During the critical period of CNS development, dendritic architecture is shaped, in part, by activity-dependent stabilization and elimination of branches. This restructuring is partly dependent on the subunit composition of glutamate receptors in a manner that is both regionally specific and temporally regulated. We used primary cultures of rodent hippocampal neurons to investigate the consequences for hippocampal dendrite development when the glutamate ?-amino-3-hydroxy-5-methyl-4-isoxazoleproprionic acid receptor (AMPAR) subunit composition was altered. Overexpression of the AMPAR subunits GluR1 or GluR2 differentially modified hippocampal dendrite architecture. We investigated signaling pathways known to be involved in activity-dependent circuit development as possible downstream effectors of AMPA-mediated morphogenesis. We identified extracellular signal regulated kinase (ERK) 1/2 as a potential candidate of GluR1-mediated dendrite outgrowth. We found that levels of docosahexaenoic acid (DHA) and a DHA-derived bioactive metabolite, neuroprotectin D1 (NPD1) are differentially regulated by GluR1 and GluR2. DHA, but not NPD1, induced extensive dendritic branching and outgrowth. Overexpression of 15 lipoxygenase 1 (15LOX1), the enzyme responsible for conversion of DHA to NPD1, interrupted outgrowth mediated by GluR1 overexpression. In order to investigate molecular mechanisms that regulated neural circuitry outside of the critical period of CNS development, we examined dendrite morphology across the CNS in response to chronic variable stress (CVS). We found wide-spread changes in circuits implicated in neurocognitive dysfunctions associated with chronic stress, and observed substantial dendritic plasticity in the adult brain. / acase@tulane.edu

The physiological responses to stressor exposure can be broadly grouped into the organismal and the cellular stress responses. The organismal stress response involves the release of hormones into general circulation, while the cellular stress response involves the synthesis of proteins, the most important being the heat shock proteins (HSPs), which play a role in maintaining protein homeostasis. Elevated HSP70 expression in response to stressors has been demonstrated in trout (Oncorhynchus mykiss) red blood cells (RBCs). The ease of repeated sampling of blood suggests the possibility of using this tissue as a non-lethal marker of cellular stress in fish. This study tested the hypothesis that stressor exposure will elevate HSP70 expression in trout RBCs and the role of stress hormones in mediating this response. Acute heat shock exposure (+12oC) significantly elevated plasma cortisol, glucose and lactate levels in heat shocked fish over 24 h. A tissue-specific response was seen in HSP70 expression in liver, brain, gill and RBCs. To enable measurement of RBC HSP70 concentrations, an enzyme-linked immunosorbent assay (ELISA) was developed using a commercially available rabbit anti-salmon HSP70 and a recombinant chinook salmon (Oncorhynchus tshawytscha) HSP70. To determine effects of chronic exposure, two studies were conducted exposing trout to either cadmium (0, 0.75 or 2.0 µg/L over 28 d) or municipal wastewater effluent (0, 20 or 90% over 14 d). However, neither exposure elicited a significant HSP70 response. Effects of stress hormones on RBC HSP70 levels were tested by exposing cells in vitro to either cortisol (10 and 100 ng/mL) or epinephrine (10 nM) with or without heat shock. Heat shock elevated HSP70 content in trout RBCs but no modulation by stress hormones was seen. It was shown for the first time that RBCs release HSP70 content into the medium in response to an acute heat shock and this release is attenuated by stress hormones. Overall, HSP70 levels in RBCs have the potential to be a reliable non-lethal marker of acute cellular stress effects in fish. The release of HSP70 from RBCs leads to the hypothesis that HSP70 may also have an extracellular role in fish, and warrants further study.

In certain species, puberty is thought to be a period of susceptibility to various stressors, resulting in pathological behavioral and physiological changes subsequent to exposure during this period. However, juvenile male golden hamsters appear to be fairly resilient to pubertal stress, as compared to adult hamsters and many other species. In these experiments, repeatedly stressed juvenile male hamsters were found to be avoidant of aggressive adult male social stimuli, but did not display anxious behavior outside of a social context. In addition, several long-term changes in neural activity were associated with social stress during early puberty. The medial preoptic area and medial preoptic nucleus, and ventral tegmental area showed decreased neural activity in subjugated juveniles than in naïve individuals. Since these brain areas are involved in the expression of motivated behaviors, specifically sexual behavior, and reward pathways, we next investigated sexual behavior in virgin juveniles. When placed in a confined space with receptive females, consummatory behavior in subjugated juveniles was similar to those observed in naive juveniles. Appetitive aspects of sexual behavior were also tested in a Y-maze to allow subjects to choose whether to approach a social stimulus. When given a choice between a sexually receptive and non-receptive female social stimulus, socially stressed individuals showed anxiety related behaviors and did not show a preference. However, naïve hamsters preferred the non-receptive female. Interestingly, this effect was less significant in naïve animals tested during late puberty and early adulthood, and a preference for sexually receptive females was not observed. In addition, stressed hamsters tested with harnessed females at mid-puberty were slower to approach females, indicating altered motivation to approach adult conspecifics. This research is unique in that it is the first to suggest the disconnect between the development of consummatory and appetitive aspects of sexual behavior. Together, these data examine the effects of stress on the development of pubertal social behaviors. / text

