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The “challenge hypothesis” predicts higher male–male aggressive behavior along with increases in testosterone levels during times of reproductive challenges and social instability. In addition, in some primate species, higher glucocorticoid levels can be observed as well, but this is usually modulated by dominance rank. We studied rank-related aggressive behavior, mating activity, and fecal testosterone and glucocorticoid metabolites (fTm and fGCm) in male stumptail macaques (Macaca arctoides) in order to test some predictions of the “challenge hypothesis”. Over a 20-month period, we collected data on aggressive behavior and copulation, as well as fecal samples (n = 700) to quantify fTm and fGCm in seven adult stumptail males living in captivity. During periods of mating activity, male-to-male aggression increased in higher- and middle-ranking males. Neither fTm nor fGCm levels predicted male-to-male aggression. fGCm levels (but not fTm) were positively associated with male-to-female aggression; however, this association was pronounced during periods of mating activity. fGCm levels differed according to social rank, with middle-ranking males having the highest levels. Both hormones were higher during periods of mating activity, but only in higher- and middle-ranking males. Taken together, our findings partially support the challenge hypothesis in a non-seasonal primate and shed some light on the unique social and mating system of the stumptail macaque.

Purpose: To evaluate alterations in cortisol and testosterone response after the exposure to images with traumatic or violent content, as well as their association with mental health indicators, by comparing an urban and a suburban population in a middle-income country. Methods: We quantified cortisol and testosterone response in a sample of 122 voluntaries from the State of Mexico, and from Mexico City, using saliva samples collected at 0, 15, 30, and 60 min after the exposure of images with violent content. Participants answered a general information questionnaire and the Symptom Checklist-90-R to assess their mental health status. Generalized Estimating Equation Models were built to analyze cortisol and testosterone levels and MANOVAs were performed to test differences in participants’ mental health between cities. Results: We found higher basal cortisol levels and a flat cortisol response in the suburban population compared to the urban one, who had lower basal levels and a peak 15 minutes after the images exposure. Testosterone levels in men decreased at 30 min, but basal levels were higher in urban men. Testosterone levels decreased 30 min after images exposure only in suburban women. Participants living in suburban areas had higher scores of somatization, obsessive-compulsive and interpersonal sensitivity, as well as more sleep disorders than participants living in urban areas. Conclusion: This study offers novel evidence about differences in cortisol and testosterone responses to a socially evaluative stressor and in mental health indicators between urban and suburban citizens, highlighting the impact of urbanization process on physiological and psychological outcomes.

This study evaluated the antidepressant-like effects of a methanol extract of

This study evaluated the antidepressant-like effects of a methanol extract of Leonotis nepetifolia in behavioural tests in mice. Our results showed that a single administration of the extract significantly reduced immobility behaviour in the tail suspension test, while three administrations were necessary to diminish immobility behaviour in the forced swimming test. A daily dose of the extract for 28 days improved body weight gain and significantly reduced corticosterone levels of mice exposed to chronic unpredictable mild stress. Metabolic profiling of the extract revealed that nepetaefolin, methoxynepataefolin, and 7-O-β-glucoside luteolin were the main products. Acute and repeated administration of the extract produced antidepressant-like effects in animals subjected to chronic stress. Our results suggest the hypothalamus-hypophysis-adrenal axis participates in the antidepressant actions of the extract. These results show that alterations in behaviour elicited by stress can be prevented with L. nepetifolia treatment.

