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Organisms must continuously navigate complex environments, balancing the drive to seek rewards with the need to avoid potential threats. This tradeoff between approach and avoidance behaviors, known as approach-avoidance conflict, is a critical determinant of survival. The medial prefrontal cortex (mPFC) plays a key role in regulating these behaviors, with the ventromedial (vmPFC) and dorsomedial components thought to suppress and promote, respectively, behavioral responses to threats. Within the vmPFC, neural populations expressing the opioid peptide dynorphin (Dyn) and its receptor, the kappa opioid receptor (KOR), have been implicated in stress responses. However, the specific role of the vmPFC Dyn system in encoding threat-related information and shaping behavioral responses remains largely unexplored. To address this, we employed a multi-faceted approach, utilizing fiber photometry, calcium imaging, shRNA-mediated knockdown, and DREADD-mediated inhibition to investigate the vmPFC Dyn system in various threat-related paradigms. These included the platform-mediated avoidance (PMA) task, which assesses approach-avoidance conflict; the repeated looming disk test, a pain-free model of innate fear suppression; and standard fear conditioning, a well-established paradigm for studying learned fear responses. Our findings reveal that while the vmPFC Dyn system is not differentially regulated under non-threatening baseline conditions, it is actively recruited upon threat exposure. Fiber photometry recordings during the PMA task showed that vmPFC Dyn neurons bidirectionally signal features related to approach and avoidance behaviors in the presence of threat. Furthermore, shRNA-mediated downregulation of Dyn in the vmPFC led to enhanced avoidance in the repeated looming disk test, indicating that Dyn is necessary for suppressing avoidance in this context. Calcium imaging of the pan-neuronal vmPFC population in conjunction with Dyn knockdown revealed that loss of Dyn impairs cortical activity, as evidenced by reduced synchrony and decreased performance of a logistic regression decoder. These findings suggest that Dyn plays a critical role in shaping the activity of vmPFC neurons during threat processing. Taken together, our results highlight a specific role for the vmPFC Dyn system in toggling threat-driven behavioral responses, particularly in the context of approach-avoidance conflict. By demonstrating how Dyn shapes both behavior and neural activity in the vmPFC during threat exposure, this study provides novel insights into an understudied area of opioidergic circuitry. Moreover, our findings contribute to a deeper understanding of how distinct cell types within the vmPFC encode threat-related features to promote or suppress avoidance behaviors, shedding light on the neural mechanisms underlying adaptive responses to environmental challenges.

Doctorat en Sciences médicales / info:eu-repo/semantics/nonPublished

Submitted by MARIA EULÁLIA BALEOTTI null (mabaleotti@yahoo.com.br) on 2017-05-06T05:24:22Z No. of bitstreams: 1 Maria Eulalia Baleotti - Unesp - Dissertação versão final _M1_ _T1_.pdf: 975486 bytes, checksum: 875b7d0e99029d3a312012a165ce439c (MD5) / Rejected by Luiz Galeffi (luizgaleffi@gmail.com), reason: Solicitamos que realize uma nova submissão seguindo a orientação abaixo: O arquivo submetido não contém o certificado de aprovação. Corrija esta informação e realize uma nova submissão com o arquivo correto. Agradecemos a compreensão. on 2017-05-08T16:42:03Z (GMT) / Submitted by MARIA EULÁLIA BALEOTTI null (mabaleotti@yahoo.com.br) on 2017-05-09T02:13:09Z No. of bitstreams: 1 Maria Eulalia Baleotti - Unesp - Dissertação versão final _M1_ _T1_.pdf: 1404968 bytes, checksum: ed93838350a715d82b43c32074f22275 (MD5) / Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-05-10T17:49:28Z (GMT) No. of bitstreams: 1 baleotti_ma_me_assis.pdf: 1404968 bytes, checksum: ed93838350a715d82b43c32074f22275 (MD5) / Made available in DSpace on 2017-05-10T17:49:28Z (GMT). No. of bitstreams: 1 baleotti_ma_me_assis.pdf: 1404968 bytes, checksum: ed93838350a715d82b43c32074f22275 (MD5) Previous issue date: 2017-03-07 / Fármacos antidepressivos como os inibidores seletivos de recaptação de serotonina (ISRSs; exemplos: fluoxetina e escitalopram) são drogas de primeira escolha no tratamento dos Transtornos de Ansiedade Generalizada (TAG) e do Transtorno do Pânico (TP). No entanto, apesar de eficazes na terapêutica, esses fármacos apresentam limitações no seu uso, tais como: os efeitos desejados ocorrem somente após administração crônica, em torno de 3 a 4 semanas após o início do tratamento; a proporção relativamente alta de