Este trabalho visa avançar o conhecimento sobre a interferência da nicotina no protocolo de treino forçado em gerbilos isquêmicos. Utilizamos 110 Gerbilos, distribuídos em 11 grupos. Grupo controle com animais ingênuos (C), falso operado (S) e isquêmicos (I). Grupos nicotina (CN, SN, SNE, IN e INE) e salina (CS, SS, IS) com ou sem treinamento. Os animais receberam uma injeção de 2mg/kg de nicotina ou salina durante 9 dias. Utilizamos uma esteira motorizada (treino contínuo, 5 dias, 5m/min por 15 minutos), um monitor de atividades e o Rota Rod. Os resultados foram analisados por uma ANOVA e pós teste de Holm-Sidak, p<0,05. Observamos aumento de apresentação de todos comportamentos no monitor de atividades, o CN maior do que os C, S, SS, SNE e INE, o SN maior do que o SNE, o I maior do que os C, S, SS, SNE, IS, INE e ainda, o IN maior do que os C, S, SS, SNE, IS e INE (cruzamento, F10,93 = 2,97), (distância, F10,93 = 2,79), (velocidade, F10,93 = 2,79) e (atividade, F10,93 = 2,81). No Rota Rod o CN apresentou maior tempo de permanência com relação aos outros grupos exceto SNE, já o SNE, em relação aos CS, S, SN, I, IN e o I menor tempo de permanência do que o C e INE (F10,93 = 3,35). Nos grupos I e IS observamos menor densidade de neurônios no hipocampo (F6,42 = 31,02), córtex motor M1 (F6,42 = 4,01) e estriado (F6,42 = 23,33). A nicotina não interferiu com a melhora do comportamento dos animais isquêmicos. / This work aims to advance the knowledge about the interference of nicotine in the forced training protocol in ischemic gerbils. We use 110 gerbils, distributed in 11 groups. Control (C), false operated (S) and ischemic (I). Nicotine groups (CN, SN, SNE, IN INE) and sham (CS, SS, SI) with or without training. The animals received an injection of 2mg/kg of nicotine or saline for 9 days. We use a treadmill (continuous training 5 days, 5m / min for 15 minutes), an activity monitor and the Rota Rod (RR). The results were analyzed by an ANOVA and post Holm-Sidak test, p <0.05. We observed increased in all behaviors in the activity monitor, increase of CN than C, S, SS and NSS INE, SN increase compared to NES, the I increase than C, S, SS, ENS, S, NSI and also the IN showed an increase compared to C, S, SS, SNE, SI and NSI (crossing, F10,93 = 2,97), (distance, F10,93 = 2,79), (speed, F10,93 = 2,79) and (activity, F10,93 = 2,81). In RR, CN showed an increase of time spent with the other groups except SNE, and an increase in the SNE, compared to the CS, S, SN, I, IN and I showed an decrease of time compared to C and INE (F10,93 = 3,35). In groups I and and IS we observed an decrease of neurons density in the hippocampus (F6,42 = 31,02), motor cortex M1 (F6,42 = 4,01) and striatum (F6,42 = 23,33). Nicotine did not interfere with the improvement of motor behavior in ischemic animals.