Chronic stress exposure during adolescence is a significant risk factor for the development of depression. Chronic social defeat (CSD) in rodents is an animal model of depression with excellent ethological, predictive, discriminative, and face validity. Because the CSD model has not been thoroughly examined as a model of stress-induced depression within the adolescence stage, the present study analyzed the short- and long-term behavioral and neuroendocrine effects of CSD during early adolescence. Therefore, adolescent male Swiss-Webster (SW) mice were exposed to the CSD model from postnatal day (PND) 28 to PND37. Twenty-four hours (mid-adolescence) or 4 weeks (early adulthood) later, mice were tested in two models of depression; the social interaction test (SIT) and forced swimming test (FST); cognitive deficits were evaluated in the Barnes maze (BM). Finally, corticosterone and testosterone content was measured before, during, and after CSD exposure, and serotonin transporter (SERT) autoradiography was studied after CSD in adolescent and adult mice. CSD during early adolescence induced enduring depression-like behaviors as inferred from increased social avoidance and immobility behavior in the SIT and FST, respectively, which correlated in an age-dependent manner with SERT binding in the hippocampus; CSD during early adolescence also induced long-lasting learning and memory impairments in the Barnes maze (BM). Finally, CSD during early adolescence increased serum corticosterone levels in mid-adolescence and early adulthood and delayed the expected increase in serum testosterone levels observed at this age. In conclusion: (1) CSD during early adolescence induced long-lasting depression-like behaviors, (2) sensitivity of SERT density during normal brain development was revealed, (3) CSD during early adolescence induced enduring cognitive deficits, and (4) results highlight the vulnerability of the adolescent brain to social stressors on the adrenal and gonadal axes, which emphasizes the importance of an adequate interaction between both axes during adolescence for normal development of brain and behavior.

The development of indirect mechanisms of intrasexual competition (e.g., visual identification of possible rivals) could be related to personality traits such as aggressiveness and self-esteem. However, the study of endocrine changes associated to indirect mechanisms of intrasexual competition is scarce. The aim of this study was to investigate the changes in testosterone levels after a rival choice test in men and how intrasexual competitiveness, aggressiveness, and self-esteem modulate these changes. A group of 160 healthy men answered four personality questionnaires, participated in a rival choice test, and donated saliva samples to measure the changes in their testosterone levels. We found a significant decrease in testosterone levels of men with lower intrasexual competitiveness, but testosterone levels remained stables in competitive men. Non-significant results were found for aggressiveness and self-esteem. These decreases in testosterone levels could be interpreted as an adaptation aimed to reduce costs in male-male contests in Western modern societies.

Ethnopharmacological relevance Calea zacatechichi is a plant with an extensive popular and ritual use in Mexico. In healthy volunteers, it induces well-being and tranquility senses, and facilitates superficial stages of sleep. However, anxiolytic, and antidepressant-like effects and changes on the sleep-waking stages have not been explored. Aim To determine anxiolytic and antidepressant-like effects of an aqueous extract of C. zacatechichi (CZ) in rodents and to analyze their effects on hippocampal activity in the rat sleep-waking cycle. Material and methods CZ anxiolytic- and antidepressant-like effects were evaluated in several mice and rat behavioral paradigms. CZ effects on temporal distribution of sleep were described, and hippocampus EEG frequency patterns were analyzed during the sleep-waking cycle; absolute and relative powers were analyzed during Rapid Eye Movements (REM) and non-REM sleep stages. CZ chemical analysis was performed by UPLC-ESI-MS. Results CZ produced specific and robust anxiolytic- and antidepressant-like effects in mice and rats, similar to those of prototypical drugs, at doses ranging from 0.5 to 50 mg/kg. CZ at 100 mg/kg produced visible mild sedative effects in rats, associated with a significant increase in Slow Wave Sleep episodes during a 6 h recording, and enhanced fast frequencies of hippocampus (gamma-band:31–50 Hz) during REM sleep. Conclusion Results could support the well-being and tranquility senses reported by healthy consumers, and to explain the oneiric content during dreams and some improvements in cognitive processes described by consumers. Anxiolytic- and antidepressant-like effects of this species, reported for first time in this study could improve some aspects of mental health.

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.

