Sex steroids in general and estrogens in particular – in addition to their effects on the reproductive organs – affect a large number of crucial bodily functions, including “higher” brain functions. Neuropeptides constitute the phylogenetically oldest neurotransmitter system and are currently thought to act mainly during stress, disease or injury. The concentration of galanin is i.a. up-regulated by injury to the nervous system and by estrogen. The main focus of the present thesis was to investigate whether the reported neuroprotective effect of 17β-estradiol in experimental animal stroke models is partially mediated through its effects on galanin and if galanin per se exerts neuroprotective effects in stroke. An exploratory study of the effects of sex steroid concentrations due to gender and pubertal development showed differences in concentrations of i.a. the neuropeptides galanin and neuropeptide Y also in brain regions of female rats important for higher brain functions, including hippocampus and cortex, brain regions not directly involved in reproduction. Puberty brings about changes in several hormonal mechanisms, and our studies showed that the major effect on the concentrations of galanin in various brain regions of ovariectomized (ovx) rats, was brought about by 17β-estradiol. The pathophysiological mechanisms involved in thrombolysis – the current treatment of choice in human stroke – attempts the re-establishment of perfusion (reperfusion) to the lesioned area of the brain. This prompted us to develop a reperfusion stroke model in rats designed to be mild, focal and transient, allowing long-term observation periods of animals thriving well postoperatively. Mortality and morbidity during and after the middle cerebral artery (MCA) occlusion are important confounding factors crucial for the results. Changing anaesthesia from intraperitoneally administered chloral hydrate to isofl urane inhalation anaesthesia using endotracheal intubation and controlled ventilation markedly reduced the mortality rate from 25% to 10.6%, which was even further reduced down to 2.7 % by successively improved surgical skills. Contrary to our initial hypothesis, long-term 17β-estradiol treatment resulted in larger ischemic lesions in our stroke model compared to control treatment. After 3 days the cerebral ischemic lesion area was doubled after 17β-estradiol treatment in rats subjected to 60 min microclip occlusion of the MCA followed by reperfusion. A similar, but not statistically signifi cant difference was found after 7 and 14 days. Three groups studying different types of experimental animal stroke and different doses of 17β-estradiol treatment have recently also demonstrated lack of neuroprotection by 17β-estradiol treatment. Furthermore, large epidemiological clinical studies have recently also reported an increased risk and poorer outcome in postmenopausal women subjected to hormone replacement therapy. The concentrations of galanin-like immunoreactivity in extracts of punch biopsies from the penumbra area after transient MCA occlusion were found unchanged, but were decreased (p=0.015) in the apparently undamaged ipsilateral hippocampus. Galanin administered by continuous intracerebroventricular infusion (2.4 nmol/day) resulted in a 30% larger ischemic lesion compared to controls, measured 7 days after the MCA occlusion. Taken together, these results indicate that galanin in the brain is primarily a factor reacting to ischemic injury rather than a neuroprotective factor in its own right. Very limited information is available about the steady state serum concentrations of 17β-estradiol in response to different modes of administration to rats for days and weeks. The need for this information has become especially apparent during recent years due to the observable dichotomy of estrogens effects – neuroprotective or not – in the various animal models of brain ischemia reported in the current scientific literature. The cause of this dichotomy is likely to be found in the experimental setup, including the mode of administration of 17β-estradiol. Delayed steady state of serum 17β-estradiol concentrations were found when comparing two common modes of exogenous administration of 17β-estradiol – slow-release osmotic pumps vs. daily subcutaneously injections of 17β-estradiol solved in sesame oil – to ovx rats during 2 times 6 weeks crossover treatment. Steady state was reached at week 4 in the daily injections group compared to at week 6 in the slow release osmotic pumps group. Once steady state was reached, the concentration was the same in both groups for the reminder of the experiment (in total 12 weeks). / On the day of the public defence of the doctoral thesis, the status of article V was: Available on line since 24th of May 2005.