A rat model of novelty-seeking phenotype predicts vulnerability to nicotine relapse where locomotor reactivity to novelty is used to rank high (HR) versus low (LR) responders. This dissertation examines the neuropeptidergic and structural substrates of the expression of locomotor sensitization to a low dose nicotine challenge and associated social anxiety-like behavior following chronic intermittent nicotine exposure during adolescence in the LRHR phenotype. Data show the long-lasting nature of behavioral sensitization to nicotine and abstinence-related social anxiety-like behavior in nicotine pre-trained HRs compared to saline pre-trained controls. Moreover, this behavior is accompanied by an imbalance between the brain antistress/antianxiety, i.e., neuropeptide Y (NPY), and stress, i.e., corticotrophin releasing factor (CRF) systems in the amygdala. Moreover, a deficit in NPY signaling marked with decreased NPY and increased NPY Y2 receptor (Y2R) mRNA levels is observed in the hip pocampus, along with mossy fiber reorganization in nicotine pre-trained HRs. Furthermore, a Y2R antagonist administered 1 wk of abstinence reverses these behavioral, molecular and morphological effects in nicotine-exposed HRs. Additionally, the role of amygdalar synaptic plasticity in longlasting social withdrawal is also investigated by assessing brain-derived neurotrophic factor (BDNF) and spinophilin mRNA levels in HRs following a behaviorally-sensitizing nicotine regimen. A persistent increase in BDNF and spinophilin mRNA levels in the basolateral amygdala (BLA) is observed in nicotine pre-trained HRs even across a long (3-wk) abstinence spanning into young adulthood. This strongly suggests BDNFmediated long-lasting neuroplasticity within the BLA that may regulate abstinence-related negative affect in HRs. / Moreover, a cannabinoid receptor 1 (CB1R) antagonist, AM251 treatment during a short (1-wk) abstinence is ineffective in reversing social anxiety, nicotine-induced neuroplasticity and the neuropeptidergic changes in the amygdala, although it is effective in reversing the expression of locomotor sensitization to challenge nicotine even following a long (3-wks) abstinence. Furthermore, the identical AM251 treatment given during the late phase of a long (3-wk) abstinence further augments social withdrawal and associated BLA plasticity in nicotine pre-trained HRs. These findings implicate neuropeptidergic and neuroplastic changes in the hippocampus and the amygdala in vulnerability to the long-lasting behavioral effects of nicotine in the novelty-seeking phenotype. / by Cigdem Aydin. / Thesis (Ph.D.)--Florida Atlantic University, 2011. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2011. Mode of access: World Wide Web.

Severas altera¸c~oes no metabolismo energ´etico, no consumo de glicose e na sinaliza¸c~ao de insulina cerebral est~ao presentes na doen¸ca de Alzheimer (DA). O modelo animal da DA obtido pela administra¸c~ao intracerebroventricular de estreptozotocina (STZ-icv) em ratos induz um estado de resist^encia `a insulina no c´erebro associado `a disfun¸c~oes colin´ergicas e a d´eficits cognitivos, tornando-o um dos poucos modelos experimentais da forma espor´adica da DA. Este trabalho tem como objetivo caracterizar, neste modelo, as disfun¸c~oes sin´apticas na via hipocampo - c´ortex pr´e-frontal medial (CA1-CPFm) e testar se o tratamento com nicotina ´e capaz de prevenir as disfun¸c~oes sin´apticas e reverter os preju´?zos cognitivos induzido pelo STZ-icv. Para isso, ratos Wistar receberam STZ e foram submetidos a 20 dias de tratamento com nicotina. Dois dias depois, foram realizados nos animais teste de campo aberto e de reconhecimento de objeto. Em seguida os animais foram anestesiados com uretana para que os registros eletrofisiol´ogicos fossem realizados. Um eletrodo foi utilizado para estimular CA1 com pulso pareado e potenciais de campo p´os-sin´apticos (fPSP1) e sua facilita¸c~ao (fPSP2) foram registradas por um eletrodo no CPFm. Ap´os 30 minutos de linha de base, uma estimula¸c~ao em alta frequ^encia foi aplicada para induzir a potencia¸c~ao de longa dura¸c~ao (LTP), seguido de mais quatro horas de registro. Outro grupo experimental foi realizado para avaliar o efeito de longo prazo da STZ-icv e do tratamento com nicotina. Neste grupo, testes