Thesis (Ph. D.)--University of Florida, 2004. / Typescript. Title from title page of source document. Document formatted into pages; contains 202 pages. Includes Vita. Includes bibliographical references.

Resumo: Os confrontos dos animais com situações que induzem medo e ansiedade resultam em uma série de respostas comportamentais defensivas (ex. luta, fuga, imobilidade, vocalização, etc.), ativação neurovegetativa (ex. taquicardia, hipertensão, defecação, etc.), antinocicepção, além de influenciar o comportamento agressivo e aumentar a vulnerabilidade à dependência e recaída ao uso de drogas. Com base no potencial efeito ansiogênico dos neurotransmissores glutamato (via ativação do complexo receptor NMDA-óxido nítrico) e fator liberador de corticotrofina (via receptores CRF1 e CRF2), este estudo investigou o papel desses mediadores, através de injeções sistêmicas, na matéria cinzenta periaquedutal (MCP) ou no núcleo dorsal da rafe (NDR), nas respostas apontadas acima. Os seguintes modelos foram utilizados: labirinto em cruz elevado (LCE, ansiedade), injeção de formalina a 2,5% (nocicepção), conflito intruso-residente (agressão) e estresse de derrota social (dependência à cocaína). Os resultados indicaram: a) o efeito ansiogênico do agonista de receptores NMDA (N-metil-D-aspartato; NMDA) na MCP foi antagonizado pela inibição da enzima de síntese de NO, b) os efeitos ansiogênico e antinociceptivo do CRF na MCP foram via ativação de receptores CRF1 (mas não CRF2) e independentes de NO, c) os efeitos aversivo e antinociceptivo do NO (via administração de um doador de NO) na MCP mostraram-se sensíveis ao bloqueio de receptores CRF1, d) a ativação de receptores CRF2 intra-NDR reduziu o comportamento agressivo induzido pelo conflito intruso-residente, e) o tratamento sistêmico com antagonista CRF1 bloqueou a sensibilização comportamental à cocaína e atenuou o aumento do consumo da mesma induzidos pelo estresse da derrota social / Abstract: Animal confrontation against fear/anxiety-induced situations results in a repertory of behavioral defensive responses (e.g., fight, flight, immobility, vocalization), neurovegetative activation (e.g., tachycardia, hypertension, defecation), antinociception, as well as affects aggressive behavior and increases animals vulnerability to addiction and relapse to drug take. Based on the potential anxiogenic effect elicited by glutamate (via activation of NMDA-nitric oxide receptor complex) and corticotropin releasing factor (via CRF1 and CRF2 receptors), this study investigated the effect of systemic, intra-periaqueductal gray (PAG) or intradorsal raphe nucleus (DRN) injections of these mediators on the above described responses. The following animal models were used: elevated plus maze (EPM, anxiety test), formalin 2.5% injection (nociceptive test), resident-intruder conflict (aggression test) and social defeat stress (to induce cocaine addiction). Results indicated that: a) the anxiogenic effect elicited by intra-PAG injection of glutamate NMDA (N-methyl-D-aspartate; NMDA) receptor agonist was antagonized by prior local infusion an NO synthase inhibitor, b) the anxiogenic and antinociceptive effects elicited by intra-PAG CRF were mediated by CRF1 (but not CRF2) receptor activation and did not depend on NO synthesis, c) the aversive and antinociceptive effects of NO production (induced by intra-PAG injection of a NO donor) were sensitive to CRF1 blockade, d) activation of the CRF2 receptor within the DRN attenuated aggressive behavior elicited by resident-intruder conflict, e) systemic treatment with CRF1 receptor antagonist inhibited cocaine behavioral sensitization and social-defeat stress-induced cocaine consumption / Orientador: Ricardo Luiz Nunes de Souza / Coorientador: Klaus A. Miczek / Banca: Cleopatra da Silva Planeta / Banca: Fabrício Moreira / Banca: Hélio Zangrossi Júnior / Banca: Marcus Lira Brandão / Doutor