Emergency Medical Technicians are health professionals commonly exposed to dangerous traumatic scenarios which can lead to an altered hypothalamus-pituitary-adrenal (HPA) axis and stress related symptoms; however, the stress intensity may be mediated by personality traits such as self-esteem. We tested, in a population of 96 EMTs from the National Red Cross, the hypothesis of reduced cortisol secretion after the exposition to traumatic content images that could represent a stressor in non-paramedic healthy volunteers (59 non-EMTs). We took three saliva samples to measure cortisol (basal, 15 and 30 min after the images) and quantified the levels of self-esteem, perceived and physiological stress. Results showed a peak of cortisol 15 min after the images in the non-EMTs population, whereas a decreased cortisol profile was observed in EMTs, suggesting a higher sensitivity for a negative feedback regulation of cortisol. EMTs had lower levels of perceived stress but higher physiological stress symptoms than non-EMTs. The most important predictors of cortisol levels in EMTs were the number of working days per week and self-esteem which also had a negative correlation with perceived and physiological stress. We suggested that, in general, this paramedic population is habituated and predisposed to accidental scenarios.

Measuring hormone metabolites in fecal samples allows the noninvasive assessment of some steroid hormones in primates. However, noninvasive hormone assays need analytical and biological validation owing to variation in hormone metabolism and excretion between the sexes and across species. We aimed to validate the measurement of fecal glucocorticoid (fGC), testosterone (fT), and progesterone (fP) metabolites in 15 captive stumptail macaques (Macaca arctoides). We collected fecal samples before and after we induced a stress response by restraining and injecting the subjects with saline solution. We then measured hormone metabolites using a methanol extraction technique and 125I radioimmunoassay kits. We analyzed the change in glucocorticoid production before and after the stressor, as well as sexual and social rank differences. For fT metabolite levels we investigated variation with sex, age, and social rank, and for fP metabolite levels, we tested for sexual and cycle phase differences. We found a significant increase in fGC metabolite levels 22–25 h poststressor in both sexes. The increase was greater in high-ranking than in low-ranking individuals. Levels of fT metabolites were higher in males than in females, correlated positively with rank only in males, and correlated negatively with age in both sexes. fP metabolite levels were higher in females than in males, and were higher during the luteal phase than in the follicular phase. These findings indicate that our assays reliably detected hormonal changes related to stress (fGC) and detected differences between social and sexual categories (fT, fP) in stumptail macaques.

An individual’s body odour is a characteristic that is used to obtain information about conspecifics. However, to our knowledge the role of body odour and the degree of facial symmetry on testosterone changes among men as indicators of possible rivals has not been investigated yet. A group of 113 men were photographed to obtain their degree of facial symmetry, i.e., the small random deviations in facial bilateral traits. They smelled and assessed the odour of men with different grades of facial symmetry, and donated two saliva samples (pre- and post-stimulus sample) to measure the change in their testosterone levels. We found that testosterone levels decreased in symmetrical men who perceived the odour of asymmetrical men. Our results suggest that men could perceive characteristics in other men that are highly valued by women through odour to identify possible rivals, and that the observed decrease in testosterone levels could be related to an inhibition of competitive behaviours.

Higher testosterone levels have been positively related to a variety of social behaviors and personality traits associated with intrasexual competition. The aim of this study was to evaluate the role of testosterone levels and personality traits such as aggressiveness, competitiveness, and self-esteem on the task of choosing a fighting competitor (a rival) with or without a motivation to fight. In Study 1, a group of 119 men participated in a task for choosing a rival through pictures of men with high-dominant masculinity versus low-dominant masculinity. Participants completed three personality questionnaires and donated two saliva samples (pre-test and post-test sample) to quantify their testosterone levels. We found that the probability of choosing high-dominant masculine men as rivals increased with higher aggressiveness scores. In Study 2, the task of choosing rivals was accompanied by motivations to fight (pictures of women with high or low waist-to-hip ratio [WHR]). In this context, we observed that the probability of choosing dominant masculine men as rivals depended on the WHR of the women. Overall, average levels of post-test testosterone, aggressiveness, and high self-esteem increased the probability to fight for women with low WHR independently of the dominance masculinity of the rivals. Our results indicate that human decisions, in the context of intrasexual competition and mate choice, are regulated by physiological and psychological mechanisms allowing men to increase their biological fitness. We discuss our results in the light of the plasticity of human behavior according to biological and environmental forces.

