Stress is a major risk factor for substance abuse. Intermittent social defeat stress increases drug self-administration (SA) and elevates brain-derived neurotrophic factor (BDNF) expression in the ventral tegmental area (VTA) in rats. Intra-VTA BDNF overexpression enhances social defeat stress-induced cross-sensitization to psychostimulants and induces nucleus accumbens (NAc) ΔFosB expression. Therefore, increased VTA BDNF may mimic or augment the development of drug abuse-related behavior following social stress. To test this hypothesis, adeno-associated virus (AAV) was infused into the VTA to overexpress either GFP alone (control) or GFP + BDNF. Rats were then either handled or exposed to intermittent social defeat stress before beginning cocaine SA training. The SA acquisition and maintenance phases were followed by testing on a progressive ratio (PR) schedule of cocaine reinforcement, and then during a 12-h access "binge" cocaine SA session. BDNF and ΔFosB were quantified postmortem in regions of the mesocorticolimbic circuitry using immunohistochemistry. Social defeat stress increased cocaine intake on a PR schedule, regardless of virus treatment. While stress alone increased intake during the 12-h binge session, socially-defeated rats that received VTA BDNF overexpression exhibited even greater cocaine intake compared to the GFP-stressed group. However, VTA BDNF overexpression alone did not alter binge intake. BDNF expression in the VTA was also positively correlated with total cocaine intake during binge session. VTA BDNF overexpression increased ΔFosB expression in the NAc, but not in the dorsal striatum. Here we demonstrate that VTA BDNF overexpression increases long-access cocaine intake, but only under stressful conditions. Therefore, enhanced VTA-BDNF expression may be a facilitator for stress-induced increases in drug abuse-related behavior specifically under conditions that capture compulsive-like drug intake.

O comportamento maternal (CM) em mamíferos tem características específicas. O período logo após o parto é particularmente sensível a alterações fisiológicas que podem modular a expressão deste comportamento importante. Mudanças comportamentais observadas em animais doentes são consideradas comportamento doentio (CD). A exposição ao LPS, uma endotoxina derivada da parede de uma bactéria gran negativa, durante a gravidez pode causar doenças mentais. A fim de investigar, uma possível relação entre CM e CD, os animais foram tratados com LPS. Para o estudo do CM e agressivo, quarenta ratas foram divididos em quatro grupos, dois controles e dois grupos experimentais, com dez animais cada. O grupo experimental recebeu 100µg/kg de LPS por via i.p, e grupo controle o veículo de endotoxina, após quarenta e oito horas de administração de LPS, ou seja, no quinto dia de lactação, as observações começaram. Para escolha deste dia, ratas virgens e ratas lactantes foram divididas em quatro grupos, dois controles e dois experimentais, com dez fêmeas cada. O peso corporal, consumo de água, ração, e a temperatura corporal foram medidas para cento e vinte horas. As fêmeas do grupo controle foram observadas da mesma forma, mas foram tratados com o veículo do LPS. Observamos que: 1) Em ratas virgens e lactantes o tratamento com LPS modificou a temperatura e peso corporal, consumo de água e ração; 2) No período de lactação houve redução da latência para busca do primeiro filhote. Na prole verificou-se que: 3) Houve alteração no padrão de vocalização dos filhotes cujas mães foram expostas ao LPS no terceiro dia de lactação; 4) houve alteração no burst e fagocitose de enutrofilos no vigésimo primeiro dia de lactação após desafio com a endotoxina indicativo de maior resposta ao LPS. Concluiu-se que a exposição de ratos ao LPS facilita o comportamento maternal, mas promove alterações na sua prole relacionadas à interação entre mãe-filhote e aumento na resposta a um desafio imunológico. / Maternal behavior (MB) in mammals has specific characteristics. The time period just after parturition is particularly sensitive to physiological changes that can modulate the expression of this important behavior. Behavioral changes observed in sick animals, are considered as sick behavior (SB). Exposure to LPS, an endotoxin derived from the wall of a gran negative bacteria, during pregnancy might cause mental diseases. In order to investigate, a possible relationship between MB and SB, animals were treated with LPS. For the study of MB and maternal aggressive behavior, 40 rats were divided in 4 groups, 2 control and 2 experimental groups. The experimental group received 100µg/kg LPS by ip, and control group the vehicle of endotoxin, after 48 hours of LPS administration the observations of SB began. For choice these days, 20 virgin and 20 lactating rats were divided in 4 groups, 2 control and 2 experimental. They received ip 100µg/kg. Body weight, water and feed consumption, and body temperature were measured for 120h. Control females were observed in the same way, but they were treated with vehicle of LPS. The results showed that: 1) In 48 hours after the LPS treatment, virgin and lactating rats showed increased body temperature, loss of body weight, increased water consumption and decreased food consumption, 2) In 48 hours after the treatment with LPS, lactating rats showed reduced latency to retrieve the first pup to the nest. In the offspring of mothers treated with LPS it was found that: 3) Pups form mothers treated with LPS on the 5th day of lactation showed changes in the vocalization pattern; 4) Those pups showed changes in oxidative burst and phagocytosis on 21th day of lactation. It is concluded that exposure of rats to LPS promoted changes in the in the interaction between mother and pups.

