The electron-electron coincidence (e,2e) technique yields complete kinematical information about the electron impact ionization process. The (e,2e) technique has been widely used to study dynamical effects in ionizing collisions with atomic targets, however studies of molecular ionization using this technique have been very limited. Recently further experimental studies of small molecules have been proposed, as the cross sections of small molecules are now computable using sophisticated theoretical approaches [77, 24]. This thesis presents dynamical investigations for the electron impact ionization of the molecular targets H2O and H2, employing the (e,2e) technique to experimentally measure the triple differential cross section (TDCS). The TDCS is defined as the probability that a bound electron will be ejected from the target atom or molecule (into a particular direction with a defined energy) and the initial electron will be scattered into a particular direction with a particular energy. All TDCSs presented within this thesis were performed using an electron coincidence spectrometer in the coplanar asymmetric geometry at intermediate incident electron energies. This thesis presents the electron impact ionization TDCSs of H2O. A series of measurements were performed using H2O in the vapour form. Measurements of the TDCS are presented for the 2a1 atomic-like orbital and the 1b2, 3a1 and 1b1 molecular orbitals at a common incident electron energy of 250eV, ejected electron energy of 10eV and scattering angle of -15o. The experimental TDCSs are compared with theoretical cross sections that were calculated by Champion et al [25, 26] using a distorted wave Born approach (DWBA). TDCS measurements for the single ionization of the hydrogen molecule, H2 were performed as in recent years there has been evidence that indicates the ejected electron angular distribution is perturbed due to Young-type interference effects. The oscillatory structure which is predicted in the cross section is due to the two-centred nature of the molecule [27, 29]. This thesis presents experimental TDCSs for the ionization of H2 which are compared to TDCSs of helium. A series of measurements for the TDCSs of H2 and He are presented at a common incident electron energy of 250eV and scattering angle of -15o, for a range of ejected electron energies between 10eV and 100eV. The experimental TDCSs are compared with two types of theoretical calculations.

No description available.

TDCS is a form of non-invasive neurostimulation that is comprised of injection of current via strategically placed scalp electrodes into targeted areas of the brain. TDCS has shown therapeutic benefit for numerous clinical applications. This technique has not however been widely adopted due to high variability of response to the stimulation. Current state of the art methods for optimizing tDCS are based on FEM models that generally model tissue as isotropic and homogeneous and do not take into account inter subject variability of head tissue electrical properties. We therefore develop an in-vivo method of measuring and analyzing bioimpedance spectroscopy measurements of the head to estimate change to tDCS dose in neural tissues for different subjects. Finite element simulations are implemented on a realistic MRI derived head model. 5\% random Gaussian noise is added. Experimental bioimpedance measurements are taken of the heads of 8 subjects. We simulate sensitivity distribution and impedance for a variety of 2 and 4 electrode configurations over a wide frequency range. We also extract Cole parameters and implement PCA on simulated and experimental impedance. We demonstrate that the Cole model of the head can be accurately approximated by the sum in series of Cole systems of each tissue. Comparison of Cole parameters from various simulated electrode configurations show statistical differences (paired t test $p<.05$). PCA shows that close to 100\% of the variance between two impedance spectra is described along a single principal component. Variation described by the second principal component increases as a function of increasing inter electrode gap which may be related to changes in dose. FEM and experimentally derived Cole parameters show different trends for various electrode configurations, good agreement is however shown for the PCA results. The outcome of this research may lead to a higher tDCS efficacy by improving standardization and control of stimulation by relation of dose and bioimpedance spectra characteristics.

