Stressor Agent Research Articles

Method for evaluation of Streptomyces growth and metabolism in the presence of glyphosate-based herbicide.

The use of pesticides, such as glyphosate, has increased due to population growth and the rising demand for food. Plant growth-promoting rhizobacteria (PGPR), such as Streptomyces, offer a more ecologically friendly alternative to the excessive use of pesticides. However, these bacteria undergo a complex life cycle involving the formation of hyphae, mycelia, and spores, which makes standardizing laboratory cultures challenging. In this context, we tested three methods for cultivating a Streptomyces isolate (CLV322) in the presence of the stressor agent glyphosate, denoted as M1, M2, and M3. These methods involved the simultaneous addition of the herbicide 24-48h after the start of cultivation. We evaluated the growth and cell viability of CLV322 using the 2,3,5-triphenyl tetrazolium chloride (TTC) assay under glyphosate-based herbicide stress (Roundup® Original DI) at concentrations ranging from 0.002 to 7.2mg mL- 1. We also assessed the ability of CLV322 to maintain PGPR characteristics in the presence of the herbicide by quantifying indolic compounds, siderophores, and phenazines. The cultivation method significantly influenced the production of metabolites by CLV322, with M3 yielding more consistent results across the evaluated parameters. Our findings suggest that germinating Streptomyces spores for 48h before introducing glyphosate (M3) enables the analysis of bacterial tolerance to herbicide stress. This methodology may also apply to evaluate other abiotic stresses on Streptomyces strains.

Analyze the factors that influence the therapeutic response to psychic trauma

IntroductionPsychic trauma profoundly affects a person’s confidence in himself and others. There is a sudden experience of helplessness, loss of control, fear for one’s own life, and the humiliation of having been violated. The victim may run out of internal and external reference elements.ObjectivesDescribe the factors that influence the development of Post-traumatic stress disorder after experiencing traumatic experiences.MethodsReview in the literature of the different factors that influence the subject’s response to the traumatic experience.Results1)Predisposing and precipitating factors:–characteristics of the traumatic evento: severity of the stressor agent: dose-dependent, Characteristics of the same: sudden, prolonged, repetitive, intentional; decrease the ability to control the situation and develop effective coping strategies; they question basic cognitive schemas; the symbolic meaning of the traumatic evento.–characteristics of the person (predisposing factors of vulnerability): genetic-constitutional vulnerability, adverse experiences in childhood, previous traumatic events: increased vulnerability, personality characteristics, recent stressors or life changes, inadequate support system, use of alcohol, perception locus control more external than internal, pre-existing psychiatric symptoms: neuroticism, anxiety, depression, critical ages of development: time of greatest vulnerability (11-16 years).2)Perpetuating and empowering factors: sharing traumatic events, seeking the logic of the facts, rupture of affective ties.3)Elements of Resistance: tendency to selectively remember the positive elements in autobiographical memory, acceptance of a certain dose of uncertainty in life, perceiving themselves as survivors, perception of the stressful stimulus as less threatening, Less physiological reactivity to stress, use of humor, positive emotions counteracting during the traumatic process.4)Elements of Resilience: ability to extract and assimilate positive elements from negative situations.ConclusionsTrauma threatens 3 basic assumptions of life: the world is good, the world has meaning, the self has value. The knowledge of these mentioned factors allow a better psychotherapeutic approach to Psychic Trauma.Disclosure of InterestNone Declared

Cold as a stressor and tissue damage agent

Cold as a stressor and tissue damage agent

Melatonin counteracts oxidative damage in lens by regulation of Nrf2 and NLRP3 inflammasome activity

