O consumo de cafeína tornou-se popular em adolescentes devido ao aumento da ingestão de bebidas comercializadas na forma de bebidas energéticas. Alguns estudos consideram que os efeitos benéficos da cafeína são atribuídos a uma reversão dos sintomas de abstinência. Neste estudo, foram investigados os efeitos da administração crônica de cafeína em ratos desde a adolescência (40 dias de idade) até à idade adulta (3 meses de idade) na memória de reconhecimento e BDNF e proteínas relacionadas a sua sinalização nas regiões do córtex e hipocampo. A cafeína (0,3 e 1,0 g/L) foi administrada na água de beber durante o ciclo de ativo dos animais (ciclo escuro) e retirada durante os fins de semana. Este protocolo foi desenvolvido a fim de mimetizar o consumo humano. Para as experiências de privação (abstinência),a administração crônica foi interrompida 24 ou 48 h antes do teste de tarefa de reconhecimento de objetos. Na tarefa de reconhecimento de objetos, foi possível observar os efeitos positivos da cafeína sobre a memória de reconhecimento, pois os animais tiveram um bom desempenho na tarefa. Entretanto, mesmo após a interrupção do tratamento os animais continuaram desempenhando bem a tarefa, dessa forma a abstinência de um tratamento crônico com cafeína não influencia a memória de reconhecimento. A cafeína na sua dose mais alta (1,0 mg / mL) e 24 h após a retirada, causou uma diminuição nos níveis de BDNF no hipocampo e nenhum efeito sobre as proteínas proBDNF e TrkB. Em contrapartida, no córtex a cafeína em ambas as doses diminuui os níveis de BDNF, um efeito que persistiu apenas para a dose mais elevada em ambos os tempos de retirada. O ProBDNF teve seus níveis diminuídos pela cafeína (1,0 mg / mL) após 48 horas da retirada, enquanto a cafeína em ambos os tempos de retirada aumentou receptores TrkB. Como mencionado anteriormente, estes resultados mostraram que a cafeína administrada durante a adolescência até a idade adulta, seguida da sua retirada não afeta a memória de reconhecimento. Estes efeitos poderiam ser atribuídos ao desenvolvimento da tolerância por tratamento crónico. Além disso, o aumento de receptores de TrkB seguido por diminuição de BDNF pode ser contribuído para a ausência de efeitos de abstinência de cafeína na memória de reconhecimento. / The caffeine consumption has become popular among adolescents due to increased intake of beverages marketed as energy drinks. Some studies consider that the beneficial effects of caffeine are attributable to a reversal of withdrawal symptoms. This study investigated the effects cronic administration caffeine in rats since adolescent period (40 days old) until adulthood (3 months old) on recognition memory and BDNF-related proteins and their signalling in the regions of the cortex and hipocampus. Caffeine (0.3 and 1.0 g/L) was administered in drinking water during the light cycle and discontinued at weekends. This protocol was developed to mimic human consumption. For withdrawal experiments, cronic administration of caffeine was interrupted 24 or 48 h before the test session on object recognition task. In the task, we observed the positive effects of caffeine on recognition memory once that animals learned the task. However, even after treatment interuption animals continued performing the task, so the withdrawal of chronic treatment with caffeine has no effect on recognition memory. Caffeine at its highest dose (1.0 mg / mL) after 24 h and after removal, showed a decrease in BDNF levels in the hippocampus and no effect on protein proBDNF and its receptor TrkB. In contrast, in the cortex caffeine decreased BDNF levels at both doses, an effect which persisted for only the highest dose at both time of withdrawal. ProBDNF levels had decreased by caffeine (1.0 mg / mL) after 48 hours of removal, while the caffeine in both periods of increased withdrawal TrkB receptors. As mentioned earlier, these results showed that caffeine administered during adolescence to adulthood, followed by its removal does not affect recognition memory. These effects could be attributed to the development of tolerance for chronic treatment. Furthermore, the increase of TrkB receptors followed by a decrease in BDNF may be contributed to the absence of withdrawal effects of caffeine in recognition memory.