Introdução: Os opioides são os analgésicos mais efetivos para tratamento da dor moderada a intensa. No entanto, evidências crescentes têm demonstrado que seu uso pode levar a mudanças na sensibilidade dolorosa. Nesse contexto, a hiperalgesia induzida pelo remifentanil (r-IH) envolve um desequilíbrio nos sistemas inibitórios e excitatórios. Postula-se que um dos mecanismos centrais seja a disfunção do sistema modulador descendente da dor. Então, neste estudo, testamos a hipótese de que a estimulação transcraniana de corrente contínua (ETCC), devido aos seus efeitos analgésicos, poderia prevenir a r-IH. Os desfechos primários incluíram a escala numérica de dor (END 0-10) durante o teste repetitivo ao frio (rCOLDT), e a alteração na END (0-10) durante o teste de modulação condicionada de dor (CPM-TASK). Os desfechos secundários foram os limiares de dor ao calor (HPT) e o tempo de reação durante o teste de dor à água gelada [zero graus oC, (IPT)]. Métodos: Ensaio clínico randomizado, fatorial, duplo cego, que incluiu 48 homens saudáveis, com idades entre 19 e 40 anos. Os sujeitos foram randomizados em quatro grupos (n=12): ativo (a) - ETCC / solução salina, Sham (s) - ETCC / solução salina, a-ETCC / remifentanil e s-ETCC / remifentanil. Foi aplicado o ETCC sobre o córtex motor primário, com uma sessão única de 20 min e 2 mA. Resultados: Durante o rCOLDT, houve um efeito significativo entre os grupos nos escores cumulativos da END (P = 0,01). O grupo s-ETCC / remifentanil apresentou maiores escores de dor durante rCOLDT, [media (SD) 5,49 (1,04)] e a-ETCC / remifentanil apresentaram escores relativamente menores [4,15 (1,62)]. Este achado mostra que o efeito da ETCC bloqueou a HI-R. Os grupos a-ETCC / solução salina e s-ETCC / salina apresentaram menor índice de dor durante rCOLDT, [3.11 (1.2)] e [3.15 (1.62)], respectivamente. A incidência de hiperalgesia definida como um aumento de 15% na END durante o rCOLDT foi de: 31% no grupo s-ETCC/remifentanil; 22% no grupo a-ETCC/remifentanil; 11% no grupo a-ETCC/salina; e 8.3% no grupo s-ETCC/salina. Os grupos com remifentanil apresentaram escore positivo na END (0-10) durante a tarefa CPM, ou seja, produziu um desengate do sistema modulador descendente de dor (DPMS). Além disso, s-ETCC / Remifentanil em comparação com a-ETCC/remifentanil apresentou menor HPT e maior tempo de reação durante o IPT. Conclusão: Esses achados sugerem que os efeitos da a-ETCC previne a disfunção da capacidade inibitória do sistema modulador descendente da dor induzido pelo remifentanil durante o rCOLDT. / Background: Opioids are the most effective analgesics to treat moderate to severe pain. However, growing evidence shows that opioids can elicit unexpected changes in pain sensitivity. In this sense, remifentanil-induced hyperalgesia (r-IH) involves an imbalance in the inhibitory and excitatory systems. It postulates that one of the central mechanisms is the dysfunction of the descending pain modulating system. We tested the hypothesis that transcranial Direct Current Stimulation (t-DCS), given its analgesics effects, could prevent r-IH. The primary outcomes included the Numerical Pain Score NPS (0-10) during the repetitive cold test (rCOLDT) and the change on the NPS (0-10) during the conditioned pain modulation (CPM)-task. The secondary outcomes were the heat pain threshold (HPT) and the reaction-time during the Ice-Water Pain Test (IPT). Methods: This double blinded, explanatory factorial randomized trial included 48 healthy males, ages ranging 19 to 40 years. They were randomized into four equal groups: active (a)-tDCS/saline, sham (s)-tDCS/saline, a-tDCS/remifentanil and s-tDCS/remifentanil. We applied tDCS over the primary motor-cortex, with a single session of 20 minutes and 2mA. Results: During the rCOLDT, there was a significant group effect on the cumulative NPS scores (P=0.01). The s-tDCS/remifentanil group presented larger pain scores during rCOLDT, [mean (SD) 5.49 (1.04)] and a-tDCS/remifentanil group had relative lower pain scores [4.15 (1.62)]; showing its blocking effect on r-IH. a-tDCS/saline and s-tDCS/saline groups showed lowest pain scores during rCOLDT, [3.11(1.2)] and [3.15(1.62)], respectively. The incidence of hyperalgesia defined as a 15% increase in NPS during rCOLDT was: 30.3% in the s-tDCS / remifentanil group; 22% in the a-tDCS / remifentanil group; 11% in the a- tDCS / saline group; 8.3% in the s-tDCS / saline group. Remifentanil groups showed positive scores in the NPS (0-10) during the CPM-task, that is, it produced a disengagement of the descending pain modulatory system (DPMS). Also, s- tDCS/Remifentanil compared to a-tDCS/Remifentanil showed lower HPT and larger reaction-time during the IPT. Conclusion: These findings suggest that the effects of a-tDCS prevents the dysfunction of the inhibitory capacity of the descending modulatory pain system induced by remifentanil during rCOLDT.

