Il existe une comorbidité entre douleur et dépression. Si les antidépresseurs inhibiteurs de recapture de monoamines représentent le traitement de première intention des troubles dépressifs unipolaires, certains d'entre eux sont également recommandés en première ligne de traitement des douleurs neuropathiques. L'objectif de ce travail a été d'étudier les propriétés analgésiques de ces antidépresseurs dans des modèles animaux co-exprimant des éléments de phénotypes douloureux et dépressifs. Pour cela nous avons développé des tests d'évaluation comportementale de la douleur chez la souris. Ces tests permettent de décrire la sensibilité douloureuse des animaux et d'évaluer les effets pharmacologiques de substances de référence et innovantes.Nous avons ainsi démontré que la fluoxétine, inhibiteur sélectif de la recapture de sérotonine (ISRS), possède des effets antalgiques sur les altérations de sensibilité d'un modèle d'anxiété/dépression chez la souris : le modèle CORT. La caractérisation d'un phénotype douloureux chronique chez ces souris renforce la pertinence de ce modèle neuropsychopharmacologique, puisqu'il exprime une des comorbidités fréquentes des pathologies dépressives. De plus, l'efficacité antalgique de la fluoxétine dans ce modèle plaide en faveur d'une modulation de la composante affective de la douleur par les ISRS.De plus, nous avons caractérisé l'effet antalgique d'une nouvelle classe d'antidépresseurs monoaminergiques, les triples inhibiteurs de recapture des monoamines capables d'augmenter à la fois les concentrations intracérébrales de sérotonine, noradrénaline et dopamine. Pour ce faire, nous avons développé un modèle de douleurs induites par injections répétées d'oxaliplatine chez la souris et comparé l'efficacité de différents traitements sur ces douleurs. Les souris " oxaliplatine " développent une hyperalgie mécanique, ainsi qu'une allodynie et hyperalgie au froid. Ces altérations de la sensibilité douloureuse sont corrigées par l'administration aigüe d'un triple bloqueur (indatraline) en faisant intervenir des mécanismes probablement supra-spinaux. La composante dopaminergique de ces substances apporte un intérêt dans le profil antalgique. Par ailleurs, les souris " oxaliplatine " développent des traits caractéristiques d'un phénotype anxio-dépressif et l'indatraline semble avoir des effets antidépresseurs dans ce modèle, ouvrant la possibilité d'une participation de la DA à la composante affective de la douleur et plus d'effets sur l'influx somatosensoriel. L'ensemble de nos travaux fait ressortir l'importance du développement et de l'utilisation de modèles animaux co-exprimant douleurs et anxiété/dépression afin de mieux définir les mécanismes liant ces pathologies et d'optimiser les critères de développement des futurs antidépresseurs et analgésiques.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Hoodia gordonii à uma planta da famÃlia das apocinÃceas. OriginÃria do sudeste da Ãfrica, onde tem sido historicamente usada para suprimir o apetite durante longas jornadas de caÃa, sendo utilizada em diversos paÃses com o objetivo de emagrecer. No Brasil foi retirada do mercado devido à falta de estudos que comprovem sua eficÃcia e seguranÃa para o uso. O objetivo deste trabalho foi avaliar as alteraÃÃes comportamentais, neuroquÃmicas e glicolipÃdicas em ratos tratados com Hoodia gordonii. Para a realizaÃÃo deste estudo H. gordonii foi administrada por via oral nas doses de 25 e 50 mg/Kg durante oito dias consecutivos em ratos Wistar machos (160-200g), D-anfetamina 2 mg/Kg foi administrada intraperitonealmente de forma aguda e usada como padrÃo positivo. Os testes aconteceram 60 minutos apÃs o ultimo dia de tratamento com a Hoodia e 30 minutos apÃs o tratamento com D-anfetamina. Foram avaliados a variaÃÃo de peso dos animais durante o tratamento, bem como o consumo de Ãgua e comida. Para os testes comportamentais foram feitos os testes de labirinto em cruz elevado, campo aberto e