The physiological responses to stressor exposure can be broadly grouped into the organismal and the cellular stress responses. The organismal stress response involves the release of hormones into general circulation, while the cellular stress response involves the synthesis of proteins, the most important being the heat shock proteins (HSPs), which play a role in maintaining protein homeostasis. Elevated HSP70 expression in response to stressors has been demonstrated in trout (Oncorhynchus mykiss) red blood cells (RBCs). The ease of repeated sampling of blood suggests the possibility of using this tissue as a non-lethal marker of cellular stress in fish. This study tested the hypothesis that stressor exposure will elevate HSP70 expression in trout RBCs and the role of stress hormones in mediating this response. Acute heat shock exposure (+12oC) significantly elevated plasma cortisol, glucose and lactate levels in heat shocked fish over 24 h. A tissue-specific response was seen in HSP70 expression in liver, brain, gill and RBCs. To enable measurement of RBC HSP70 concentrations, an enzyme-linked immunosorbent assay (ELISA) was developed using a commercially available rabbit anti-salmon HSP70 and a recombinant chinook salmon (Oncorhynchus tshawytscha) HSP70. To determine effects of chronic exposure, two studies were conducted exposing trout to either cadmium (0, 0.75 or 2.0 µg/L over 28 d) or municipal wastewater effluent (0, 20 or 90% over 14 d). However, neither exposure elicited a significant HSP70 response. Effects of stress hormones on RBC HSP70 levels were tested by exposing cells in vitro to either cortisol (10 and 100 ng/mL) or epinephrine (10 nM) with or without heat shock. Heat shock elevated HSP70 content in trout RBCs but no modulation by stress hormones was seen. It was shown for the first time that RBCs release HSP70 content into the medium in response to an acute heat shock and this release is attenuated by stress hormones. Overall, HSP70 levels in RBCs have the potential to be a reliable non-lethal marker of acute cellular stress effects in fish. The release of HSP70 from RBCs leads to the hypothesis that HSP70 may also have an extracellular role in fish, and warrants further study.

Over 50% of the world’s human population resides in urban centres, and this is expected to increase as the global human population grows and people migrate from non-urban to urban centres. Concentrated in these urban areas are anthropogenic disturbances that impose additional challenges on wildlife compared to their non-urban counterparts. These challenges can be stress provoking. Through the release of corticosterone (CORT) reptiles can adapt to these stressors, physiologically and behaviourally, both in the short- and long-term. To investigate the relationships between stress activation and defensive tactics in wild urban Northwestern Gartersnakes (Thamnophis ordinoides) I conducted visual encounter surveys, along edge-focused transects, following a semi-constrained random sampling method. I sampled snakes at five sites, each with a different level of anthropogenic disturbance, in the Greater Victoria Area, BC. I sampled blood, observed anti-predator behaviour, and collected data on characteristics of snakes. The most disturbed site (with the most people, pets, and natural predators) also had the most snakes: those snakes also had highest H:L values (a proxy of CORT) in their blood compared to the other populations. Nevertheless, none of the snakes had H:L values that indicated chronic stress. Stress physiology was not correlated with anti-predator behaviour. More important to anti-predator behaviour was the size, sex/reproductive condition, and cloacal temperature of snakes. Although anthropogenic development can reduce habitat quality for some reptiles, Northwestern Gartersnakes coexist with recreationists at many sites in the District of Saanich. A multi-disciplinary approach is of paramount importance to understand the full effect of anthropogenic influences on wildlife. / Graduate / 0433 / 0329

