone Research Articles

Fluctuations in Cortisol and Testosterone Map to Fluctuations in Opinion Strength in Healthy Men

PurposeOpinions are often linked to emotions and stress. It is well established that testosterone and cortisol are useful biomarkers of stress and can predict human emotion and behavior. Therefore, the purpose of this work was to explore whether changes in testosterone and cortisol concentration map to shifts in opinions.MethodsWe present three studies with healthy men, where we (1) monitored diurnal changes in testosterone and cortisol alongside political opinion change using a descriptive longitudinal design, (2) assessed testosterone, cortisol and political opinion change in an experimental trial using a physical exercise intervention designed to decrease cortisol concentration and/or increase testosterone concentration, and (3) monitored testosterone and cortisol change with political opinion in a trial with psychosocial intervention designed to increase cortisol concentration/decrease testosterone concentration.ResultsTestosterone concentration and opinion changes were observed across the day (p < 0.05). Furthermore, opinions changed similarly to exercise-induced increases in testosterone (8.6–11.5%), but inversely to exercise-induced reductions in cortisol (p < 0.05). Opinion changes also occurred in similar fashion to testosterone changes following psychosocial intervention (-5.6% to -10.0%), and inversely to cortisol changes (p < 0.05). Finally, opinion change and testosterone change correlated at the within person level (r = 0.17 to 0.33; p < 0.05).ConclusionWe showed natural fluctuations in testosterone and cortisol covaried in parallel with shifts in opinion. Further, given the emergence of relationships for opinion change with hormone change, we contend that physiological stress response (i.e., testosterone and cortisol change) may predict, or even cause, opinion change.

Serological and histolomorphological investigation of camel bulls testes (Camelus dromedaries) during the rutting and non-rutting seasons

BackgroundCamels are bred for their milk, meat, wool and hair, transportation, and their excrement as fuel. The seasonal reproduction of camel bull is accompanied by changes in sexual activity, the morphology, and function of the testes. This study aimed to evaluate the seasonal fluctuations in serum testosterone (T) levels as well as total antioxidant capacity (TAC) and malondialdehyde (MDA) levels in the testes of dromedary bulls (Camelus dromedarius) during the rutting and non-rutting seasons. Moreover, the impact of rutting season on the testicular size and histomorphology was also observed. Seventy mature dromedary bulls were divided into a rutting group (n = 35) and a non-rutting group (n = 35). From these bulls, blood samples and testes were collected during the rutting season (October to April) and non-rutting season (May to September) from a local slaughterhouse.ResultsAll parameters changed significantly during rutting and non-rutting periods in camel bulls. The levels of TAC in testes, and serum T were significantly (P < 0.05) higher in the rutting group than in the non-rutting group. However, testicular MDA was significantly (P < 0.05) lower in the rutting group than in the non-rutting group. TAC was negatively correlated with MDA (r = -0.59, p < 0.01). Moreover, in the rutting group and the non-rutting group, T was positively correlated with levels of TAC (r = 0.66, p < 0.0003). Additionally, testicular size (length, breadth, and thickness) was significantly greater in camels during the rutting season than in camels during the non-rutting season. Moreover, the number and diameter of seminiferous tubules, and spermatogenesis increased during the rutting season, whereas, the collagen content and apoptosis increased during the non-rutting season.ConclusionThis study revealed that the rutting normal breeding season (NBS, rutting group) was associated with higher levels of total antioxidant capacity (TAC), T, and spermatogenic activity while the collagen content, concentrations of MDA (the oxidative stress factor) and apoptosis (an outcome of oxidative stress) were lower than those in the low breeding season (LBS, non-rutting group). In addition, the testicular size and seminiferous tubule diameter and number were higher during the NBS.