Oxidative stress, generated because of an imbalance between reactive oxygen species (ROS) generation and elimination, is associated with lens damage and cataract progression. ROS generation is known to activate NLRP3 (nucleotide-binding oligomerization domain-like receptor family, pyrin domain-cointaining 3) inflammasome, and is believed to be an important link between oxidative stress and inflammation, that is also related to cataract development. Potential oxidative hazard to the lens by white light-emitting diode (LED) light, a source of illumination commonly used nowadays, has been suggested, although available information is limited. In this work, we evaluated the cytotoxicity induced by hydrogen peroxide (an oxidative stressor agent) and white LED light in lens epithelial cells as well as melatonin ability to counteract the effects induced by them. Melatonin is a neurohormone secreted by different ocular structures that could be useful to alleviate oxidative damage induced by different oxidative stressors in lens. Particularly, the modulation of Nrf2 (nuclear erythroid 2-related factor)/Keap 1 (Kelch-like ECH-associated protein 1), an essential oxidative stress regulator, and NLRP3 activity by melatonin was evaluated in lens epithelial cells. ROS levels rose after white LED light exposure and cell viability was reduced after challenge with oxidative stressor agents. Melatonin prevented cell death triggered by hydrogen peroxide and white LED light, precluded ROS generation induced by white LED light and promoted antioxidant lens capacity through upregulation of Nrf2 protein levels and SOD activity. NLRP3, caspase-1 and IL1-β expression significantly increased in human lens cells exposed to H2O2 or irradiated with white LED light. Activation of NLRP3 inflammasome triggered by oxidative stressors was also abrogated by melatonin. Attenuation of inflammatory and cytotoxic effects induced by oxidative stressors provided by melatonin in lens indicate the interest of this molecule as a potential therapeutic agent for cataract prevention/management.

Neonatal Maternal Separation Alters Gelatinase Activity in Mouse Ovarian Preantral Follicles.

ObjectiveThe early life environment is critical for normal growth and development for future reproductive function. This study aims to investigate the effect of neonatal maternal separation (MS) on gelatinase activity of mouse ovarian follicles.Materials and MethodsIn this experimental study, infants from female NMRI mice were randomly allocated into two groups immediately after birth: i. MS isolated from their mothers for 6 hours per day, from postpartum days 2 to 16) and ii. Control (undisturbed during the 16 days). Ovarian tissues were dissected to perform differential counts of the ovarian follicle type by haematoxylin and eosin staining. The isolated follicles were cultured for 12 days. Gelatinase activity and the gene expressions of matrix metalloproteinases, MMP2 and MMP9, and their tissue inhibitors, TIMP1 and TIMP2, were evaluated by zymography and real-time polymerase chain reaction (PCR), respectively. Results Follicle counts at the different developmental stages were significantly different between the control and MS groups. There was a significant decrease in gelatinase activity in the MS group compared to the control group. The MS group showed significantly decreased gene expression levels of MMP2 and MMP9 compared to the control group. In contrast, the gene expression levels of TIMP1 and TIMP2 significantly increased in the MS group compared to the control group. ConclusionMS is a stressor agent that compromises ovarian follicle development, at least via disruption of gelatinase activity and its related gene expressions.

Effects of the salinity variation on the survival and reproductive success of Xiphophorus maculatus (Cyprinodontiformes: Poeciliidae)

Fish are affected by environmental variables that influence their survival and reproduction, showing physiological responses in an attempt to maintain internal homeostasis. Several Poeciliidae, native from brackish water body regions, can be acclimated to live in saltwater. The introduction of Xiphophorus maculatus in saline environments is possible, although it is not a brackish water species. Thus, to evaluate the effects of the salinity variation on the acclimatization of X. maculatus, the specimens were exposed to different salinities (from 15 to 30 ppt) for up to 40 days, acutely and gradually. After exposing, their gonads, gills, cortisol and glucose levels were analysed. When transferred to salt or brackish water, cortisol and glucose levels increased, peaking at 30 min. Immunohistochemistry showed increased expression of Na+/K+-ATPases in the mitochondria-rich cells (MRCs) of the gill, as salinity increased. The female and male germinal epithelium remained unchanged. Xiphophorus maculatus was able to acclimatize and reproduce in saltwater, and their offspring survived in this environment, when there was gradual acclimatization of the adults to different salinities. However, in an abrupt exposure, the salinity became a stressor agent and could cause its mortality.

Coccoloba alnifolia Leaf Extract as a Potential Antioxidant Molecule Using In Vitro and In Vivo Assays.