comportamentais e eletrofisiol´ogicos foram realizados 60 dias ap´os o fim do tratamento. Independentemente do tempo, os resultados indicam que a STZ produziu uma redu¸c~ao na indu¸c~ao e na manuten¸c~ao da LTP, mas a facilita¸c~ao por pulso pareado (PPF = fPSP2 / fPSP1) mostra que a STZ prejudica a plasticidade pr´e-sin´aptica apenas a curto prazo. O tratamento com nicotina atenua a disfun¸c~ao na LTP induzida pela STZ. Al´em disso, apenas o tratamento de nicotina tamb´em ´e capaz de reduzir a plasticidade pr´e-sin´aptica no grupo controle dois dias ap´os o fim do tratamento. Estes resultados tamb´em est~ao associados com os dados comportamentais, uma vez que a nicotina reverteu os d´eficits de mem´oria de reconhecimento nos animais STZ mas manteve o comportamento explorat´orio reduzido. Sugerimos com isso que o sistema colin´ergico, que desempenha um papel importante em fun¸c~oes cognitivas e na LTP, est´a afetado nos animais injetados com STZ e o tratamento cr^onico com nicotina consegue reduzir os danos na plasticidade sin´aptica e comportamentais, induzidos pela STZ. / Severe abnormalities in brain glucose/energy metabolism and insulin signaling have been documented to play an important role in early stage of alzheimer disease (AD) pathology. Intracerebroventricular administration (icv) of streptozotocin (STZ) in rats can induce an insulin-resistant brain state associated with cholinergic dysfunctions and memory impairments, which make it a suitable experimental model of the sporadic form of AD. The present work aimed to extend the characterization of this model by probing synaptic plasticity dysfunctions in the medial prefrontal cortex (mPFC)- hippocampal (CA1) pathway and test if nicotine can prevent synaptic dysfunction and revert cognitive impairment induced by icv STZ. Here, Wistar rats received bilateral microinjection of STZ and were submitted to 20 days of nicotine treatment. After 2 days of withdrawing the subjects were submitted to open field and object recognition tests. After that, animals were anesthetized with urethane for electrophysiological tests. A twisted bipolar electrode was used to stimulate posterior-dorsal hippocampus (CA1/subiculum) with paired-pulse. Basal field post-synaptic potentials (fPSP1) and facilitated responses (fPSP2) were recorded by a monopolar electrode in the medial mPFC. After 30min of baseline, high frequency stimulation was applied to induce long-term potentiation (LTP) and additional four hours of electrophysiological recordings was performed. Another experimental group was performed to evaluate the long term effect of both icv STZ and nicotine treatment. In this group behavioral and electrophysiological tests were performed with 60 days after chronic treatment. Independently of time, our results indicate that STZ produced a significant decrease in the induction and maintenance of LTP, but paired pulse facilitation (PPF = fPSP2/fPSP1) shows that only the short-term pre-synaptic plasticity was impaired after STZ injection. The nicotine treatment attenuates the STZ-induced LTP dysfunction in the CA1-mPFC pathway. However, just the nicotine treatment (in control group) can reduce pre-synaptic plasticity two days after chronic treatment. These results are also associated with behavioral data, since nicotine treatment reversed the deficits in recognition memory of STZ animals but maintained the reduced exploratory behavior. We suggest that the brain cholinergic system, which plays a role in cognition function and LTP, is affected in STZ injected animals and chronic treatment with nicotine can attenuate the STZ-induced synaptic plasticity and behavioral dysfunctions.

