Submitted by Nayara Passos (nayara.passos@ufpe.br) on 2015-03-05T13:37:24Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DISSERTAÇÃO Walesca Barros.pdf: 1692408 bytes, checksum: f567172a5e3e90940b17911d95b8bead (MD5) / Made available in DSpace on 2015-03-05T13:37:24Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DISSERTAÇÃO Walesca Barros.pdf: 1692408 bytes, checksum: f567172a5e3e90940b17911d95b8bead (MD5) Previous issue date: 2013 / CNPq, FACEPE / O sistema nervoso (SN) possui habilidade para modificar sua organização morfofuncional em resposta a mudanças internas ou demandas externas, caracterizando-se assim a plasticidade cerebral. Fatores externos como a desnutrição durante as fases iniciais da vida podem alterar o desenvolvimento adequado do organismo e ocasionar na fase adulta danos nas funções do sistema nervoso. Entretanto, um outro fator ambiental, o ambiente enriquecido (AE), pode favorecer a memória através de alterações na expressão de fatores tróficos, especialmente o fator derivado do cérebro (BDNF) no hipocampo. O presente estudo objetivou avaliar o efeito do ambiente enriquecido sobre a plasticidade sináptica no hipocampo de ratos adultos que foram submetidos à desnutrição no período perinatal. Foram utilizados ratos machos Wistar divididos em grupos segundo a dieta durante a gestação e lactação: controle (C) e desnutrido (D). Após o desmame, os filhotes receberam dieta Presence® e foram subdivididos segundo a exposição ao AE de 30 até 90 dias de vida: controle com AE (CAE); ou sem AE (CSAE); desnutrido com AE (DAE) ou sem AE (DSAE). A evolução ponderal foi modificada pela desnutrição e o peso ao nascer até os 70 dias de vida, após a exposição ao AE, foi menor que o controle; aos 80 dias, o grupo CAE apresentou menor peso, igualando-se ao DAE. Quanto aos aspectos de memória de reconhecimento de objetos, comparando intragrupo, tanto o CSAE quanto o DAE apresentaram memória de curta duração. A comparação entre grupos mostrou que a dieta e o ambiente enriquecido influenciaram na memória de longa duração, pois apenas o DAE aumentou o tempo de exploração do objeto novo. A dieta não modificou o comportamento dos grupos com relação à ansiedade. No entanto, após a exposição ao AE, o grupo CAE apresentou menor ansiedade e o DAE mostrou aumento no conflito de decisão de escolha. Quanto à expressão gênica do bdnf, a dieta provocou menor expressão no grupo DSAE e maior expressão após exposição ao AE nos grupos controle e desnutrido. Já quanto ao receptor TrkB, houve uma tendência à menor expressão no grupo DSAE e uma maior expressão no CAE e DAE. Esses resultados indicam que a dieta hipoproteica induziu baixo peso ao nascer e que essa modificação foi prolongada ao longo da vida, porém o AE não reverteu esse perfil, mostrando que há o efeito da plasticidade fenotípica sobre esse aspecto. Além disso, a dieta e o AE modificaram, a longo prazo, tanto o perfil gênico do bdnf quanto do seu receptor, bem como o comportamento de memória, demonstrando que o AE estimulou eventos plásticos no hipocampo dos indivíduos desnutridos, modificando assim a memória de longa duração.