The genus Coccoloba is widely used in traditional folk medicine, but few scientific data exist for this genus. The goal of this study was to characterise the chemical composition and antioxidant activities of C. alnifolia leaf extracts using in vitro and in vivo assays. Six extracts were obtained: hexane (HE), chloroform (CE), ethanol (EE), methanol (ME), water end extract (WEE), and water extract (WE). Thin-layer chromatography (TLC) analysis showed the presence of phenols, saponins, terpenes, and flavonoids. In vitro assays demonstrated substantial antioxidant potential, especially for polar extracts (EE, ME, WEE, and WE). Moreover, no toxic effects were observed on mammalian cell lines for most of the extracts at the concentrations evaluated. The nematode Caenorhabditis elegans was also used as an in vivo model for testing antioxidant potential. The EE and WE were chosen, based on previously obtained results. It was observed that neither the EE nor the WE had any toxic effect on C. elegans development. Additionally, the antioxidant potential was evaluated using tert-butyl hydroperoxide as a stressor agent. The EE increased the life span of C. elegans by 28% compared to that of the control, and the WE increased the range to 39.2-41.3%. High-performance liquid chromatography (HPLC-DAD) showed the presence of gallic acid, p-coumaric acid, and vitexin in the WE. Therefore, in vitro and in vivo data demonstrated the antioxidant potential of C. alnifolia extracts and their possible biotechnological applications.

A Medium-Throughput System for In Vitro Oxidative Stress Assessment in IPEC-J2 Cells.

The feed industry continuously seeks new molecules with antioxidant capacity since oxidative stress plays a key role in intestinal health. To improve screening of new antioxidants, this study aims to set up an assay to assess oxidative stress in the porcine small intestinal epithelial cell line IPEC-J2 using plate-reader-based analysis of fluorescence. Two oxidants, H2O2 and menadione, were tested at 1, 2 and 3 mM and 100, 200 and 300 µM, respectively. Trolox (2 mM) was used as the reference antioxidant and the probe CM-H2DCFDA was used to indicate intracellular oxidative stress. Cell culture, reactive oxygen species (ROS) production and assessment conditions were optimized to detect a significant ROS accumulation that could be counteracted by pre-incubation with trolox. Menadione (200 µM) reproducibly increased ROS levels, H2O2 failed to do so. Trolox significantly decreased intracellular ROS levels in menadione (200 µM)-exposed cells in a consistent way. The system was further used to screen different concentrations of the commercially available antioxidant ELIFE®. Concentrations between 100 and 200 ppm protected best against intracellular ROS accumulation. In conclusion, the combination of CM-H2DCFDA fluorescence analysis by a plate-reader, trolox as a reference antioxidant and 200 µM of menadione as a stressor agent, provides a replicable and reliable medium-throughput setup for the evaluation of intracellular oxidative stress in IPEC-J2 cells.

Safety profile of adenosine stress cardiac MRI in a tertiary hospital in India.

Background:Coronary artery disease (CAD) is a major cause of morbidity and mortality in India. Stress Cardiac Magnetic Resonance (CMR) using vasodilator agent is well established in assessing the functional significance of CAD. Adenosine is the preferred agent, but can have severe side effects including dyspnoea, chest pain, atrioventricular block or bronchospasm. The stress CMR examination is not routinely performed in many of the clinical imaging departments in India.Objective:The aim of this study was to establish safety of adenosine as a pharmacological stressor agent for CMR in a tertiary care radiology department in India.Methods:A review of all patients undergoing stress CMR in our institution from May 2018 to May 2019 was made. Records were reviewed to collect response parameters and documented adverse reactions.Results:A total of 1057 patients underwent stress CMR during this period. No death, myocardial infarction or atrio-ventricular block related complications were seen. Transient hypotension was seen in 20 patients (1.8') with spontaneous recovery after stopping infusion. Chest pain and breathlessness severe enough to discontinue the scan were seen in 6 (0.5') and 10 (0.9') patients, respectively. All patients with breathlessness recovered on low flow oxygen therapy with three requiring bronchodilator. Out of six patients with chest pain, three had immediate relief with sublingual nitroglycerin, and three required hospital admission for unstable angina. Of the latter three, 1 underwent revascularization on the same day and other two later in the week.Conclusion:Stress CMR using adenosine in appropriately selected patients is a highly safe procedure with significant side effects seen in less than 1’ of patients. Therefore, it is safe to perform stress CMR studies in a fully equipped and well-trained radiology department in India.