We evaluated the antidepressant-like effect of kaempferitrin (Km) isolated from the plant Justicia spicigera (Asteraceae), which is used in traditional medicine for relieving emotional disorders, such as “la tristeza” (sadness or dysthymia) and “el humor” (mood changes). The actions of Km were evaluated in a forced swimming test (FST) and a suspension tail test (TST) in mice. We explored the involvement of the serotonergic system and the hypothalamic-hypophysis-adrenal axis (HPA) in the antidepressant-like effect of Km. To evaluate nonspecific effects of Km on general activity, the open field test (OFT) was performed. Km at 5, 10, and 20 mg/kg induced an antidepressant-like effect. Sub-effective dose of Km (1 mg/kg) produced a synergistic effect with imipramine (6.25 mg/kg) and fluoxetine (10 mg/kg) but not with desipramine (3.12 mg/kg). Pretreatment with p-chlorophenylalanine methyl ester (PCPA), a serotonin synthesis inhibitor, N-{2-(4-(2-methoxyphenyl)-1-piperazinyl}-N-(2-pyridinyl)cyclohexecarboxamide (WAY-100635), a selective 5-HT1A receptor antagonist, and 8OH-DPAT, a selective 5-HT1A agonist, but not pindolol (10 mg/kg) blocked the anti- immobility effect induced by Km. Taken together, these results indicate that the antidepressant-like effect of Km is related to the serotonergic system, principally 5-HT1A. This effect was not related to changes in locomotor activity.

Stress response is associated with increased activity in the hypothalamic-pituitary-adrenocortical axis. Chronic stress-induced elevation in cortisol may alter its own negative regulation with multiple long-term consequences for physical and psychological health. One of the most reliable physical traits associated with mental, apparent physical health, and competitiveness is the degree of facial fluctuating asymmetry. However, to our knowledge there are no studies regarding the relationship between cortisol levels, facial symmetry and male competitiveness, and how cortisol changes after a stressful test depending on these traits. Here, a group of 100 college men were photographed to obtain their facial asymmetry levels. They then, answered the perceived stress scale and the intrasexual competition test and donated two saliva samples (pre-and post-test sample) to measure the change in their cortisol levels after a stressful test. We found that basal cortisol levels were positively correlated with both perceived stress and competitiveness, but not with facial fluctuating asymmetry. Cortisol levels increased in most symmetrical men after a short stressful test, but it decreased in most asymmetrical men. The results suggest differences in endocrine responses according to facial fluctuating asymmetry in men and how these responses could be related to the maintenance of social status.

Analyze results with respect to cortisol reactivity (CR) in experimental stress paradigms in adults with or without a psychiatric disorder who suffered violence in early developmental stages (infancy or early adolescence); and use these results to propose a clinical tool to determine biological stress indicators.A systematic review was conducted using several databases and following PRISMA criteria; of a total of 231 articles, 16 satisfied the inclusion criteria and the results were analyzed qualitatively.Despite heterogeneity, the results suggested that the people who suffered violence at an early age present a pattern of low CR. In contrast, people who also developed symptoms of post-traumatic stress disorder and depression, regardless of the type of violence, showed increased CR. The majority of studies focused on people who suffered childhood sexual abuse and half of the articles supported the hypothesis that CR is more pronounced in men than in women.The results of this review suggest that cortisol hyperreactivity can be considered a biomarker for treatment and intervention in people with post-traumatic stress disorder and depression who suffered violence at an early age. The results also support evidence that experiencing violence alters stress response and mental health in the long term. However, it is necessary to conduct more studies, in particular studies on hyporeactivity and gender differences.Analisar os resultados da reatividade do cortisol segundo um modelo de estresse experimental em adultos com ou sem transtorno psiquiátrico que foram precocemente expostos à violência durante o desenvolvimento (infância e início da adolescência) e propor um instrumento clínico para determinar indicadores biológicos de estresse.Uma revisão sistemática foi conduzida em diferentes bases de dados conforme os critérios PRISMA. Dos 231 artigos selecionados, 16 satisfizeram os critérios de inclusão. Foi realizada uma análise qualitativa dos resultados.Apesar de serem heterogêneos, os resultados indicam que adultos com exposição precoce à violência apresentam baixa reatividade do cortisol. De maneira oposta, os indivíduos que desenvolveram sintomas de transtorno de estresse pós-traumático e depressão, independentemente do tipo de violência sofrida, apresentaram elevada reatividade do cortisol. A maioria dos estudos se centrou em vítimas de abuso sexual na infância e, em metade dos artigos, sustentou-se a hipótese de que a reatividade do cortisol é mais acentuada no sexo masculino que no feminino.Os resultados deste estudo de revisão apontam que se pode considerar a hiper-reatividade do cortisol como biomarcador para o tratamento e a intervenção de pacientes que foram expostos precocemente à violência e que apresentam transtorno de estresse pós-traumático e depressão. Além disso, é reforçada a evidência de que sofrer violência afeta a resposta ao estresse e a saúde mental a longo prazo. Porém, fazem-se necessários mais estudos, sobretudo investigando hiporreatividade e diferenças de gênero.