Plasticity in dorsal root ganglion (DRG) neurons that promotes pain requires activity-dependent mRNA translation. Protein synthesis inhibitors block the ability of many pain-promoting molecules to enhance excitability in DRG neurons and attenuate behavioral signs of pain plasticity. In line with this, we have recently shown that phosphorylation of the 5' cap-binding protein, eIF4E, plays a pivotal role in plasticity of DRG nociceptors in models of hyperalgesic priming. However, mRNA targets of eIF4E phosphorylation have not been elucidated in the DRG. Brain-derived neurotrophic factor (BDNF) signaling from nociceptors in the DRG to spinal dorsal horn neurons is an important mediator of hyperalgesic priming. Regulatory mechanisms that promote pain plasticity via controlling BDNF expression that is involved in promoting pain plasticity have not been identified. We show that phosphorylation of eIF4E is paramount for Bdnf mRNA translation in the DRG. Bdnf mRNA translation is reduced in mice lacking eIF4E phosphorylation (eIF4E(S209A)) and pro-nociceptive factors fail to increase BDNF protein levels in the DRGs of these mice despite robust upregulation of Bdnf-201 mRNA levels. Importantly, bypassing the DRG by giving intrathecal injection of BDNF in eIF4E(S209A) mice creates a strong hyperalgesic priming response that is normally absent or reduced in these mice. We conclude that eIF4E phosphorylation-mediated translational control of BDNF expression is a key mechanism for nociceptor plasticity leading to hyperalgesic priming.

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / There is accumulating evidence for the role of brain-derived neurotrophic factor (BDNF) in the pathophysiology of depression. However, the role of BDNF in the pathophysiology of post-traumatic stress disorder (PTSD) remains controversial, and no study has assessed BDNF concentrations among pregnant women with PTSD. We examined early-pregnancy BDNF concentrations among women with PTSD with and without depression. A total of 2928 women attending prenatal care clinics in Lima, Peru, were recruited. Antepartum PTSD and depression were evaluated using PTSD Checklist—Civilian Version (PCL-C) and Patient Health Questionnaire-9 (PHQ-9) scales, respectively. BDNF concentrations were measured in a subset of the cohort (N = 944) using a competitive enzyme-linked immunosorbent assay (ELISA). Logistic regression procedures were used to estimate odds ratios (OR) and 95 % confidence intervals (95 % CI). Antepartum PTSD (37.4 %) and depression (27.6 %) were prevalent in this cohort of low-income pregnant Peruvian women. Approximately 19.9 % of participants had comorbid PTSD-depression. Median serum BDNF concentrations were lower among women with comorbid PTSD-depression as compared with women without either condition (median [interquartile range], 20.44 [16.97–24.30] vs. 21.35 [17.33–26.01] ng/ml; P = 0.06). Compared to the referent group (those without PTSD and depression), women with comorbid PTSD-depression were 1.52-fold more likely to have low (<25.38 ng/ml) BDNF concentrations (OR = 1.52; 95 % CI 1.00–2.31). We observed no evidence of reduced BDNF concentrations among women with isolated PTSD. BDNF concentrations in early pregnancy were only minimally and non-significantly reduced among women with antepartum PTSD. Reductions in BDNF concentrations were more pronounced among women with comorbid PTSD-depression. / Revisión por pares

Epilepsy, a disease characterized by recurring spontaneous seizures, affects over 65 million people, 2% of the world’s population. Over 30% of patients are refractory to all current medical therapy, and for those that can be treated, many suffer from severe drug side-effects. Understanding the molecular basis of epilepsy is vital to the advancement of better therapeutic options and an eventual cure. Upregulation of brain-derived neurotrophic factor (BDNF) is highly associated with epileptogenesis in human patients, as well as animal models. Our laboratory discovered that BDNF induces the Janus Kinase/Signal Transducer and Activator of Transcription (JAK/STAT) pathway in neurons and that inhibition attenuates spontaneous seizures in a temporal lobe epilepsy model. The mechanism behind JAK/STAT signaling in neurons and its relationship to epilepsy still remains to be elucidated and is the subject of my thesis. Surprisingly, even though BDNF is such a major signaling molecule, its full genomic impact has never been assessed. We conducted a high-density RNA-sequencing analysis of the BDNF transcriptome in cortical neurons and probed such regulation with selective JAK inhibitors. Results suggest that 68% of BDNF-induced changes in gene expression implicated in epilepsy are regulated by JAK/STAT signaling. Eighty percent of BDNF-induced changes coding for proteins involved in synaptic neurotransmission (receptor subunits and ion channels) involve JAK/STATs. Additionally, these datasets include genes that have never been associated with BDNF regulation (such as Dopamine Receptor D5 and Galanin Receptor 1). Most interestingly, the datasets reveal that BDNF-induced JAK/STAT signaling in neurons is