Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Deep brain stimulation (DBS) has emerged as a potential intervention for treatment-resistant tardive dyskinesia (TD). Despite promising case reports, no consensus exists regarding optimal stimulation parameters, neuroanatomical target for DBS in TD, or mechanisms underlying its anti-dyskinetic effects. We used vacuous chewing movements (VCMs) in rats treated chronically with haloperidol (HAL) as a TD model to address some of these issues. We show that acute DBS applied to the subthalamic nucleus (STN) or the entopeduncular nucleus (EPN) suppresses VCMs without affecting locomotor activity. Using immediate early gene mapping with zif268 as an index of neuronal activity, we found that STN-DBS induced decreases in activity throughout the basal ganglia, whereas EPN-DBS increased activity in projection regions. While chemical inactivation of the STN or EPN with the GABAA agonist muscimol also suppressed VCMs, muscimol infusion did not mimic the changes in neuronal activity induced by DBS, suggesting that DBS is not equivalent to functional inactivation. We next examined the contribution of serotonin (5-HT) and dopamine (DA) to the anti-dyskinetic effects of DBS. Decreasing 5-HT transmission pharmacologically or with serotonergic lesions decreased VCMs. Using microdialysis and zif268 mapping, we determined that STN- but not EPN-DBS decreased 5-HT release and activity of raphe neurons. However, when the decrease in 5-HT induced by STN-DBS was prevented by pre-treating rats with fluoxetine or fenfluramine, we found that decreasing 5-HT is not necessary for the anti-dyskinetic effects of DBS. STN-DBS transiently increased striatal DA release in intact rats only, whereas EPN-DBS had no effect on DA release. Moreover, pharmacologically elevating DA levels did not suppress VCMs. Together these findings lead us to conclude that increased DA release does not contribute to the anti-dyskinetic effects of DBS. Finally, we compared depressive- and anxiety-like behaviours induced by chronic DBS of the EPN and STN, since adverse psychiatric effects of DBS have become a significant clinical concern. STN-DBS but not EPN-DBS induced depressive-like behaviour in a learned helplessness task. We established that the chronic HAL VCM model preparation may be used to explore mechanisms underlying anti-dyskinetic and psychiatric effects of DBS, and provided the first investigations into these mechanisms.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Deep brain stimulation (DBS) has emerged as a potential intervention for treatment-resistant tardive dyskinesia (TD). Despite promising case reports, no consensus exists regarding optimal stimulation parameters, neuroanatomical target for DBS in TD, or mechanisms underlying its anti-dyskinetic effects. We used vacuous chewing movements (VCMs) in rats treated chronically with haloperidol (HAL) as a TD model to address some of these issues. We show that acute DBS applied to the subthalamic nucleus (STN) or the entopeduncular nucleus (EPN) suppresses VCMs without affecting locomotor activity. Using immediate early gene mapping with zif268 as an index of neuronal activity, we found that STN-DBS induced decreases in activity throughout the basal ganglia, whereas EPN-DBS increased activity in projection regions. While chemical inactivation of the STN or EPN with the GABAA agonist muscimol also suppressed VCMs, muscimol infusion did not mimic the changes in neuronal activity induced by DBS, suggesting that DBS is not equivalent to functional inactivation. We next examined the contribution of serotonin (5-HT) and dopamine (DA) to the anti-dyskinetic effects of DBS. Decreasing 5-HT transmission pharmacologically or with serotonergic lesions decreased VCMs. Using microdialysis and zif268 mapping, we determined that STN- but not EPN-DBS decreased 5-HT release and activity of raphe neurons. However, when the decrease in 5-HT induced by STN-DBS was prevented by pre-treating rats with fluoxetine or fenfluramine, we found that decreasing 5-HT is not necessary for the anti-dyskinetic effects of DBS. STN-DBS transiently increased striatal DA release in intact rats only, whereas EPN-DBS had no effect on DA release. Moreover, pharmacologically elevating DA levels did not suppress VCMs. Together these findings lead us to conclude that increased DA release does not contribute to the anti-dyskinetic effects of DBS. Finally, we compared depressive- and anxiety-like behaviours induced by chronic DBS of the EPN and STN, since adverse psychiatric effects of DBS have become a significant clinical concern. STN-DBS but not EPN-DBS induced depressive-like behaviour in a learned helplessness task. We established that the chronic HAL VCM model preparation may be used to explore mechanisms underlying anti-dyskinetic and psychiatric effects of DBS, and provided the first investigations into these mechanisms.

Thesis (MSc)--University of Stellenbosch, 2007. / Bibliography. Also available via the Internet.