The involvement of dopamine (DA) in the emotional and psychiatric disturbances associated with schizophrenia and psychomotor stimulant abuse is well known; however, the mechanism by which DA mediates fear expression and anxiety is not well defined. Accordingly, the objective of the present thesis was to determine the fear-motivational functions of DA neurons in the ventral tegmental area (VTA) and to examine the role of DA in fear extinction using the potentiated startle paradigm. In Experiment 1, it was observed that electrical stimulation of the VTA produced a pronounced increase in the amplitude of the acoustic startle reflex. In subsequent experiments fear-potentiated startle was assessed following axon-sparing N-methyl-D-aspartic acid (NMDA) lesions of the VTA and after bilateral intra-VTA infusion of the DA D_2/3 receptor agonist quinpirole (Experiments 2-4). The NMDA lesions resulted in substantial cell loss in the medial ventral tegmentum and blocked fear-potentiated startle. Similarly, inhibition of DA neuronal activity associated with locally-administered quinpirole suppressed the expression of the conditioned fear-induced increase in startle amplitudes. The quinpirole results implicate DA neuronal functioning in fear motivation. To explore further the involvement of DA in aversive emotional behavior, pharmacological experiments were conducted in which the effects of peripherally-administered DA agonist drugs on fear extinction were assessed. Subjects in Experiment 5 received an acute injection of either cocaine hydrochloride (40.0 mg/kg), d-amphetamine sulphate (5.0 mg/kg), the D_2/3 agonist quinpirole hydrochloride (5.0 mg/kg), or the D₁-type agonist SKF 38393 (5.0 mg/kg) during a single extinction session following fear acquisition. Animals treated with cocaine, d-amphetamine, and SKF 38393 exhibited fear-potentiated startle, whereas quinpirole treatment failed to alter fear extinction to the nonreinforced conditioned stimulus (CS). Also, it was revealed using a within-subjects design in Experiment 6 that cocaine administration reinstated fear-potentiated startle following extinction. Taken together, the results of the present experiments suggests fundamental role for DA and DA D₁ receptors in fear expression. It was proposed that VTA DA neurons gate levels of aversive emotional arousal within the amygdala-based fear system.

The long-term consequences of adolescent drug use in shaping a network primed for addiction is an issue of utmost importance. The use of cocaine during adolescent development could alter the normal growth of the reward system and affect the adult mesolimbic system, however, there is scant literature aimed at finding out if animals are more vulnerable to the adverse effects of drugs during adolescence. The present study investigated whether cocaine pretreatment in adolescent and adult rats produced differences in cocaine-induced neurochemical cross-sensitization to a naturally reinforcing substance in adulthood. To evaluate the responsivity of the mesolimbic system after repeated cocaine, sucrose was offered during the dialysis procedure and dialysate was collected. All saline pretreated rats had significant increases in DA levels compared to baseline levels and there were no difference in the age of pretreatment. Rats pretreated with cocaine as adults also had significant increases in DA levels after sucrose. Interestingly, sucrose intake significantly enhanced DA levels in cocaine pretreated adolescent rats. The results from this experiment clearly show that in rats pretreated with cocaine during adolescence there is an enhance response of the DAergic system in response to a naturally reinforcing substance therefore; cocaine exposure during adolescence results in persistent long term changes in the mesolimbic pathway. Future studies need to ascertain the underlying mechanisms and their role in the process of addiction.

The hydrophobic plasma membrane constitutes an indispensable barrier for cells in living animals. Albeit being pivotal for the maintenance of cells, the inability to cross the plasma membrane is still one of the major obstacles to overcome in order to progress current drug development. A group of substances, with restricted access to the interior of cells, which has shown great promise for future clinical use is oligonucleotides that are exploited to interfere with gene expression. Short interfering RNAs that are utilized to confer gene silencing and splice correcting oligonucleotides, applied for the manipulation of splicing patterns, are two classes of oligonucleotides that have been explored in this thesis. Cell-penetrating peptides (CPPs) are a class of peptides that has gained increasing focus in last years. This ensues as a result of their remarkable ability to convey various, otherwise impermeable, macromolecules across the plasma membrane of cells in a relatively non-toxic fashion. This thesis aims at further characterizing well-established, and newly designed, CPPs in terms of toxicity, delivery efficacy, and internalization mechanism. Our results demonstrate that different CPPs display different toxic profiles and that cargo conjugation alters the toxicity and uptake levels. Furthermore, we confirm the involvement of endocytosis in translocation of CPPs, and in particular the importance of macropinocytosis. All tested peptides facilitate the delivery of splice correcting oligonucleotides with varying efficacy, the newly designed CPP, M918, being the most potent. Finally we conclude that by promoting endosomolysis, by exploring new CPPs with improved endosomolytic properties, the biological response increases significantly. In conclusion, we believe that these results will facilitate the development of new CPPs with improved delivery properties that could be used for transportation of oligonucleotides in clinical settings.

