Adult-generated neurons born during chronic social stress are uniquely adapted to respond to subsequent chronic social stress.

Chronic stress is a recognized risk factor for psychiatric and psychological disorders and a potent modulator of adult neurogenesis. Numerous studies have shown that during stress, neurogenesis decreases; however, during the recovery from the stress, neurogenesis increases. Despite the increased number of neurons born after stress, it is unknown if the function and morphology of those neurons are altered. Here we asked whether neurons in adult mice, born during the final 5 days of chronic social stress and matured during recovery from chronic social stress, are similar to neurons born with no stress conditions from a quantitative, functional and morphological perspective, and whether those neurons are uniquely adapted to respond to a subsequent stressful challenge. We observed an increased number of newborn neurons incorporated in the dentate gyrus of the hippocampus during the 10-week post-stress recovery phase. Interestingly, those new neurons were more responsive to subsequent chronic stress, as they showed more of a stress-induced decrease in spine density and branching nodes than in neurons born during a non-stress period. Our results replicate findings that the neuronal survival and incorporation of neurons in the adult dentate gyrus increases after chronic stress and suggest that such neurons are uniquely adapted in the response to future social stressors. This finding provides a potential mechanism for some of the long-term hippocampal effects of stress.

The Psychoexposome: A holistic perspective beyond health and disease / Psicoexposoma: una perspectiva holística más allá de la salud y la enfermedad

Background: The concept of the exposome has emerged as a new strategy for studying all environmental exposures throughout an individual’s life and their impact on human health. Nowadays, electronic devices are available to collect data about an individual’s geolocation, biological function, or exposure biomarkers. The appearance of "omic" sciences and advances in bioinformatics have allowed massive data-gathering and analysis from various scientific fields. Objective: to propose the term Psychoexposome in line with the concept of the exposome from the field of environmental sciences. Method: a literature review of psychological terms associated with the exposome concept was carried out and the rationale and benefits of a psychoexposme approach for psychological sciences is discussed. Results: the terms psychology, psychiatry and neurological diseases are scarce in the exposome approach. A long tradition in psychology of performing epidemiological studies and in the study of multifactorial influences traits places psychologists at an advantageous starting point for conducting psychoexposome studies. Conclusion: psychology may take advantage from both exposome and omic sciences to create an integrated psychoexposome approach that may help in deciphering the etiology of psychological disorders and improving people's mental health (AU)

Antecedentes: el concepto de exposoma surgió como una estrategia para impulsar el estudio exhaustivo de las exposiciones ambientales a lo largo de la vida del individuo y su impacto en la salud. El desarrollo de dispositivos electrónicos para obtener datos de geolocalización, biológicos o biomarcadores de exposición y los avances en las ciencias "ómicas" y en bioinformática permiten la recopilación y el análisis masivo de datos muy diversos. Objetivo: proponer el término psicoexposoma en línea con el concepto de exposoma generado desde las ciencias ambientales. Método: se llevó a cabo una revisión de la literatura para buscar la inclusión de términos psicológicos asociados al concepto de exposoma. Se discute la justificación de un enfoque de psicoexposición para las ciencias psicológicas. Resultados: los términos psicología, psiquiatría o enfermedades neurológicas son escasos en el enfoque del exposoma. La experiencia en el control de variables ambientales sitúa al psicólogo en un punto de partida ventajoso para realizar estudios de psicoexposoma. Conclusión: la psicología puede aprovechar tanto las ciencias de la exposición como las ciencias "ómicas" para crear un enfoque integrado de psicoexposición que pueda ayudar a descifrar la etiología de los trastornos psicológicos y a promover la salud mental del individuo (AU)

The Psychoexposome: A holistic perspective beyond health and disease.

BACKGROUND: The concept of the exposome has emerged as a new strategy for studying all environmental exposures throughout an individual’s life and their impact on human health. Nowadays, electronic devices are available to collect data about an individual’s geolocation, biological function, or exposure biomarkers. The appearance of “omic” sciences and advances in bioinformatics have allowed massive data-gathering and analysis from various scientific fields. OBJECTIVE: to propose the term Psychoexposome in line with the concept of the exposome from the field of environmental sciences. METHOD: a literature review of psychological terms associated with the exposome concept was carried out and the rationale and benefits of a psychoexposme approach for psychological sciences is discussed. RESULTS: the terms psychology, psychiatry and neurological diseases are scarce in the exposome approach. A long tradition in psychology of performing epidemiological studies and in the study of multifactorial influences traits places psychologists at an advantageous starting point for conducting psychoexposome studies. CONCLUSION: psychology may take advantage from both exposome and omic sciences to create an integrated psychoexposome approach that may help in deciphering the etiology of psychological disorders and improving people’s mental health.