Tardive dyskinesia (TD) is a serious side effect of certain antipsychotic medications that are used to treat schizophrenia (SCZ) and other mental illnesses. The methylation status of the insulin receptor substrate 1 (IRS1) gene is reportedly associated with SCZ; however, no study, to the best of the authors' knowledge, has focused on the quantitative DNA methylation levels of the IRS1 gene using pyrosequencing in SCZ with or without TD. The present study aimed to quantify DNA methylation levels of 4 CpG sites in the IRS1 gene using a Chinese sample including SCZ patients with TD and without TD (NTD) and healthy controls (HCs). The general linear model (GLM) was used to detect DNA methylation levels among the 3 proposed groups (TD vs. NTD vs. HC). Mean DNA methylation levels of 4 CpG sites demonstrated normal distribution. Pearson's correlation analysis did not reveal any significant correlations between the DNA methylation levels of the 4 CpG sites and the severity of SCZ. GLM revealed significant differences between the 3 groups for CpG site 1 and the average of the 4 CpG sites (P=0.0001 and P=0.0126, respectively). Furthermore, the TD, NTD and TD + NTD groups demonstrated lower methylation levels in CpG site 1 (P=0.0003, P<0.0001 and P<0.0001, respectively) and the average of 4 CpG sites (P=0.0176, P=0.0063 and P=0.003, respectively) compared with the HC group. The results revealed that both NTD and TD patients had significantly decreased DNA methylation levels compared with healthy controls, which indicated a significant association between the DNA methylation levels of the IRS1 gene with SCZ and TD.

Certains neuropeptides (enképhaline et neurotensine) sont des modulateurs du système dopaminergique. Chez les rongeurs, le traitement avec l’antipsychotique typique halopéridol (antagoniste des récepteurs D2), augmente fortement leurs niveaux d’ARNm dans le striatum, une structure centrale du système dopaminergique qui contrôle l’activité locomotrice. Comme l’halopéridol est associé avec de nombreux effets secondaires moteurs, on peut penser que la modulation des neuropeptides est possiblement un mécanisme d’adaptation visant à rétablir l’homéostasie du système dopaminergique après le blocage des récepteurs D2. Cependant, le mécanisme moléculaire de cette régulation transcriptionnelle n’est pas bien compris. Nur77 est un facteur de transcription de la famille des récepteurs nucléaires orphelins qui agit en tant que gène d’induction précoce. Le niveau de son ARNm est aussi fortement augmenté dans le striatum suivant un traitement avec halopéridol. Plusieurs évidences nous suggèrent que Nur77 est impliqué dans la modulation transcriptionnelle des neuropeptides. Nur77 peut former des hétérodimères fonctionnels avec le récepteur rétinoïde X (RXR). En accord avec une activité transcriptionnelle d’un complexe Nur77/RXR, l’agoniste RXR (DHA) réduit tandis que l’antagoniste RXR (HX531) augmente les troubles moteurs induits par un traitement chronique à l’halopéridol chez les souris sauvages tandis que ces ligands pour RXR n’ont aucun effet chez les souris Nur77 nulles. Nos travaux ont révélé que l’antagoniste RXR (HX531) réduit l’augmentation des niveaux d’enképhaline suivant un traitement chronique avec l’halopéridol. Nous avons ensuite démontré la liaison in vitro de Nur77 sur un élément de réponse présent dans le promoteur proximal de la proenképhaline, le peptide précurseur de l’enképhaline. Ces résultats supportent l’hypothèse que Nur77, en combinaison avec RXR, pourrait participer à la régulation transcriptionnelle des neuropeptides dans le striatum et donc contribuer à la neuroadaptation du système dopaminergique suivant un traitement aux antipsychotiques typiques. / Neuropeptides (enkephalin and neurotensin) are modulators of dopaminergic system. In the rodent’s striatum, antipsychotic drugs strongly modulate their mRNA levels. For exemple, haloperidol (D2 receptor antagonist) increases their mRNA levels in the striatum, a central structure of dopaminergic system that control locomotor activity. Since haloperidol is associated with many motor side effects, it is likely that neuropeptides modulation is a compensatory mechanism to restore the dopaminergic system homeostasis after D2 receptor blockade. However, molecular mechanism of this transcriptional regulation is not well understood. Nur77 is a transcription factor of the orphan nuclear receptor family that acts as an immediate early gene. In the striatum, its mRNA level is strongly increased following haloperidol treatment. Several evidences suggest that Nur77 is involved in neuropeptides transcriptional modulation. Nur77 can form functional heterodimers with retinoid X receptor (RXR). In agreement with a transcriptional activity of Nur77/RXR complex, RXR agonist (DHA) decreases while the RXR antagonist (HX531) exacerbates acute and chronic motor side effects of haloperidol treatment in wild type mice but remain without effect in Nur77 knockout mice. Our work shows that RXR antagonist (HX531) significantly reduced the increased levels of enkephalin following chronic treatment with haloperidol. We have set up the EMSA (electro-mobility shift assay) to demonstrate the in vitro binding of Nur77 on a responsive element from proenkephalin’s proximal promotor. These results support the hypothesis that Nur77 could be involve in transcriptional modulation of neuropeptides in the striatum and thus, contribute to neuroadaptation of dopaminergic system after treatment with typical antipsychotic drugs.