Objetivo: Em nossos estudos objetivamos investigar os níveis séricos de BDNF e também da PCR em pacientes bipolares durante a mania, a depressão e a eutimia, comparando com controles normais. Método: Somente pacientes com THB tipo I, diagnóstico confirmado através da SCID I, tiveram seus sintomas maníacos e depressivos analisados através das escalas Young (YMRS) e Hamilton (HDRS). Os pacientes foram considerados eutímicos com score menor que 7 em ambas as escalas. O grupo controle foi composto por voluntários correspondentes em idade e gênero com os pacientes bipolares. Resultados: Nível sérico do BDNF estavam diminuídos em maníacos (p=0,019) e depressivos (p=0,027), quando comparados com eutímicos e controles. O nível sérico do BDNF foi negativamente correlacionado com a gravidade dos sintomas maníacos (r= -0,37,p=0,005) e depressivos (r= -0,30, p=0,033). Já o nível sérico da PCR estava aumentado em pacientes no episódio maníaco, quando comparados com pacientes deprimidos, eutímicos e com controles normais (p=0,001). Conclusão: Nos pacientes com THB tem sido demonstrado evidências de disfunção mitocondrial, aumento dos marcadores do estresse oxidativo, ativação de mecanismos inflamatórios, danos ao DNA e apoptose. Atualmente sabemos que o sistema imune, através das citocinas, e o sistema nervoso, através dos fatores neurotróficos, modulam o crescimento e a diferenciação celular. Nossos achados sugerem o envolvimento do BDNF na fisiopatologia do THB e do sistema inflamatório na fase maníaca do THB. / Objective: In our studies we investigated the serum levels of BDNF and PCR in bipolar patients during mania, depression and euthimic episodes, comparing to normal controls. Method: Only bipolar patients type I with confirmed diagnostic through SCID I instrument had their manic and depressive symptoms analyzed through the Young (YMRS) and Hamilton (HDRS) scales. The patients were considered euthimic when they scored less than 7 in both scales. The control group was formed by volunteers with corresponding age and gender to the bipolar patients. Results: Serum levels of BDNF were diminished in manic (p=0,019) and depressive (p=0,027) patients, when compared to euthimics and controls. Serum levels of BDNF were negatively correlated with the severity of the manic (r=-0,37, p=0,005) and depressive (r=- 0,30, p=0,033) symptoms. The serum levels of PCR were increased in patients in manic episode, when compared to depressed, euthimic and normal controls (p=0,001). Conclusion: Evidences of mitochondrial dysfunction, increase of oxidative stress, activation of inflammatory mechanisms, DNA damage and apoptosis have been demonstrated in patientes with Bipolar Disorder. Nowadays we know that the immune system, through the cytokines, and the nervous system, through the neurotrophic factors, modulate the cellular growth and differentiation. Our findings suggest the involvement of BDNF in the pathofisiology of bipolar disorder and of the inflammatory system in the manic phase of bipolar disorder.

O consumo de cafeína tornou-se popular em adolescentes devido ao aumento da ingestão de bebidas comercializadas na forma de bebidas energéticas. Alguns estudos consideram que os efeitos benéficos da cafeína são atribuídos a uma reversão dos sintomas de abstinência. Neste estudo, foram investigados os efeitos da administração crônica de cafeína em ratos desde a adolescência (40 dias de idade) até à idade adulta (3 meses de idade) na memória de reconhecimento e BDNF e proteínas relacionadas a sua sinalização nas regiões do córtex e hipocampo. A cafeína (0,3 e 1,0 g/L) foi administrada na água de beber durante o ciclo de ativo dos animais (ciclo escuro) e retirada durante os fins de semana. Este protocolo foi desenvolvido a fim de mimetizar o consumo humano. Para as experiências de privação (abstinência),a administração crônica foi interrompida 24 ou 48 h antes do teste de tarefa de reconhecimento de objetos. Na tarefa de reconhecimento de objetos, foi possível observar os efeitos positivos da cafeína sobre a memória de reconhecimento, pois os animais tiveram um bom desempenho na tarefa. Entretanto, mesmo após a interrupção do tratamento os animais continuaram desempenhando bem a tarefa, dessa forma a abstinência de um tratamento crônico com cafeína não influencia a memória de reconhecimento. A cafeína na sua dose mais alta (1,0 mg / mL) e 24 h após a retirada, causou uma diminuição nos níveis de BDNF no hipocampo e nenhum efeito sobre as proteínas proBDNF e TrkB. Em contrapartida, no córtex a cafeína em ambas as doses diminuui os níveis de BDNF, um efeito que persistiu apenas para a dose