Dissertation (PhD)--University of Stellenbosch, 2006. / Bibliography. Also available via the Internet.

Thesis (Ph.D.)--University of Alberta, 2009. / A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Neurochemistry, Department of Psychiatry. Title from pdf file main screen (viewed on October 23, 2009). Includes bibliographical references.

Thesis (Ph. D.)--Florida State University, 2004. / Advisor: Cathy W. Levenson, Florida State University, College of Human Sciences, Dept. of Nutrition, Food and Exercise Sciences. Title and description from dissertation home page (viewed Jan. 30, 2006). Document formatted into pages; contains viii, 94 pages. Includes bibliographical references.

Thesis (M.S.)--University of Alabama at Birmingham, 2009. / Title from PDF t.p. (viewed June 30, 2010). Additional advisors: Lori McMahon, Stephen Watts. Includes bibliographical references (p. 31-35).

Resumo: As aranhas do gênero Phoneutria (Aranae, Ctenidae) são comumente conhecidas como "aranha armadeira" ou "aranha da banana", devido à posição de ataque/defesa que elas assumem contra uma presa/competidor e devido sua alta incidência nas plantações de bananas. Estas aranhas são solitárias, errantes (não constroem teias), muito agressivas e responsáveis por muitos casos graves de acidentes por envenenamento e de morte registrados. Estas aranhas são amplamente distribuídas nas regiões temperadas da América do Sul, com várias espécies já descritas. A espécie Phoneutria nigriventer é mais comum nas regiões centroeste e sudeste do Brasil. Um grande número de neurotoxinas tem sido purificado de venenos de aranhas do gênero Phoneutria. No entanto, as neurotoxinas não - protéicas de baixa massa molecular precisam ser isoladas e caracterizadas estrutural e funcionalmente. Essas toxinas são de potencial interesse na neuroquímica como ferramentas para investigações do sistema nervoso. O objetivo do presente estudo foi a caracterização estrutural e funcional da "Nigriventrina", uma nova neurotoxina não-protéica de baixa massa molecular, isolada da fração hidrofílica do veneno da aranha Phoneutria nigriventer por (RPHPLC) sob gradiente de acetonitrila. A elucidação estrutural foi realizada com HRESIMS, ESI-MS, ESI-MS/MS e espectroscopia de Ressonância Magnética Nuclear 1D e 2D. A toxina apresentou massa molecular de 422Da (C12H14N4O13) e foi caracterizada como hidrazil-dioxopiperidina. A caracterização biológica foi realizada pela aplicação icv da Nigriventrina em cérebro de rato, seguido pelo acompanhamento da expressão da proteína Fos e dupla marcação imunoistoquímica. Todos os neurônios duplamente marcados foram associados ao receptor ionotrópico de glutamato NMDA (N-metil-D-aspartato), subtipo NMDA-NR1. A Nigriventrina apresentou afinidade... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The spiders of the genus Phoneutria (Aranae, Ctenidae) are commonly known as "armed spider" or "banana spider", because of the attack-defense position that they assume against a prey/competitor and their high incidence in banana plantations. These spiders are solitary, wandering (no web), very aggressive, responsible for many cases of severe envenomation and recorded mortality. These spiders are widely distributed in the warm regions of South America, and several species have been described. The Phoneutria nigriventer are the most common in central and south-eastern regions of Brazil. A large number of neurotoxins have been purified from the venoms of Phoneutria spiders. However, the non-proteic low molecular mass neurotoxins must be isolated and structural and functionally characterized. These toxins have an interesting potential in neurochemistry as tools for investigations of nervous system. The objective of the present study was the structural and functional characterization of "Nigriventrine", a novel non-proteic low molecular mass neurotoxin, isolated from the hydrophilic fraction of Phoneutria nigriventer spider venom by (RP-HPLC) under gradient of acetonitrile. The structural elucidation was carried out with HRESIMS, ESI-MS, ESI-MS/MS and Nuclear Magnetic Resonance 1D and 2D spectroscopy. The toxin presented molecular mass of 422Da (C12H14N4O13) and was characterized as hydroxyl-hydrazyl-dioxopiperidine. The biological characterization was performed by the i.c.v application of nigriventrine in rat brain, followed by the monitoring of the expression of Fos protein and doublelabeling immunohistochemistry. All doubly labeled neurons were associated to Nmethyl- D- aspartate/subtype of ionotropic glutamate receptor (NMDA-NR1). The nigriventrine presented affinity mainly to cortical regions, which are linked to perceptions and the voluntary muscles control of the animals... (Complete abstract click electronic access below) / Orientador: Mario Sergio Palma / Coorientador: Marta do Nascimento Cordeiro / Banca: Michael Richardson / Banca: Yara Curi / Banca: Claudio Francisco Tormena / Banca: Roberta Cornelio Ferreira Nocelli / Doutor