O procedimento de omissão do reforço, em esquemas de reforçamento em intervalo-fixo, produz uma redução na pausa pós-reforço e, consequentemente, um aumento na frequência de respostas no próximo intervalo. Existem diferentes interpretações relacionadas ao efeito de omissão do reforço (EOR), baseadas em componentes atencionais / motivacionais. Estudos preliminares têm examinado o papel da ativação de alguns núcleos da amígdala na modulação destes componentes. Estudos recentes sugerem que as subestruturas da amígdala podem estar envolvidas em diferentes processos, e as conexões entre diferentes núcleos da amígdala e estruturas corticais / subcorticais também parecem estar envolvidas em processos relacionados a recompensas e expectativa. Outros estudos sugerem que a interação entre a amígdala e nucleus accumbens (NAC) é importante para a modulação de processos motivacionais. No entanto, não há estudos na literatura avaliando se lesões neurotóxicas em diferentes regiões corticais e subcorticais podem interferir nos EORs. Este estudo teve como objetivo analisar os EORs sobre o repertório comportamental em ratos com lesões do NAC, em procedimentos de condicionamento clássico e reforçamento não-contingente. Trinta ratos Wistar machos, divididos nos grupos accumbens e controle sham, foram submetidos a 28 sessões de treinamento com 8 práticas cada uma: 20 sessões pré-lesão, duas sessões de retreino e seis sessões pós-lesão (com omissão de reforço). Cada prática constituía de um sinal de 20 segundos (tom), seguindo-se a libertação de uma gota de água no 19º segundo. Em sessões com omissão, a água foi liberada em metade das práticas. Foram analisadas dez categorias comportamentais. A comparação entre taxas de duração durante as práticas de liberação e omissão do reforço mostrou que os grupos accumbens e controle sham apresentaram EORs. O grupo accumbens foi menos sensível aos EORs. Em relação às categorias comportamentais Farejar o bebedouro e Farejar a região do bebedouro, as taxas de duração do grupo controle sham durante a omissão foram maiores em relação às taxas do grupo accumbens. Já para as categorias Lamber o bebedouro, Farejar distante do bebedouro, Levantar, Locomoção e Limpeza, as taxas de duração do grupo controle sham foram menores do que o grupo accumbens. Os resultados sugerem que o NAC pode fazer parte da circuitaria envolvida na modulação dos EORs e também indicam a necessidade de se considerar o envolvimento de uma rede neural mais complexa para avaliação dos EORs. / The reinforcement omission procedure, in fixed-interval schedules of reinforcement, produces a reduction in post-reinforcement pause and, consequently, an increase in frequency responses in the next interval. There are different interpretations related to reinforcement omission effect (ROE), based upon motivational and / or attentional components. Preliminary studies have examined the role of activation of some amygdala nuclei to modulate these components. Recent studies suggest that the substructures of the amygdala may be involved in different processes, and connections between different amygdala nuclei and cortical/subcortical structures seem to be involved in processes related to rewards and expectancy. Other studies suggest that the interaction between the amygdala and nucleus accumbens (NAC) is important for the modulation of motivational processes. However, there are no studies in the literature assessing whether neurotoxic lesions in different cortical and subcortical regions may interfere in ROEs. This study aimed to examine the ROEs on the behavioral repertoire of rats with lesions of the NAC, in classical conditioning procedures and non-contingent reinforcement. Thirty male Wistar rats, divided in NAC and SHAM groups, were submitted to 28 training sessions with 8 practices each one: 20 pre-lesion, two retraining sessions and six post-lesions sessions with omission of reinforcement. Each practice constituted of a 20 seconds signal (tone), followed by the release of a drop of water in the 19th second. In sessions with omission, the water was released in the half of practices. Ten categories of behaviors were analyzed. Comparison between duration rates during omission and reinforcement practices showed that NAC and SHAM groups showed the ROEs. NAC group was less sensitive to the ROEs. Regarding the behavioral categories Magazine sniffing and Near magazine sniffing, the duration rates of SHAM group during omission were higher in relation to rates of NAC group. For the categories Magazine licking, Far from magazine sniffing, Rearing, Locomotion and Grooming duration rates of SHAM group were lower than the NAC group. The results suggest that NAC can be part of circuitry involved in the modulation of ROEs and indicate the need to consider the involvement of more complex neural network for evaluating the ROEs.