non-canonical, as STAT3 phosphorylation at tyrosine 705 is not required for action. To directly examine STAT3’s role in epileptogenesis, we studied the transcriptome of transgenic mice that express lower levels of STAT3 specifically in neurons. Using the intrahippocampal kainic-acid (KA) model of epilepsy, our datasets suggest that STAT3 knockdown in vivo, and selectively in neurons, protects mice from KA-induced dysregulation of the sphingolipid metabolism pathway that is associated with the trafficking, sorting, and stability of membrane-bound proteins, including neurotransmitter receptors and ion channels. Finally, we discuss a model for JAK/STAT signaling in neurons that includes structural aspects of an intracellular BDNF receptor (p75NTR) associated with JAK2. / 2021-06-14T00:00:00Z

Rationale: Psychotic disorders such as schizophrenia are often accompanied by high rates of cigarette smoking, reduced quit success, and high relapse rates, negatively affecting patient outcomes. However, the mechanisms underlying altered relapse-like behaviors in individuals diagnosed with psychosis are poorly understood. Objectives: The present study analyzed changes in extinction and reinstatement of nicotine conditioned place preference (CPP) and resulting changes in brain-derived neurotrophic factor (BDNF) in a novel heritable rodent model of psychosis, demonstrating increased dopamine D2 receptor sensitivity, to explore mechanisms contributing to changes in relapse-like behaviors. Methods: Male and female offspring of two neonatal quinpirole-treated (QQ) and two neonatal saline-treated (SS) Sprague-Dawley rats (F1 generation) were tested on an extended CPP paradigm to analyze extinction and nicotine-primed reinstatement. Brain tissue was analyzed 60 min after the last nicotine injection for BDNF response in the ventral tegmental area (VTA), the infralimbic (IfL) and prelimbic (PrL) cortices. Results: F1 generation QQ offspring demonstrated delayed extinction and more robust reinstatement compared to SS control animals. In addition, QQ animals demonstrated an enhanced BDNF response to nicotine in the VTA, IfL and Prl cortices compared to SS offspring. Conclusions: This study is the first to demonstrate altered relapse-like behavior in a heritable rodent model with relevance to comorbid drug abuse and psychosis. This altered pattern of behavior is hypothesized to be related to elevated activity-dependent BDNF in brain areas associated with drug reinforcement during conditioning that persists through the extinction phase, rendering aberrantly salient drug associations resistant to extinction and enhancing relapse vulnerability.

Indiana University-Purdue University Indianapolis (IUPUI) / Depression is a heterogeneous mental health condition, varying in presentation across individuals. A candidate etiology that may help account for this heterogeneity is the neurotrophin hypothesis of depression, which proposes that stress downregulates brain-derived neurotrophic factor (BDNF) expression, leading to aberrant neurogenesis and depression. This etiology may manifest in a distinct symptom profile that may be reflected in depressive symptoms or symptom clusters. The effect of psychological interventions on BDNF is not known. Additionally, it is not known if BDNF levels mediate intervention effects on depressive symptom clusters. Using data from the eIMPACT trial (NCT02458690, supported by R01 HL122245), I examined baseline associations of BDNF with depressive symptoms and depressive symptom clusters. Also, I examined if the modernized collaborative care intervention for depression (internet CBT, telephonic CBT, and select antidepressant medications) affected BDNF and if changes in BDNF mediated intervention effects on cognitive/affective and somatic depressive symptom clusters. 216 participants (primary care patients with depression and elevated cardiovascular disease risk ≥50 years from a safety net healthcare system) were randomized to 12 months of the eIMPACT intervention (n=107) or usual primary care for depression (primary care providers supported by embedded behavioral health clinicians and affiliated psychiatrists; n=109). Plasma BDNF was measured with commercial ELISA kits. Depressive symptoms were assessed by the PHQ-9 (M=15.1, SD=5.0) from which cognitive/affective and somatic subscale scores were computed. No significant baseline associations were observed between BDNF and individual depressive symptoms or depressive symptom clusters. The intervention did not improve BDNF over 12 months. Similarly, 12-month changes in BDNF were not associated with 12-month changes in PHQ-9 cognitive/affective or somatic subscale scores. However, the intervention significantly improved PHQ-9 cognitive/affective and somatic subscale scores over 12 months. 12-month changes in BDNF did not mediate the effect of the intervention on 12-month changes in the PHQ-9 subscale scores. These findings suggest that modernized collaborative care for depression does not improve BDNF. Modernized collaborative care does yield improvements in both cognitive/affective and somatic depressive symptom clusters, albeit not via changes in BDNF.