pacientes que não respondem à medicação e o frequente aumento nos níveis de ansiedade desse pacientes no início do tratamento, levando à descontinuidade do uso destas drogas. Nesse sentido, há grande interesse na busca de novas estratégias de tratamento, identificando outros sistemas de neurotransmissão que possam estar relacionados à etiologia e, consequentemente, ao tratamento desses transtornos de ansiedade. Estudos prévios apontaram o envolvimento de opioides endógenos na modulação da ansiedade. Mais especificamente em relação ao TP, já se constatou que mecanismos opioides favorecem a atividade inibitória da serotonina em neurônios da Substância Cinzenta Periaquedutal Dorsal (SCPD) que modulam a fuga/pânico, possivelmente por meio da formação de heterodímeros entre receptores 5-HT1A e μ-opioide. Com base em tais aspectos, o presente estudo teve por objetivo investigar o efeito da Buprenorfina, um agonista parcial de receptores µ-opioide e antagonista de receptores κ-opioide, sobre a manifestação de comportamentos defensivos relacionados com o TAG e com o TP. O uso de agonistas parciais justifica-se pela possibilidade de atenuar efeitos adversos sobrevindos do uso contínuo de agonistas plenos para os receptores µ-opioide, tais como a euforia, a tolerância e a dependência. Para isto, foram conduzidos dois experimentos utilizando ratos Wistar, seguindo-se em cada um deles dois tipos de avaliação: Teste de analgesia, como parâmetro da eficácia do fármaco e testes comportamentais Labirinto em T Elevado (LTE), Campo Aberto e Transição Claro-Escuro. No primeiro experimento foi implantado cirurgicamente um adesivo de Buprenorfina (5mg) entre a pele e o tecido subcutâneo, cujas avaliações foram conduzidas 27 horas após o implante. No segundo experimento utilizou-se um extrato liofilizado da Buprenorfina a partir dos adesivos, em 3 doses diferentes: 1,5 mg/kg; 3,0 mg/kg; 6,0 mg/kg. Todas as avaliações ocorreram 10 minutos após as injeções intraperitoneais. Os resultados mostraram que a Buprenorfina nas doses e vias estudadas desinibiu o comportamento de esquivas inibitórias no LTE e o comportamento motor dos ratos no Teste do Campo Aberto, mas não afetou as fugas no LTE e nem outras manifestações comportamentais no Teste de Transição Claro-Escuro, exceto no implante do adesivo, quando se observou ansiólise nesse teste. Na administração por via IP, esses resultados ocorreram em todos os testes, mas somente na reexposição, 24 horas após a primeira avaliação comportamental. Em conclusão, a Buprenorfina nas doses e vias estudadas apresentou efeito analgésico e desinibiu o comportamento de esquivas e o comportamento motor dos ratos, mas não afetou as fugas, o que indica seu envolvimento na modulação de comportamentos defensivos apenas relacionados com a manifestação da ansiedade generalizada. Nesta dissertação, para maior aprofundamento do tema, foi inicialmente apresentada uma fundamentação teórica geral sobre as variáveis sob foco de investigação. Na sequência, foi exposto um artigo contendo uma fundamentação teórica mais específica, a descrição metodológica, bem como a análise e discussão dos resultados dos experimentos realizados. / Antidepressant drugs such as the selective serotonin reuptake inhibitors (SSRI; examples: fluoxetine and escitalopram) are first choice drugs for treating Generalized Anxiety Disorders (GAD) and Panic Disorder (PD). However, in spite of being therapeutically effective, such drugs present use limitations, such as: the desired effects occur only after chronic administration, within 3 to 4 weeks after the beginning of treatment; a relatively high proportion of patients who do not respond to the drug and the frequent increase of anxiety levels of such patients at the beginning of the treatment, leading to discontinuity in the use of such drugs. Along these lines, there is a great interest in the search of new treatment strategies, identifying other neurotransmission systems which may be related to the etiology and, consequently, to the treatment of such anxiety disorders. Previous studies pointed to the involvement of endogenous opioids in anxiety modulation. More specifically in relation to PD, one has found out that opioid mechanisms favor the inhibitory activity of serotonin in periaqueductal grey matter (dPAG) neurons which modulate escape/panic, probably by means of the formation of heterodimers between 5-HT1A and μ-opioide receptors. Based on such features, this study was carried out aiming at investigating buprenorfine effects, a partial μ-opioide receptor agonist and κ- opioidereceptor antagonist, on the manifestation of defensive behaviors related to GAD and PD. The use of partial agonists is justified by the possibility of