Resumo: O estresse é entendido como um processo complexo e multidimensional, cuja resposta adaptativa é vista como um processo dinâmico no qual mecanismos fisiológicos do indivíduo mudam continuamente para ajustarem-se ao ambiente. Esse fator pode contribuir para alterações na função cardíaca, associada, ou não, ao trânsito de Ca2+ e a alteração vascular devido ao aumento da atividade da via l-arginina/óxido nítrico. A obesidade é uma doença complexa, caracterizada pelo acúmulo excessivo de tecido adiposo, levando a disfunções cardíacas e vasculares, que podem estar envolvidas com alteração no fluxo de Ca2+ e comprometimento da resposta vasodilatadora. O estresse é considerado um fator ambiental, portanto, responsável por alterações no balanço energético e peso corpóreo, uma vez que o peso corpóreo é a interação entre fatores genéticos e ambientais. Devido à escassez de estudos que avaliam o estresse crônico e dieta hipercalórica nas alterações cardiovasculares, e considerando a hipótese de que esta associação é capaz de atenuar o desenvolvimento da obesidade e intensificar as alterações cardiovasculares, o objetivo do presente trabalho foi confirmar essa hipótese em animais submetidos à dieta hipercalórica e ao estresse crônico. Ratos machos Wistar, divididos em quatro grupos: DN: dieta normocalórica; DN/Es: dieta normocalórica e submetidos ao estresse crônico; DH: dieta hipercalórica; DH/Es: dieta hipercalórica e submetidos ao estresse crônico, foram avaliados quanto aos perfis nutricionais, metabólicos e a remodelação cardiovascular. Os dados demonstraram que o estresse crônico impediu o desenvolvimento da obesidade, e em oposição à hipótese, o estresse crônico melhorou a função cardíaca e vascular, independente do tipo de dieta utilizada / Abstract: The stress is a complex and multidimensional process, the adaptive response is a dynamic process, in which individual physiologic mechanisms change to adjust to the environment, that causes alteration in the cardiac function, involved, or not, with Ca2+ flux and vascular alterations due to the increase of the l-arginine/nitric oxide pathway activity. The obesity is a complex disease, characterized by the excess of adipose tissue that causes cardiac and vascular dysfunction, involved with Ca2+ flux alterations and injury the vasodilating response. The stress is considered an environmental factor, therefore, it is responsible for the energetic balance alterations and weight gain, once the body weight is an interaction between genetic and environmental factors. There are few studies about chronic stress associated with the hypercaloric diet that evaluate the cardiovascular alterations, and considering the idea that this association can decrease the obesity development and increase the cardiovascular alterations, the aim of this research was evaluate the cardiovascular alterations and the obesity development in animals submitted to the hypercaloric diet and chronic stress. Male Wistar rats were separated into four groups: DN: standard diet; DN/Es: standard diet and chronic stress; DH: hypercaloric diet; DH/Es: hypercaloric diet and chronic stress were evaluated in relation to the nutritional and metabolic profile and cardiovascular remodellating. The data show that the chronic stress inhibited the obesity development, and different of the initial idea, the chronic stress improved the cardiac and vascular function, in both diets / Orientador: Sandra Cordellini / Coorientador: Antônio Carlos Cicogna / Banca: Rita de Cássia Aleixo Tostes Passaglia / Banca: André Sampaio Pupo / Mestre

abstract: Chronic stress results in functional and structural changes to the hippocampus. Decades of research has led to insights into the mechanisms underlying the chronic stress-induced deficits in hippocampal-mediated cognition and reduction of dendritic complexity of hippocampal neurons. Recently, a considerable focus of chronic stress research has investigated the mechanisms behind the improvements in hippocampal mediated cognition when chronic stress ends and a post-stress rest period is given. Consequently, the goal of this dissertation is to uncover the mechanisms that allow for spatial ability to improve in the aftermath of chronic stress. In chapter 2, the protein brain derived neurotrophic factor (BDNF) was investigated as a mechanism that allows for spatial ability to show improvements following the end of chronic stress. It was found that decreasing the expression of BDNF in the hippocampus prevented spatial memory improvements following a post-stress rest period. Chapter 3 was performed to determine whether hippocampal CA3 apical dendritic complexity requires BDNF to show improvements following a post-stress rest period, and whether a receptor for BDNF, TrkB, mediates the improvements of spatial ability and dendritic complexity in a temporal manner, i.e. during the rest period only. These experiments showed that decreased hippocampal BDNF expression prevented improvements in dendritic complexity, and administration of a TrkB antagonist during the rest period also prevented the improvements in spatial ability and dendritic complexity. In chapter 4, the role of the GABAergic system on spatial ability following chronic stress and a post-stress rest period was investigated. Following chronic stress, it was found that male rats showed impairments on the acquisition phase of the RAWM and this correlated with limbic glutamic acid decarboxylase, a marker for GABA. In chapter 5, a transgenic mouse that expresses a permanent marker on all GABAergic interneurons was used to assess the effects of chronic stress and a post-stress rest period on hippocampal GABAergic neurons. While no changes were found on the total number of GABAergic interneurons, specific subtypes of GABAergic interneurons were affected by stressor manipulations. Collectively, these studies reveal some mechanisms behind the plasticity seen in the hippocampus in response to a post-stress rest period. / Dissertation/Thesis / Doctoral Dissertation Psychology 2018