Introdução: Os sintomas psíquicos e vasomotores são altamente prevalentes na transição menopáusica e na pós-menopausa, e estão relacionados ao hipoestrogenismo decorrente da falência ovariana que ocorre na mulher na meiaidade. Sua exata fisiopatogenia é desconhecida, porém alterações de neurotransmissores, como a serotonina e a noradrenalina, parecem estar relacionados ao aparecimento dessa sintomatologia. A terapia estrogênica geralmente é efetiva em aliviar esses sintomas, no entanto muitas mulheres não podem ou não desejam este tipo de tratamento, por isso, diversas alternativas têm sido estudadas. Objetivos: esta tese teve como objetivo avaliar, em um modelo experimental de climatério em ratas, parâmetros fisiológicos, comportamentais e bioquímicos, visando testar duas novas terapias: a cetamina, um antagonista não competitivo do receptor N-metil-D-aspartato (NMDA) e a eletroestimulação transcraniana de corrente contínua (ETCC) respectivamente, para o comportamento do tipo depressivo e a disfunção termorregulatória. Métodos: Ratos Wistar fêmeas adultas (200 a 250 g) foram randomizadas pelo peso e submetidas a modelo de menopausa por meio de ovariectomia bilateral ou a procedimento sham (falsa cirurgia). No primeiro experimento, os animais foram submetidos ao teste do nado forçado para avaliar comportamento do tipo depressivo e posteriormente receberam uma dose de cetamina 10mg/kg de peso intraperitoneal. No segundo experimento, os animais foram avaliados quanto à disfunção termorregulatória e tratados com ETCC catódica. Resultados: No primeiro experimento, as ratas em estado hipoestrogênico apresentaram comportamento do tipo depressivo que foi revertido pela cetamina. As ratas sham apresentaram um quadro de menopausa precoce indexado por citologia vaginal, provavelmente decorrente da manipulação de anexos. Além disso, as ratas ovariectomizadas apresentaram comportamento tipo ansioso. No entanto, não houve alteração da atividade locomotora e exploratória entre os grupos. No segundo experimento, as ratas ovariectomizadas apresentaram aumento da temperatura retal que foi parcialmente revertido pela eletroestimulação transcraniana de corrente contínua; as ratas ovariectomizadas apresentaram níveis elevados de interleucina 8 no soro, em relação às não ovariectomizadas, sem diferença nos níveis hipotalâmicos; houve aumento dos níveis séricos e diminuição dos níveis hipotalâmicos de BDNF nas ratas ovariectomizadas e interação do modelo com a ETCC em relação aos níveis corticais de BDNF. Nos testes nociceptivos, as ratas ovariectomizadas apresentaram diminuição do tempo de latência de resposta no teste da placa quente e alodinia mecânica no teste Von Frey, parcialmente revertida pela ETCC, no entanto, não houve diferença entre os grupos no teste tail flick. Conclusão: Nossos estudos demonstram que o modelo de ovariectomia utilizado foi eficaz em reproduzir os sintomas apresentados no período perimenopausa tendo, portanto, potencial translacional. Adicionalmente, sugerem que, além dos sistemas serotoninérgico e noradrenérgico, outros sistemas parecem estar associados ao aparecimento de sintomas na transição menopáusica como, por exemplo, o sistema glutamatérgico. Demonstram ainda que a cetamina e a ETCC podem ser eficazes como adjuvantes no tratamento dos sintomas do climatério, respectivamente, farmacológico (nos sintomas depressivos) e não farmacológico (nos “fogachos”). / Introduction: Psychological and vasomotor symptoms have a high prevalence in women during menopause transition and post menopausal years. Though these symptoms are associated to decline of estrogen levels due to ovarian failure, their exact pathophysiology is unknown. Variations on neurotransmitters such as serotonin and norepinephrine seem to be responsible by great amount of these symptoms. Estrogen therapy is usually effective in relieving these symptoms. However, many women have contraindications or do not wish to use this kind of treatment, thus several therapeutic alternatives have been studied. Objectives: This thesis was designed to evaluate, in an experimental model of menopause in rats, physiological, behavioral and biochemical parameters, aiming to test two new therapies: ketamine, a noncompetitive antagonist of the N-methyl-D-aspartate (NMDA) receptor and transcranial direct current stimulation (tDCS) respectively for the depressive-like behavior and thermoregulatory dysfunction. Methods: Female adult Wistar rats (200- 250g) were randomized by weight and subjected to a menopause model through bilateral ovariectomy or sham (false surgery) procedure. In the first experiment, the animals were subjected to the forced swimming test to assess depressive-like behavior and subsequently received a dose of 10mg/kg of weight of intraperitoneal ketamine. In the second experiment, the animals were evaluated for thermoregulatory dysfunction and treated with cathodal tDCS. Results: In the first experiment, the rats in hypoestrogenic state showed depressive-like behavior that was reversed by ketamine. The sham rats presented a precocious menopause indexed by vaginal cytology, probably due to the surgical handling of the tubes and ovaries. Moreover, the ovariectomized rats showed anxiety-like behavior. However, there was no change in locomotor activity between groups. In the second experiment, the ovariectomized rats showed an increase in rectal temperature that was partially reversed by tDCS. Moreover, the ovariectomized rats showed elevated serum levels of interleukin-8, compared to non-ovariectomized rats, with no difference in hypothalamic levels; there was an increase in serum levels and decreased hypothalamic BDNF levels in ovariectomized rats, and there was interaction of ovariectomy and ETCC in relation to cortical BDNF levels. In the nociceptive tests, the ovariectomized rats presented decreased response latency in the hot plate test and mechanical alodinia in the von Frey test; however, there was no difference between groups in the tail flick test. Conclusion: Our studies demonstrate that the ovariectomy model used was effective in reproducing the symptoms that women present during perimenopause and therefore has translational potential. Additionally, these data suggest that, beyond the serotonergic and noradrenergic systems, other systems seem to be associated with the onset of symptoms in menopausal transition such as the glutamatergic system. Our data also demonstrate that ketamine and ETCC can be effective adjuvant therapeutic tools to the relief of climacteric symptoms, respectively, pharmacological (on depressive symptoms) and non pharmacological (on "hot flashes").