Beta-estradiol protects against copper-ascorbate induced oxidative damage in goat liver mitochondria in vitro by binding with ascorbic acid

Aimsβ-Estradiol (β-E), one of the chemical forms of female gonad hormone exhibited antioxidant efficacy in biochemical system, in vitro. The aim of the study was to investigate whether any other mechanism of protection by β-E to hepatic mitochondria in presence of stressor agent i.e.,a combination of Cu2+ and ascorbic acid is involved. Main methodsFreshly prepared goat liver mitochondria was incubated with stressors and 1 μM β-E and post incubated with the same concentration at 37 °C at pH 7.4. Mitochondrial viability, biomarkers of oxidative stress, activities of Krebs cycle enzymes, mitochondrial membrane potential, Ca2+ permeability were measured. Mitochondrial morphology and binding pattern of β-E with stressors were also studied. Key findingsUpon incubation of mitochondria with Cu, ascorbic acid and their combination there is a significant decline in activities of four of Krebs cycle enzymes in an uncompetitive manner with a concomitant increase in Ca2+ permeability and membrane potential of inner mitochondrial membrane, which is withdrawn during co-incubation with β-E, but was not reversed during post incubation with the β-E. The final studies on mitochondrial membrane morphology using scanning electron microscope also exhibited damage. Isothermal titration calorimetry data also showed the negative heat change in the mixture of β-E with ascorbic acid and also its combination with Cu2+. SignificanceOur results for the first time demonstrated that β-E protects againstCu2+-ascorbate induced oxidative stress by binding with ascorbic acid. The new mechanism of binding of β-E with stress agents may have a future therapeutic relevance.

P327 Concordance between regadenoson stress echocardiography and spect-MIBI (99mTc) in patients with suspected myocardial ischemia

Abstract Background Regadenoson is a selective A2A adenosine receptor agonist approved for the detection of myocardial with SPECT-MIBI. To date, few studies have appraised the utility of this drug using transthoracic echocardiography with the same purpose. We designed this prospective study to evaluate the diagnostic agreement between these two techniques used simultaneously to detect myocardial ischemia. We report our first results evaluating the concordance between both techniques. Methods Patients enrolled were referred to our clinic for the evaluation of chest pain. Myocardial perfusion imaging was performed with regadenoson (400 µg ) which was injected before 99mTc-MIBI. Stress and rest sets of images were evaluated for relative uptake of the radiotracer in order to detect and characterize perfusion defects. The echocardiogram was acquired 60-90 seconds after the administration of the drug using a standardized technique. Two independent observers (one cardiologist and one specialist in nuclear medicine) interpreted the images, both unaware of the result of the complementary technique. Results One hundred twenty five patients were included, 69 (55%) of them males. Median age was 73 years (IQR 65-79). One hundred seventeen patients had both studies interpretable. Thirty-nine (32.5%) patients had had a diagnosis of ischemic heart disease before the study (either a myocardial infarction or a coronary revascularization). The median pre-test probability of coronary artery disease in those without a true previous diagnosis was 30.5% (16.0-50.8), being 50% in the intermediate risk (15-85%) and 49% in the low risk stratum (less than 15%). Significant reductions is systolic and diastolic blood pressure were detected with regadenoson [systolic 134 (21) mmHg Vs 131 (23) mmHg, p < 0.001; diastolic: 78 (12) mmHg Vs 73 (13) mmHg, p < 0.001], with a striking increase in heart rate: 67 (13) bpm Vs 91 (17) bpm, p < 0.001. More patients had a SPECT test showing myocardial ischemia (28% Vs 16%; p < 0.001). Agreement between both tests were 84%. The kappa index obtained from this sample was 0.34 (CI95% 0.15-0.53). Segregating those patients without a history of coronary artery disease (n = 81), the positive test rate were 14% for echo and 20% for SPECT-MIBI (p = 0.019). Kappa index was even lower: 0.29 (CI95% 0.02-0.56). Conclusions. SPECT-MIBI provides more positive tests than stress echocardiography when regadenoson is used as the stressor agent. The concordance between tests is low.

Engineering mesenchymal stromal/stem cell-derived extracellular vesicles with improved targeting and therapeutic efficiency for the treatment of central nervous system disorders.