placa perfurada. Para os estudos neuroquÃmicos foi feito HPLC com detecÃÃo eletroquÃmica. Para os testes glicolipÃdicos foi feita dosagem de Glicose, HDL, LDL, TG, colesterol total, ALT e AST. Os resultados mostraram que H. gordonii à capaz de reduzir o ganho de massa corpÃrea, bem como reduzir o consumo de comida e Ãgua. Os resultados dos testes comportamentais mostraram que ela à capaz de reduzir os parÃmetros observados no teste do labirinto em cruz e placa perfurada sem mostrar alteraÃÃo significante no campo aberto. Os resultados dos experimentos neuroquÃmicos evidenciaram um aumento do conteÃdo de noradrenalina e dopamina em corpo estriado de ratos, detectados eletroquimicamente pelo HPLC. Nos testes bioquÃmicos foi visto que ela tem a capacidade de reduzir os nÃveis de glicose, bem como a concentraÃÃo de triglicerÃdeos e colesterol total em soro de ratos, sem mostrar alteraÃÃo significante da ALT e AST. Foi possÃvel concluir que H. gordonii à capaz de reduzir a ingestÃo de alimentos e que este efeito pode estar de alguma forma ligado à neurotransmissÃo noradrenÃrgica e dopaminÃrgica, possuindo tambÃm atividade ansiogÃnica evidenciada pelos estudos comportamentais. / Hoodia gordonii is a plant of the family apocinaceae. Originally from southeastern Africa, where it has historically been used to suppress appetite during long hunting trips, being used in several countries in order to lose weight. In Brazil was withdrawn from the market due to lack of studies proving its efficacy and safety for use. The aim of this study was to evaluate the behavioral changes and neurochemical glicolipÃdicas in rats treated with Hoodia gordonii. For this study H. gordonii was administered orally at doses of 25 and 50 mg/kg for eight consecutive days in male Wistar rats (160-200g), D-amphetamine 2 mg/kg was intraperitoneally administered acutely and used as a positive standard. The tests took place 60 minutes after the last day of treatment with the Hoodia and 30 minutes after treatment with D-amphetamine. We evaluated the weight change of the animals during treatment, as well as the consumption of water and food. For behavioral tests were performed tests elevated plus-maze, open field and hole board. For neurochemical studies was done HPLC with electrochemical detection. For testing was done glycolipid glucose, HDL, LDL and TG, total cholesterol, ALT and AST. The results showed that H. gordonii is capable of reducing body mass gain and reduce the consumption of food and water. The results of behavioral tests showed that it is able to reduce the parameters observed in the plus-maze test and hole board showing no significant change in the open field. The results of experiments showed an increase in the neurochemical content of noradrenaline and dopamine in the striatum of rats electrochemically detected by HPLC. In biochemical tests it was seen that it has the ability to lower blood glucose levels as well as the concentration of triglycerides and total cholesterol in serum from mice, showing no significant change in ALT and AST. It was concluded that H. gordonii is able to reduce food intake, and this effect may be somehow linked to the dopaminergic and noradrenergic neurotransmission, having also anxiogenic activity evidenced by behavioral studies.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Os efeitos da melatonina (Mel) in vivo foram estudados no sistema dopaminÃrgico nigroestriatal de ratos, utilizando um modelo experimental da doenÃa de Parkinson que consiste na injeÃÃo intraestriatal da neurotoxina 6-hidroxidopamina (6-OHDA). Ratos Wistar, machos (200-250g) foram submetidos a lesÃo unilateral com 6-OHDA, tratados com melatonina nas doses de 2, 5, 10 e 25 mg/kg, i.p. 1 hora apÃs a lesÃo e depois, diariamente durante 7 dias, quatro semanas apÃs a lesÃo, foi realizado o teste rotacional e 24 horas depois os animais foram sacrificados, os seus cÃrebros dissecados e os estriados direito (ipsilateral â lado lesionado) e