abstract: Transcranial electrical stimulation (tES) is a non-invasive brain stimulation therapy that has shown potential in improving motor, physiological and cognitive functions in healthy and diseased population. Typical tES procedures involve application of weak current (< 2 mA) to the brain via a pair of large electrodes placed on the scalp. While the therapeutic benefits of tES are promising, the efficacy of tES treatments is limited by the knowledge of how current travels in the brain. It has been assumed that the current density and electric fields are the largest, and thus have the most effect, in brain structures nearby the electrodes. Recent studies using finite element modeling (FEM) have suggested that current patterns in the brain are diffuse and not concentrated in any particular brain structure. Although current flow modeling is useful means of informing tES target optimization, few studies have validated tES FEM models against experimental measurements. MREIT-CDI can be used to recover magnetic flux density caused by current flow in a conducting object. This dissertation reports the first comparisons between experimental data from in-vivo human MREIT-CDI during tES and results from tES FEM using head models derived from the same subjects. First, tES FEM pipelines were verified by confirming FEM predictions agreed with analytic results at the mesh sizes used and that a sufficiently large head extent was modeled to approximate results on human subjects. Second, models were used to predict magnetic flux density, and predicted and MREIT-CDI results were compared to validate and refine modeling outcomes. Finally, models were used to investigate inter-subject variability and biological side effects reported by tES subjects. The study demonstrated good agreements in patterns between magnetic flux distributions from experimental and simulation data. However, the discrepancy in scales between simulation and experimental data suggested that tissue conductivities typically used in tES FEM might be incorrect, and thus performing in-vivo conductivity measurements in humans is desirable. Overall, in-vivo MREIT-CDI in human heads has been established as a validation tool for tES predictions and to study the underlying mechanisms of tES therapies. / Dissertation/Thesis / Doctoral Dissertation Biomedical Engineering 2017

Introdução: Os opioides são os analgésicos mais efetivos para tratamento da dor moderada a intensa. No entanto, evidências crescentes têm demonstrado que seu uso pode levar a mudanças na sensibilidade dolorosa. Nesse contexto, a hiperalgesia induzida pelo remifentanil (r-IH) envolve um desequilíbrio nos sistemas inibitórios e excitatórios. Postula-se que um dos mecanismos centrais seja a disfunção do sistema modulador descendente da dor. Então, neste estudo, testamos a hipótese de que a estimulação transcraniana de corrente contínua (ETCC), devido aos seus efeitos analgésicos, poderia prevenir a r-IH. Os desfechos primários incluíram a escala numérica de dor (END 0-10) durante o teste repetitivo ao frio (rCOLDT), e a alteração na END (0-10) durante o teste de modulação condicionada de dor (CPM-TASK). Os desfechos secundários foram os limiares de dor ao calor (HPT) e o tempo de reação durante o teste de dor à água gelada [zero graus oC, (IPT)]. Métodos: Ensaio clínico randomizado, fatorial, duplo cego, que incluiu 48 homens saudáveis, com idades entre 19 e 40 anos. Os sujeitos foram randomizados em quatro grupos (n=12): ativo (a) - ETCC / solução salina, Sham (s) - ETCC / solução salina, a-ETCC / remifentanil e s-ETCC / remifentanil. Foi aplicado o ETCC sobre