O núcleo acumbens (Acb) é envolvido em comportamentos adaptativos e emocionais. A maioria dos neurônios do Acb são neurônios de projeção (MSNs) que contém a fosfoproteína DARPP-32 e são modulados por distintos tipos de interneurônios. Há pouca informação sobre os receptores de glutamato (Glu) expressos no Acb. Este estudo investiga, através de técnicas de imunohistoquímica, a distribuição e co-localização de marcadores do sistema dopaminérgico, dos receptores de Glu do tipo AMPA (GluR1-GluR4) e NMDAR1 e marcadores de interneurônios. Nossos resultados mostram que o Acb possui uma neuroquímica semelhante ao estriado dorsal. Porém, detectamos uma distribuição distinta de alguns dos marcadores no Acb. Os estudos de co-localização revelam que quase todos os neurônios no Acb expressam GluR2/3 ou GluR2. Em contraste, GluR1 e GluR4 são fracamente expressas e co-localizam com parvalbumina. Esses resultados indicam que GluR2 e GluR2/3 são expressas em MSNs DARPP-32+ e na maioria dos interneurônios do Acb enquanto GluR1 e GluR4 são exclusivamente expressas em interneurônios. / The nucleus accumbens is involved in adaptive and emotional behaviors. The majority of neurons in the Acb are projection neurons that express the phosphoprotein DARPP-32 and are modulated by distinct types of interneurons. There is little information about the glutamate receptors expressed in the Acb. This study investigates by immunohistochemical methods the distribution and co-localization of markers of the dopaminergic system, AMPA (GluR1-4) and NMDAR1 type Glu receptor subunits and specific markers of interneurons. Our results show that the neurochemistry of the Acb is similar to that of the dorsal striatum. However, we detected a distinct distribution of some markers in the Acb. Our co-localization studies reveal that almost all neurons of the Acb express GluR2/3 or GluR2. In contrast, GluR1 and GluR4 are weakly expressed and are co-localized with parvalbumin. These results indicate that GluR2 and GluR2/3 are expressed by MSNs DARPP-32+ and by the majority of interneurons of the Acb, whereas GluR1 and GluR4 are exclusively expressed by interneurons.

Maternal behaviours are those that increase offspring survival. Estrogens affect maternal behaviour by activating Estrogen Receptors (ER) in the brain. Maternal brain plasticity was explored by characterizing the effects of exposure to a mixture of environmental pollutants on number of ERs. Following exposure to the toxicants during pregnancy and lactation, brains of female rats were collected, sectioned at 30 μm and immunohistochemistry for ERα performed. Immuno-positive cells in the mPOA, VTA and NAc were counted. A two way ANOVA revealed no main effect of Treatment on the number of immunopositive cells for all three brain regions. However, a significant difference between the High and Low Doses with the high dose reducing the number of ERα+ cells in the mPOA and VTA. Our work showcases the importance of studying the effects of multiple chemical co-exposures on the mother's brain, as maternal brain changes impact maternal behaviour consequently affecting offspring neurodevelopment.