esquerdo (contralateral â lado nÃo lesionado) utilizados para dosagens de monoaminas em HPLC e ensaios de binding dopaminÃrgico. Para as dosagens de malonildialdeÃdo (MDA), os animais foram sacrificados no oitavo dia apÃs a lesÃo. Os resultados demonstraram que a injeÃÃo intraestriatal de 6-OHDA diminuiu cerca de 77 à 85% os conteÃdos das monoaminas e dos seus metabÃlitos no lado ipsilateral quando comparado com o lado contralateral nos controles. O tratamento com melatonina, nas doses estudadas, reverteu parcialmente as diminuiÃÃes causadas pela lesÃo com 6-OHDA nos nÃveis destes neurotransmissores, e os conteÃdos se aproximaram de 50% daqueles observados nos lados contralaterais dos controles ou dos grupos tratados com melatonina. A Mel foi mais eficiente na dose de 5 mg/kg, i.p., e os efeitos foram similares entre as doses mais baixas e as mais altas, caracterÃstica de um tipo de resposta com a curva em forma de sino. O prÃ-tratamento e o tratamento crÃnico com melatonina na dose que obteve o melhor efeito tambÃm foram estudados, o tratamento crÃnico promoveu uma melhor recuperaÃÃo dos nÃveis de monoaminas enquanto os efeitos do prÃ-tratamento foram similares aos do grupo Mel 5 mg/kg, durante 7dias. O comportamento rotacional induzido pela apomorfina (3 mg/kg) foi bloqueado em cerca de 60, 89, 78 e 47% nos grupos tratados com melatonina nas doses de 2, 5, 10 e 25 mg/kg, i.p., respectivamente. O tratamento crÃnico bloqueou o comportamento rotacional em cerca de 96% e o prÃ-tratamento 86%. A melatonina (5 mg/kg) produziu uma upregulation dos receptores D1 (Bmax: 277,8+/-25,8) associada com uma diminuiÃÃo nos valores do Kd (1,5+/-0,1) quando comparado ao controle (Bmax:194,8+/-19,0; Kd:2,9+/-0,38). Um efeito similar foi observado com o tratamento com NAS (Bmax: 245,3+/-27,6; Kd: 1,1+/-0,28), precursor da melatonina. Foi verificado um aumento nos nÃveis de MDA, nos controles (127%), quando comparado com o grupo falso operado (104%), o tratamento com melatonina (106%) recuperou esses nÃveis à valores prÃximos do normal, sugerindo uma aÃÃo antioxidante da melatonina in vivo. Os resultados apresentados podem indicar uma aÃÃo neuroprotetora da melatonina e sugerem um possÃvel papel no tratamento de doenÃas neurodegenerativas causadas pelo estresse oxidativo, como a doenÃa de Parkinson. / The present work studied the neuroprotective effects of melatonin In vivo on the nigrostriatal dopaminergic system in rats after a unilateral 6-hydroxydopamine (6-OHDA) lesions in rat striatum. Results showed that the intrastriatal injection of 6-OHDA significantly decreases DA, DOPAC and HVA levels. Although there is also a decrease in 5-HT levels no changes were observed in 5-HIAA levels as compared to controls. On the other hand, melatonin (2, 5, 10 and 25 mg/kg, i.p., daily for 7 days) treatment starting 1 h after 6-OHDA lesions, partially reverses the decreases caused by 6-OHDA lesions on these neurotransmitter levels, and contents were brought to approximately 50% of that observed in the contralateral sides of controls or the melatonin treated group. Melatonin was more efficient at the doses of 5 and 10 mg/kg, i.p., and effects were similar between the lowest and highest doses characteristic of a bell-shaped type of response. Pretreatment and cronic treatment with melatonin at the 5mg/kg dose were also tested, cronic treatment promoted a recovey of monoamines levels more efficiently while the pretreatment effects were similar to the melatonin treatment at the dose of the 5mg/kg for 7 days. The apomorphine-induced rotational behavior (3 mg/kg, i.p.) was blocked by 60, 89, 78 and 47% after the doses of 2, 5, 10 and 25 mg/kg, i.p., respectively. Similarly, in this case the doses of 5 and 10 mg/kg were also more efficient. The cronic treatment blocked the rotational behavior by 86%. Melatonin (5mg/kg) produced an upregulation of D1 receptors associated with a decrease in Kd value. While no change was observed in maximum density