o córtex motor primário, com uma sessão única de 20 min e 2 mA. Resultados: Durante o rCOLDT, houve um efeito significativo entre os grupos nos escores cumulativos da END (P = 0,01). O grupo s-ETCC / remifentanil apresentou maiores escores de dor durante rCOLDT, [media (SD) 5,49 (1,04)] e a-ETCC / remifentanil apresentaram escores relativamente menores [4,15 (1,62)]. Este achado mostra que o efeito da ETCC bloqueou a HI-R. Os grupos a-ETCC / solução salina e s-ETCC / salina apresentaram menor índice de dor durante rCOLDT, [3.11 (1.2)] e [3.15 (1.62)], respectivamente. A incidência de hiperalgesia definida como um aumento de 15% na END durante o rCOLDT foi de: 31% no grupo s-ETCC/remifentanil; 22% no grupo a-ETCC/remifentanil; 11% no grupo a-ETCC/salina; e 8.3% no grupo s-ETCC/salina. Os grupos com remifentanil apresentaram escore positivo na END (0-10) durante a tarefa CPM, ou seja, produziu um desengate do sistema modulador descendente de dor (DPMS). Além disso, s-ETCC / Remifentanil em comparação com a-ETCC/remifentanil apresentou menor HPT e maior tempo de reação durante o IPT. Conclusão: Esses achados sugerem que os efeitos da a-ETCC previne a disfunção da capacidade inibitória do sistema modulador descendente da dor induzido pelo remifentanil durante o rCOLDT. / Background: Opioids are the most effective analgesics to treat moderate to severe pain. However, growing evidence shows that opioids can elicit unexpected changes in pain sensitivity. In this sense, remifentanil-induced hyperalgesia (r-IH) involves an imbalance in the inhibitory and excitatory systems. It postulates that one of the central mechanisms is the dysfunction of the descending pain modulating system. We tested the hypothesis that transcranial Direct Current Stimulation (t-DCS), given its analgesics effects, could prevent r-IH. The primary outcomes included the Numerical Pain Score NPS (0-10) during the repetitive cold test (rCOLDT) and the change on the NPS (0-10) during the conditioned pain modulation (CPM)-task. The secondary outcomes were the heat pain threshold (HPT) and the reaction-time during the Ice-Water Pain Test (IPT). Methods: This double blinded, explanatory factorial randomized trial included 48 healthy males, ages ranging 19 to 40 years. They were randomized into four equal groups: active (a)-tDCS/saline, sham (s)-tDCS/saline, a-tDCS/remifentanil and s-tDCS/remifentanil. We applied tDCS over the primary motor-cortex, with a single session of 20 minutes and 2mA. Results: During the rCOLDT, there was a significant group effect on the cumulative NPS scores (P=0.01). The s-tDCS/remifentanil group presented larger pain scores during rCOLDT, [mean (SD) 5.49 (1.04)] and a-tDCS/remifentanil group had relative lower pain scores [4.15 (1.62)]; showing its blocking effect on r-IH. a-tDCS/saline and s-tDCS/saline groups showed lowest pain scores during rCOLDT, [3.11(1.2)] and [3.15(1.62)], respectively. The incidence of hyperalgesia defined as a 15% increase in NPS during rCOLDT was: 30.3% in the s-tDCS / remifentanil group; 22% in the a-tDCS / remifentanil group; 11% in the a- tDCS / saline group; 8.3% in the s-tDCS / saline group. Remifentanil groups showed positive scores in the NPS (0-10) during the CPM-task, that is, it produced a disengagement of the descending pain modulatory system (DPMS). Also, s- tDCS/Remifentanil compared to a-tDCS/Remifentanil showed lower HPT and larger reaction-time during the IPT. Conclusion: These findings suggest that the effects of a-tDCS prevents the dysfunction of the inhibitory capacity of the descending modulatory pain system induced by remifentanil during rCOLDT.

