Este estudo visa o desenvolvimento de microemulsões que, após captação de água do tecido subcutâneo, transformar-se-ão em gel nanoestruturado de fase hexagonal para liberação sustentada de naltrexona e tratamento do alcoolismo. A microemulsão selecionada, composta por monooleína, tricaprilina, propilenoglicol e água (ME-MO) resultou na liberação in vitro de 31 % de naltrexona em 96 h. Após sua administração subcutânea, foi observada formação do gel em 48 h, o qual persistiu por mais de 30 dias in vivo, promovendo liberação prolongada do marcador fluorescente Alexa flúor. A eficácia da formulação foi avaliada em modelo de preferência condicionada por lugar induzida por etanol; ME-MO com 5 e 10% de naltrexona foi comparada à solução de naltrexona diária. Não observou-se diferença significativa entre a solução de naltrexona e ME-MO 5%, enquanto que ME-MO 10% diferiu destas, e antagonizou a preferência condicionada por lugar. Esses resultados demonstram o potencial de ME-MO como uma plataforma para liberação prolongada de fármacos no tratamento de dependência química. / This study focuses on the development of microemulsions that after in vivo water uptake of the subcutaneous tissue will turn into liquid-crystalline gels for sustained release of naltrexone, used in the treatment of alcoholism. Three microemulsions based on monoolein and tricapryline (ME-MO), vitamin E TPGS and propylene glycol, TPGS and Span were selected. The latter resulted is faster drug release (65% in 96 h). Based on the ability of the gel formed to withstand dilution, ME-MO was selected for in vivo studies. After subcutaneous administration, hexagonal phase formation was observed in 48 h and its persistence for more than 30 days in those animals. The efficacy of the formulation was assessed using conditioned preference place model. The animals were divided into four groups: Saline (control); Naltrexone solution (1 mg / kg) daily for 8 days (30 min before ethanol administration), and ME-MO with 5% or 10% naltrexone (single administration). The results suggest that ME-MO 10% antagonized the preference induced by ethanol.

This investigation was an analysis of the interaction of adolescent exposure to methylphenidate (MPH; trade name: Ritalin) on nicotine sensitization and conditioned place preference (CPP) in a rodent model and underlying mechanisms of this effect. Animals were treated IP with 1 mg/kg MPH or saline using a ―school day‖ regimen of five days on, two days off, from postnatal day (P) 28-50. During the final two weeks of MPH treatment, animals were either behaviorally sensitized to nicotine (0.5 mg/kg free base) or saline for 10 days, or conditioned to nicotine or saline using the CPP behavioral paradigm. In addition, three days after behavioral sensitization was complete, animals were analyzed for stress behavior using the forced swim stress behavioral test. In addition, 24 hours after post-test conditioning animals were analyzed for the effect of a clinically relevant dose of pre-exposed MPH (1mg/kg) and nicotine treatment on the expression of BDNF in the nucleus accumbens and dorsal hippocampus. Behavioral results revealed that adolescent pre-exposure to MPH blunted nicotine behavioral sensitization in both male and female rats during the first week of testing. However, MPH enhanced nicotine CPP in both adolescent male and female rats. Interesting, animals administered MPH demonstrated a significantly decreased latency to immobility in the forced swim stress behavioral test. In addition, pre-exposure to a 1 mg/kg dose of MPH appears to have sensitized the BDNF response to nicotine in females as compared to all other groups.