O comportamento maternal (CM) em mamíferos tem características específicas. O período logo após o parto é particularmente sensível a alterações fisiológicas que podem modular a expressão deste comportamento importante. Mudanças comportamentais observadas em animais doentes são consideradas comportamento doentio (CD). A exposição ao LPS, uma endotoxina derivada da parede de uma bactéria gran negativa, durante a gravidez pode causar doenças mentais. A fim de investigar, uma possível relação entre CM e CD, os animais foram tratados com LPS. Para o estudo do CM e agressivo, quarenta ratas foram divididos em quatro grupos, dois controles e dois grupos experimentais, com dez animais cada. O grupo experimental recebeu 100µg/kg de LPS por via i.p, e grupo controle o veículo de endotoxina, após quarenta e oito horas de administração de LPS, ou seja, no quinto dia de lactação, as observações começaram. Para escolha deste dia, ratas virgens e ratas lactantes foram divididas em quatro grupos, dois controles e dois experimentais, com dez fêmeas cada. O peso corporal, consumo de água, ração, e a temperatura corporal foram medidas para cento e vinte horas. As fêmeas do grupo controle foram observadas da mesma forma, mas foram tratados com o veículo do LPS. Observamos que: 1) Em ratas virgens e lactantes o tratamento com LPS modificou a temperatura e peso corporal, consumo de água e ração; 2) No período de lactação houve redução da latência para busca do primeiro filhote. Na prole verificou-se que: 3) Houve alteração no padrão de vocalização dos filhotes cujas mães foram expostas ao LPS no terceiro dia de lactação; 4) houve alteração no burst e fagocitose de enutrofilos no vigésimo primeiro dia de lactação após desafio com a endotoxina indicativo de maior resposta ao LPS. Concluiu-se que a exposição de ratos ao LPS facilita o comportamento maternal, mas promove alterações na sua prole relacionadas à interação entre mãe-filhote e aumento na resposta a um desafio imunológico. / Maternal behavior (MB) in mammals has specific characteristics. The time period just after parturition is particularly sensitive to physiological changes that can modulate the expression of this important behavior. Behavioral changes observed in sick animals, are considered as sick behavior (SB). Exposure to LPS, an endotoxin derived from the wall of a gran negative bacteria, during pregnancy might cause mental diseases. In order to investigate, a possible relationship between MB and SB, animals were treated with LPS. For the study of MB and maternal aggressive behavior, 40 rats were divided in 4 groups, 2 control and 2 experimental groups. The experimental group received 100µg/kg LPS by ip, and control group the vehicle of endotoxin, after 48 hours of LPS administration the observations of SB began. For choice these days, 20 virgin and 20 lactating rats were divided in 4 groups, 2 control and 2 experimental. They received ip 100µg/kg. Body weight, water and feed consumption, and body temperature were measured for 120h. Control females were observed in the same way, but they were treated with vehicle of LPS. The results showed that: 1) In 48 hours after the LPS treatment, virgin and lactating rats showed increased body temperature, loss of body weight, increased water consumption and decreased food consumption, 2) In 48 hours after the treatment with LPS, lactating rats showed reduced latency to retrieve the first pup to the nest. In the offspring of mothers treated with LPS it was found that: 3) Pups form mothers treated with LPS on the 5th day of lactation showed changes in the vocalization pattern; 4) Those pups showed changes in oxidative burst and phagocytosis on 21th day of lactation. It is concluded that exposure of rats to LPS promoted changes in the in the interaction between mother and pups.

abstract: Nicotine self-administration is associated with decreased expression of the glial glutamate transporter 1 (GLT-1) and the cystine-glutamate exchange protein xCT in the nucleus accumbens core (NAcore). N-acetylcysteine (NAC), which is an antioxidant, anti-inflammatory, and glutamatergic agent, restores these proteins associated with increased relapse vulnerability. However, the specific molecular mechanisms driving NAC inhibitory effects on cue-induced nicotine reinstatement are unknown. Thus, the present study assessed NAC’s effects on cue-induced nicotine reinstatement are dependent on NAcore GLT-1 expression. Here, rats were treated with NAC in combination with intra-NAcore vivo-morpholinos to examine the role of GLT-1 in NAC-mediated inhibition of cue-induced nicotine seeking. Subchronic NAC treatment attenuated cue-induced nicotine seeking in male rats and an antisense vivo-morpholino (AS) designed to selectively suppress GLT-1 expression in the NAcore blocked this effect. NAC treatment was also associated with an inhibition of pro-inflammatory tumor necrosis factor alpha (TNFα) expression in the NAcore. As well, GLT-1 AS markedly increased expression of CD40, a known marker of pro-inflammatory M1 activation of microglia and macrophages. To further examine whether NAC-induced decreases in nicotine seeking involve suppression of TNFα, we manipulated a downstream mediator of this pathway, nuclear factor kappa B (NF-kB). Considering the putative role of NF-κB in learning, memory, and synaptic plasticity, separate experiments were performed where rats were treated with herpes simplex virus (HSV) vectors designed to increase (HSV-IKKca) or decrease (HSV-IKKdn) NF-κB signaling through interactions with IκB Kinase (IKK). The goal was to examine the role of NF-κB signaling in mediating nicotine seeking behavior and if NF-κB signaling regulates GLT-1 expression. HSV-IKKdn alone and in combination with NAC inhibited cue-induced nicotine reinstatement, while HSV-IKKca blocked the attenuating effect of NAC on reinstatement. Interestingly, both HSV-IKKdn and HSV-IKKca, regardless of NAC treatment, inhibited GLT-1 expression. Taken together, these results suggest that while GLT-1 may be a conserved neurobiological substrate underlying relapse vulnerability across drugs of abuse, immunomodulatory mechanisms may regulate drug-induced alterations in glutamatergic plasticity that mediate cue-induced drug-seeking behavior through GLT-1-independent mechanisms. / Dissertation/Thesis / Masters Thesis Psychology 2019