A hipertensão arterial é um problema de saúde pública no Brasil, pois aproximadamente 20 % da população adulta desenvolve hipertensão essencial, cujas causas ainda não são conhecidas. No entanto, sua gênese pode estar relacionada com disfunção nas áreas do sistema nervoso central (SNC) que regulam o sistema cardiovascular. O núcleo do trato solitário (NTS) e o bulbo ventrolateral são áreas importantes no controle neural da pressão arterial. Os receptores de adenosina A2a (rA2a) são encontrados em todo o SNC e estão relacionados com estudos terapêuticos de diversas doenças. No NTS a estimulação dos rA2a provoca ajustes pontuais em outros sistemas de neurotransmissão, além de diminuir a pressão arterial. A nicotina é uma molécula com uma vasta faixa de efeitos modulatórios em nosso organismo. Entre esses efeitos se destacam a capacidade de interagir com diversos sistemas de neurotransmissão nas áreas do bulbo relacionadas com a regulação da pressão arterial e de antecipar e/ou intensificar o desenvolvimento da hipertensão em sujeitos com pré-disposição genética. Desta forma, o objetivo do presente trabalho é avaliar o efeito modulatório da nicotina sobre o rA2a em cultura mista de neurônios e células gliais da porção dorso-medial do bulbo de ratos geneticamente hipertenso (SHR) e normotensos (WKY). Para isso, utilizaram-se técnicas como a de PCR em tempo real, Western Blotting e análise de ligação do receptor. Nossos resultados demonstraram que: 1) em condição basal células de ratos normotensos apresentam maior ligação do rA2a do que células de ratos hipertensos; 2) tratamento com nicotina resultou na diminuição da ligação do receptor em ambas as cepas, com um efeito de maior magnitude em células de ratos WKY; 3) nas duas linhagens o tratamento com nicotina alterou os níveis protéicos do rA2a, assim como o RNAm do receptor; 4) a linhagem e o tratamento separadamente, como a interação entre ambos influenciaram na expressão do RNAm , níveis protéicos e ligação do rA2a nas células dos ratos WKY e SHR. Por fim, os resultados apresentados aqui indicam que o rA2a em células de ratos hipertensos tem sua função deprimida em comparação com as células de ratos normotensos; e que a nicotina foi capaz de modular o funcionamento do rA2a, o qual pode influenciar no controle da pressão arterial. Esses dados são bastante interessantes, pois abrem novas perspectivas de análise dos mecanismos intracelulares envolvidos na modulação dos rA2a pela nicotina, assim como a importância desse sistema no desenvolvimento da hipertensão / Hypertension is one of the most common worldwide diseases afflicting humans. Because of the associated with morbidity and mortality and the cost to the society, it became an important public health challenge in Brazil. The mechanisms involved in development of hypertension still remain unclear However, hypertension can result from neuronal network imbalance in areas of the central nervous system that control blood pressure. The nucleus tractus solitarius (NTS) plays an important role in cardiovascular control. Within the NTS there are several neurotransmitters and neuromodulatory substances, such as adenosine, which acts on purinoreceptors A2a (A2ar). The A2ar modulates neurotransmission in the NTS and its activation may induce decrease in blood pressure by different mechanisms. Nicotine is a molecule that cross the blood-brain barrier and acts in several areas of central nervous system including the NTS. In this nucleus, nicotine is able to interact with some neurotransmitter systems and contributes for the development of hypertension in subjects with genetic predisposition to this disease. The goal of this study was to analyze the modulatory effects of nicotine on A2ar in cultured neurons and glial cells from medulla oblongata of normotensive (WKY) and spontaneously hypertensive rats (SHR). By means of real time PCR, Western Blotting and binding receptor assay. We have demonstrated that in basal condition cells of WKY presents increased binding of A2ar than the cells of SHR. Nicotine treatment induced a decrease in the binding of A2ar in both strains, however, this response was more pronounced in cells of WKY than SHR. Changes in mRNA and protein levels of A2ar was also observed in response to nicotine treatment. The strains and treatment separately, as well as the interaction between them influenced mRNA expression, protein level and binding of A2ar in NTS cells of WKY and SHR rats. Finally, these results show for the first time changes in A2ar mRNA expression, protein level and binding in cells from the medulla oblongata of WKY and SHR rats, as well as, the nicotine modulation upon this system, which might influence cardiovascular control. These data open up new approaches for the study of intracellular mechanisms involved in the modulation of adenosine A2a receptor by nicotine, as well as the importance of this interaction in the development of hypertension.