Multiple interactions between dopamine (DA), glutamate, and nitric oxide (NO) in mesolimbic and corticostriatal circuits suggest that NO may play a critical role in cocaine-induced behavioral and neural plasticity. Clinical and preclinical studies have revealed that females and adolescents display unique vulnerabilities to the behavioral and neurochemical effects of cocaine as a result of sex-dependent and ontogeny-dependent differences in dopaminergic systems. Thus, my research objectives were to investigate the contributions of the neuronal nitric oxide synthase (nNOS) gene, ontogeny, and gender on the rewarding and sensitizing effects of cocaine. I found that nNOS significantly influences the rewarding aspects of cocaine in adolescent mice and adult male mice (i.e., major deficits in several phases of cocaine conditioned place preference (CPP) were detected in nNOS knockout (KO) adolescent mice and nNOS KO adult male mice). However, the contribution of nNOS was sex-dependent as CPP phases were normal in KO adult females. In contrast to CPP, I found a major ontogeny-dependent contribution of nNOS to the sensitizing effects of cocaine. Namely, while nNOS is essential for the development of behavioral sensitization in adult males, this type of behavioral plasticity develops independently of nNOS during adolescence. The contribution of nNOS was once again sex-dependent as behavioral sensitization was normal in adult KO females. Together, this line of investigation has revealed that the NO-signaling pathway has a) a sex-dependent role in the neuroplasticity underlying cocaine CPP and b) a sex-dependent and ontogeny-dependent influence on cocaine-induced behavioral sensitization. Stereological and western blot analysis revealed that a sensitizing regimen of cocaine resulted in an increase in nNOS and tyrosine hydroxylase (TH) immunoreactivity in the dorsal striatum (dST) of adult, but not adolescent, wild-type (WT) male mice. In the absence of nNOS, dopaminergic neurons in the ventral tegmental area (VTA) were severely reduced and cocaine caused a downregulation of dST TH suggesting that nitrergic levels modulate TH. Thus, the finding that nNOS is essential for the development of sensitization in adulthood, but not adolescence, together with the fact that cocaine upregulated nNOS and TH in the dST in adult, but not adolescent mice, strongly suggest that the nitrergic system underlies behavioral sensitization through modulation of the dopaminergic system in adulthood. These findings suggest different approaches in the clinical treatment of drug craving and drug-seeking behavior in adolescent and adult patients.

Benzodiazepines are widely abused by anxious individuals. Consequently, this thesis modeled anxiety in a mouse model in order to investigate benzodiazepine motivation within this sub-population. Using the Tube test of Social Dominance and the Resident/Intruder Paradigm I investigated whether animals identified as dominant or submissive/defeated would differentially display a preference for 0.25 mg/kg midazolam in a conditioned place preference paradigm. Consistent with my hypotheses, benzodiazepine preference was mediated by negative reinforcement as submissive but not dominant mice displayed a preference for midazolam. Furthermore, different neural systems mediated benzodiazepine preference dependent on the stress status of the animal (acute vs. chronic stress) such that, acutely stressed animals experienced benzodiazepine preference through a dopamine-independent pathway whereas chronically stressed animals experienced benzodiazepine preference through a dopamine-dependent pathway. Within chronically stressed mice, blockade of either D1 or D2 receptors attenuated benzodiazepine preference.

Benzodiazepines are widely abused by anxious individuals. Consequently, this thesis modeled anxiety in a mouse model in order to investigate benzodiazepine motivation within this sub-population. Using the Tube test of Social Dominance and the Resident/Intruder Paradigm I investigated whether animals identified as dominant or submissive/defeated would differentially display a preference for 0.25 mg/kg midazolam in a conditioned place preference paradigm. Consistent with my hypotheses, benzodiazepine preference was mediated by negative reinforcement as submissive but not dominant mice displayed a preference for midazolam. Furthermore, different neural systems mediated benzodiazepine preference dependent on the stress status of the animal (acute vs. chronic stress) such that, acutely stressed animals experienced benzodiazepine preference through a dopamine-independent pathway whereas chronically stressed animals experienced benzodiazepine preference through a dopamine-dependent pathway. Within chronically stressed mice, blockade of either D1 or D2 receptors attenuated benzodiazepine preference.