As teneurinas (TENs) são de proteínas de transmembrana com significante expressão no sistema nervoso central (SNC). Foi verificado que o último éxon dos genes das TENs codifica um peptídeo com elevada identidade ao fator liberador de corticotropina (CRF) sendo este denominado de peptídeo associado ao terminal carboxila da teneurina (TCAP-1 a 4). Estudos mostram que TCAP-1 controla o comportamento emocional possivelmente por modular as ações mediadas pelo (CRF). A distribuição do TCAP-1 no SNC de primatas poderia subsidiar os seus efeitos funcionais e as possíveis aplicações terapêuticas. O presente trabalho analisou a imunorreatividade e a expressão do RNA mensageiro do TCAP-1 no encéfalo de primatas não-humanos. Cortes frontais do SNC de macacos da espécie Cebus apella (n=3) foram selecionados e utilizados nas técnicas de hibridização in situ e de imuno-histoquímica. Neurônios imunorreativos e que expressam o RNAm para TCAP-1 foram encontrados principalmente em áreas que estão direta ou indiretamente envolvidas na modulação da resposta ao estresse e ansiedade. / Teneurins are transmembrane proteins expressed mainly in the central nervous system (CNS). The last exon of the teneurins exhibits a peptide sequence with high homology to corticotrophin-releasing factor (CRF), named teneurin c-terminal associated peptide (TCAP-1 to 4). TCAP-1 effectively modulates stress induced by CRF. Studies have pointed tha TCAP-1 could have important therapeutic applications in stress disorders. The analysis of TCAP-1 distribution in the primate brain could also give anatomical support to the understanding of its functional effects and possible therapeutic use. Thus, the present study focused on the distribution of neurons exhibiting immunoreactivity and mRNA expression to TCAP-1 in the monkey brain (Cebus apella). Frontal brain sections of three young male Cebus apella monkeys were submitted to immunohistochemistry and in situ hybridization. Immunohistochemistry and in situ hybridization results showed that TCAP-1 is preserved in primate brain, mainly in areas directly or indirectly involved in the modulation of stress and anxiety.

A homeostase energética é controlada por fatores neurais, endócrinos, adipocitários e intestinais. O sistema nervoso central (SNC) recebe sinalização de fatores periféricos e exerce uma função fundamental no controle da homeostase energética, estando bem estabelecido que existem populações neuronais que expressam neuropeptídeos que medeiam efeitos específicos na ingestão e/ou gasto energético. O fator liberador de corticotrofina (CRF), além de seus efeitos no controle da atividade do eixo hipotálamo-hipófise-adrenal, tem sido descrito como potente neuropeptídeo anorexígeno, modulando a ingestão alimentar e o gasto energético. Foi observado que a síntese de CRF é influenciada pela leptina, que atuaria aumentando a ativação de neurônios produtores de CRF no núcleo paraventricular (PVN). Os hormônios gonadais também participam na regulação da ingestão alimentar, do peso e da composição corporal. O efeito anorexígeno do estradiol é mediado pela ativação de receptores presentes nas áreas envolvidas no controle da homeostase energética. Em trabalho prévio de nosso laboratório foi observado que o menor ganho de peso e ingestão alimentar com o tratamento com estradiol em ratas ovariectomizadas está associado à maior expressão de RNAm de CRF no PVN. Dessa forma, este trabalho visa esclarecer a participação do CRF nos efeitos do estradiol no controle da homeostase energética. Para tanto, foram utilizadas ratas Wistar adultas, pesando entre 200-230g, provenientes do Biotério Central do Campus de Ribeirão Preto USP. Todos os animais foram submetidos à cirurgia de ovariectomia bilateral. Em todos os experimentos, houve três grupos de animais: ratas ovariectomizadas (OVX), ratas ovariectomizadas com reposição de estradiol (OVX+E) e ratas ovariectomizadas com dieta pareada ao grupo OVX+E (OVX+DP). Durante os oitos dias de cada experimento, estes animais receberam injeção subcutânea de cipionato de estradiol (10 g/Kg peso corporal, Grupo OVX+E) ou veículo (óleo de milho: 0,2 mL/rata, Grupos OVX e OVX+DP) entre 8h e 10h. Para avaliarmos a participação do CRF nos efeitos da leptina nos animais castrados com e sem reposição de estradiol, foi realizado o tratamento com injeção central de leptina (10g/5L) com e sem injeção central prévia de antagonista de CRF (antisauvagina-30). Observamos que o tratamento com cipionato de estradiol causa a redução na ingestão alimentar e no ganho de peso corporal. Ainda, quando realizamos a administração central de leptina há anorexia, perda de peso corporal, aumento na expressão de UCP-1 no BAT e na ativação neuronal no ARQ. Esses efeitos são revertidos quando realizamos administração central prévia do antagonista de CRF-R2. Os dados obtidos sugerem que o estradiol aumenta a sensibilidade à leptina, sendo este efeito mediado, pelo menos em parte, pelo receptor tipo 2 do CRF. / Energy homeostasis is controlled by neural, endocrine, adipocyte and gut factors. Central nervous system plays a key role in the control of energy homeostasis; it receives signals from peripheral factors and it is well established that the hypothalamus contains neuronal populations that express important neuropeptides to the control of food intake and energy expenditure. Besides its action in the control of hypothalamus-pituitary-adrenal axis, corticotropin releasing factor (CRF), has been described as an anorexigenic neuropeptide, modulating food intake and energy expenditure. It was shown that CRF synthesis is influenced by leptin, which would act increasing CRF neuron activation in the paraventricular nucleus (PVN). Gonadal hormones also participate in the regulation of food intake, body weight and body composition. Estradiol anorexigenic effect is mediated by specific receptors located in areas involved in the control of energy homeostasis. It was previously demonstrated that the reduction of food intake and body weight gain in ovariectomized treated rats is associated with an increase in CRF mRNA expression in the PVN. The present study aimed to investigate the role of CRF on estradiol regulation of energy homeostasis. Wistar female rats, weighing 200 230g, were bilaterally ovariectomized and divided into three groups: ovariectomized rats (OVX), ovariectomized rats treated with estradiol (OVX+E) and ovariectomized rats pair-fed with OVX+E rats (OVX+PF). The animals received daily subcutaneous injections of either estradiol cypionate (10 g/Kg bw, OVX+E) or vehicle (corn oil, OVX, OVX+PF) between 8 10 am, during 8 days. To evaluate the role of CRF on leptins effects we performed intracerebroventricular (icv) injection of recombinant leptin (10g/5L) with or without previous icv treatment with CRF-R2 antagonist (ansauvagin-30). We observed that estradiol replacement in OVX rats induced lower food intake and body weight gain. Leptin icv treatment reduced food intake, body weight gain and increased UCP-1 expression in brown adipose tissue and neuronal activation in the arcuate nucleus. These effects were abolished with previous icv administration of CRF-R2 antagonist. In conclusion, our data suggest that estradiol increases central sensitivity to leptin and this effect is mediated, at least in part, by CRF type 2 receptor.