of D2 receptors, the Kd value was also decreased, a similar effect was observed with its precursor N-acetylserotonin. Compared with sham-operated and expressed as a ratio relative to the contralateral side, there was an increase in the lipid peroxidation product malondialdehyde (MDA, 127%) on controls which was restored to normal levels on the melatonin treated group, suggesting the in vivo action of melatonin as an antioxidant. The present results may indicate a neuroprotective action of melatonin and suggest a possible role in the treatment of oxidative stress-induced neurodegenerative disease such as Parkinsonâs disease.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / O extrato padronizado de chambÃ, preparado a partir das partes aÃreas da Justicia pectoralis Jacq. var stenophylla Leonard, foi avaliado em modelos animais clÃssicos para screening de drogas com atividade em ansiedade, depressÃo, sedaÃÃo e convulsÃo, tais como, labirinto em cruz elevado (LCE), claro/escuro, campo aberto, rota rod, nado forÃado, suspensÃo da cauda, tempo de sono induzido por pentobarbital e convulsÃo induzida por pentilenotetrazol, e em estudo neuroquÃmico, atravÃs da concentraÃÃo de monoaminas e seus metabÃlitos, tais como dopamina (DA), Ãcido diidrofenil acÃtico (DOPAC), Ãcido homovalÃnico (HVA), noradrenalina (NE), 5-hidroxitriptamina (5-HT) e Ãcido 5-hidroxindolacÃtico (5-HIAA). O chambà foi administrado de forma aguda em todos os testes, nas doses de 50, 100 e 200 mg/kg, atravÃs da via oral (v.o.) Os resultados mostraram que o extrato apresentou efeito ansiolÃtico nos modelos LCE e claro/escuro, pois aumentou todos os parÃmetros analisados no LCE, como NEBA, PEBA, TPBA e PTBA, assim como o tempo de permanÃncia no box claro no claro/escuro. Este efeito està possivelmente relacionado com o sistema gabaÃrgico jà que o flumazenil, antagonista dos receptores GABAA/BenzodiazepÃnico, reverteu o efeito ansiolÃtico do chambà no LCE. No teste do campo aberto, nÃo foi observado nenhuma alteraÃÃo na atividade locomotora, bem como no nÃmero de grooming e rearing. O chambà apresentou efeito depressor do Sistema Nervoso Central (SNC), pois nos testes nado forÃado e suspensÃo da cauda, aumentou o tempo de imobilidade dos animais. A avaliaÃÃo sedativa/hipnÃtica do chambÃ, no teste do tempo de sono induzido por pentobarbital, mostrou que nÃo houve alteraÃÃo na duraÃÃo do sono dos animais, descartando efeito sedativo. No teste da convulsÃo induzida por pentilenotetrazol, o chambà nÃo alterou a latÃncia de convulsÃo, bem como a latÃncia de morte. Esse resultado sugeriu que o chambà nÃo possui efeito anticonvulsivante. A avaliaÃÃo neuroquÃmica comprovou o efeito depressor do extrato, pois foi verificada uma reduÃÃo da concentraÃÃo das monoaminas. Em conclusÃo, esses efeitos mostraram que o chambà apresenta efeito ansiolÃtico, provavelmente relacionado com o sistema gabaÃrgico e efeito depressor, desprovido de atividade anticonvulsivante e sedativa. / The standardized extract of chamba, prepared from the aerial parts of Justicia pectoralis Jacq. var stenophylla Leonard, was evaluated in classical animal models to the screening of drugs with activity in axiety, depression, sedation and convulsion, such as elevated plus maze (EPM), light/dark, open field, rota rod, forced swimming, tail suspension, pentobarbital-induced sleep time and pentilenotetrazole-induced seizures and a neurochemistry study, through the level of monoamines and its metabolites, such as dopamine (DA), 3,4-dihydroxyphenyl acetic acid (DOPAC), homovanilic acid (HVA), norepinephrine (NE), 5-hydroxytryptamine (5HT) and 5-hydroxyindoleacetic acis (5HIAA). Chambà was administered acutely in all tests, in the doses of 50, 100 and 200 mg/kg, through the oral via (p.o.). Results showed that the extract presented an anxiolytic effect in the models of EPM and light/dark, since increased all the parameters analyzed in the EPM, such as NEOA, PEOA, TPOA, PTOA, as well as the