The attribution of incentive salience to cues that become associated with drugs of abuse is a critical characteristic of individuals who may be vulnerable to drug addiction. Rodents with the propensity to sign track are thought to be vulnerable to drug abuse. The goal of the current work was to investigate whether sign trackers (STs) would acquire cocaine conditioned place preference (CPP) to a discrete cue using an avian species. In Experiment 1, sign and goal trackers (GTs) were first identified using a one third rank order split. Following identification, cocaine-CPP was conducted with a discrete cue in each end chamber. Contrary to previous research, results showed that GTs showed a CPP to the discrete cue but STs did not. Experiment 2 was conducted to determine whether sign and GTs had been misclassified with the rank order split. Experiment 2 compared the rank order method with a t-test method (absolute criterion). Misclassification of both sign and GTs occurred using the rank order split. The findings indicated that use of a more accurate method to identify sign and GTs may have led to different results for Experiment 1. The t-test method may be useful for models that require identification of STs.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / Amphetamine compounds and its derivatives are widely used in clinical medicine, but it is known that frames can cause dependence, tolerance and withdrawal. Furthermore, these drugs can alter metabolism and the functions of central neurotransmitters causing oxidative imbalances. In this sense it is already documented that exercise improves the conditions of well-being and self-esteem, and improve the plasticity and thus neuronal protection. In this context, the present study aimed to evaluate the influence of regular and continuous exercise on anxiety and behavioral parameters related to relapse to the use of amphetamine in an animal model of conditioned place preference (CPP). Male Wistar rats were conditioned to the use of AMPH or vehicle for 14 days and then half of each group was subjected to aerobic, regular and continuous physical activity for 5 weeks, while the others were not exercised. At the end of the last exercise session, the animals were re-conditioned to the use of AMPH/vehicle for more 3 days. After this phase, the animals were subjected to behavioral testing CPP to evaluate relapse to drug use, and the elevated plus maze to measure anxiety parameters. Hippocampal oxidative status was evaluated by levels of generation of reactive species (RS), carbonyl protein (CP), and activity levels of catalase (CAT) and Na+K+-ATPase, respectively. It was observed that the per amphetamine was able to develop is the CPP in the animals, however after the completion of 5 weeks of aerobic exercise, there was a reduction in the rate preferably compared to sedentary rats indicating a lower rate of relapse to amphetamine. In addition, exercise was shown to be beneficial to reduce the degree of anxiety and oxidative damage in these animals by amphetamine. Thus, regular and continuous exercise is a promising tool in the treatment of dependence and relapse to the indiscriminate use of drugs. / Compostos anfetamínicos e seus derivados são amplamente utilizados na clínica médica, porém podem provocar quadros de dependência, tolerância e abstinência. Além disso, estas drogas são capazes de afetar as funções e o metabolismo de neurotransmissores do sistema nervoso central (SNC) provocando desequilíbrios oxidativos. Neste sentido, já é documentado que o exercício físico melhora as condições de bem estar e auto-estima, favorecendo a plasticidade e, consequentemente, a proteção neuronal. Nesse contexto, o presente estudo visou avaliar a influência do exercício físico regular e contínuo sobre parâmetros comportamentais e de ansiedade relacionados à recaída ao uso de anfetamina em modelo animal de preferência condicionada de lugar (PCL). Ratos Wistar adultos foram condicionados com anfetamina no protocolo de PCL ou veículo por 14 dias e, na sequência, metade de cada grupo foi submetida à atividade física aeróbica regular e contínua por 5 semanas, enquanto os demais não foram exercitados. Ao término da última sessão de exercício físico, os animais foram re-condicionados ao uso de anfetamina ou veículo por mais 3 dias. Após esta fase, os animais foram submetidos aos testes comportamentais de PCL para avaliar sintomas de recaída pela preferência à droga, sendo também avaliados parâmetros de ansiedade em labirinto em cruz elevado. O status oxidativo na região do hipocampo foi avaliado através da geração de espécies reativas (RS), dos níveis de proteína carbonilada (PC) e atividade das enzimas catalase (CAT) e Na+K+-ATPase. Observou-se que a anfetamina per se foi capaz de desenvolver a PCL nos animais. Entretanto, após 5 semanas de exercício físico aeróbico regular e contínuo, os animais expostos à anfetamina mostraram menor PCL pela droga quando comparados ao grupo sedentário, indicando menor índice de recaída à anfetamina. Além disso, o exercício físico regular e contínuo exerceu influência favorável ao reduzir o nível de ansiedade e os danos oxidativos cerebrais, os quais foram associados ao condicionamento com anfetamina. Desse modo, o exercício físico regular e contínuo é uma ferramenta promissora no tratamento de dependência e recaída ao uso abusivo de drogas.

The effects of the kappa opioid agonist U-50,488 on morphine-induced condtioned place preference (CPP), locomotor activity and Fos immunoreactivity and assessed in 10-, 17- and 35-day old rats. It was predicted that kappa agonist treatment would block the unconditioned and conditioned behaviors produced by morhine (a mu opioid receptor agonist).