Engineering mesenchymal stromal/stem cell-derived extracellular vesicles with improved targeting and therapeutic efficiency for the treatment of central nervous system disorders.

Effects of Phosphorus and Zinc on the Neotropical Cladoceran Ceriodaphnia silvestrii by Dietary Routes

Aquatic systems are seldom disturbed by a single stressor agent. Considering that nutrients and metals occur simultaneously in the environment, studies on the combined effects of these elements on the biota need to be carried out. The aim of this study was to evaluate the effect of the microalga Raphidocelis subcapitata exposed to different combinations of phosphorus (P) and zinc (Zn) on the neotropical cladoceran Ceriodaphnia silvestrii. The algae acclimated to P concentrations of 2.3 × 10−4 and 2.3 × 10−6 mol L−1 were exposed to concentrations of 0.10, 0.57, 1.13, and 2.27 × 10−6 mol Zn2+ L−1. The P acclimated algal cells showed different capacity to deal with external free Zn level, resulting in higher susceptibility to metal as P decreased in the test medium. Elevated cell metal values were observed in R. subcapitata acclimated to 2 × 10−6 mol P L−1 and exposed to Zn, as compared to the values found in the microalga exposed to 2 × 10−4 mol P L−1. A significant reduction in number of newborn produced by cladoceran was verified when the organism was fed alga containing 47 × 10−15 g Zn cell−1 (2 neonates per female) and 60 × 10−15 g Zn cell−1 (5 neonates per female). It was observed a decrease of 90% of C. silvestrii survival for the treatment with 47 × 10−15 and 60 × 10−15 g Zn cell−1. Algal cells acclimated to high and low concentrations of P were an important exposure route to Zn for C. silvestrii.

Implications from early life stress on the development of mouse ovarian follicles: Focus on oxidative stress.

The early life stress has significant long-term effects on the development of the offspring. This study was undertaken to verify if maternal separation as a stressor agent affects the oxidative status and developmental competence of mouse pre-antral follicles (PF) during in vitro culture period. Female litters of National Medical Research Institute mice were divided into two groups: maternally separated group (MS), separated from the mothers for 6 h per day from postnatal days 2-16; and the rest considered as the control group, which left undisturbed over the 14 days. The litters were sacrificed and the ovarian tissue was harvested to isolate the PF. The PF were in vitro cultured up to 12th day when ovulation was induced. The developmental parameters and oxidative status (i.e., total antioxidant capacity and Malondialdehyde levels, as well as the activities of superoxide dismutase, glutathione peroxidase and catalase) were assessed. The rates of survival, antrum formation, ovulation and oocyte maturation of PF derived from the MS group were significantly lower compared with those of the control group. Furthermore, the Malondialdehyde level of the MS group was significantly higher than that of the control group. By contrast, the total antioxidant capacity level was lower in the MS group with respect to the control group. Also, the activity of superoxide dismutase, glutathione peroxidase and catalase of PF, derived from the MS group, was significantly lower compared with those of the control group. Early life stress damages the developmental competence of mouse PF through induction of oxidative stress.

O ruído em neonatologia: perceção dos profissionais de saúde

Background: The negative impact of noise in the newborn in neonatology units, as well as in the parents and health professionals, is known, so it is essential to raise awareness of the reduction and control of this stressor agent. Objectives: To identify the perception of health professionals about noise in neonatology. Methodology: Qualitative-quantitative and descriptive study. A non-probabilistic sample of 52 health professionals. An ad-hoc questionnaire designed for this purpose was used. Results: The majority of professionals considers neonatology units noisy and uncomfortable in performing functions and believes that noise has adverse effects, although there is little knowledge about the decibel values recommended for the neonatal unit. Conclusion: The perception of health professionals about noise indicates the need to implement a noise reduction program. We consider the training and involvement of the team relevant, so professionals can be active and inciting in the adoption of measures that promote an acoustically healthy environment for the newborn and the well-being of parents and health professionals

Alteration of oxidative stress markers and behavior of rats in a novel model of depression