Certains neuropeptides (enképhaline et neurotensine) sont des modulateurs du système dopaminergique. Chez les rongeurs, le traitement avec l’antipsychotique typique halopéridol (antagoniste des récepteurs D2), augmente fortement leurs niveaux d’ARNm dans le striatum, une structure centrale du système dopaminergique qui contrôle l’activité locomotrice. Comme l’halopéridol est associé avec de nombreux effets secondaires moteurs, on peut penser que la modulation des neuropeptides est possiblement un mécanisme d’adaptation visant à rétablir l’homéostasie du système dopaminergique après le blocage des récepteurs D2. Cependant, le mécanisme moléculaire de cette régulation transcriptionnelle n’est pas bien compris. Nur77 est un facteur de transcription de la famille des récepteurs nucléaires orphelins qui agit en tant que gène d’induction précoce. Le niveau de son ARNm est aussi fortement augmenté dans le striatum suivant un traitement avec halopéridol. Plusieurs évidences nous suggèrent que Nur77 est impliqué dans la modulation transcriptionnelle des neuropeptides. Nur77 peut former des hétérodimères fonctionnels avec le récepteur rétinoïde X (RXR). En accord avec une activité transcriptionnelle d’un complexe Nur77/RXR, l’agoniste RXR (DHA) réduit tandis que l’antagoniste RXR (HX531) augmente les troubles moteurs induits par un traitement chronique à l’halopéridol chez les souris sauvages tandis que ces ligands pour RXR n’ont aucun effet chez les souris Nur77 nulles. Nos travaux ont révélé que l’antagoniste RXR (HX531) réduit l’augmentation des niveaux d’enképhaline suivant un traitement chronique avec l’halopéridol. Nous avons ensuite démontré la liaison in vitro de Nur77 sur un élément de réponse présent dans le promoteur proximal de la proenképhaline, le peptide précurseur de l’enképhaline. Ces résultats supportent l’hypothèse que Nur77, en combinaison avec RXR, pourrait participer à la régulation transcriptionnelle des neuropeptides dans le striatum et donc contribuer à la neuroadaptation du système dopaminergique suivant un traitement aux antipsychotiques typiques. / Neuropeptides (enkephalin and neurotensin) are modulators of dopaminergic system. In the rodent’s striatum, antipsychotic drugs strongly modulate their mRNA levels. For exemple, haloperidol (D2 receptor antagonist) increases their mRNA levels in the striatum, a central structure of dopaminergic system that control locomotor activity. Since haloperidol is associated with many motor side effects, it is likely that neuropeptides modulation is a compensatory mechanism to restore the dopaminergic system homeostasis after D2 receptor blockade. However, molecular mechanism of this transcriptional regulation is not well understood. Nur77 is a transcription factor of the orphan nuclear receptor family that acts as an immediate early gene. In the striatum, its mRNA level is strongly increased following haloperidol treatment. Several evidences suggest that Nur77 is involved in neuropeptides transcriptional modulation. Nur77 can form functional heterodimers with retinoid X receptor (RXR). In agreement with a transcriptional activity of Nur77/RXR complex, RXR agonist (DHA) decreases while the RXR antagonist (HX531) exacerbates acute and chronic motor side effects of haloperidol treatment in wild type mice but remain without effect in Nur77 knockout mice. Our work shows that RXR antagonist (HX531) significantly reduced the increased levels of enkephalin following chronic treatment with haloperidol. We have set up the EMSA (electro-mobility shift assay) to demonstrate the in vitro binding of Nur77 on a responsive element from proenkephalin’s proximal promotor. These results support the hypothesis that Nur77 could be involve in transcriptional modulation of neuropeptides in the striatum and thus, contribute to neuroadaptation of dopaminergic system after treatment with typical antipsychotic drugs.