Melanoma tumors alter proinflammatory cytokine production and monoamine brain function, and induce depressive-like behavior in male mice.

Depression is a commonly observed disorder among cancer patients; however, the mechanisms underlying the relationship between these disorders are not well known. We used an animal model to study the effects of tumor development on depressive-like behavior manifestation, proinflammatory cytokine expression, and central monoaminergic activity. Male OF1 mice were inoculated with B16F10 melanoma tumor cells and subjected to a 21-day behavioral evaluation comprising the novel palatable food (NPF) test and tail suspension test (TST). The mRNA expression levels of proinflammatory cytokines, interleukin (IL)-1ß and IL-6, and tumor necrosis factor-alpha (TNF-α), were measured in the hypothalamus and hippocampus and the levels of IL-6 and TNF-α were measured in the blood plasma. We similarly determined the monoamine turnover in various brain areas. The tumors resulted in increasing the immobility in TST and the expression level of IL-6 in the hippocampus. These increases corresponded with a decrease in dopaminergic activity in the striatum and a decrease in serotonin turnover in the prefrontal cortex. Similarly, a high level of tumor development produced increases in the brain expression levels of IL-6 and TNF-α and plasma levels of IL-6. Our findings suggest that these alterations in inflammatory cytokines and monoaminergic system function might be responsible for the manifestation of depressive-like behaviors in tumor-bearing mice.

Coping with chronic social stress in mice: hypothalamic-pituitary-adrenal/ sympathetic-adrenal-medullary axis activity, behavioral changes and effects of antalarmin treatment: implications for the study of stress-related psychopathologies.

The aim of this study was to analyze the individual differences that lead to the development of psychopathological changes in response to chronic social stress. We also assessed the ability of an antagonist of the corticotrophin-releasing hormone (CRH) receptors to reverse the effects of stress. Male adult mice were exposed to repeated defeat experiences for 21 days using a sensorial contact model. After 18 days of defeat, two groups of subjects were established (active and passive), according to their behaviors during social confrontation. Antalarmin treatment was given for 4 and 6 days. The results corroborated previous data indicating that subjects who adopted a passive coping strategy had higher corticosterone levels after 21 days of defeat and decreased resting levels 3 days later. Moreover, they showed higher resting expression levels of hypothalamic CRH than their active counterparts. On day 24, the experimental animals were subjected to another social defeat to determine whether the stress response remained. The increase in corticosterone and hypothalamic CRH levels was similar for all of the stressed subjects, but the passive subjects also had a greater CRH response in the amygdala. Passive subjects had decreased levels of adrenal dopamine ß-hydroxylase, tyrosine hydroxylase and plasma adrenaline compared to the active subjects, and lower plasma noradrenaline levels than manipulated controls. The passive profile of physiological changes in both the hypothalamic-pituitary-adrenal and sympathetic-adrenal-medullary (SAM) axes has been associated with changes related to mood disorders, such as posttraumatic stress disorder and depression. The active coping profile is characterized by similar corticosterone resting levels to controls and increased SAM activity. Both profiles showed alterations in the novel palatable and forced swimming tests, with the passive profile being the most vulnerable to the effects of stress in this last test. Pharmacological treatment with antalarmin failed to reverse the effects of stress.

Effects of a putative antidepressant with a rapid onset of action in defeated mice with different coping strategies.

There is evidence suggesting that stressful social events may result in depressive-like disorders, but the development of these disorders depend on the way in which people cope with stress. Although antidepressants are useful their drawback is a delay in the therapeutic effects, moreover not all the patients show an adequate response to this treatment. The aim of this study was to analyse the effect of RS 67333, which is a 5-HT(4) receptor partial agonist and a putative antidepressant which exhibits a rapid onset of action and to determine whether this drug reverses the behavioural and physiological effects that are generated by chronic defeat in subjects who manifest a more vulnerable profile in their response to stress. Male mice were exposed to defeat for 21 consecutive days using a sensorial contact model. After 18 days of defeat, 2 groups of subjects were established, active and passive, in accordance with the behaviour that was manifested during social confrontation, and drug treatment was initiated for 5 days. Finally, the animals were subjected to a forced swimming test (FST). The results revealed higher corticosterone levels in passive mice after the last defeat. Additionally, 3 days after the last defeat, they showed lower corticosterone levels and higher splenic IL-6 and TNF-α levels and hypothalamic GR mRNA levels when compared to their active and manipulated control counterparts. Passive mice had higher 5-HT(1A) receptor mRNA levels than the manipulated controls and a lower MR/GR ratio than active mice. Similar to stress, the drug increased hypothalamic GR mRNA levels, but it did not affect other measured physiological variables or social behaviour, which suggested that the mechanism of this drug is not the most adequate for reversing stress-induced effects in this model. Nevertheless, the treatment increased swimming and decreased immobility in the FST, suggesting an antidepressant potential for this drug.