Assessment of spermatogenesis in camels via seminiferous tubule staging and testosterone profiling

Objective: To investigate the successive morphological stages of spermatogenesis, hormonal regulation, and testosterone profile in dromedary camel reproduction. Methods: Testicular tissue samples were obtained from 12 dromedary bull camels aged 7 to 8 at a local abattoir. The histological assessment involved tissue processing, hematoxylin and eosin (H &amp; E) staining, and examination under a microscope. Stereological analysis, germ cell identification, and assessment of seminiferous tubules and maturation were conducted. Testosterone assay was performed by radioimmunoassay using blood samples collected at regular intervals. Results: The study revealed 12 phases of the dromedary camel's seminiferous epithelium cycle, highlighting distinct morphological characteristics and cellular processes. Acrosomal migration, maturation, cap formation, and the Golgi-mediated synthesis of proacrosomal vesicles were also explained in dimension, as were the steps of acrosome biogenesis. Spermatids and mature sperm cells were present when spermatogenesis phases were examined. An analysis of the dimensions of seminiferous tubules revealed specific measures for diameter, area, and epithelial height about luminal characteristics. Moreover, there were noticeable variations in the serum testosterone concentrations during the study period, indicating temporal dynamics. Conclusions: This study outlines the spermatogenesis process in dromedary camels across 12 stages, emphasizing cellular dynamics and acrosomal biogenesis. It also provides seminiferous tubule measurements and observes seasonal testosterone fluctuations, offering insights into reproductive regulation and potential strategies for camel breeding conservation.

Diurnal Fluctuations in Steroid Hormones Tied to Variation in Intrinsic Functional Connectivity in a Densely Sampled Male.

Most of mammalian physiology is under the control of biological rhythms, including the endocrine system with time-varying hormone secretion. Precision neuroimaging studies provide unique insights into how the endocrine system dynamically regulates aspects of the human brain. Recently, we established estrogen's ability to drive widespread patterns of connectivity and enhance the global efficiency of large-scale brain networks in a woman sampled every 24 h across 30 consecutive days, capturing a complete menstrual cycle. Steroid hormone production also follows a pronounced sinusoidal pattern, with a peak in testosterone between 6 and 7 A.M. and nadir between 7 and 8 P.M. To capture the brain's response to diurnal changes in hormone production, we carried out a companion precision imaging study of a healthy adult man who completed MRI and venipuncture every 12-24 h across 30 consecutive days. Results confirmed robust diurnal fluctuations in testosterone, 17β-estradiol-the primary form of estrogen-and cortisol. Standardized regression analyses revealed widespread associations between testosterone, estradiol, and cortisol concentrations and whole-brain patterns of coherence. In particular, functional connectivity in the Dorsal Attention Network was coupled with diurnally fluctuating hormones. Further, comparing dense-sampling datasets between a man and a naturally cycling woman revealed that fluctuations in sex hormones are tied to patterns of whole-brain coherence in both sexes and to a heightened degree in the male. Together, these findings enhance our understanding of steroid hormones as rapid neuromodulators and provide evidence that diurnal changes in steroid hormones are associated with patterns of whole-brain functional connectivity.

Fluctuations of testosterone and cortisol levels in male dromedary camels in response to behavioral and management situations.

Biostimulation is a management practice that improves the reproductive parameters, potentiates the desire, and improves the reproductive efficiency during the short breeding season in camels. This study aims to investigate the concurrent changes in hormonal profiles in response to management and behavioral situations on camel farms in the Eastern region of Saudi Arabia. A total of 10 male and 50 female camels were used in this study. The hormonal profile of male camels was evaluated weekly starting from December to August. The results show that both serum testosterone and cortisol levels increased (p < 0.01) from December to March compared to April to August. A strong negative correlation was observed between testosterone levels and temperature (r = -0.81, p < 0.05), and a similarly robust negative correlation was found between cortisol levels and temperature (r = -0.83, p < 0.05). The dominant rutting males showed higher levels of testosterone than the submissive males. Serum testosterone levels increased (p < 0.01) in males out of rutting after hearing the sounds of other couples before and during mating. Hearing sounds emitted during mating increases the testosterone output, and improves the libido of male camels during the nonrutting period. It is important to keep two individually housed males for mating purposes. One male joins the herd alone in winter (winter rutter), and the other joins in spring (spring rutter), this could keep the libido extended rutting and improve the reproductive performance in camel herds.

Biobehavioral mechanisms underlying testosterone and mood relationships in peripubertal female adolescents.