attenuating adverse effects occurred after the continuous use of full agonists for μ- opioidereceptors, such as euphoria, tolerance and dependence. Therefore, two experiments werecarread out using Wistar rat, each one followed by two assessment types: analgesia test, as efficiency parameter of the drug and behavioral tests the elevated T-maze (ETM), Open Field and Light-Dark Transition. In the first experiment was surgically implanted a buprenorfine patch (5 mg) between the skin and the subcutaneous tissue, whose assessments were carried out 27 hours after the implantation. In the second experiment was used a buprenorfine extract based on the patches, with three different doses: 1.5 mg/kg; 3.0 mg/kg; 6.0 mg/kg. All the assessments were carried out 10 minutes after the intra-peritoneal injections. The results showed that buprenorfine administered in the studied doses and means uninhibited the inhibiting escape behavior in LTE and the motor behavior of rat in the Open Field Test, but did not affect escapes in LTE nor in other behavioral manifestations in the Light-Dark Transition Test, with the exception of the patch implant, when we were observed anxiolysis in this test. In the IP administration, such results occurredin all the tests, but only in the re-exposure, 24 hours after the first behavioral assessment. In conclusion, buprenorfine administered in doses and methods produced analgesic effect and impaired of the avoidance, but did not affected the escapes, which shows the involvement of this drug in the modulation of defensive behaviors only related whit manifestation of generalized anxiety. In this dissertation, presented a general theoretical foundation on the variables focused on the investigation and afterwards, a paper with a more specific theoretical foundation, the methodological description, as well as the analysis and discussion of the results yielded in the conducted experiments.

Indiana University-Purdue University Indianapolis (IUPUI) / Naltrexone (NTX) is clinically efficacious at attenuating alcohol intake in non-abstinent alcoholics and, to a lesser extent, craving, independent of intake. While generally regarded as a non-selective opioid antagonist, NTX has been shown to have concentration dependent selectivity with lower doses (< 1.0 mg/kg) selective for the mu receptor and doses exceeding 1.0 mg/kg capable of binding to delta and kappa receptors. Like the mu system, the delta receptor system has also been implicated in mediating the rewarding effects of EtOH. In contrast, the role of the kappa system is less clear though recent evidence suggests that kappa activation may mediate EtOH aversion. Thus, the present study sought to evaluate the effects of both mu-selective and non-selective doses of naltrexone, the selective delta antagonist naltrindole (NTI), and the selective kappa agonist U50,488H (U50) in a paradigm that procedurally separates the motivation to seek versus consume a reinforcer to assess whether these receptor-selective drugs differentially affects these behaviors in both selected (alcohol-preferring P rats) and non-selected (Long Evans) rats, and whether these effects are specific to EtOH. Rats were trained to complete a single response requirement that resulted in access to either 2% sucrose or 10% EtOH for a 20-min drinking session. In three separate experiments, rats were injected (using a balanced design) with either vehicle or 1 of 3 doses of drug: U50 (IP; 2.5, 5.0, or 10.0mg/kg), NTI (IP; 2.5, 5.0, or 10.0 mg/kg), low NTX (SC; 0.1, 0.3, or 1.0 mg/kg) or high NTX (SC; 1.0, 3.0, or 10.0 mg/kg) on both consummatory and appetitive treatment days. Following either a 20 (U50), 15 (NTI), or 30 minute (NTX) pretreatment, rats were placed into an operant chamber and intake (consummatory) or lever responses (appetitive) and response latencies were recorded. The results showed that overall: U50, NTI, and NTX attenuated intake and responding for sucrose and EtOH. Independent of reinforcer, LE rats were more sensitive to U50’s effects on intake while P rats were more sensitive to the effects on seeking. P rats reinforced with EtOH were more sensitive to NTI’s effects on intake and seeking than all other rat groups. P rats were more sensitive overall to lower doses of NTX than LE rats and lower doses of NTX were more selective in attenuating EtOH responding vs. sucrose. Higher doses of NTX suppressed intake and responding across both lines and reinforcers. These results demonstrate that craving and intake may be differentially regulated by the kappa, delta, and mu opioid receptor systems as a function of “family history” and suggest that different mechanisms of the same (opioid) system may differentially affect craving and intake.