abstract: Cognitive reappraisal, or redefining the meaning of a stressful circumstance, is useful in regulating emotional responses to acute stressors and may be mobilized to up- or down- regulate the stressors’ emotional salience. A conceptually-related but more targeted emotion regulation strategy to that offered by cognitive reappraisal, termed positive cognitive shift, was examined in the current study. Positive cognitive shift (“PCS”) is defined as a point of cognitive transformation during a chronic, stressful situation that alters the meaning and emotional salience of the situation for the individual. Key aspects of the PCS that differentiate it from the broader reappraisal construct are that it 1) is relevant to responses to chronic (versus acute) aversive events, 2) is deployed when there is a mismatch between coping and stressors, and 3) involves insight together with redefinition in meaning of the situation generating stress. The current study used qualitative and quantitative analyses to 1) examine whether PCS is an observable, reliable, and valid experience in response to a stressful event that occurred in the past year, and 2) test whether PCS moderates the relations between the number of past-year stressful life circumstances and subsequent emotional well-being and functional health. A community sample of 175 middle-aged individuals were interviewed regarded a past chronic stressor and completed questionnaires regarding number of past year stressors and health outcomes. Theory-based coding of interviews was conducted to derive reliable scores for PCS, and findings indicated that PCS was evident in 37.7 % of participant responses. Furthermore, PCS scores were related positively to openness, personal growth from one’s most difficult lifetime event, and affect intensity-calm, in line with predictions. Also in line with prediction, PCS moderated the relations between number of past-year life events and health outcomes, such that the deleterious relations between past year stressful events and cognitive functioning, wellbeing, positive affect, and negative affect were weaker among individuals higher versus lower in PCS. Of note, PCS moderation effects diminished as the number of stressful events increased. / Dissertation/Thesis / Doctoral Dissertation Psychology 2018