The pubertal transition is characterized by pronounced sex hormone fluctuation, refinement of affective neural circuitry, and an increased risk of depression in female adolescents. Sex hormones, including testosterone, exert modulatory effects on frontal-limbic brain networks and are associated with emotion dysregulation and depressive symptoms. Weekly changes in hormones predict affective symptoms in peripubertal female adolescents, particularly in the context of stress; however, the biobehavioral mechanisms underlying hormone change and mood relationships during the pubertal transition have yet to be determined and was the objective of the present study. Forty-three peripubertal female adolescents (ages 11-14) collected 8-weekly salivary hormone (estrone, testosterone) samples and mood assessments to evaluate hormone-mood relationships, followed by a biobehavioral testing session with psychosocial stress and EEG. Within-person correlations between weekly hormone changes and corresponding mood were performed to determine individual differences in mood sensitivity to weekly hormone change. Increased frontal theta activity indexing emotion reactivity, reduced cortisol reactivity, and reduced vagal efficiency predicted the strength of the relationship between testosterone and mood. Further, testosterone-sensitivity strength was associated with the enhancement of negative affect following stress testing. Results identify divergent frontal theta and stress responses as potential biobehavioral mechanisms underlying mood sensitivity to peripubertal testosterone fluctuation.

P684. Diurnal Fluctuations in Testosterone Tied to Variation in Intrinsic Functional Connectivity in a Densely Sampled Male

Sex hormones are powerful neuromodulators of learning and memory, influencing the brain at the level of microscopic intracellular events to macroscopic brain organization. A central feature of the mammalian endocrine system is that hormone secretion varies over time. Human neuroimaging studies that densely sample individuals over timescales of days, weeks, and months provide unique insight into the role our endocrine system plays in regulating the dynamic properties of the human brain. For example, we recently established estrogen’s ability to drive widespread patterns of connectivity and enhance the global efficiency of large-scale brain networks in a densely-sampled female (Pritschet et al., 2020). In men, sex hormone production follows a sinusoidal pattern with a peak in testosterone between 6-7am and nadir between 7-8pm.

Novel protein markers of androgen activity in humans: proteomic study of plasma from young chemically castrated men.

Reliable biomarkers of androgen activity in humans are lacking. The aim of this study was, therefore, to identify new protein markers of biological androgen activity and test their predictive value in relation to low vs normal testosterone values and some androgen deficiency linked pathologies. Blood samples from 30 healthy GnRH antagonist treated males were collected at three time points: (1) before GnRH antagonist administration; (2) 3 weeks later, just before testosterone undecanoate injection, and (3) after additional 2 weeks. Subsequently, they were analyzed by mass spectrometry to identify potential protein biomarkers of testosterone activity. Levels of proteins most significantly associated with testosterone fluctuations were further tested in a cohort of 75 hypo- and eugonadal males suffering from infertility. Associations between levels of those markers and cardiometabolic parameters, bone mineral density as well as androgen receptor (AR) CAG repeat lengths, were explored. Using receiver operating characteristic analysis, 4-hydroxyphenylpyruvate dioxygenase (4HPPD), insulin-like growth factor-binding protein 6 (IGFBP6), and fructose-bisphosphate aldolase (ALDOB), as well as a Multi Marker Algorithm, based on levels of 4HPPD and IGFBP6, were shown to be best predictors of low (<8 nmol/l) vs normal (>12 nmol/l) testosterone. They were also more strongly associated with metabolic syndrome and diabetes than testosterone levels. Levels of ALDOB and 4HPPD also showed association with AR CAG repeat lengths. We identified potential new protein biomarkers of testosterone action. Further investigations to elucidate their clinical potential are warranted. The work was supported by ReproUnion2.0 (grant no. 20201846), which is funded by the Interreg V EU program.

Testosterone fluctuations in response to a democratic election predict partisan attitudes toward the elected leader

Intergroup competitions such as democratic elections can intensify intergroup polarization and conflict. Partisan attitudes toward the elected leader can also shift from before to after an election, but the biology underlying these attitudinal shifts remains largely unknown. An important factor could be the hormone testosterone, which is theorized to fluctuate during competition and to influence status seeking. In a naturalistic study of 113 registered voters, we measured changes in testosterone levels and attitudes toward the winner of the 2012 US Presidential Election. We found that supporters of the losing candidate (Mitt Romney) showed acute increases in testosterone levels compared to supporters of the winner (Barack Obama) on the evening of Election Day. Supporters of the losing candidate also demonstrated flatter diurnal testosterone slopes on Election Day that persisted up to two days after the election. Furthermore, greater increases in acute testosterone levels and flatter diurnal slopes among supporters of the losing candidate were associated with less positive evaluations of the winning candidate. These testosterone-moderated attitudinal shifts observed in the days after the election showed a directionally similar pattern with a weaker effect size six months later. Finally, we confirmed that the main results were robust to alternative data analytic choices using multiverse specification curve analysis. The findings from this paper suggest that hormonal responses to large-scale intergroup competitions may shape how we perceive our elected leaders, shedding light on the biology of intergroup relations.