<p>Depression is a heterogeneous mental health condition, varying in presentation across individuals. A candidate etiology that may help account for this heterogeneity is the neurotrophin hypothesis of depression, which proposes that stress downregulates brain-derived neurotrophic factor (BDNF) expression, leading to aberrant neurogenesis and depression. This etiology may manifest in a distinct symptom profile that may be reflected in depressive symptoms or symptom clusters. The effect of psychological interventions on BDNF is not known. Additionally, it is not known if BDNF levels mediate intervention effects on depressive symptom clusters. Using data from the eIMPACT trial (NCT02458690, supported by R01 HL122245), I examined baseline associations of BDNF with depressive symptoms and depressive symptom clusters. Also, I examined if the modernized collaborative care intervention for depression (internet CBT, telephonic CBT, and select antidepressant medications) affected BDNF and if changes in BDNF mediated intervention effects on cognitive/affective and somatic depressive symptom clusters. 216 participants (primary care patients with depression and elevated cardiovascular disease risk ≥50 years from a safety net healthcare system) were randomized to 12 months of the eIMPACT intervention (<em>n</em>=107) or usual primary care for depression (primary care providers supported by embedded behavioral health clinicians and affiliated psychiatrists; <em>n</em>=109). Plasma BDNF was measured with commercial ELISA kits. Depressive symptoms were assessed by the PHQ-9 (<em>M</em>=15.1, <em>SD</em>=5.0) from which cognitive/affective and somatic subscale scores were computed. No significant baseline associations were observed between BDNF and individual depressive symptoms or depressive symptom clusters. The intervention did not improve BDNF over 12 months. Similarly, 12-month changes in BDNF were not associated with 12-month changes in PHQ-9 cognitive/affective or somatic subscale scores. However, the intervention significantly improved PHQ-9 cognitive/affective and somatic subscale scores over 12 months. 12-month changes in BDNF did not mediate the effect of the intervention on 12-month changes in the PHQ-9 subscale scores. These findings suggest that modernized collaborative care for depression does not improve BDNF. Modernized collaborative care does yield improvements in both cognitive/affective and somatic depressive symptom clusters, albeit not via changes in BDNF.</p>

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The developing brain is highly sensitive to environmental influences. Unfavorable nutrition is one kind of stress that can cause acute metabolic disorders during the neonatal period [1,2,3] and severe diseases in later life [4,5]. These early life experiences occurring during heightened periods of brain plasticity help determine the lifelong structural and functional aspects of brain and behavior. In humans, for example, weight gain during the first week of life increased the propensity for developing obesity several decades later [5]. This susceptibility is, if not all, related to the dynamic reversible epigenetic imprints left on the histones [6,7,8], especially during the prenatal and postpartum period [9]. Histones are highly dynamic and responsive towards environmental stress [10,11]. Through covalent modification of the histone tail, histones are able to direct DNA scaffolding and regulate gene expression [10,12]. Thus far, various types of post translational modifications have been identified on various histones tails [12]. Among them, the methylation and acetylation on lysine residue (K) 27 on histone 3 (H3) has been tightly linked to gene repression [13,14] and activation [15], respectively. EZh2 (enhancer of zeste 2) in the polycomb repressive complex 2 (PRC2) is the only methyltransferase that has been linked to catalyze this methylation reaction. In addition, SUZ (suppressor of zeste) and EED (embryonic ectoderm development) are two other key proteins in PRC2 function core that help EZH2. As previous reported, increased H3K27 methylation was