O anestésico cetamina, amplamente consumido por jovens frequentadores de clubs e raves, apresenta forte efeito dissociativo, sendo essa uma das razões para sua utilização. Apesar disso, pouco ainda se sabe sobre seus efeitos reforçadores assim como sobre o resultado da interrupção de seu consumo, após ingestão crônica. Ingerido continuamente, apresenta tolerância ao efeito sedativo. Com base em estudos pré-clínicos e clínicos anteriores que descrevem a capacidade da cetamina para induzir o relaxamento e euforia, apesar do seu efeito sedativo bem conhecido, que a hipótese de que a tolerância de cetamina, mesmo em doses mais elevadas, vai emergir, e será notado efeito de reforço da droga. Este estudo procurou determinar se os efeitos sedativos da cetamina podem ser condicionados à sugestão ambiental, como outras drogas de abuso. Avaliamos os efeitos de doses escalonadas de administração crônica de cetamina na reatividade motora e emocional de ratos. E investigamos a existência de tolerância condicionada induzida pelo contexto em ratos previamente tratados. A análise dos efeitos de cetamina sobre o comportamento motor e emocional foi realizada com o uso de um campo aberto (Monitor de atividade eletrônico). Os animais receberam por 14 dias uma única injeção diária de cetamina ou placebo em diferentes doses (10, 20, 40 e 80 mg / kg). Para o protocolo de preferência condicionada ao lugar, os animais foram submetidos a um baseline de três sessões seguidas com livre acesso a uma caixa de dois contextos, e foram condicionados no contexto que apresentou menor tempo de permanência por 4 dias por 1 hora, recebendo uma injeção diária de placebo ou cetamina (10, 20, 40 e 80 mg/kg), o teste foi realizado após o tratamento com ausência de droga para avaliação de reforço/aversão da droga emparelhada as pistas contextuais. Para o protocolo de tolerância condicionada os animais foram submetidos, durante 4 dias, a dose de cetamina ou placebo (10 mg/kg, 1x dia) e posteriormente testados, foram utilizadas duas câmaras visuais e tatilmente diferenciadas, sendo A câmara de condicionamento e B a câmara de teste. A análise sobre as alterações promovidas pela droga na reatividade comportamental dos animais foi realizada com a utilização de um campo aberto (monitor de atividade eletrônico) em diferentes contextos, após a administração de uma overdose (80 m/kg). Portanto os grupos experimentais se dividiram em A x A ou A x B. As alterações induzidas pela administração da dose de 10 mg/kg de cetamina nos sistemas serotoninérgico e dopaminérgico do córtex infra-límbico (IL) e núcleo accumbens shell (NAcSh), regiões encefálicas envolvidas nos aspectos motivacionais do uso e abuso de drogas, foram avaliadas com a utilização das técnicas de microdiálise in vivo e cromatografia de alta pressão. Todos os experimentos foram conduzidos com a anuência do CEUA (FFCLRPUSP, protocolo 16.5.736.59.1). Para análise dos dados foi utilizada a ANOVA de um ou dois fatores seguida, quando necessário, pelo teste de Tukey-HSD, com p estabelecido em <0,05. Os resultados indicam que semelhante a outras drogas de abuso, encontramos tolerância aumentada aos efeitos sedativos para cetamina induzidos por pistas contextuais. Além disso, o uso prolongado de cetamina aumenta o tempo gasto no centro do monitor de forma dependente da dose, uma medida bem conhecida de comportamento de baixa reatividade em roedores. Este aumento parece não ser devido aos efeitos sedativos da cetamina, uma vez que a imobilidade (tempo) diminuiu à medida que as doses aumentam nos grupos pré-tratados com cetamina. Além disso, a velocidade, a distância percorrida e a ambulação não diferem em relação ao grupo de placebo. Os resultados indicam também a existência de tolerância condicionada aos efeitos sedativos da cetamina sem prejuízo da resposta motora, assim como alterações significativas no tônus de dopamina e serotonina que se diferenciam se os animais são testados durante o efeito ou com 24 horas de abstinência. Em conclusão, nosso estudo aponta os efeitos antiaversivos de doses mais elevadas de cetamina. Este efeito parece ser acompanhado de tolerância farmacológica aos efeitos sedativos da cetamina que pode ajudar a explicar o uso de doses mais elevadas deste medicamento para propósitos recreativos em seres humanos. E dessa forma, a cetamina partilha algumas características comuns com outras drogas de abuso, como a instalação de tolerância condicionada ao contexto e alterações neuroquímicas