Menstrual variation in the acute testosterone and cortisol response to laboratory stressors correlate with baseline testosterone fluctuations at a within- and between-person level

Studies have compared HPA and HPG stress reactivity across the follicular and luteal phases to assess the menstrual impact of estradiol and progesterone fluctuations. Ovulatory shifts in baseline and stressor-induced testosterone among athletic women offer a new framework to explore these responses. Here we investigated menstrual variation in baseline testosterone as a predictor of the acute testosterone and cortisol response to laboratory stressors in female athletes. Using a semi-randomized crossover design, thirty athletic women completed a physical (4 × 6-s bike sprints) and psychological (5 × 2-min cognitive tests with social evaluation) stressor on day seven (D7), 14 (D14), and 21 (D21) of a menstrual cycle. Baseline fluctuations and acute changes in salivary testosterone and cortisol were measured. The D14 testosterone response to both stressors (13.7%) exceeded D7 (7.3%) and D21 (7.0%), whereas cortisol was less responsive on D14 (9.8%) than D7 (13.0%) and D21 (12.0%); all moderate to large effect size differences (p < 0.01). Baseline testosterone, which presented large individual and menstrual variation with a D14 peak, was significantly related (moderate correlations) to testosterone and cortisol stress reactivity on a between-person level. Both outcomes were related (weak correlations) to within-person fluctuations in baseline testosterone, but these effects were mediated by testing day. In conclusion, menstrual variation in baseline testosterone concentration correlated with testosterone and cortisol reactivity to a physical and psychological stressor. Thus, gradients of stressor-induced hormonal change showed some dependency to endogenous testosterone, both individual differences and fluctuations over time, among naturally cycling athletic women. Lay summary The female menstrual cycle is accompanied by dramatic shifts in estradiol and progesterone concentration, but less is known about testosterone variability and its role in stress regulation. In this study, menstrual fluctuations in baseline testosterone concentration correlated with acute testosterone and cortisol reactivity to laboratory stressors.

Within-person coupling of estradiol, testosterone, and cortisol in women athletes.

PurposeIn variety of settings cortisol and testosterone are positively “coupled.” That is, within-person fluctuations of cortisol and testosterone levels occur in parallel—increases and decreases in one hormone are associated with corresponding increases and decreases in the other. The present report explored hormone coupling in women athletes in two studies selected because they included measurements of salivary levels of cortisol, testosterone, and estradiol—a hormone that has been only infrequently studied in the context of competitive athletics.MethodsConsenting members of Emory University’s varsity volleyball and soccer teams gave saliva samples on multiple occasions in the run-up to and over the course of two different intercollegiate contests.ResultsVolleyball and soccer players showed remarkably similar hormone-specific patterns of increase in relationship to the different stages of competition—before warm-up, after warm-up, and after competition. For both the volleyball and soccer team, Hierarchical Linear Model (HLM) analyses showed estradiol as being significantly coupled with testosterone which was also coupled with cortisol.ConclusionsThis is, apparently, the first report of significant within-person coupling between estradiol and testosterone in the context of competitive athletic stress. These two hormones may be coupled in a wide variety of circumstances not limited to ones involving sport competition, and results reported here should encourage exploration of the extent to which coordinated fluctuations in estradiol, testosterone, and cortisol levels are present in other, more neutral settings and the ways in which the coordination of these fluctuating hormone levels may benefit human performance.