Introdução: Os sintomas psíquicos e vasomotores são altamente prevalentes na transição menopáusica e na pós-menopausa, e estão relacionados ao hipoestrogenismo decorrente da falência ovariana que ocorre na mulher na meiaidade. Sua exata fisiopatogenia é desconhecida, porém alterações de neurotransmissores, como a serotonina e a noradrenalina, parecem estar relacionados ao aparecimento dessa sintomatologia. A terapia estrogênica geralmente é efetiva em aliviar esses sintomas, no entanto muitas mulheres não podem ou não desejam este tipo de tratamento, por isso, diversas alternativas têm sido estudadas. Objetivos: esta tese teve como objetivo avaliar, em um modelo experimental de climatério em ratas, parâmetros fisiológicos, comportamentais e bioquímicos, visando testar duas novas terapias: a cetamina, um antagonista não competitivo do receptor N-metil-D-aspartato (NMDA) e a eletroestimulação transcraniana de corrente contínua (ETCC) respectivamente, para o comportamento do tipo depressivo e a disfunção termorregulatória. Métodos: Ratos Wistar fêmeas adultas (200 a 250 g) foram randomizadas pelo peso e submetidas a modelo de menopausa por meio de ovariectomia bilateral ou a procedimento sham (falsa cirurgia). No primeiro experimento, os animais foram submetidos ao teste do nado forçado para avaliar comportamento do tipo depressivo e posteriormente receberam uma dose de cetamina 10mg/kg de peso intraperitoneal. No segundo experimento, os animais foram avaliados quanto à disfunção termorregulatória e tratados com ETCC catódica. Resultados: No primeiro experimento, as ratas em estado hipoestrogênico apresentaram comportamento do tipo depressivo que foi revertido pela cetamina. As ratas sham apresentaram um quadro de menopausa precoce indexado por citologia vaginal, provavelmente decorrente da manipulação de anexos. Além disso, as ratas ovariectomizadas apresentaram comportamento tipo ansioso. No entanto, não houve alteração da atividade locomotora e exploratória entre os grupos. No segundo experimento, as ratas ovariectomizadas apresentaram aumento da temperatura retal que foi parcialmente revertido pela eletroestimulação transcraniana de corrente contínua; as ratas ovariectomizadas apresentaram níveis elevados de interleucina 8 no soro, em relação às não ovariectomizadas, sem diferença nos níveis hipotalâmicos; houve aumento dos níveis séricos e diminuição dos níveis hipotalâmicos de BDNF nas ratas ovariectomizadas e interação do modelo com a ETCC em relação aos níveis corticais de BDNF. Nos testes nociceptivos, as ratas ovariectomizadas apresentaram diminuição do tempo de latência de resposta no teste da placa quente e alodinia mecânica no teste Von Frey, parcialmente revertida pela ETCC, no entanto, não houve diferença entre os grupos no teste tail flick. Conclusão: Nossos estudos demonstram que o modelo de ovariectomia utilizado foi eficaz em reproduzir os sintomas apresentados no período perimenopausa tendo, portanto, potencial translacional. Adicionalmente, sugerem que, além dos sistemas serotoninérgico e noradrenérgico, outros sistemas parecem estar associados ao aparecimento de sintomas na transição menopáusica como, por exemplo, o sistema glutamatérgico. Demonstram ainda que a cetamina e a ETCC podem ser eficazes como adjuvantes no tratamento dos sintomas do climatério, respectivamente, farmacológico (nos sintomas depressivos) e não farmacológico (nos “fogachos”). / Introduction: Psychological and vasomotor symptoms have a high prevalence in women during menopause transition and post menopausal years. Though these symptoms are associated to decline of estrogen levels due to ovarian failure, their exact pathophysiology is unknown. Variations on neurotransmitters such as serotonin and norepinephrine seem to be responsible by great amount of these symptoms. Estrogen therapy is usually effective in relieving these symptoms. However, many women have contraindications or do not wish to use this kind of treatment, thus several therapeutic alternatives have been studied. Objectives: This thesis was designed to evaluate, in an experimental model of menopause in rats, physiological, behavioral and biochemical parameters, aiming to test two new therapies: ketamine, a noncompetitive antagonist of the N-methyl-D-aspartate (NMDA) receptor and transcranial direct current stimulation (tDCS) respectively for the depressive-like behavior and thermoregulatory dysfunction. Methods: Female adult Wistar rats (200- 250g) were randomized by weight and subjected to a menopause model through bilateral ovariectomy or sham (false surgery) procedure. In the first experiment, the animals were subjected to the forced swimming test to assess depressive-like behavior and subsequently received a dose of 10mg/kg of weight of intraperitoneal ketamine. In the second experiment, the animals were evaluated for thermoregulatory dysfunction and treated with cathodal tDCS. Results: In the first experiment, the rats in hypoestrogenic state showed depressive-like behavior that was reversed by ketamine. The sham rats presented a precocious menopause indexed by vaginal cytology, probably due to the surgical handling of the tubes and ovaries. Moreover, the ovariectomized rats showed anxiety-like behavior. However, there was no change in locomotor activity between groups. In the second experiment, the ovariectomized rats showed an increase in rectal temperature that was partially reversed by tDCS. Moreover, the ovariectomized rats showed elevated serum levels of interleukin-8, compared to non-ovariectomized rats, with no difference in hypothalamic levels; there was an increase in serum levels and decreased hypothalamic BDNF levels in ovariectomized rats, and there was interaction of ovariectomy and ETCC in relation to cortical BDNF levels. In the nociceptive tests, the ovariectomized rats presented decreased response latency in the hot plate test and mechanical alodinia in the von Frey test; however, there was no difference between groups in the tail flick test. Conclusion: Our studies demonstrate that the ovariectomy model used was effective in reproducing the symptoms that women present during perimenopause and therefore has translational potential. Additionally, these data suggest that, beyond the serotonergic and noradrenergic systems, other systems seem to be associated with the onset of symptoms in menopausal transition such as the glutamatergic system. Our data also demonstrate that ketamine and ETCC can be effective adjuvant therapeutic tools to the relief of climacteric symptoms, respectively, pharmacological (on depressive symptoms) and non pharmacological (on "hot flashes").