Orientadora: Profª Drª Marcela Bermúdez Echeverry / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Neurociência e Cognição, 2015. / Estudos tem mostrado que o fator de transcricao FosB/ delta FosB e regulado em resposta ao tratamento cronico com antipsicoticos. Porem, so a regulacao do fator FosB no estriado pode ter uma relevancia funcional nas alteracoes motoras pelos antipsicoticos tipicos e atipicos, uma vez que o gene e expressado na via direta e indireta do estriado. Assim, o objetivo do presente trabalho foi determinar se as alteracoes motoras induzidas pela administracao cronica de haloperidol, olanzapina ou clozapina regulam a expressao do FosB de maneira diferenciada no estriado motor e limbico. Metodos: Camundongos adultos machos C57Bl receberam injecao intraperitoneal agudo, subcronico ou cronico de Haloperidol, Olanzapina ou Clozapina. Tambem foram avaliados os efeitos extrapiramidais. Experimento 1: Administracao subcronica (5 dias) foi estudado com haloperidol 4 mg/Kg, olanzapina 15 mg/Kg ou Clozapina 20 mg/Kg para confirmar o efeito cataleptico. Experimento 2: As alteracoes motoras apos do tratamento cronico (77 dias) foram avaliadas com o teste de catalepsia, campo aberto, rota rod, pole test e vacuous chewing movement, com as mesmas doses do experimento 2. No ultimo experimento a expressao da proteina FosB foi avaliada. Resultados: Experimento 1: Com a administracao subcronica tipicos e atipicos induzem a catalepsia, sendo menor com os atipicos. Experimento 2: O tratamento cronico com os dois grupos de neurolepticos induzem alteracoes motoras. Foi observado aumenta da imobilizacao no teste de catalepsia e no campo aberto, sendo maior no grupo Haloperidol. Tambem foi observado alteracao no rota rod. Los grupos Haloperidol e Olanzapina tiveram aumento da expressao do FosB no estriado dorsal e ventral. Porem, o grupo Olanzapina no mostrou aumento na regiao Core do nucleo accumbens, resultado oposto observado com a Clozapina, onde mostrou aumento da expressao na regiao limbica do estriado, sem ser significativo na parte dorsal. Conclusoes: O padrao da expressao do FosB na regiao Core do nucleo accumbens, pode ser correlacionado com os sintomas parkinsonianos induzidos pelos antipsicoticos atipicos como a Clozapina. Assim, a regiao Core, poder ser inclusa na circuitaria dos nucleos basais para o estudo das alteracoes motoras induzidas pelos antipsicoticos. / Background: Studies have shown that the transcription factor FosB/ÄFosB is upregulated in response to chronic neuroleptic treatment. Moreover, regulation of only the factor FosB in striatum might have functional relevance to the motor side effects by either typical or atypical neuroleptics, once this gene is expressed in striatal direct and indirect pathways. Therefore, the goal of this study was determine whether the motor side effects after chronic administration of haloperidol, olanzapine or clozapine shown differential regulation FosB expression in motor and limbic caudate putamen. Methods: Adult male mice C57Bl received either acute, subchronic, or chronic intraperitoneally injections of haloperidol, olanzapine or clozapine, and extrapyramidal effects were evaluated.. Experiment 1: Subchronic administration (5 days) was studied with haloperidol 4 mg/Kg, Olanzapine 15 mg/Kg and clozapine 20 mg/Kg to confirm a steady cataleptic effect. Experiment 2: the motor side effects after chronic treatment (77 days) was evaluated through the catalepsy test, open field, Rota Rod, pole test and vacuous chewing movements, with same doses that experiment 2. Expression FosB protein in the last experiment was examined. Results: Experiment 1: with subchronic administration both typical and atypical neuroleptics induced cataleptic effect, even though the effect was lower with olanzapine and clozapine Experiment 2: chronic treatment showed motor side effects in both neuroleptics groups, evaluated with catalepsy test, open field, with an increased immobilization time in haloperidol group. Also, an alteration in Rota Rod test was observed with both neuroleptics groups, however, haloperidol group was unique showing increased time in pole test, with a little number of vacuous chewing movements but not significant. Haloperidol and olanzapine groups showed increased FosB protein expression in dorsal and ventral striatum. However, olanzapine group had not expression in the Core region in accumbens nucleus, opposite to clozapine group that showed an enlarged expression in this limbic/motor region, with scarcely expression in dorsal striatum. Conclusions: A unique pattern of regulation of FosB expression in core region, accumbens nucleus, may correlates with parkinsonism effect of the atypical neuroleptics, clozapine. Therefore, core region could be included in the basal ganglia circuit to study motor alterations by neuroleptics.