No evidence that hormonal contraceptive use or circulating sex steroids predict complex emotion recognition

Relatively little is known about the effects of endogenous and exogenous steroid hormones on ecologically relevant behavioral and cognitive phenotypes in women, such as emotion recognition, despite the widespread use of steroid hormone-altering hormonal contraceptives (HCs). Though some previous studies have examined the effect of HC use, estradiol, progesterone, and testosterone on emotion recognition in women, they have been limited by cross-sectional designs, small sample sizes (total n < 100), and compromised statistical power to detect significant effects. Using data from two test sessions in a large sample of naturally cycling women (NC; n = 192) and women on HCs (n = 203), we found no group differences in emotion recognition; further, the lack of group differences in emotion recognition was not modulated by item difficulty or emotional valence. Among NC women who provided saliva samples across two sessions that were assayed for estradiol and progesterone concentrations, we found no compelling evidence across models that between-subject differences and within-subject fluctuations in these ovarian hormones predicted emotion recognition accuracy, with the exception that between-subjects estradiol negatively predicted emotion recognition for emotions of neutral valence (p = .042). Among HC women who provided saliva samples across two sessions that were assayed for testosterone, we found no compelling evidence that between-subjects differences and within-subject fluctuations in testosterone predicted emotion recognition accuracy. Overall, our analyses provide little support for the idea that circulating endogenous or exogenous ovarian hormones influence emotion recognition in women.

Testosterone Status Following Short-term, Severe Negative Energy Balance Predicts Fat-free Mass Loss in U.S. Marines

Male US military personnel exposed to periods of severe negative energy balance often experience marked reductions in circulating total testosterone, and it is not uncommon for concentrations to fall below normal levels (<300 ng/dL). However, testosterone fluctuations following severe negative energy balance are variable, and little is known about the metabolic and physiological differences between males who experience low testosterone (LT) and those who maintain normal testosterone (NT). PURPOSE: To determine metabolic and physiological differences between males with LT versus those with NT following 8 d of strenuous military training. METHODS: Male US Marines (n = 68) were dichotomized based on testosterone concentration (< or ≥ 300 ng/dL) following 8 d of severe negative energy balance incurred during military training. Body composition (DEXA) and whole-body protein turnover (15N alanine) were measured and blood and urine samples collected before (PRE) and after (POST) training. Linear mixed models were used to assess the effects of testosterone status, time, and their interaction on outcomes. RESULTS: Testosterone concentrations decreased PRE (505 ± 135 ng/dL) to POST (284 ± 115 ng/dL, P < 0.01). When volunteers were dichotomized by POST testosterone status (NT, n = 24: 407 ± 97 vs. LT, n = 44: 217 ± 52 ng/dL, P < 0.01), PRE BMI, total fat mass, and testosterone were greater in NT compared to LT (P < 0.05). LT lost more fat-free mass (FFM, -3.4 ± 1.3 kg) and less fat mass (-2.4 ± 1.2 kg) compared to NT (-2.4 ± 2.0 and -3.2 ± 1.6 kg, respectively; P-interaction < 0.03). Insulin (+5.55 ± 9.35 μU/mL) and norepinephrine (+0.23 ± 0.29 ng/mL) increased from PRE to POST in LT, whereas no changes occurred in NT (+1.03 ± 3.75 μU/mL and +0.04 ± 0.30 ng/mL, respectively), resulting in significant differences between groups (P-interaction < 0.02). Independent of time, LT had greater whole-body protein synthesis, breakdown, and flux (P-status < 0.01), but not net balance (P-status = 0.2), compared to NT. CONCLUSION: Military personnel susceptible to operational stress-induced LT may be predisposed to greater FFM loss during periods of negative energy balance incurred during short-term, strenuous military training. Supported by US Army Medical Research and Materiel Command; authors’ views not official US Army or DoD policy.

Predictors of decreased libido in women during the late reproductive years.