associadas (depressão acentuada nos níveis de DA e 5-HT no NAcSh) durante a exposição a um contexto previamente pareado com os efeitos da droga. / The anesthetic ketamine, widely consumed by young club and rave people in, has a strong dissociative effect, which is one reason for its use. Despite this, little is known about its reinforcing effects as well as the result of discontinuation of its consumption after chronic ingestion. Ingested continuously shows tolerance to the sedative effect. Based on previous preclinical and clinical studies that describe the ability of ketamine to induce relaxation and euphoria, despite its well-known sedative effect, that the hypothesis that ketamine tolerance, even at higher doses, will emerge,and it will be noted strengthening effect of the drug. This study aimed to determine whether the sedative effects of ketamine can be conditioned to environmental cues such as other drugs of abuse. We evaluated the effects of staggered doses of chronic ketamine administration on the motor and emotional reactivity of rats. We also investigated the existence of context-induced conditioned tolerance in previously treated rats. The analysis of the effects of ketamine on motor and emotional behavior was performed with the use of an open field (e-activity monitor). The animals received a single daily injection of ketamine or placebo for 14 days at different doses (10, 20, 40 and 80 mg / kg). For the place-based preference protocol, the animals were submitted to a baseline of three consecutive sessions with free access to a box of two contexts, and were conditioned in the context that presented the shorter residence time for 4 days for 1 hour, receiving a Daily injection of placebo or ketamine (10, 20, 40, and 80 mg / kg), the test was performed after drug-free treatment for drug-boosted / aversion assessment paired with contextual clues. For the conditioned tolerance protocol the animals were submitted to a dose of ketamine or placebo (10 mg / kg, 1x day) for 4 days and then tested. Two visual and tactile differentiated chambers were used, the conditioning chamber and the test chamber. The analysis of the changes promoted by the drug in the behavioral reactivity of the animals was performed using an open field (electronic activity monitor) in different contexts, after the administration of an overdose (80 m / kg). Therefore the experimental groups were divided into A x A or A x B. The changes induced by administration of the 10 mg / kg ketamine dose in the infra-limbic (IL) and nucleus accumbens shell (NAcSh) serotonergic and dopaminergic systems, Encephalic regions involved in the motivational aspects of drug use and abuse were evaluated using in vivo microdialysis and high pressure chromatography techniques. All experiments were conducted with the consent of CEUA (FFCLRP-USP, protocol 16.5.736.59.1). For data analysis, one or two-factor ANOVA was used, followed when necessary by the Tukey-HSD test, with p established at <0.05. The results indicate that similar to other drugs of abuse, we found an increased tolerance to contextual clue-induced sedative effects for ketamine. In addition, prolonged use of ketamine increases the time spent in the center of the monitor in a dose-dependent manner, a well-known measure of low reactivity behavior in rodents. This increase does not appear to be due to the sedative effects of ketamine, since immobility (time) has decreased as doses increase in the ketamine pretreated groups. In addition, the speed, distance traveled and ambulation did not differ in relation to the placebo group. The results also indicate the existence of conditioned tolerance to the sedative effects of ketamine without impairment of the motor response, as well as significant alterations in the dopamine and serotonin tonus that differ if the animals are tested during the effect or with 24 hours of abstinence. In conclusion, our study points to the anti-aversive effects of higher doses of ketamine. This effect appears to be accompanied by pharmacological tolerance to the sedative effects of ketamine which may help explain the use of higher doses of this drug for recreational purposes in humans. In this way, ketamine shares some common characteristics with other drugs of abuse, such as the installation of context-dependent tolerance and associated neurochemical changes (marked depression in AD and 5-HT levels in NAcSh) during exposure to a previously paired context With the effects of the drug.