About 20 to 25 % of psychiatric patients treated with typical antipsychotics may develop an important movement disorder named tardive dyskinesia, with complex etiology and no effective treatment. Cognitive loss is also associated with antipsychotic treatment being harmful and often difficult to identify. Some studies have shown beneficial effects of Omega 3 polyunsaturated fatty acids on tardive dyskinesia and on cognition. Considering the available evidences, we conducted a randomized, double-blind, placebo-controlled, clinical trial, which evaluated the effect of fish oil supplementation rich in n-3 polyunsaturated fatty acids (3 g/dia) or placebo (3 capsules / day), for 12 weeks, on motor and cognitive disturbances of patients on use of neuroleptics. Two evaluations were performed, one before supplementation (baseline) and another at the end of it. For this, were used the following evaluation tools: Abnormal Involuntary Movement Scale for tardive dyskinesia and Mini-Mental State Examination for cognition. Peripheral blood samples were collected before supplementation (baseline) and 4, 8 and 12 weeks after, in order to monitor the supplementation effects on biochemical parameters- triglycerides (TG), fasting glucose, total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and on parameters of blood clotting- prothrombin time and partial thromboplastin time. The biological material collected was also used to run the Comet Assay in leukocytes with the aim of investigate the treatment effect on the DNA damage index. After 3 months of supplementation, we observed that fish oil caused an improvement of 18.5 % in tardive dyskinesia, while cognitive performance did not change when compared with the baseline assessment. Furthermore, lipid profile of the patients was not modified, fasting glucose was reduced in all assessments and prothrombin time increased in the last evaluation. In addition, fish oil did not show genotoxic effect (DNA damage index did not change). Therefore, we have demonstrated the therapeutic potential of fish oil rich in Omega 3 on tardive dyskinesia of patients treated with neuroleptics and its low risk of side effects. The increase of prothrombin time suggests a possible anticoagulant effect, requiring its monitoring during chronic treatment. / Cerca de 20 a 25 % dos pacientes psiquiátricos tratados com antipsicóticos típicos podem desenvolver uma importante síndrome motora denominada discinesia tardia (DT), de etiologia complexa e ainda sem tratamento efetivo. Perdas cognitivas também estão associadas ao uso desses medicamentos, sendo muitas vezes de difícil identificação e igualmente prejudiciais. Alguns estudos têm demonstrado efeitos benéficos dos ácidos graxos poliinsaturados Omega 3 (AGPI n-3) sobre a DT e sobre a cognição. Considerando as evidências disponíveis, realizamos este trabalho que consistiu de um ensaio clínico randomizado, duplo-cego, controlado por placebo. Avaliamos os efeitos da suplementação com de óleo de peixe rico em AGPI n-3 (3 g/dia) ou placebo (3 cápsulas/dia) sobre distúrbios motores e cognitivos de pacientes sob uso de neurolépticos, por um período de 12 semanas. Foram efetuadas duas avaliações, uma antes da suplementação (basal) e outra ao final da mesma. Para isso utilizamos as seguintes ferramentas de avaliação: Escala de Movimentos Involuntários Anormais (EMIA), para a DT e Mini-Exame do Estado Mental (MEEM), para a cognição. Amostras de sangue periférico foram colhidas antes da suplementação (basal) e 4, 8 e 12 semanas após, com o propósito de acompanhar seus os efeitos sobre parâmetros bioquímicos- triglicerídeos (TG), glicemia de jejum, colesterol total, colesterol ligado à lipoproteína de alta densidade (HDL-C) e colesterol ligado à lipoproteína de baixa densidade (LDL-C), bem como sobre parâmetros de coagulação sanguínea- tempo de protrombina (TP) e tempo de tromboplastina parcial (TTP). Com o material biológico colhido, também executamos o Ensaio Cometa em leucócitos, para investigar a influência do tratamento sobre o índice de dano no DNA. Após 3 meses de suplementação, observamos que o óleo de peixe produziu uma melhora de 18,5 % na DT, enquanto o desempenho cognitivo não sofreu alteração em relação à avaliação basal. Por sua vez, o perfil lipídico dos pacientes não foi modificado, a glicemia de jejum foi reduzida em todas as avaliações e o TP aumentou na última avaliação. Ainda, o índice de dano no DNA não foi alterado, mostrando que o óleo de peixe não apresentou efeito genotóxico. Com isso, demonstramos o potencial terapêutico do óleo de peixe rico em Omega 3 sobre a DT de pacientes tratados com neurolépticos e seu baixo risco de efeitos colaterais. O aumento do TP sugere um possível efeito anticoagulante, necessitando de acompanhamento durante tratamentos crônicos.