To identify risk factors for decreased libido among women in the late reproductive years. Prospective cohort. Women aged 35 to 47 years identified through random digit dialing were prospectively followed for 4 years with serial hormone assays and standardized questionnaires. Mean hormone values, hormone trends over 4 years, and fluctuation in hormone levels were compared among women with and without a decrease in libido at the last assessment period. Total testosterone, dihydroepiandrosterone sulfate, estradiol, follicle-stimulating hormone, luteinizing hormone, body mass index, psychosocial, and socioeconomic variables were evaluated using multivariable logistic regression. Of 326 women, 87 (27%) reported a decreased libido, whereas 239 (73%) did not. Participant-specific means for all hormone levels over the study period were similar among both groups. However, total testosterone fluctuation over the study was significantly different between groups. Women whose testosterone levels fluctuated from 3.8 to 21.5 ng/dL around a mean value of 9 ng/dL were four times more likely to report decreased libido compared with women with little fluctuation in testosterone [odds ratio (OR) 4.0; 95% CI, 1.6-10.0]. Depression (OR 3.4; 95%CI, 1.9-6.1), vaginal dryness (OR 3.5; 95%CI, 1.8-6.6), and children living at home (OR 1.4; 95%CI, 1.1-1.7) were also independently associated with decreased libido. Decreased libido in the late reproductive years is associated with a pronounced fluctuation in total testosterone over time. Other independent risk factors for decreased libido include vaginal dryness, depression, and living with children. Sexual dysfunction is a complex disorder, related to physiological and psychosocial factors, requiring further investigation.

Health-related physical fitness and quality of life in men with congenital hypogonadotropic hypogonadism.

Congenital hypogonadotropic hypogonadism is a rare disorder characterised by impaired testosterone secretion since birth, and represents a valuable model for studying the effects of testosterone replacement therapy (TRT) in humans. This cross-sectional study aimed to investigate all health-related physical fitness (HRPF) components and quality of life in a series of eight men with hypogonadotropic hypogonadism under regular TRT. The study group was compared to a control group of 16 healthy subjects paired for age, body mass index and physical activity. Body composition, aerobic capacity, muscular strength and endurance, and joint flexibility were evaluated in two different 7-day interval time points, based on the pharmacokinetics of testosterone in the hypogonadal group. Quality of life was assessed by the WHOQOL-brief questionnaire. Both groups had similar performances in all HRPF components evaluated, independently of plasma testosterone levels (p>.05). Quality of life was also similar in the four domains analysed (p>.05). The results of this pilot study suggest that regular testosterone replacement was efficient in providing HRPF and quality of life in a series of congenitally hypogonadal men to levels like those observed in healthy men. In addition, acute fluctuations in plasma testosterone did not correlate with changes in muscle strength and endurance.

Testosterone and intrasexual competition in men: is there any relation with digit ratio (2D:4D)?

Digit ratio 2D:4D is a sexually dimorphic characteristic and it is believed that this difference is related to high levels of prenatal testosterone and circulating testosterone in men. High levels of testosterone are also associated with traits related to competitiveness. Therefore, this study aimed to examine the relation between intrasexual competition and 2D:4D in men. One hundred thirteen college men answered a questionnaire to measure their scores of intrasexual competition and donated a saliva sample to measure their testosterone levels; finally, the finger length from both hands was measured. It was found a positive correlation between testosterone levels and intrasexual competition scores, and a negative correlation between testosterone levels and left 2D:4D. Finally, we did not find a significant association between digit ratios 2D:4D and intrasexual competition scores. Our study shows that men with higher testosterone levels also have higher intrasexual competition scores and lower values of left digit ratio 2D:4D. Further studies will have to take into account fluctuations in testosterone over the time to observe if the relation between competitiveness scores and digit ratios 2D:4D becomes significant.

Daily Fluctuations of Progesterone and Testosterone Are Associated With Fibromyalgia Pain Severity

The purpose of this longitudinal blood sampling study was to examine relationships between sex hormones and fibromyalgia pain. Eight women meeting case definition criteria for fibromyalgia provided venous blood samples and reported their fibromyalgia pain severity over 25 consecutive days. All women exhibited normal menstrual cycles and were not taking oral contraceptives. Cortisol, and the sex hormones estradiol, progesterone, and testosterone, were assayed from serum. A linear mixed model was used to determine if fluctuations of sex hormones were associated with changes in pain severity. In the entire sample, day to day changes in progesterone (P = .002) as well as testosterone (P = .015) were significantly and inversely correlated with pain severity. There was no relationship between estradiol and pain (P = .551) or cortisol and pain (P = .633). These results suggest that progesterone and testosterone play a protective role in fibromyalgia pain severity. Sex and other hormones may serve to increase as well as decrease fibromyalgia pain severity. PerspectiveSex hormones fluctuate normally in women with fibromyalgia, but may still contribute to pain severity.

Functional significance of men's testosterone reactivity to social stimuli.