Parkinson’s Disease (PD) is a progressively debilitating neurodegenerative disease that affects the central nervous system and leads to severe difficulties with body movements. PD occurs due to the selective degeneration of neurons in the region of the brain known as the substantia nigra pars compacta. To date PD remains an incurable disease. Currently prescribed drugs provide only symptomatic relief to patients. Furthermore, they have considerable side effects and are often ineffective in the later stages of the disease or need to be used in combination in order to be effective. The role of neuroprotectants as a preventative measure in PD therapy is consequently receiving a great deal of attention and is being subjected to extensive research. This study sought to develop a novel prolonged-release drug delivery device for providing site-specific administration of newly researched neuroprotective agents. Nicotine was employed as the model neuroprotectant to incorporate in a novel reinforced crosslinked multiple-unit multi-polymeric drug delivery device. The study was the first of its kind to develop and employ the alkaloid for this purpose in a formulated delivery system. The device was intended to be one that provided zero-order prolonged release of the drug over a period of 1-2 months. The device was formulated such that its design was in keeping with the potential for implantation into the substantia nigra pars compacta to provide site-specific drug delivery. In order to do so, polymers, with biocompatible and bioerodable characteristics were selected to incorporate the drug within a reinforced crosslinked matrix. The study elucidated the mechanism of crosslinking of ionotropically crosslinked alginate spheres (gelispheres) with a variety of crosslinking agents through an evaluation of physicomechanical properties of the crosslinked system. The presence of barium in the crosslinked matrices generated densely networked gelispheres which retained their robustness following exposure to hydrating media and displayed promising potential for 4 entrapping drug molecules and retarding their release. The system was reinforced employing hydroxyethylcellulose (HEC) and polyacrylic acid (PAA). A Design of Experiments approach employing a Plackett-Burman screening design enabled optimisation of the proposed device in terms of reinforcing polymers (HEC and PAA) and crosslinking agents (barium and calcium). In order to further attenuate drug release rate the optimised crosslinked gelispheres were exposed to dilute hydrochloric acid (HCl) which significantly decreased gelisphere matrix swelling and erosion following exposure to simulated cerebrospinal fluid (CSF). These gelispheres were thereafter incorporated into a compressed release-rate modulating polymeric discs. Zero-order drug release was observed for a period of 50 days in simulated CSF when the optimised gelispheres were incorporated into compressed poly(lactic-co-glycolic) acid (PLGA) discs. Alternative approaches to modify drug release kinetics were also evaluated including the use of PLGA coatings on compressed hydroxypropylmethylcellulose-polyethylene oxide (HPMC-PEO) discs incorporating gelispheres and the use of crosslinked alginate-pectinate gelispheres as carrier systems to deliver PLGA-PLA (polylactic acid) microparticles incorporating drug. A Box-Behnken statistical design was employed to formulate and optimise the drug carrying PLGA-PLA microparticles. In both of the abovementioned cases we obtained sustained zeroorder drug release.

Environmental enrichment, for more than fifty years, has shown to increase learning in behaviors and to alter some brain structures (Renner and Rosenzweig). Some brain changes that occur when environmental enrichment is implemented include the following: increases in cortical thickness, especially the occipital cortex, increases in size of neuronal cell bodies, number of dendrites and dendritic spines, increases in astrocyte branching, increases in the number of brain blood capillaries, and increases in mitochondria (an indication of higher metabolic activity) (Stairs and Bard). It has been shown in research studies that rats in the environmental enrichment group are less sensitive to nicotine effects, both repeated and acute, than rats in isolated situations (Green et al). This is so because enrichment changes the intensity of the acute administration of drugs of abuse. Rats are stimulated by the environment, rather than a particular stimulant.

One of the most common childhood disorders, attention-deficit hyperactivity disorder (ADHD) places individuals at a higher risk for nicotine (NIC) dependence. Approximately 37.2% of individuals with ADHD currently smoke compared to the 18.3% of individuals with no record of mental illness. Methylphenidate (MPH; Trade name Ritalin) is the most commonly prescribed treatment for ADHD. Research regarding the synergistic effects of MPH and NIC, however, is divided. Some research indicates that MPH may enhance susceptibility to NIC effects, whereas other studies report that MPH may inhibit sensitization to NIC. The present study examines the effects of pre-exposure to MPH (1.0 mg/kg) on the behavioral effects of NIC (0.5 mg/kg) in adolescent male and female Sprague-Dawley rats. We used behavioral sensitization and conditioned place preference (CPP) on animals postnatal day (P)28-50; this is defined as adolescence in rats. For behavioral sensitization, results revealed a significant interaction between day of testing, drug pre-exposure, and adolescent drug treatment (p = .004). On the other hand, CPP results revealed a significant interaction between adolescent drug treatment and drug pre-exposure (p = .031). Findings suggest that pre-exposure to MPH reduces behavioral sensitization to NIC during adolescence. In addition, results indicate that MPH enhances NIC CPP in adolescent male and female rats, suggesting that MPH may enhance the rewarding effect of NIC.