monitored after fasting stress during neonatal period in chicks' paraventricular nucleus (PVN). In this study, we investigated the detailed mechanism behind changes in H3K27 methylation following fasting stress. After 24 hours fasting on 3 days-of-age (D3), chicks exhibited elevated mRNA levels of PRC2 key components, including EZH2, SUZ and EED, in the PVN on D4. Western blots confirmed this finding by showing increased global methylation status at the H3K27 site in the PVN on D4. In addition, until 38 days post fasting, SUZ and EZH2 remained inhibited. A newly identified anorexigenic factor, Brain-derived neurotrophic factor (BDNF), was used as an example of multiple hormones expressed in PVN to verify this finding. Both BDNF protein and mRNA exhibited compatible changes to global changes of tri- (me3) and di-methylated (me2) H327. Furthermore, by using chromatin immunoprecipitation assays (ChIP), we were able to monitor the changes of H3K27me2/me3 deposition along the Bdnf gene. Fasting significantly increased H3K27me2/me3 as well as EZH2 at the Bdnf's promoter, transcription start site and 3'-untranslated region. These data show that fasting stress during the early life period could leave epigenetic imprinting in PVN for a long time. Next, we tried to understand the function of this epigenetic imprinting in the chicks' PVN. Thus, we compared naive chicks (never fasted) to chicks that received either a single 24 hour fast on D3 or two 24 hour fast on both D3 and 10 days-of-age (D10). We found that the D3 fasted group significantly increased the level of PRC2 key components and its product H3K27me2/me3 compared to the naive group. However, D3 fasting and D10 fasting together decreased the surges of H3K27me2/me3, SUZ and EED (not EZH2) compared to the naive group. We called this phenomenon "epigenetic memory". The Western blot, qPCR and CHIP assay results from BDNF all confirmed the existence of "epigenetic memory" for PRC2. These data suggested that fasting stress during the early period of brain development could leave long term epigenetic modifications in neurons. These changes could be beneficial to the body, which keeps homeostasis of inner environment and prevent massive response to future same stress. The EZH2 protein was knocked down and the H3K27 methylation status changes were monitored after applying the same treatment. We first confirmed that EZH2 antisense oligonucleotides (5.5 ug), but not EZH2 siRNA and artificial cerebrospinal fluid (ACSF), inhibit EZH2 protein by 86 % in the PVN. Then, on D3, chicks were subjected to a 24 hour fasting stress (D3-fasting) post either EZH2 antisense or ACSF injection. The EZH2 antisense blocked the surge of both EZH2 mRNA and H3K27 methylation after D3-fasting. At the same time, BDNF exhibited elevated expression levels and less methylated H3K27 deposition along the Bdnf gene. In addition, we were also interested in the changes of "epigenetic memory" post EZH2 antisense injection. We found that after EZH2 antisense injection, chicks' PVN no longer exhibited any "epigenetic memory" to repetitive fasting stress. While EZH2 mRNA was constantly inhibited, SUZ, EED and H3K27me2/3 levels were unpredictable. These findings suggested that neurons in the PVN utilized PRC2 as a major H3K27 methylation tool. Knockdown of EZH2 in the PRC2 impaired the proper response in PVN to fasting stress and PVN's ability to acclimate to repetitive fasting stresses. Thus, EZH2 is an important H3K27 methyltransferase inside chicken hypothalamus to maintain homeostasis. In conclusion, fasting stress during the early life period could leave epigenetic markers on chromosomes of neurons in the feeding regulation center. These epigenetic markers will be left on chromosomes for a long period of time and have a beneficial role in keeping homeostasis when individuals face future fasting stress again. H3K27 methylation is one of these epigenetic markers and inhibits expression of various genes inside neurons. EZH2 is so far the only detected methyltransferases for H3K27 that form the PRC2. Thus EZH2 plays a key function in the body's response to fasting. / Ph. D.