permanence time in the light compartment. This effect is probably related with the GABAergic system since Flumazenil, an antagonist of GABAA/benzodiazepinic, reversed the anxiolytic effect of chamba in the EPM. In the open field, it was not observed any alteration in the locomotor activity, as well as the number of grooming and rearing. Chamba presented depressor effect of Central Nervous System (CNS), since in the forced swimming and tail suspension, increased the immobility time of animals. The sedative/hypnotic evaluation of chamba, in pentobarbital-induced sleep time showed that it has no alteration in the duration of sleep of animals, discarding sedative effect. In the pentilenotetrazole-induced seizures, chamba did not change the convulsion latency, as well the death latency. This result suggests that chamba did not have anticonvulsivant effect. The neurochemistry evaluation comproved the depressor effect of the extract, since it was verified a reduction in the level of monoamine levels, involved in the depression. In conclusion, these effects showed that chamba presented anxiolytic effect, probably related with the GABAergic system and depressor effect disproved anticonvulsant and sedative effects.

Only one third of depressed patients experience a beneficial therapeutic effect after using a first-line medication, leaving two-thirds of patients without effective treatment. It has been shown that a combination of two drugs with different modes of action result in an increase in the number of patients responding to treatment. One of the most effective strategies is the addition of low doses of an atypical antipsychotic. In depth evaluation of the neurobiological properties of atypical antipsychotics have revealed that these agents produce antidepressant effects and enhance the therapeutic response of first-line medications through antagonism of the 5-HT2A, 5-HT2C, 5-HT1B/D, 5-HT7 receptors and NET; agonism of the 5-HT1A receptor; and/or D2/3 partial agonism. The present experiments focused on determining the mode of action of this combination of drugs to help design better antidepressant treatment in the future. A series of electrophysiological experiments were proposed to assess 5-HT and NE neurotransmission in the rat hippocampus, as well as DA transmission in the rat forebrain.

La fonction cardiaque est finement régulée par des hormones de type monoamines qui constituent des régulateurs cruciaux de l’activité cardiaque (chronotropie et inotropie). Ces hormones dérivées d’acides aminés aromatiques comprenant les catécholamines et la sérotonine maintiennent l’activité du myocarde dans un cadre physiologique tout en lui permettant de s’adapter aux contraintes environnementales. Les récepteurs cellulaires des monoamines sont couplés à des voies de signalisation qui impliquent un nucléotide cyclique, l’AMPc, et modulent la contractilité des cardiomyocytes par l’intermédiaire de multiples phosphorylations des protéines régulatrices du cycle du calcium (canal calcique de type L, RyR2 ou phospholamban) par la protéine kinase A AMPc-dépendante. Lorsque les monoamines voient leurs activités dérégulées en contextes pathologiques tels que l’insuffisance cardiaque (IC) ou un lors d'un traitement antidépresseur, elles conduisent à une hyperstimulation de leurs récepteurs spécifiques. Cette dernière altère alors les voies impliquant l’AMPc et les flux calciques engendrant des évènements ectopiques proarythmogéniques nommés post-dépolarisations. Ces dysfonctions de la contractilité cellulaire et de l'homéostasie calcique peuvent être à l’origine d’arythmies tissulaires et de morts subites cardiaques. Les altérations de l’homéostasie calcique subsistent en dépit des approches thérapeutiques actuelles (!