FundaÃÃo de Amparo à Pesquisa do Estado do Cearà / Maytenus rigida Mart. (Celastraceae) pupularly known as âbom-homemâ, âbom-nomeâ, âCabelo de Negroâ, âCasca-grossaâ, ChapÃu de couroâ or âpau-de-colherâ is a native species in the northeast region of Brazil, used in folk medicine in the tratament of inflammatory diseases, gastrointestinal disorders such diarrhea, dysentery and ulcers, kidney problems, hypertension, impotence and rheumatism. The aim of this work was to demonstrate the possible mechanism (s) of action underlying the gastroprotective effect of aqueous extract (AE) of Maytenus rigida in Swiss mice, in the gastric injury model induced by absolute ethanol. Fasted mice received AE (100, 200 or 400 mg/Kg, p.o.) 1h prior to oral administration of absolute ethanol (0,2 mL/animal). Groups treated with saline and ranitidine were used as controls. The stomachs were macroscopically and microscopically examined. Additionally, different pharmacologixal tools (naloxone, morphine, misoprostol, indomethacin, L-NAME, L-arginine, clonidine or yohimbine) were used in different tests, trying to clarify the possible mechanism (s) of action of AE. The macro and microscopic gastroprotective effect of AE was compared to that showed by ranitidine, on ethanol-induced model (p<0.05); the use of pharmacological tools revealed that the protective effect of AE involves the activation of &#945;-2-adrenergic receptors, opioid receptor and nitric oxide, but do not depends on prostaglandins. The EA has a gastroprotective effects, supporting its traditional use. Its effect is multifactorial, involving the participation of &#945;-2-adrenergic receptors, nitric oxide release and activation of opioids receptors. / Maytenus rigida Mart., (Celastraceae) popularmente conhecida como âbom-homemâ, âbom-nomeâ, âcabelo de negroâ, âcasca-grossaâ, âchapÃu de couroâ ou âpau-de-colherâ à uma espÃcie nativa do nordeste brasileiro, utilizada na medicina popular no tratamento das doenÃas inflamatÃrias, desordens gastrointestinais como diarreia, disenteria e Ãlceras, problemas renais, hipertensÃo, impotÃncia sexual e reumatismo. O objetivo deste trabalho foi evidenciar o(s) possÃvel(is) mecanismo(s) de aÃÃo subjaentes ao efeito gastroprotetor do extrato aquoso (EA) de Maytenus rigida em camundongos suÃÃos, no modelo de lesÃo gÃstrica induzida por etanol absoluto. Camundongos em jejum receberam EA (100, 200 ou 400 mg/Kg, p.o.) 1 h antes da administraÃÃo oral de etanol absoluto (0,2ml/animal). Grupos tratados com salina e ranitidina foram utilizados como controles. Os estÃmagos foram analisados macro e microscopicamente. Adicionalmente, foram utilizadas diferentes ferramentas farmacolÃgicas (naloxona, morfina, misoprostol, indometacina, L-NAME, L-arginina, clonidina ou ioimbina) em diferentes ensaios, para tentar esclarecer o(s) possÃvel(is) mecanismo(s) de aÃÃo do EA. O efeito gastroprotetor macro e microscÃpico do EA foi comparado ao exercido pela ranitidina no modelo etanol-induzido (p < 0,05); a utilizaÃÃo de ferramentas farmacolÃgicas revelou que o efeito protetor do EA envolve a ativaÃÃo de receptores &#945;2-adrenÃrgicos, receptores opioides, Ãxido nÃtrico, mas nÃo depende de prostaglandinas. O EA possui efeito gastroprotetor, corroborando com seu uso tradicional. Seu efeito à multifatorial, envolvendo a participaÃÃo de receptores &#945;2-adrenÃrgicos, liberaÃÃo de Ãxido nÃtrico, e ativaÃÃo de receptores opioides.