mais elevada em ambos os tempos de retirada. O ProBDNF teve seus níveis diminuídos pela cafeína (1,0 mg / mL) após 48 horas da retirada, enquanto a cafeína em ambos os tempos de retirada aumentou receptores TrkB. Como mencionado anteriormente, estes resultados mostraram que a cafeína administrada durante a adolescência até a idade adulta, seguida da sua retirada não afeta a memória de reconhecimento. Estes efeitos poderiam ser atribuídos ao desenvolvimento da tolerância por tratamento crónico. Além disso, o aumento de receptores de TrkB seguido por diminuição de BDNF pode ser contribuído para a ausência de efeitos de abstinência de cafeína na memória de reconhecimento. / The caffeine consumption has become popular among adolescents due to increased intake of beverages marketed as energy drinks. Some studies consider that the beneficial effects of caffeine are attributable to a reversal of withdrawal symptoms. This study investigated the effects cronic administration caffeine in rats since adolescent period (40 days old) until adulthood (3 months old) on recognition memory and BDNF-related proteins and their signalling in the regions of the cortex and hipocampus. Caffeine (0.3 and 1.0 g/L) was administered in drinking water during the light cycle and discontinued at weekends. This protocol was developed to mimic human consumption. For withdrawal experiments, cronic administration of caffeine was interrupted 24 or 48 h before the test session on object recognition task. In the task, we observed the positive effects of caffeine on recognition memory once that animals learned the task. However, even after treatment interuption animals continued performing the task, so the withdrawal of chronic treatment with caffeine has no effect on recognition memory. Caffeine at its highest dose (1.0 mg / mL) after 24 h and after removal, showed a decrease in BDNF levels in the hippocampus and no effect on protein proBDNF and its receptor TrkB. In contrast, in the cortex caffeine decreased BDNF levels at both doses, an effect which persisted for only the highest dose at both time of withdrawal. ProBDNF levels had decreased by caffeine (1.0 mg / mL) after 48 hours of removal, while the caffeine in both periods of increased withdrawal TrkB receptors. As mentioned earlier, these results showed that caffeine administered during adolescence to adulthood, followed by its removal does not affect recognition memory. These effects could be attributed to the development of tolerance for chronic treatment. Furthermore, the increase of TrkB receptors followed by a decrease in BDNF may be contributed to the absence of withdrawal effects of caffeine in recognition memory.

abstract: Stroke remains the leading cause of adult disability in developed countries. Most survivors live with residual motor impairments that severely diminish independence and quality of life. After stroke, the only accepted treatment for these patients is motor rehabilitation. However, the amount and kind of rehabilitation required to induce clinically significant improvements in motor function is rarely given due to the constraints of our current health care system. Research reported in this dissertation contributes towards developing adjuvant therapies that may augment the impact of motor rehabilitation and improve functional outcome. These studies have demonstrated reorganization of maps within motor cortex as a function of experience in both healthy and brain-injured animals by using intracortical microstimulation technique. Furthermore, synaptic plasticity has been identified as a key neural mechanism in directing motor map plasticity, evidenced by restoration of movement representations within the spared cortical tissue accompanied by increase in synapse number translating into motor improvement after stroke. There is increasing evidence that brain-derived neurotrophic factor (BDNF) modulates synaptic and morphological plasticity in the developing and mature nervous system. Unfortunately, BDNF itself is a poor candidate because of its short half-life, low penetration through the blood brain barrier, and activating multiple receptor units, p75 and TrkB on the neuronal membrane. In order to circumvent this problem efficacy of two recently developed novel TrkB agonists, LM22A-4 and 7,8-dihydroxyflavone, that actively penetrate the blood brain barrier and enhance functional recovery. Findings from these dissertation studies indicate that administration of these pharmacological compounds, accompanied by motor rehabilitation provide a powerful therapeutic tool for stroke recovery. / Dissertation/Thesis / Ph.D. Neuroscience 2013