Electroconvulsive therapy (ECT) is one of the oldest and most effective treatments for depression; however, its biological underpinnings are poorly understood. Brain-derived neurotrophic factor (BDNF) and the hypothalamic-pituitary-adrenal (HPA) axis are two chemical messenger systems implicated in the antidepressant action and cognitive side effects of ECT. The Wistar-Kyoto (WKY) strain is a genetic model of depression that shows biological, cognitive, behavioural, and treatment-response abnormalities, making it potentially a useful model in which to investigate the underpinnings of the action of electroconvulsive stimulus (ECS: the amimal model of ECT). In addition, the WKY presents a potentially useful model for translational research on depression. The WKY strain is particularly valuable for the measurement of serum BDNF protein, for which the association with antidepressant treatments is much less clear (mostly stemming from investigations in humans) than that between brain BDNF and antidepressant treatments in rodent studies. The three studies presented add insight into the biological and behavioural effects of ECS. The first study (chapter 2) found no evidence of increased (R)-[11C]rolipram binding (an indirect marker of cyclic-adenosine monophosphate, cAMP) in the brain, despite significant increases of brain BDNF protein expression after repeated ECS. The second study (chapter 3) demonstrated the validity of the WKY strain in the investigation of ECS. Relative to Wistar controls, WKY showed similar antidepressant and cognitive effects (despite some abnormal behavioural responses), immediate but not sustained increases in brain BDNF protein, and a novel finding of increased extra-hypothalamic CRF after 5 daily ECS. The final study (chapter 4) demonstrated baseline strain differences in serum (WKY < Wistar) but not brain BDNF and, in both strains, no change in serum BDNF despite significant changes in brain BDNF after repeated ECS treatment. Preliminary results from a human pilot study investigating similar measures in a small group of people receiving ECT for depression are also presented. The results of this body of work advance our understanding of the activation and role of brain and serum measures of BDNF and the HPA axis in ECS/ECT, and raise important issues in the translation of research from basic science to the human condition of depression.