Submitted by ADRIANA BEATRIZ BARRETTO (adriana.barretto@gmail.com) on 2018-04-25T17:07:16Z No. of bitstreams: 1 Tese Definitiva.pdf: 1000337 bytes, checksum: aa40cdf128c269fcfa1393bb66b32c79 (MD5) / Approved for entry into archive by Sulamita Selma C Colnago null (sulamita@btu.unesp.br) on 2018-04-26T18:52:18Z (GMT) No. of bitstreams: 1 barreto_ab_dr_bot_int.pdf: 1000337 bytes, checksum: aa40cdf128c269fcfa1393bb66b32c79 (MD5) / Made available in DSpace on 2018-04-26T18:52:18Z (GMT). No. of bitstreams: 1 barreto_ab_dr_bot_int.pdf: 1000337 bytes, checksum: aa40cdf128c269fcfa1393bb66b32c79 (MD5) Previous issue date: 2018-03-06 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / CAPÍTULO 1 – Neste estudo avaliamos o efeito do estresse agudo e crônico na memória de aprendizagem de tilápias-do-Nilo com diferentes perfis de personalidade. Inicialmente definimos a personalidade dos peixes através de testes de objeto novo e exposição a um predador, classificando-os em shy (tímido) ou bold (ousado) e em seguida estes indivíduos foram condicionados por um método simples de condicionamento clássico como forma de aprendizagem para posterior avaliação da memória. Os peixes shy foram então divididos em dois grupos, sendo que em um deles os peixes foram diariamente estressados por hipóxia, perseguição com rede ou confinamento (grupo shy-experimental) por 64 dias consecutivos, enquanto que no outro grupo os peixes permaneceram apenas isolados (grupo shy-controle) pelo mesmo período de tempo. O mesmo procedimento foi adotado com os peixes classificados como bold. Nesse mesmo período, testes de memória foram realizados em dias específicos, tanto nos grupos experimental quanto nos grupos controle. Ao final do experimento, reavaliamos se as personalidades se mantiveram. Obtivemos que o estresse agudo afetou a memória de aprendizado em peixes, principalmente em indivíduos com perfil de personalidade shy. CAPÍTULO 2 – Aqui desenvolvemos uma metodologia simples de condicionamento clássico facilmente aplicável em laboratórios de experimentação com peixes, quando comparados aos métodos descritos na literatura atual, onde os estímulos geralmente aplicados para condicionamento (som ou luz) podem interferir nas respostas dos animais experimentais presentes no mesmo laboratório. Para tal condicionamento, isolamos os peixes em aquários individuais e introduzimos um jato de água em cada aquário (sem que os peixes pudessem perceber a presença do pesquisador) causando movimentação da água (estímulo condicionado) neste local específico do aquário. Em seguida, um pellet de ração (estímulo incondicionado) foi introduzido no mesmo local da movimentação da água (novamente sem que os peixes pudessem perceber a presença do pesquisador). Esses procedimentos foram realizados durante 20 dias seguidos, 4 vezes ao dia. Obtivemos que após 14 dias de condicionamento todos os peixes associaram estímulo condicionado e incondicionado, confirmando a efetividade deste método simples e sem interferência nos demais animais experimentais presentes no ambiente. / CHAPTER 1 - In this study we evaluated the effect of acute and chronic stress in learning memory of Nile tilapia with different personality profiles. Initially we defined the personality of the fish through the testo f new object and exposure to a predator, classifying them as shy or bold, and then these individuals were conditioned by a simple method of classical conditioning as a way of learning to evaluation of memory. The shy fish were divided into two groups, and in one group the fish were daily stressed by hypoxia, net chase or confinement (shy-experimental group) for 64 consecutive days, while in the other group the fish remained only isolated (shy-control group) for the same time period. The same procedure was adopted with fish classified as bold. During the same period, memory tests were performed on specific days, in both groups, experimental and control group. At the end of the experiment, we reevaluated whether the personalities held. We found that acute stress affected learning memory in fish, especially in individuals with shy personality profiles. CHAPTER 2 - Here we develop a classical conditioning methodology easily applicable in fish experimentation laboratories when compared to the methods described in the current literature, where the stimuli generally applied for conditioning (sound or light) can interfere with the responses of experimental animals present in the same laboratory. For this conditioning, we isolate the fish in individual aquariums and introduce a jet of water into each aquarium (without the fish could perceive the presence of the researcher) causing water movement (conditioned stimulus) in this specific aquarium site. Then a feed pellet (unconditioned stimulus) was introduced in the same place as the water movement (again without the fish being able to perceive the presence of the researcher). These procedures were performed for 20 consecutive days, 4 times daily. We obtained that after 14 days of conditioning all the fish associated conditioned and unconditioned stimulus, confirming the effectiveness of this simple method and without interference in the other experimental animals present in the environment.

abstract: Chronic restraint stress impairs hippocampal-mediated spatial learning and memory, which improves following a post-stress recovery period. Here, we investigated whether brain derived neurotrophic factor (BDNF), a protein important for hippocampal function, would alter the recovery from chronic stress-induced spatial memory deficits. Adult male Sprague-Dawley rats were infused into the hippocampus with adeno- associated viral vectors containing the coding sequence for short interfering (si)RNA directed against BDNF or a scrambled sequence (Scr), with both containing the coding information for green fluorescent protein to aid in anatomical localization. Rats were then chronically restrained (wire mesh, 6h/d/21d) and assessed for spatial learning and memory using a radial arm water maze (RAWM) either immediately after stressor cessation (Str-Imm) or following a 21-day post-stress recovery period (Str-Rec). All groups learned the RAWM task similarly, but differed on the memory retention trial. Rats in the Str-Imm group, regardless of viral vector contents, committed more errors in the spatial reference memory domain than did non-stressed controls. Importantly, the typical improvement in spatial memory following recovery from chronic stress was blocked with the siRNA against BDNF, as Str-Rec-siRNA performed worse on the RAWM compared to the non-stressed controls or Str-Rec-Scr. These effects were specific for the reference memory domain as repeated entry errors that reflect spatial working memory were unaffected by stress condition or viral vector contents. These results demonstrate that hippocampal BDNF is necessary for the recovery from stress-induced hippocampal dependent spatial memory deficits in the reference memory domain. / Dissertation/Thesis / M.A. Psychology 2013