Emotional stress is considered a serious pathogenetic factor of depression. In this study an ultrasound model of emotional stress developed in our laboratory was applied. It is characterized by the use of ultrasound as the stressor agent. Animals are triggered not by any organic or physical disturbances but by the perception of adverse information. This type of stress can induce depressive-like behavioral changes in rodents, manifested by decreased sucrose preference and increased time of immobility in a forced swim test. Ultrasound stress also increased the levels of oxidative stress markers. This is important, as stress has an established association with increased oxidative processes in the central nervous system. Total glutathione and carbonyl protein content were selected as relevant brain markers, as glutathione plays a critical role in cellular defensive mechanisms during oxidative stress and the level of protein carbonyls can be a measure of global protein oxidation. We demonstrated that two weeks of chronic exposure to ultrasound was enough to cause depressive-like behavioral changes in rats. Increased levels of oxidative stress markers in the hippocampus and prefrontal cortex were also observed after two weeks of such stress. The current study has two goals: the first is to study the relationship of depression and oxidative stress; the second is an additional validation of our approach to modeling stress‑induced depressive-like states in rats. The present data further support the validity of the ultrasound model by expanding information related to the influence of ultrasound stress on behavioral and physiological parameters, which are of great importance in the development of stress-induced depression. A time correlation between the onset of symptoms and a change in the level of oxidative stress markers in the brain is also demonstrated.

Exposure to fluctuating temperatures leads to reduced immunity and to stress response in rattlesnakes.

Ectothermic organisms often experience considerable variation in their body temperature throughout the circadian cycle. However, studies focusing on the measurement of physiological traits are usually performed under constant temperature regimes. This mismatch between thermal exposure in the field and experimental conditions could act as a stressor agent, as physiological functions are strongly influenced by temperature. Herein, we asked the question whether constant thermal regimes would cause a stress response and impact the immunity of the South American rattlesnake (Crotalus durissus) when compared with a fluctuating thermal regime. We addressed this question by determining heterophil:lymphocyte (H:L) ratio, plasma bacteria-killing ability (BKA) and corticosterone (CORT) levels in snakes kept under a constant temperature regime at 30°C, and under a fluctuating regime that oscillated between 25°C at night and 35°C during the day. The experiments had a mirrored design, in which half of the snakes were subjected to a fluctuating-to-constant treatment, while the other half was exposed to a constant-to-fluctuating treatment. The shift from constant to fluctuating thermal regime was accompanied by an increase in plasma CORT levels, indicating the activation of a stress response. Exposure to a fluctuating thermal regime at the onset of the experiments induced a decrease in the BKA of rattlesnakes. H:L ratio was not affected by treatments and, therefore, the shift between thermal regimes seems to have acted as a low-intensity stressor. Our results suggest that removal from temperatures close to the snake's preferred body temperature triggers a stress response in rattlesnakes.

Strawberry and Achenes Hydroalcoholic Extracts and Their Digested Fractions Efficiently Counteract the AAPH-Induced Oxidative Damage in HepG2 Cells.

Strawberry fruits are highly appreciated by consumers worldwide due to their bright red color, typical aroma, and juicy texture. While the biological activity of the complete fruit has been widely studied, the potential beneficial effects of the achenes (commonly named seeds) remain unknown. In addition, when raw fruit and achenes are consumed, the digestion process could alter the release and absorption of their phytochemical compounds, compromising their bioactivity. In the present work, we evaluated the protective effects against oxidative damage of nondigested and digested extracts from strawberry fruit and achenes in human hepatocellular carcinoma (HepG2) cells. For that purpose, cells were treated with different concentration of the extracts prior to incubation with the stressor agent, AAPH (2,2′-azobis(2-amidinopropane) dihydrochloride). Subsequently, intracellular accumulation of reactive oxygen species (ROS) and the percentage of live, dead, and apoptotic cells were determined. Our results demonstrated that all the evaluated fractions were able to counteract the AAPH-induced damage, suggesting that the achenes also present biological activity. The positive effects of both the raw fruit and achenes were maintained after the in vitro digestion process.

Impact of Hypothermic Stress During Special Operations Training of Chilean Military Forces.