Objetivo: Em nossos estudos objetivamos investigar os níveis séricos de BDNF e também da PCR em pacientes bipolares durante a mania, a depressão e a eutimia, comparando com controles normais. Método: Somente pacientes com THB tipo I, diagnóstico confirmado através da SCID I, tiveram seus sintomas maníacos e depressivos analisados através das escalas Young (YMRS) e Hamilton (HDRS). Os pacientes foram considerados eutímicos com score menor que 7 em ambas as escalas. O grupo controle foi composto por voluntários correspondentes em idade e gênero com os pacientes bipolares. Resultados: Nível sérico do BDNF estavam diminuídos em maníacos (p=0,019) e depressivos (p=0,027), quando comparados com eutímicos e controles. O nível sérico do BDNF foi negativamente correlacionado com a gravidade dos sintomas maníacos (r= -0,37,p=0,005) e depressivos (r= -0,30, p=0,033). Já o nível sérico da PCR estava aumentado em pacientes no episódio maníaco, quando comparados com pacientes deprimidos, eutímicos e com controles normais (p=0,001). Conclusão: Nos pacientes com THB tem sido demonstrado evidências de disfunção mitocondrial, aumento dos marcadores do estresse oxidativo, ativação de mecanismos inflamatórios, danos ao DNA e apoptose. Atualmente sabemos que o sistema imune, através das citocinas, e o sistema nervoso, através dos fatores neurotróficos, modulam o crescimento e a diferenciação celular. Nossos achados sugerem o envolvimento do BDNF na fisiopatologia do THB e do sistema inflamatório na fase maníaca do THB. / Objective: In our studies we investigated the serum levels of BDNF and PCR in bipolar patients during mania, depression and euthimic episodes, comparing to normal controls. Method: Only bipolar patients type I with confirmed diagnostic through SCID I instrument had their manic and depressive symptoms analyzed through the Young (YMRS) and Hamilton (HDRS) scales. The patients were considered euthimic when they scored less than 7 in both scales. The control group was formed by volunteers with corresponding age and gender to the bipolar patients. Results: Serum levels of BDNF were diminished in manic (p=0,019) and depressive (p=0,027) patients, when compared to euthimics and controls. Serum levels of BDNF were negatively correlated with the severity of the manic (r=-0,37, p=0,005) and depressive (r=- 0,30, p=0,033) symptoms. The serum levels of PCR were increased in patients in manic episode, when compared to depressed, euthimic and normal controls (p=0,001). Conclusion: Evidences of mitochondrial dysfunction, increase of oxidative stress, activation of inflammatory mechanisms, DNA damage and apoptosis have been demonstrated in patientes with Bipolar Disorder. Nowadays we know that the immune system, through the cytokines, and the nervous system, through the neurotrophic factors, modulate the cellular growth and differentiation. Our findings suggest the involvement of BDNF in the pathofisiology of bipolar disorder and of the inflammatory system in the manic phase of bipolar disorder.

The mesocorticolimbic system is involved in fundamental processes that drive motivational behaviors essential for survival (feeding, reproduction and sexual behavior, etc.), as well as neurochemical activity involved in mood regulation. Stressful life events are an important cause of dysregulated psychological functioning, which in some leads to a pathophysiology of mood disorders. A source of such disorder could be, among other underlying factors, an impairment of synaptic plasticity induced by alterations in the levels of neurotrophins and/or aberrant glucocorticoid responses. The role of the brain derived neurotrophic factor (BDNF) and its high affinity receptor tyrosine-related kinase B (TrkB) in the mesocorticolimbic reward circuitry has been largely studied in adulthood, yet a possible role of this system in mediating memory and emotional responses induced by stress during the juvenile, adolescence period has not been elucidated. The proposed set of thesis studies are designed to investigate the roles of BDNF and TrkB signaling, via the selective and non-competitive TrkB antagonist, ANA-12 (N-[2-[[(Hexahydro-2-oxo-1H-azepin-3-yl)amino]carbonyl]phenyl] benzo[b]thiophene-2-carboxamide), in the expression of stress-induced changes in the brain stress circuitry (including the medial prefrontal cortex (mPFC), hypothalamic-pituitary-adrenal (HPA) axis, and hippocampus) and reward signaling systems of the brain (including the nucleus accumbens (NAc) and ventral tegmental area (VTA)). In addition, experiments aim to determine behavioral changes following stress exposure in