Research has revealed that schizophrenics are significantly more likely to smoke cigarettes than the general population, and consume nicotine products at a much more prevalent rate. Further exacerbating this issue, it has been previously demonstrated in clinical populations that the type of antipsychotic treatment administered (typical versus atypical) may result in either an increase or a decrease of already heightened smoking behavior within the schizophrenic population. With these clinical issues in mind, the present study sought to examine the effects of antipsychotic treatment upon the associative reward of nicotine within the neonatal quinpirole model of schizophrenia. We found that treatment with the typical antipsychotic haloperidol blocked the associative reward of nicotine. Clozapine, an atypical antipsychotic, merely reduced the rewarding effects. These findings illustrate the centrality of the dopamine system, specifically the D2 receptor subtype, as an underlying mechanism of the rewarding effects of nicotine among rodents neonatally treated with quinpirole.

Our lab has shown that neonatal treatment with quinpirole, a dopamine D2/D3 agonist, to rats resulted in an increase in dopamine D2‐like receptor sensitivity that persists throughout the animal’s lifetime without a change in receptor number, consistent with schizophrenia. Approximately 80‐85% of schizophrenics smoke cigarettes, and there is no delineated mechanism for this observation. Our lab has also shown more robust sensitization and accumbal dopamine release in response to nicotine in adolescent rats neontally treated with quinpirole compared to controls. This study analyzed whether environmental enrichment, known to reduce sensitization to psychostimulants, may also reduce or block enhanced sensitization to nicotine in this model. Male and female rats were treated with either quinpirole (1 mg/kg) or saline from postnatal day (P)1‐21. After weaning at P21, animals were raised in either environmentally enriched or isolated housing throughout the experiment. Beginning on P33, animals were ip administered either nicotine (0.5 mg/kg free base) or saline 10 min before placement in a square locomotor arena and behavioral activity measured every second day from P33‐49. Results revealed that animals given neonatal quinpirole treatment and reared in an enriched environment demonstrated more robust sensitization to nicotine than all other groups. Animals given neonatal quinpirole or saline treatment followed by nicotine in adolescence and raised in isolated housing conditions were equivalent, but demonstrated more robust sensitization compared to enriched rats Page 13 of 35 neonatally treated with saline and administered nicotine in adolescence. Results here show that environmental enrichment enhanced nicotine sensitization in rats neonatally treated with quinpirole, which is in contrast to the blockade of sensitization to nicotine which has previously been shown in normal animals. Importantly, these results show that increases in D2 receptor sensitivity interacts with environmental enrichment differently than in normal animals and the manner in which the animal responds to nicotine, which may have implications towards smoking cessation in schizophrenia.

Aims: Neonatal quinpirole (a dopamine D2-like agonist) treatment to rats has been shown to increase dopamine D2 receptor sensitivity throughout the animal’s lifetime, and increased dopamine D2 sensitivity is a hallmark of schizophrenia. Schizophrenics are 3 to 4 times more likely to smoke than the normal population, but there is no delineating mechanism. Aim 1: Behaviorally test a rewarding versus averisve dose of nicotine in adolescent rats neonatally treated with quinpirole tested in a place preference paradigm; Aim 2: Analyze phosphorylated cylic AMP response element bidning protein (CREB) in brain areas that mediate drug reward. Methods: Rats were neonatally treated with quinpirole from postnatal days (P)1- 21. After two drug free preferene tests were given in a place preference shuttle box at P41-42, animals were conditioned with saline, a 0.6 or a 1.8 mg/kg free base dose of nicotine for eight consecutive days. A post-conditioning test was given 24 h after conditioning. Time in the paired and unpaired context were measured. Approximately 24 h after the post-condioning test, brain tissue was harvested, flash frozen, and later analyzed for pCREB in the dorsal and nucleus accumbens. Results: Results revealed that neonatal quinpirole enhanced the rewarding associative effects of the lower dose of nicotine compared to animals neonatally treated with saline and conditioned with the same dose of nicotine, which showed a slight place preference. Interestingly, although neonatal saline animals conditioned with the higher dose of nicotine demonstrated conditioned place aversion, neonatal quinpirole treated animals demonstrated no aversion to this same dose. Analyses for p-CREB will be presented. Conclusions: Rats neonatally treated with quinpirole demonstrate an enhancement of the rewarding properties of nicotine, but do not demonstrate an aversion to higher doses of nicotine. These data are congruent with recent self-administration data in our lab, and suggest that increases of dopamine D2 sensitivity may blunt aversive aspects of nicotine.