Alcohol use disorder is a debilitating disorder affecting nearly 5% of people in the United States. Despite the prevalence of alcohol use disorder few affected individuals seek treatment and of those who do many will relapse. This highlights a need to develop new treatments for alcohol use disorder that are both more accessible and more effective. This dissertation characterizes a novel pathway involved in ethanol enhancement of dopamine levels in the nucleus accumbens as well as investigating alterations in dopamine 2 receptor expression and function following an acute dose of ethanol. This was done by using microdialysis to measure dopamine levels in the nucleus accumbens, single-unit recordings of dopamine neurons in the ventral tegmental area to measure dopamine neuron activity and place conditioning to measure the rewarding properties of the intravenous dopamine and ethanol. It was found that activation of peripheral dopamine 2 receptors by intravenous dopamine enhanced dopamine levels in the nucleus accumbens and dopamine neuron firing rate in the ventral tegmental area. Additionally, intravenous dopamine produced a modest conditioned place preference. Domperidone, a peripheral dopamine 2 receptor antagonist blocked each of these effects. Further, domperidone blocked ethanol enhancement of dopamine release in the nucleus accumbens and bidirectionally modulated the sedating effects of ethanol depending on the dose of ethanol administered. The involvement of peripheral dopamine 2 receptors in ethanol reward could not be ascertained in these studies as domperidone produced a weak conditioned place aversion. Finally, acute ethanol was found to enhance dopamine 2 receptor expression in the nucleus accumbens and medial prefrontal cortex while also enhancing dopamine 2 receptor expression on NK and B cells. Additionally, ethanol was found to reduce desensitization of dopamine 2 receptors in the ventral tegmental area. These results demonstrate that activation of peripheral dopamine 2 receptors can enhance dopamine levels in the nucleus accumbens and that this effect has relevance in understanding the effects of ethanol on dopamine release in the mesolimbic pathway. These results also provide evidence for transient upregulation of dopamine 2 receptors in the brain and on leukocytes suggesting that dopamine 2 receptor levels on leukocytes may be a useful biomarker for central dopamine function.

Alcohol use disorder is a debilitating disorder affecting nearly 5% of people in the United States. Despite the prevalence of alcohol use disorder few affected individuals seek treatment and of those who do many will relapse. This highlights a need to develop new treatments for alcohol use disorder that are both more accessible and more effective. This dissertation characterizes a novel pathway involved in ethanol enhancement of dopamine levels in the nucleus accumbens as well as investigating alterations in dopamine 2 receptor expression and function following an acute dose of ethanol. This was done by using microdialysis to measure dopamine levels in the nucleus accumbens, single-unit recordings of dopamine neurons in the ventral tegmental area to measure dopamine neuron activity and place conditioning to measure the rewarding properties of the intravenous dopamine and ethanol. It was found that activation of peripheral dopamine 2 receptors by intravenous dopamine enhanced dopamine levels in the nucleus accumbens and dopamine neuron firing rate in the ventral tegmental area. Additionally, intravenous dopamine produced a modest conditioned place preference. Domperidone, a peripheral dopamine 2 receptor antagonist blocked each of these effects. Further, domperidone blocked ethanol enhancement of dopamine release in the nucleus accumbens and bidirectionally modulated the sedating effects of ethanol depending on the dose of ethanol administered. The involvement of peripheral dopamine 2 receptors in ethanol reward could not be ascertained in these studies as domperidone produced a weak conditioned place aversion. Finally, acute ethanol was found to enhance dopamine 2 receptor expression in the nucleus accumbens and medial prefrontal cortex while also enhancing dopamine 2 receptor expression on NK and B cells. Additionally, ethanol was found to reduce desensitization of dopamine 2 receptors in the ventral tegmental area. These results demonstrate that activation of peripheral dopamine 2 receptors can enhance dopamine levels in the nucleus accumbens and that this effect has relevance in understanding the effects of ethanol on dopamine release in the mesolimbic pathway. These results also provide evidence for transient upregulation of dopamine 2 receptors in the brain and on leukocytes suggesting that dopamine 2 receptor levels on leukocytes may be a useful biomarker for central dopamine function.