male and female Wistar rats. Finally, the possible interplay between BDNF, dopamine, glutamate and orexins in response to repeated stress is examined. Articles 1 and 2, aimed to assess the biochemical and behavioral effects of direct ANA-12 infusion (0.25 µg/ 0.5µl) into the nucleus accumbens shell during exposure to a 10-day heterotypic stress paradigm in male rats. Specifically, Article 1 demonstrated a key role for BDNF/TrkB signaling to regulate stress-induced effects. Notably, the impact of ANA-12 to attenuate anxiety-like behavior in repeatedly stressed rats while increasing anxiety behavior in non-stress rats suggest an interesting behavioral and neurochemical state-dependent process induced by TrkB receptor signaling. Article 2 supports the key role for BDNF secretion in basal and stress-induced behaviors in rats suggesting an influence of TrkB in sociability, motivation and passive avoidance. Furthermore, this role of TrkB extended to increased expression of orexin A in the Perifornical area (PfA) and a decrease in the ventral CA1 of the hippocampus, and in stress-induced elevations in orexinergic projections to the VTA, of which reductions were observed in non-stress groups treated with ANA-12. Article 3 demonstrated gender-specific behavioral and biochemical responses in different developmental periods and the impact of TrkB activation, dependent on stress exposure, to affect the regulation of TrkB receptor isoforms (full length and truncated TrkB, TrkB.FL and TrkB.T1, respectively) in adulthood. Results revealed increased CORT responses in adolescent females relative to males and attenuated CORT secretions in both genders by TrkB inhibition. Elevated activity levels in young adult females and increased passive coping behavior in the forced swim in stress-naïve females were also noted, in addition to novel observations on brain region and sex differences in TrkB receptor isoforms. Taken together, thesis findings derived from applications of ANA-12, shall foster knowledge on the contribution of BDNF in regulation of mood upon stress exposure at times when the brain is undergoing important maturation and remodelling, as well as on the relationship of stress exposure during adolescence and lasting brain and behavioral disorders in adulthood.

Le brain-derived neurotrophic factor (BDNF) est une protéine de la famille des neurotrophines ayant été initialement découverte au système nerveux central, où elle est impliquée dans la mémoire et l‘apprentissage par la régulation de la croissance et de la survie neuronale. Les effets du BDNF sont médiés par le tropomyosin receptor kinase B (TrkB) et le récepteur pan-neurotrophique de 75 kDa (p75NTR). Le BDNF est le résultat du clivage d’une protéine précurseur, le proBDNF, laquelle a plutôt des effets pro-apoptotiques sur les neurones. Malgré sa découverte au cerveau, le BDNF est retrouvé en concentrations beaucoup plus importantes dans la circulation sanguine, où il est majoritairement contenu dans les plaquettes. Il est rapporté que ces cellules peuvent contenir des concentrations de BDNF allant de 100 à 1000 fois celles retrouvées au cerveau et que celles-ci peuvent être altérées par certaines maladies neurologiques. Malgré les importantes concentrations de BDNF qu’elles contiennent, très peu d’études ont investigué la présence du proBDNF ainsi que des récepteurs TrkB et p75NTR dans les plaquettes. Dans ces études, l’identification de ces protéines au niveau plaquettaire ne représentait pas un objectif primaire et les résultats obtenus ne sont souvent pas présentés. Jusqu’à présent, le proBDNF et les récepteurs TrkB et p75NTR n’ont pas été répertoriés dans les plaquettes. L’objectif principal de ce mémoire était d’investiguer la présence du proBDNF ainsi que des récepteurs TrkB et p75NTR dans les plaquettes de volontaires sains humains et de caractériser ces protéines dans le cas où elles seraient présentes. Les résultats obtenus suggèrent que les plaquettes expriment chacune de ces trois protéines, mais que les isoformes retrouvées au niveau plaquettaire diffèrent de celles retrouvées au cerveau. Les résultats proposent également que ces différences ne résident pas dans le profil de N-glycosylation des protéines. L’identité exacte des protéines étudiées n’a pas pu être confirmée par séquençage et leur nature demeure donc à confirmer. La présence plaquettaire du proBDNF et des récepteurs TrkB et p75NTR pourrait s’avérer intéressante au niveau des biomarqueurs périphériques de certaines maladies neuronales et psychiatriques. Leur présence pourrait aussi permettre la progression des connaissances dans le domaine