-bloquants, inhibiteurs de l’enzyme de conversion de l’angiotensine) qui vise à freiner le remodelage myocardique post-ischémique et constituent donc une cible active de la recherche cardiovasculaire. Les Rycals, stabilisateurs pharmacologiques du RyR2, représentent une nouvelle approche visant à remédier à ces altérations. Au sein de ces travaux de recherche, nous avons axé nos études sur les deux voies monoaminergiques AMPc cardiaques majeures, les voies adrénergiques et sérotoninergiques. Un premier axe d’étude a consisté en l’évaluation des bénéfices potentiels d’un nouveau Rycal, le S44121, sur la survenue d’arythmies cellulaires et tissulaires en comparaison d’un !-bloquant de référence, le métoprolol, dans un contexte d’IC post-infarctus chez le rat. L’étude n’a cependant pas mise en évidence de bénéfices du S44121 mais a confirmé la cardioprotection exercée par le métoprolol. Un deuxième axe d’étude a évalué l’implication potentielle au niveau cardiaque de la protéine S100A10 dans la modulation de la voie du récepteur à la sérotonine de type 4 (5-HT4R) en conditions physiologiques ou en contexte d’IC. Cette étude originale a mis en avant pour la première fois dans le coeur sain un rôle de la S100A10 dans l’apparition d’une voie 5-HT4R proarythmogène lorsque son expression est induite par une neurotrophine (Brain-derived neurotrophic factor) ou un antidépresseur (imipramine). En revanche, le rôle de la S100A10 dans la modulation de la voie 5-HT4R en contexte d’IC n’a pas été déterminé de façon certaine. / Cardiac function is tightly regulated by hormones such as monoamines which are substantial modulators of cardiac activity (chronotropy and inotropy). These hormones, derived from aromatic amino acids, maintain myocardial activity in a physiological range and allow the cardiac adaptation to environmental conditions. The cellular receptors to monoamines are coupled to signaling pathways involving a cyclic nucleotide, cAMP, and modulate cardiac activity by phosphorylating several key proteins of calcium handling (L-type calcium channel, RyR2 or phospholamban) by the cAMP-dependent protein kinase A. Deregulation of monoamines in pathological conditions such as heart failure (HF) or during antidepressanttreatment leads to a hyperstimulation of their specific receptors. It therefore induces alterations of the cAMP signaling pathway and calcium handling leading to the occurrence of proarrhythmogenic ectopic cellular events known as afterdepolarizations. These dysfunctions in cellular contractility and calcium handling may cause tissue arrhythmias andeven sudden cardiac death. Calcium handling alterations leading to cardiac arrhythmias remain a clinically relevant issue despite the current therapeutical approaches (!-blockers, angiotensin-converting-enzyme inhibitors) which slow the post-ischemic myocardial remodeling and thus represent an active target in the cardiovascular research field. Rycals, RyR2 pharmacological stabilisers, are a new approach to prevent these alterations. In this work, we focused on the two major monoaminergic cAMP-dependent pathways in the heart, the adrenergic and serotoninergic pathways. In the first part of this work, we aimed to evaluate the potential benefits of a new Rycal, S44121, on cellular and tissue arrhythmias occurrence in post-myocardial infarction rat model. These effects were compared to those of the well-known !-blocker, metoprolol. This study failed to show any strong benefit of S44121 but confirmed the cardioprotection associated with the metoprolol use. In a second part of the work presented here, we aimed to evaluate the potential involvement of the S100A10 protein in the modulation of the cardiac serotonin receptor 4 pathway (5-HT4R) in physiological conditions or during HF. This original study unraveled for the first time a new role for S100A10 in the healthy heart by revealing a functional 5-HT4R pathway when S100A10 expression is induced by neurotrophins such as brain-derived neurotrophic factor or by antidepressant drugs such as imipramine. However, we failed to conclude on a direct evidence for a role of S100A10 in the modulation of the 5-HT4R pathway in the failingheart.