Introdução: Os sintomas psíquicos e vasomotores são altamente prevalentes na transição menopáusica e na pós-menopausa, e estão relacionados ao hipoestrogenismo decorrente da falência ovariana que ocorre na mulher na meiaidade. Sua exata fisiopatogenia é desconhecida, porém alterações de neurotransmissores, como a serotonina e a noradrenalina, parecem estar relacionados ao aparecimento dessa sintomatologia. A terapia estrogênica geralmente é efetiva em aliviar esses sintomas, no entanto muitas mulheres não podem ou não desejam este tipo de tratamento, por isso, diversas alternativas têm sido estudadas. Objetivos: esta tese teve como objetivo avaliar, em um modelo experimental de climatério em ratas, parâmetros fisiológicos, comportamentais e bioquímicos, visando testar duas novas terapias: a cetamina, um antagonista não competitivo do receptor N-metil-D-aspartato (NMDA) e a eletroestimulação transcraniana de corrente contínua (ETCC) respectivamente, para o comportamento do tipo depressivo e a disfunção termorregulatória. Métodos: Ratos Wistar fêmeas adultas (200 a 250 g) foram randomizadas pelo peso e submetidas a modelo de menopausa por meio de ovariectomia bilateral ou a procedimento sham (falsa cirurgia). No primeiro experimento, os animais foram submetidos ao teste do nado forçado para avaliar comportamento do tipo depressivo e posteriormente receberam uma dose de cetamina 10mg/kg de peso intraperitoneal. No segundo experimento, os animais foram avaliados quanto à disfunção termorregulatória e tratados com ETCC catódica. Resultados: No primeiro experimento, as ratas em estado hipoestrogênico apresentaram comportamento do tipo depressivo que foi revertido pela cetamina. As ratas sham apresentaram um quadro de menopausa precoce indexado por citologia vaginal, provavelmente decorrente da manipulação de anexos. Além disso, as ratas ovariectomizadas apresentaram comportamento tipo ansioso. No entanto, não houve alteração da atividade locomotora e exploratória entre os grupos. No segundo experimento, as ratas ovariectomizadas apresentaram aumento da temperatura retal que foi parcialmente revertido pela eletroestimulação transcraniana de corrente contínua; as ratas ovariectomizadas apresentaram níveis elevados de interleucina 8 no soro, em relação às não ovariectomizadas, sem diferença nos níveis hipotalâmicos; houve aumento dos níveis séricos e diminuição dos níveis hipotalâmicos de BDNF nas ratas ovariectomizadas e interação do modelo com a ETCC em relação aos níveis corticais de BDNF. Nos testes nociceptivos, as ratas ovariectomizadas apresentaram diminuição do tempo de latência de resposta no teste da placa quente e alodinia mecânica no teste Von Frey, parcialmente revertida pela ETCC, no entanto, não houve diferença entre os grupos no teste tail flick. Conclusão: Nossos estudos demonstram que o modelo de ovariectomia utilizado foi eficaz em reproduzir os sintomas apresentados no período perimenopausa tendo, portanto, potencial translacional. Adicionalmente, sugerem que, além dos sistemas serotoninérgico e noradrenérgico, outros sistemas parecem estar associados ao aparecimento de sintomas na transição menopáusica como, por exemplo, o sistema glutamatérgico. Demonstram ainda que a cetamina e a ETCC podem ser eficazes como adjuvantes no tratamento dos sintomas do climatério, respectivamente, farmacológico (nos sintomas depressivos) e não farmacológico (nos “fogachos”). / Introduction: Psychological and vasomotor symptoms have a high prevalence in women during menopause transition and post menopausal years. Though these symptoms are associated to decline of estrogen levels due to ovarian failure, their exact pathophysiology is unknown. Variations on neurotransmitters such as serotonin and norepinephrine seem to be responsible by great amount of these symptoms. Estrogen therapy is usually effective in relieving these symptoms. However, many women have contraindications or do not wish to use this kind of treatment, thus several therapeutic alternatives have been studied. Objectives: This thesis was designed to evaluate, in an experimental model of menopause in rats, physiological, behavioral and biochemical parameters, aiming to test two new therapies: ketamine, a noncompetitive antagonist of the N-methyl-D-aspartate (NMDA) receptor and transcranial direct current stimulation (tDCS) respectively for the depressive-like behavior and thermoregulatory dysfunction. Methods: Female adult Wistar rats (200- 250g) were randomized by weight and subjected