Objetivo. Analizar los resultados con respecto a la reactividad del cortisol (RC) ante un paradigma de estrés experimental en adultos con o sin algún trastorno psiquiátrico que sufrieron violencia en etapas tempranas de desarrollo (infancia y adolescencia temprana) y con ello proponer una herramienta clínica para el establecimiento de indicadores biológicos de estrés. Métodos. Se realizó una revisión sistemática en diversas bases de datos, siguiendo los criterios PRISMA; de un total de 231 artículos, 16 cumplieron los criterios de inclusión y los resultados fueron analizados de manera cualitativa. Resultados. A pesar de la heterogeneidad, los resultados sugieren que las personas que sufrieron violencia temprana presentan un patrón de baja RC. Contrariamente, la población que además desarrolló síntomas de trastorno de estrés postraumático y depresión, independientemente del tipo de violencia, mostró incrementada RC. La mayoría de los trabajos se centraron en población que sufrió abuso sexual en la infancia y la mitad de los artículos apoya la hipótesis de que la RC es más pronunciada en hombres que en mujeres. Conclusiones. Los resultados de esta revisión nos permiten sugerir que es posible considerar la hiperreactividad del cortisol como un biomarcador para el tratamiento e intervención de población con trastorno de estrés postraumático y depresión que sufrieron violencia temprana. Además, apoyan la evidencia de que sufrir violencia altera la respuesta del estrés y la salud mental a largo plazo. Sin embargo, es necesario realizar más estudios principalmente los que se refieren a la hiporreactividad y a las diferencias de género.

O objetivo deste estudo foi identificar mudanças do epitélio vaginal em fêmeas de "Cerdo Pelón Mexicano", que ovularam durante o lactação, estágio causado pelo efeito da presença de macho e retirada da leitegada. A avaliação do estro foi feita através de citologia de raspado vaginal, observação do comportamento das fêmeas e por determinação de 17 ß estradiol e de progesterona no 8º dia após o início de lactação. Foram formados quatro grupos de fêmeas: Grupo 1 não sofreu estímulo; Grupo 2 permaneceu com o macho; Grupo 3 foi separado sua leitegada por 4 h e grupo 4 recebeu ambos estímulos. Amostras de raspado vaginal foram coletadas a cada 24 horas durante 5 dias após o estímulo. ANOVA para amostras repetidas foi realizada durante os 5 dias do teste. O estímulo utilizado no Grupo 4 causou modificações significativas (P < 0·001) quando comparado aos Grupos 1, 2 e 3. Os níveis de estradiol foram mais altos que 30 pg/ml no Grupo 4 no 10º dia pós parto e 4.5 ng/ml de progesterona nos 11º e 12º dias pós parto. Ficou evidente que 100% das fêmeas nos Grupos 1, 2 e 3 não mostraram atividade de estro quando foi relacionado citologia vaginal com o comportamento estral e determinação hormonal da fase de lactação das fêmeas, ao passo que 100% das fêmeas no Grupo 4 apresentaram estro 72 horas após os estímulos e ovularam 24 a 36 horas do início do cio, o que foi comprovado pela determinações de estradiol e progesterona, respectivamente.