Abstract Light acts as the most important regulating and entraining factor of the mammalian circadian rhythm. This rhythm has evolved to set phases, in which different physiological and behavioral events occur at the right time of the day to synchronize the organism. The mechanism of light transduction via eyes to the brain and its effects on circadian rhythmicity is well known. Yet, it has also been shown that light is able to penetrate the skull bone directly, but it is still unknown, whether transcranial light is able to affect molecules regulating circadian rhythmicity. Monoamines and especially opsins have been shown to act as important regulators in circadian rhythmicity. Both group of molecules can mediate the effects of light on regulation and entrainment. In this thesis, mice and hamsters have been illuminated transcranially and the expression of three different opsins and the concentrations of several monoamines have been measured. The animals were illuminated under anesthesia either just after the onset of the light period or just after the beginning of the dark period. The opsin expression in rodent brain were measured by western blot and the monoamine concentrations from mouse brain, plasma and adrenal gland were measured by HPLC. It was observed that both opsin expression and monoamine concentrations can be influenced by transcranial illumination. The effect varied depending on the studied molecule, tissue and time of illumination. The findings of this study demonstrate that opsins, which are considered to be the most important molecules regulating circadian rhythmicity, can be directly and specifically affected not only via the eyes but also by light illuminated through the skull. Furthermore, monoamine production can be altered in both the central nervous system and the peripheral tissues by transcranial illumination. This thesis demonstrates an alternate pathway for circadian entrainment and regulation by light involving specific molecular mediators such as opsins and monoamines. / Tiivistelmä Valo on tärkein yksittäinen tekijä nisäkkäiden vuorokausirytmiikassa. Tämä rytmi on kehittynyt ajoittamaan fysiologiset ja käyttäytymiseen perustuvat ilmiöt tapahtumaan oikeaan aikaan vuorokaudesta. Valosignaalin välittyminen silmien kautta aivoihin ja sen vaikutukset vuorokausirytmiikkaan ovat hyvin tunnetut ja paljon tutkitut, mutta vielä on epäselvää, pystyykö kallon läpi annettava valo samaan, vaikka valon on osoitettu pystyvän läpäisemään nisäkkäiden kallon. Monoamiinit ja opsiinit ovat molekyylejä, jotka ovat tärkeässä roolissa vuorokausirytmiikan säätelyssä, ja molempien ilmeneminen on riippuvainen valon määrästä. Tässä väitöskirjassa valotettiin hiirien ja hamstereiden aivoja korvan kautta annettavalla valolla ja mitattiin kolmen eri opsiinin ekspressiota sekä monoamiinien määrää. Eläimiä valotettiin nukutuksessa joko valojakson alussa aamulla tai valojakson päätyttyä illalla. Opsiinien ekspressio aivoissa mitattiin western blot -menetelmällä ja monoamiinien HPLC-menetelmällä. Tuloksista huomattiin, että sekä opsiinien ekspressioon että monoamiinien pitoisuuksiin voidaan vaikuttaa suoraan kallon läpi annettavalla valolla. Valohoidon vaikutus riippui tutkittavasta molekyylistä, kudoksesta ja valohoidon ajankohdasta. Näiden tulosten avulla pystyttiin osoittamaan, että opsiinien, jotka ovat tärkeimpiä molekyylejä vuorokausirytmiikan säätelyssä, määrää voidaan manipuloida myös kallon läpi annettavan valon vaikutuksesta. Lisäksi kallon läpi annettavalla valolla voidaan vaikuttaa monoamiinien pitoisuuksiin sekä keskushermostossa että muissa kudoksissa. Tämä väitöskirja antaa tärkeää tietoa vuorokausirytmiikkaa säätelevistä molekyyleistä ja osoittaa, että niihin pystytään vaikuttamaan myös muuten kuin silmien kautta annettavalla valolla.

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No description available.