Rapid testosterone fluctuations in response to social stimuli are observed across a wide range of species, and the highly conserved nature of these fluctuations suggests an adaptive function. This paper reviews the current literature on testosterone reactivity, primarily in human males, and illustrates how life-history theory provides an adequate theoretical framework to interpret findings. The review is structured around supporting evidence suggesting that situations implicated in mating effort either directly (e.g., interactions with a mate) or indirectly (e.g., intrasexual competition) are generally associated with a brief elevation of testosterone, while situations implicated in parenting effort (e.g., nurturant interactions with offspring) are generally associated with a decline in testosterone. Further, we discuss how these fluctuations in testosterone have been linked to future behaviors, and how situational, motivational, and physiological variables moderate the interplay between social stimuli, testosterone reactivity, and behavior. Supporting the notion that testosterone can play a causal role in modulating behavior in response to social stimuli, we also summarize recent single administration studies examining the effects of testosterone on physiology, neurobiology, and behavior. A conceptual model provides links between supported findings, and hypothesized pathways requiring future testing.

A hormonal approach to anti-social behaviour.

Altered levels of cortisol and testosterone have previously been associated with anti-social personality disorder (ASPD) and psychopathy, but there is some conflicting evidence as to how characteristic these findings are. To test the hypothesis that diurnal fluctuations in cortisol and/or testosterone will differentiate ASPD and psychopathy among male forensic psychiatric inpatients and distinguish both groups from healthy men not in treatment. One hundred and sixty-six men participated: 81 patients with ASPD, 42 of whom had a Psychopathy Checklist-Revised (PCL-R) score of 26 or more and 39 with a score of 25 or less, 51 forensic hospital employees and 34 general population men. None in the latter two groups had abnormal personality traits. For each person, diurnal cortisol and testosterone saliva samples were collected. Both patient groups and the forensic hospital employees showed significantly higher diurnal testosterone levels than the general population, community-based men. The community men showed significantly lower values in their diurnal cortisol variation than the ASPD and psychopathy groups but, in this, were similar to the forensic employee group. Neither cortisol nor testosterone levels differentiated the higher from lower Psychopathy Checklist-Revised scorers. We replicated findings of diurnal testosterone deficiencies among men with psychopathy and ASPD, but we were unable to differentiate patients groups from each other or from the hospital employees on cortisol measures. This suggests a case for more research with more diverse comparison groups and more differentiation of personality traits before drawing definitive conclusions about distinctive hormonal patterns among men with psychopathy, as external environmental variables may prove more influential than previously suspected. Copyright © 2015 John Wiley & Sons, Ltd.

English

Vibration is a mechanical stimulus that is characterized by an oscillatory motion. When there is a direct contact of a person, in general standing on the base of this type of platform, the vibration that is produced in these machines is transmitted to the body of the subject producing whole body vibration (WBV) exercises. Biological effects can be associated with the WBV exercises with desirable and undesirable consequences. These effects of the WBV exercises seem to be related to a direct effect in a tissue/organ/system and/or or to indirect effects due to alteration of the plasma concentration of some hormonal and non hormonal biomarkers. The aim of this investigation is to present a revision about hormonal and non hormonal biomarkers in human beings submitted to WBV exercises that have suffered alteration in the plasma concentrations. Searches were performed in the PubMed and Scopus databases with the key words &ldquo;whole body vibration&rdquo;. Papers were selected following defined criteria. Considering the WBV exercise, hormonal fluctuations of testosterone, growth, insulin-like growth factor1, epinephrine, norepinephrine, cortisol, irisin, parathyroid hormone and sclerotin are observed. Non hormonal biomarkers have suffered alterations in response to WBV, as glucose, free fatty acids, adiponectin, transforming growth factor-beta1, nitric oxide, osteopontin, interleukin-1beta, bone-specific alkaline phosphatase, cartilage oligometric matrix protein and tumor necrosis factor-alpha in plasma concentration. In conclusion, putting together the findings related to the alterations of the concentration of hormonal and non hormonal biomarkers due to the WBV exercises, it is possible that the fluctuations in the plasma concentrations of these biomarkers might help us understand better the biological effects of this kind of exercises, probably due to neuroendrocrine responses. &nbsp; Key words: Whole body vibration exercise, vibration, hormonal and non hormonal fluctuations &nbsp