Depression occurs in about one third of patients with stroke and cardiac arrest. Hyperactivity of the stress system is the most commonly observed neuroendocrine change in major depressive disorder (MDD), which involves elevated levels in the cerebrospinal fluid of corticotropin-releasing hormone (CRH), a key stress neurohormone. Substantial evidence suggests that normalization of the stress system may be a requirement for successful treatment of MDD through region-specific changes in the mesocorticolimbic circuitry. Thus, alteration in the stress system may underlie the emotional and functional impairments observed following brain ischemic events. In addition, recent findings suggest that ischemic brain injury triggers a restorative process, creating a cerebral environment similar to that of early brain development, a period characterized by rapid neuronal growth and neuroplasticity, critical to optimize functional recovery of individuals post stroke. In particular brain-derived neurotrophic factor (BDNF), has been shown to play an important role in the pathophysiology of major depression and cerebral ischemia. However, whether CRH can mediate the expression of BDNF in the reparative process triggered by ischemic injury remains to be characterized. Therefore, the purpose of the current thesis is to characterize the effect of pharmacological blockade of CRH signaling at the onset of a global ischemic stroke, on emotional and cognitive behaviors, alteration in the neuroendocrine stress system, and markers of neuroplasticity including BDNF. To do this, an animal model of global cerebral ischemia with subsequent behavioral testing and postmortem brain analysis was used to determine underlying biochemical and behavioral changes modulated by CRH signaling following brain ischemia. This doctoral work will help elucidate the relationship between CRH and BDNF in the context of cerebral ischemia, and may provide insights for therapies targeting the stress system. These studies address considerations such as: the interplay between stress, neuroplasticity and emotionality, and whether global ischemia can affect mood via changes in the HPA axis response.

<p>Some individuals with alcohol use disorder (AUD) continue to drink because they have developed a habit in which they are not considering the consequences of their actions. Habitual actions persist despite changes in reward and are often studied using devaluation procedures. Stress hormones, such as corticotropin releasing factor (CRF), have been linked to AUD when examining binge-like drinking and withdrawal in rodents. Stress has been examined in the switch from goal-directed to habitual behavior, and CRF has often mimicked the effects of stress exposure. This study looked at the possible direct effects of CRF on habit expression in rats using an operant paradigm. Finding possible novel mechanisms of habit could create an avenue for future novel treatment options. Female and male Long Evans rats were trained on a variable interval schedule using sucrose as a reward. Rats then underwent devaluation procedures including both sensory-specific satiety and conditioned taste aversion (CTA) to test for habitual behaviors. Prior to an extinction session post-CTA, animals were treated with either 20 mg/kg R121919, a CRF1 receptor antagonist, or vehicle. A second extinction session was conducted where animals received the alternative treatment. Lever presses were recorded as a measure of goal-directed or habitual behavior. Sensory-specific satiety devaluation tests revealed that animals were not sensitive to devaluation. This was further supported by both post-CTA extinction sessions. R121919 had no effect on lever pressing in either devalued or valued groups. Further research is needed to explore how a CRF receptor antagonist may affect habit formation or the transition from goal-directed to habit behaviors. Future studies should also examine any possible interaction effects CRF may have with alcohol or stress on habitual behaviors.</p>

Corticotropin releasing factor (CRF) has been implicated to act as a neurotransmitter or modulator in central nervous activation during stress. In this study, we examined the regulatory effect of CRF on the expression and function of the norepinephrine transporter (NET) in vitro. SK-N-BE (2) M17 cells were exposed to different concentrations of CRF for different periods. Results showed that exposure of cells to CRF significantly increased mRNA and protein levels of NET in a concentration- and time-dependent manner. The CRF-induced increase in NET expression was mimicked by agonists of either CRF receptor 1 or 2. Furthermore, similar CRF treatments induced a parallel increase in the uptake of [3H] norepinephrine. Both increased expression and function of NET caused by CRF were abolished by simultaneous administration of CRF receptor antagonists, indicating a mediation by CRF receptors. However, there was no additive effect for the combination of both receptor antagonists. Chromatin immunoprecipitation assays confirm an increased acetylation of histone H3 on the NET promoter following treatment with CRF. Taken together, this study demonstrates that CRF up-regulates the expression and function of NET in vitro. This regulation is mediated through CRF receptors and an epigenetic mechanism related to histone acetylation may be involved. This CRF-induced regulation on NET expression and function may play a role in development of stress-related depression and anxiety. This study demonstrated that corticotropin release factor (CRF) up-regulated the expression and function of norepinephrine transporter (NET) in a concentration- and time-dependent manner, through activation of CRF receptors and possible histone acetylation in NET promoter. The results indicate that their interaction may play an important role in stress-related physiological and pathological status. This study demonstrated that corticotropin release factor (CRF) up-regulated the expression and function of norepinephrine transporter (NET) in a concentration- and time-dependent manner, through activation of CRF receptors and possible histone acetylation in NET promoter. The results indicate that their interaction may play an important role in stress-related physiological and pathological status.

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