Depression and other mood disorders, as well as cognitive and motor dysfunction have been linked with changes in monoamine levels in the brain. Environmental acetylcholinesterase (AChE) inhibitors, such as organophosphate insecticides (OPs), have also been shown to induce these problems. This study investigated whether insecticide-induced AChE inhibition, induced by chlorpyrifos (CPS), may contribute to the types of forebrain monoaminergic alterations associated with psychiatric, cognitive and motor dysfunction. Increased synaptic ACh, resulting from CPS-induced AChE inhibition, may alter the synthesis or release of monoamines through prolonged action of ACh on monoaminergic neurons that contain ACh receptors. Adult, male Sprague-Dawley rats were subjected to a single subcutaneous dose of CPS or corn oil vehicle. Brains were rapidly removed and the frontal cortex, hippocampus and striatum were bilaterally dissected on ice. These three regions from one side were assayed for AChE activity, while those from the opposite side were processed for high performance liquid chromatography with electrochemical detection (HPLC-ED) analysis of monoamine neurotransmitters and their metabolites. In the initial, exploratory experiment, inhibition of AChE activity was 66.8% in the frontal cortex, 43.8% in the hippocampus and 46.9% in the striatum, 7 days after a 60mg/kg dose of CPS. No significant differences in concentration of monoamine neurochemicals were observed between vehicle control and CPS-treated groups in either the hippocampus or striatum. However, in the frontal cortex of the CPS-treated rats there was a significant increase in median dihydroxyphenylacetic acid (DOPAC) concentration (P=0.019) and a very strong statistical trend toward increased dopamine (DA) concentration (P=0.0506). The second experiment examined the time course of AChE inhibition produced by a higher dose (200mg/kg) of CPS and how monoamine levels changed in conjunction with this pattern of AChE inhibition. Percent inhibition of AChE activity in CPS-treated animals, at 4, 14 and 21 days post-exposure was 77.0%, 86.6% and 81.9% in the frontal cortex, 86.1%, 85.9% and 83.2% in the hippocampus and 90.1%, 89.8% and 85.5% in the striatum. No significant differences in monoamine neurochemicals were observed between vehicle control and CPS-treated groups in either the hippocampus or striatum. A statistical trend toward a decrease in serotonin (5-HT) was seen in the frontal cortex at 14 days (P=0.0753) following CPS exposure. A very consistent, yet non-significant pattern of an increase in monoamines at 4 days post-CPS was observed in all instances, except for 5-hydroxyindoleacetic acid (5-HIAA) in the striatum. Therefore, the final experiment employed a more powerful design to focus on monoamine levels during, or shortly after, the change in AChE activity that rapidly follows exposure to 200mg/kg CPS. This experiment also employed a behavioral analysis on the day of sacrifice to assess the presence or absence of clinical signs of toxicity associated with this dose. Of the 30 CPS-treated rats, only 1 animal displayed a single behavioral sign of cholinergic poisoning. Percent inhibition of AChE activity at 2 and 4 days after treatment was 81.4% and 79.4% in the frontal cortex, 53.4% and 83.5% in the hippocampus, and 80.5% and 87.8% in the striatum. No significant changes in monoamine neurochemicals were observed between vehicle control and CPS-treated groups in either the frontal cortex or hippocampus. However, a significant increase in DOPAC (P=0.0285) in the striatum, 2 days after CPS treatment, was observed. In addition, a strong statistical trend toward decreased striatal 5-HT (P=0.0645) was reported 4 days after CPS treatment. The only significant correlation between AChE activity and monoamine concentration was observed for 5-HIAA in the striatum of CPS-treated, 2 day survivors (P=0.0445). However, it was of low magnitude (r=0.525, r2=0.276). CPS has a limited capacity to produce changes in monoamine neurotransmitters and/or their metabolites in the frontal cortex and striatum of the mammalian brain. These changes are primarily seen in the dopaminergic system. Alterations of monoamines do not appear to be strongly associated with incident levels of AChE inhibition. The biological implication of the limited OP induced changes in central monoamines remains significant, as changes in monoamines in the CNS nervous system have been linked to psychiatric, cognitive and motor dysfunction. / Master of Science