The mesolimbic dopamine (DA) system projects from the ventral tegmental area (VTA) to structures associated with the limbic system, primarily the nucleus accumbens (NAc). This system has been implicated in the rewarding effects of drugs of abuse. Many drugs of abuse act in the VTA, the NAc, or both. Dopamine neurons in the VTA that project to the NAc, and the GABA neurons that inhibit DA neurons locally in the VTA or project to the NAc, play an important role in mediating addiction to various drugs of abuse, in particular alcohol. There is a growing body of evidence of co-dependence of nicotine and ethanol drug abuse. Given this evidence, it is possible that both ethanol and nicotine target similar receptors in the NAc. The GABA-A and GABA-B receptors have also been implicated in the modulation of ethanol's reinforcing properties (Anstrom, Cromwell, Markowski, & Woodward, 2003; Besheer, Lepoutre, & Hodge, 2004; Colombo et al., 2000; Moore & Boehm, 2009; Stromberg, 2004; Walker & Koob, 2007). Thus, there is a growing literature suggesting that GABA receptors are implicated in ethanol reward. In these studies, we evaluated the possibility of co-dependence of nicotine and ethanol by activity on a similar receptor in the NAc. In addition, we evaluated the role of GABA modulation of DA release, in particular GABA-A receptors and GABA-B receptors, in modulating DA release in the NAc with acute ethanol exposure. The rationale for this study was predicated on the belief that advancement in the understanding of the brain mechanisms underlying the recreational use and abuse potential of alcohol will pave the way for more effective treatment strategies that could reverse alcohol dependence and co-dependence and save lives and resources throughout the world.

Methamphetamine (METH) is a highly addictive substance that is highly prevalent in today’s society, with over 1 in 20 adults over 26 having taken it at least once. While it is known that METH, a common psychostimulant, acts on both the mesolimbic dopamine (DA) and nigrostriatal DA systems by affecting proteins involved in DA reuptake and vesicular packaging, the specific mechanism of what is known as METH neurotoxicity remains obscure, but has been shown to involve oxidative stress. Studies have shown that reactive oxygen species act on the same proteins that METH affects. Oxidative species have also been known to catalyze the formation of melanins in dopaminergic cells. We explore this link more fully here. In an in vitro system, oxidative species (including Fe3+, an inorganic catalyst for oxidative stress), enhance the rate of melanization of DA. Methamphetamine increased oxidative stress in an in vivo model. Additionally, METH enhanced phasic (stimulated) DA release and caused an electrically-independent efflux of DA. Lidocaine abolished phasic DA release, but did not affect METH-induced DA efflux, indicating action-potential dependent and independent mechanisms behind METH’s effects. The sigma-1 receptor antagonist BD 1063 significantly attenuated METH’s effect on DA release. Depletion of intracellular calcium (Ca2+) reserves also attenuated METH-enhancement of DA release. We investigated the role of oxidative species in METH-induced DA efflux. Reduced glutathione (the substrate for glutathione peroxidase) and 4-hydroxy-TEMPOL (a superoxide dismutase mimetic) blocked METH’s effect on DA release, suggesting that a reactive oxygen species (ROS), most likely superoxide, is necessary for METH-induced DA efflux. Finally, oxidative stress as well as acute METH impairs the vesicular monoamine transporter 2 (VMAT2) by S-glutathionylation modification of Cys-488, highlighting VMAT2 as a likely regulator of METH’s effects on electrically independent DA release. These findings help outline a model in which METH induces DA release in the NAc through a signaling cascade involving the sigma receptor and ROS signaling molecules.

Nitric Oxide (NO) is a powerful endogenous free radical that has numerous biological functions including vasodilation and serves as a post synaptic second messenger in the central nervous system (CNS). Numerous studies implicate NO• involvement in CNS disorders such as schizophrenia and drug abuse. These studies address the direct in vivo determination of an FDA-approved NO• donor (nitroglycerin) on extracellular levels of NO• in the frontal cortex and core of the nucleus accumbens in a lightly anesthetized rat. State-of-the-art in vivo amperometric recording techniques coupled with a novel 4-channel low noise pre-amplifier system and new generation microelectrode arrays (MEAs) will be used to record extracellular levels of NO• at 100Hz before and during nasal administration of either placebo (1) or nitroglycerin. This studies will determine the feasibility of measuring NO• in the CNS while administering the NO• donor nasally and determine the amplitude and kinetic time course effects of a nasally delivered NO• donor in two rat brain areas, the frontal cortex and core of the nucleus accumbens.