de la biologie plaquettaire. / The brain-derived neurotrophic factor (BDNF) is a protein that was initially identified in the central nervous system, where it is involved in learning and memory by promoting neuronal growth and survival. These effects of BDNF are mediated through its binding to the tropomyosin receptor kinase B (TrkB) and the 75 kDa pan-neurotrophic receptor (p75NTR). Mature BDNF results from the cleavage of its precursor protein proBDNF, which rather has a proapoptotic effect on neurons. While discovered in the brain, BDNF is found in much higher abundance in the blood circulation, where it is mostly contained within platelets. It has been shown that BDNF concentration in platelets can reach up to 1000 times those of the brain, and that peripheral BDNF levels are altered in certain neurological and psychiatric diseases. Despite these important BDNF concentrations in platelets, very few studies assessed the presence of proBDNF, TrkB and p75NTR in these cells. Furthermore, identification of these proteins in platelets was not a main objective of the studies that did assess that question. Consequently, methodology is not always described, and the results are mostly reported as data not shown. Until now, proBDNF, TrkB and p75NTR have not been reported in platelets. The main objective of this master’s thesis was to investigate the presence of proBDNF as well as receptors TrkB and p75NTR in healthy human platelets, and to characterize them if they were found in these cells. The results suggest that platelets express all three proteins, but that the isoforms found in platelets differ from the ones found in the brain. Also, the results show that these differences are not explained by differential N-glycosylation patterns. The identity of the proteins of interest could not be verified by protein sequencing, and their exact nature is yet to be confirmed. The presence of proBDNF as well as the TrkB and p75NTR receptors in platelets could be of interest in the search of peripheral biomarkers for neurological diseases. In addition, presence of these proteins at the platelet level could pave the way for further studies investigating their functions in platelets, and possibly result in advances in our knowledge of platelet biology.

No description available.

No description available.

Ketamine is a non-competitive N-methyl-D-aspartate (NMDA)-channel blocker that has recently shown promise in the treatment of major depressive disorder, distinguishing itself from classical anti-depressants through its rapid and lasting effects when given at sub-anaesthetic doses. Animal models of depression are commonly used to research individual mechanisms of action and this literature review aimed to investigate how ketamine influences BDNF-TrkB neurotransmission in the hippocampus and prefrontal cortex within animal models of depression. Reduced levels of BDNF and TrkB-transmission, as well as downstream signalling, are common in both humans experiencing depression and in rodent models of depression, and ketamine was found to counteract this reduction in the majority of studies reviewed. In the majority of studies ketamine’s anti-depressant actions were viewed to be at least partially connected to its effects on BDNF-TrkB neurotransmission. This was supported by the anti-depressant effects being readily blocked by pharmacological inhibition of TrkB. Inhibition also blocked the downstream neurobiological changes associated with ketamines anti-depressant effects. / Ketamin är en icke-kompetitiv N-methyl-D-aspartate (NMDA)-kanal antagonist som nyligen har visat lovande resultat i behandling av depression. Substansen särskiljer sig från klassiska antidepressiva läkemedel genom att dess effekt infinner sig snabbt och kvarstår under en längre period om det ges i låga doser. Djurmodeller av depression används för att undersöka individuella mekanismer relaterade till depression och denna litteraturstudie ämnade att undersöka hur ketamin påverkar BDNF-TrkB signallering inom hippocampus och prefrontala cortex i djurmodeller av depression. Minskade nivåer av BDNF och TrkB-signalering är vanligt förekommande både hos männsikor med depression och i djurmodeller av depression. I majoriteten av studierna återställde ketamin nivåerna av BDNF och TrkB-signalering till normala värden. Dess antidepressiva effekt kopplades till denna signalväg eftersom farmakologisk inhibering av TrkB i majoriteten av studierna resulterade i att den anti-depressiva effekten uteblev. Inhiberingen blockerade även nedströms neurobiologiska förändringar som anses kopplade till ketamins antidepressiva effekter.