The Chilean Army considers processes that can optimize physical capacities for responding to the impact of situations and given stressors. The study of the effect of hypothermia as a stressor agent (HSA) and its relationship with cardiovascular, hematological, anthropometric, endocrine, and immunological parameters has not been fully addressed experimentally in military populations. To identify the endocrine, hematological, cardiovascular, and immunological changes caused by HSA and to associate these variables with body composition and physical fitness in the military special operation courses of the Chilean Army. Forty-two male subjects were exposed to remain in cold water (10.6 °C) in the context of regular military operations training, the longest time of exposure was determined by individual volitional limits. The measurements were taken in pre-hypothermia conditions, then 2 d later under acute hypothermia condition, and finally during the course period of lesser physical and psychological stressors where the baseline measurements were taken. The statistical analysis consisted of testing normality of the distribution through the Shapiro-Wilk test, assessing the equality of variances through the Levene test, and variance analysis by applying the ANOVA test (analysis of variance). The Bonferroni test was used for multiple comparison correction and the Pearson test for correlations between two variables. The level of significance was of p < 0.05. The main finding of this study is that HSA has a significant impact at the cardiovascular level and produces an increment in the cell population of the immune and hematologic systems. Significant hormonal changes were observed: ACTH (r = 0.50, p < 0.002), cortisol (r = 0.32, p < 0.03), free testosterone (r = 0.13, p < 0.002), total testosterone r = 0.31, p < 0.002), and anthropometrics (r = -0.51, p < 0.05). However, there is no significant correlation between physical fitness and HAS. All subjects experienced hypothermia stress elicited by immersion in cold water. This was evidenced by the decrease in core temperature as well as cardiovascular, endocrine, anthropometric, and immunological changes. Individual differences exist between subjects and their resistance to hypothermia in cold water. These differences are not explained by the physical fitness profile but rather respond to a greater body adiposity index and minor changes in the adrenocorticotropic hormone and cortisol hormone. An acute hypothermia stress condition also affects the anabolic/catabolic environment. Finally, HSA produces an increase in the cell population of the immune system. The authors believe that this study allows to standardize HSA exposure times during regular military operations training by identifying the physiological impacts under this extreme environment. At present, the availability of intra-abdominal temperature measurement apparatus with capsule thermometers raises the interest of corroborating the findings of the current study through the use of such measuring devices. Likewise, an interesting line of research for the future would be to compare the HSA against a psychological evaluation with the purpose of identifying the stress management mechanisms among subjects of these characteristics and include heart rate variability measurements as an indicator of sympathetic stress.

Environmental enrichment decreases avoidance responses in the elevated T-maze and delta FosB immunoreactivity in anxiety-related brain regions

Environmental enrichment (EE) is an animal management technique, which seems to improve adaptation to the experimental conditions of housing in laboratory animals. Previous studies have pointed to different beneficial effects of the procedure in the treatment of several disorders, including psychiatric conditions such as depression. The anxiolytic effects induced by EE, on the other hand, are not as clear. In fact, it has been proposed that EE acts as a mild stressor agent. To better understand the relationship of EE with anxiety-related responses, the present study exposed rats to one week of EE and subsequently tested these animals in the inhibitory avoidance and escape tasks of the elevated T-maze (ETM). In clinical terms, these responses have been respectively related to generalized anxiety and panic disorder. All animals were tested in an open field, immediately after the ETM, for locomotor activity assessment. Additionally, analysis of delta FosB protein immunoreactivity (FosB-ir) was used to map areas activated by EE exposure and plasma corticosterone measurements were performed. The results obtained demonstrate that exposure to EE for one week impaired avoidance responses, an anxiolytic-like effect, without altering escape reactions. Also, in animals submitted to the avoidance task EE exposure decreased FosB-ir in the cingulate cortex, dorsolateral and intermediate lateral septum, hippocampus (cornus of Ammon), anterior and dorsomedial hypothalamus, medial and basolateral amygdala and ventral region of the dorsal raphe nucleus. Although no behavioral differences were observed in animals submitted to the escape task, EE exposure also decreased FosB-ir in the cingulate cortex, hippocampus (dentate gyrus), lateral amygdala, paraventricular, anterior and ventromedial hypothalamus, dorsomedial periaqueductal gray and ventral and dorsal region of the dorsal raphe. No changes in corticosterone levels, however, were observed. These results contribute to a better understanding of the effects of EE on anxiety.