to a menopause model through bilateral ovariectomy or sham (false surgery) procedure. In the first experiment, the animals were subjected to the forced swimming test to assess depressive-like behavior and subsequently received a dose of 10mg/kg of weight of intraperitoneal ketamine. In the second experiment, the animals were evaluated for thermoregulatory dysfunction and treated with cathodal tDCS. Results: In the first experiment, the rats in hypoestrogenic state showed depressive-like behavior that was reversed by ketamine. The sham rats presented a precocious menopause indexed by vaginal cytology, probably due to the surgical handling of the tubes and ovaries. Moreover, the ovariectomized rats showed anxiety-like behavior. However, there was no change in locomotor activity between groups. In the second experiment, the ovariectomized rats showed an increase in rectal temperature that was partially reversed by tDCS. Moreover, the ovariectomized rats showed elevated serum levels of interleukin-8, compared to non-ovariectomized rats, with no difference in hypothalamic levels; there was an increase in serum levels and decreased hypothalamic BDNF levels in ovariectomized rats, and there was interaction of ovariectomy and ETCC in relation to cortical BDNF levels. In the nociceptive tests, the ovariectomized rats presented decreased response latency in the hot plate test and mechanical alodinia in the von Frey test; however, there was no difference between groups in the tail flick test. Conclusion: Our studies demonstrate that the ovariectomy model used was effective in reproducing the symptoms that women present during perimenopause and therefore has translational potential. Additionally, these data suggest that, beyond the serotonergic and noradrenergic systems, other systems seem to be associated with the onset of symptoms in menopausal transition such as the glutamatergic system. Our data also demonstrate that ketamine and ETCC can be effective adjuvant therapeutic tools to the relief of climacteric symptoms, respectively, pharmacological (on depressive symptoms) and non pharmacological (on "hot flashes").

Background: While pain is essential for physiological functioning, chronic or pathologic pain is responsible for a major burden of disease in society. Novel approaches to treating acute and chronic pain have employed neuromodulatory tools to target the central and peripheral neural structures that mediate pain. Transcranial direct current stimulation (tDCS), for example, is a safe, non-invasive brain stimulation technique that has been shown in preliminary studies to reduce chronic pain when applied to the primary motor cortex. In contrast to this exogenous neuromodulatory approach, diffuse noxious inhibitory controls (DNIC) refers to endogenous pain regulatory mechanisms that decrease pain following introduction of heterotopic noxious stimuli. This thesis explores whether combining these exogenous and endogenous pain modulation approaches synergistically increases the threshold at which pain is perceived. Methods: We conducted a double-blinded, randomized, placebo-controlled trial with a crossover design to investigate the effects of tDCS and DNIC on pain thresholds in 15 healthy human subjects. Pain thresholds were assessed prior to and following administration of active tDCS, sham tDCS, cold-water-induced DNIC, and combined active tDCS and DNIC. Using magnetic resonance spectroscopy, we examined whether baseline concentrations of brain metabolites such as N-acetylaspartate in pain-related regions of interest were associated with responses to the varying neuromodulatory conditions. Results: Pain thresholds significantly increased following both active tDCS and the DNIC paradigm. These modulatory approaches appeared to have additive effects when combined. Pain threshold increases after active tDCS were positively correlated with baseline levels of N-acetylaspartate, a marker of good neural function, in the anterior cingulate cortex and negatively correlated with baseline levels of glutamine in the thalamus. Conclusions: Combining endogenous pain regulatory mechanisms with exogenous stimulation of the motor cortex can more effectively increase pain thresholds in healthy humans. Future studies should examine whether existing pain therapies may be enhanced with noninvasive brain stimulation and activation of DNIC. They should also assess whether brain metabolite levels can be utilized to predict clinical response to therapeutic interventions.