Behavioral coping strategies in response to social stress are associated with distinct neuroendocrine, monoaminergic and immune response profiles in mice.

Individual variation in behavioral coping strategies to stress implies that animals may have a distinct physiological adaptation to stress; these differences may underlie differences in vulnerability to stress-related diseases. This study was designed to test the hypothesis that different behavioral coping strategies (active vs. passive) are stable over time and that they would be associated with differences in hypothalamic-pituitary-adrenal (HPA) and sympathetic-adreno-medular (SAM) axes, and monoaminergic and immune activity. Male mice were subjected to social stress. Twelve days after the first social interaction, mice were subjected to a second identical social stress interaction. Behavior was videotaped and assessed during both sessions. One hour after the final social interaction, serum was collected for corticosterone and adrenaline concentrations and brains were collected for hypothalamic corticotrophin-releasing hormone (CRH) mRNA expression. Monoaminergic system activity was determined by mRNA expression of serotonin, dopamine and noradrenaline synthetic enzymes in the brain stem. Immune system activity was determined by mRNA expression of hypothalamic interleukin-1ß (IL-1ß) and splenic IL-1ß and interleukin-2 (IL-2). Mice engaging in a passive strategy had higher serum corticosterone and lower serum adrenaline concentrations than the active group. The passive group showed lower hypothalamic mRNA expression of IL-1ß and CRH and lower splenic mRNA expression of IL-2 and IL-1ß relative to mice in the active group. An active strategy was associated with higher expression of the dopaminergic synthetic enzyme, while a passive strategy was associated with decreased expression of the serotonergic synthetic enzyme. These findings indicate that individual coping strategies are stable over time and are related to differences in the physiological stress response and immune activity.

Individual differences in chronically defeated male mice: behavioral, endocrine, immune, and neurotrophic changes as markers of vulnerability to the effects of stress.

This study aimed to analyze different behavioral profiles in response to chronic social defeat using the sensorial contact model. We hypothesized that a passive profile, unlike an active one, would be associated with behavioral and physiological characteristics related to depression. Six-week-old OF1 male mice were subjected to defeat for 21 consecutive days. A combination of cluster and discriminant analyses of the behavior exhibited during confrontation on Day 21 established two behavioral profiles: active (n = 22) and passive (n = 34). Passive mice, with a high level of immobility and low non-social exploration, had higher plasma corticosterone concentrations than active mice after 21 days of defeat. Three days after the last defeat, passive mice had lower corticosterone levels than manipulated-control mice (n = 11). Higher levels of interleukin-6 and tumor necrosis factor-α (TNF-α) in the spleen and lower hippocampal brain-derived neurotrophic factor levels were observed in passive mice in comparison with those in active mice and the manipulated controls. The only differences observed in active mice in relation to the manipulated control were higher plasma corticosterone (Day 21) and TNF-α levels. The results show that different behavioral profiles in response to chronic defeat are associated with different physiological profiles, and that the passive profile presents physiological characteristics previously associated with depression.

Social stress, coping strategies and tumor development in male mice: behavioral, neuroendocrine and immunological implications.

The relationships between acute social stress, immunological alterations and the development of pulmonary metastases of B16F10 melanoma were analyzed. In particular, the effects of different behavioral coping strategies on the development of the metastases were studied. Tumor bearing and tumor non-bearing mice were subjected for 24h to a sensory contact social stress model. This included two 5 min sessions of direct social interaction with their resident cagemates (which had been selected for consistent levels of aggression). The subjects' behavior was videotaped and assessed. Corticosterone, IL-2, IL-12 and splenic cell proliferation responses to Con-A were determined 1h and 3 days post-stress. Lung metastatic foci numbers were determined 21 days after inoculation (15 days post-stress). Social stress increased the number of pulmonary metastases and the serum level of corticosterone but decreased the splenic proliferative capacity. No direct relationship could be established between the development of the metastases and the assayed interleukin response. A combination of cluster and discriminant analyses established that there were three types of coping strategies. Subjects engaging in a strategy characterized by an absence of attack, low non-social exploration levels and high levels of defense, subordination and avoidance, developed most pulmonary metastases. Social stress effects on tumor development appear to depend on the subject's coping strategy in such situations (although one cannot rule out the possibility that differences in the development of the disease per se are responsible for the different behavioral patterns observed).