Au delà de son rôle métabolique essentiel, le glutamate est le neurotransmetteur excitateur majeur dans le système nerveux central des mammifères. C’est pourquoi la neurotransmission glutamatergique, peu étudiée à cause de l’absence d’outils spécifiques, est l’objet d’un intérêt croissant pour tenter d’élucider son implication dans la physiopathologie de troubles psychiatriques tels que la schizophrénie et la dépression principalement caractérisés par des déficits affectifs, cognitifs, exécutifs dans lesquels le glutamate serait impliqué. Récemment, la caractérisation moléculaire et fonctionnelle de trois transporteurs vésiculaires du glutamate, nommés VGLUT1-3, a permis une approche expérimentale plus spécifique de la neurotransmission glutamatergique. Les VGLUTs diffèrent par leur distribution anatomique. En effet, les neurones VGLUT1 sont majoritairement corticaux alors que ceux exprimant VGLUT2 sont principalement sous-corticaux. VGLUT3, par contre, est retrouvé dans des neurones hétérologues à savoir sérotoninergiques, cholinergiques ou GABAergiques. Ainsi, l’objectif de cette thèse a été d’étudier chez la souris la neurotransmission glutamatergique dans des modèles pharmacologiques et génétique de maladies psychiatriques comme la dépression ou la schizophrénie. Il s’agit d’une part (i) de mesurer l’impact sur la neurotransmission glutamatergique de traitements aigus et chroniques par des psychotropes chez des souris sauvages et d’autre part (ii) d’une étude neurochimique et comportementale de la neurotransmissionn glutamatergique d’une lignée de souris mutantes (DAT-KO) dont l’invalidation du gène du transporteur de la dopamine en fait un modèle pertinent pour certains symptômes de la schizophrénie et de l’hyperactivité avec déficit attentionnel. Dans un premier temps, l’état de la neurotransmission glutamatergique corticale et sous-corticale a été évalué en mesurant l’expression soit des ARNm (hybridation in situ), soit des protéines (immunoautoradiographie et/ou immunofluorescence) de VGLUT1 et 2. De plus, la densité de certains sous-types de récepteurs glutamatergiques par la technique de radioliaison a été mesurée. Dans un second temps, des tests comportementaux pour mesurer l’activité locomotrice et tester les performances cognitives des souris DAT-KO ont été réalisés en réponse soit à des traitements pharmacologiques proglutamatergiques, soit en modifiant des conditions environnementales. Les résultats obtenus après traitement aigu par différents psychotropes ne révèlent pas de différence dans l’expression des ARNm et des protéines de VGLUT1 et de VGLUT2 dans l’ensemble des régions étudiées. En revanche, les résultats obtenus après un traitement chronique montrent une augmentation significative de l’expression des ARNm de VGLUT1 dans des régions frontales (cortex, hippocampe) et des protéines de VGLUT1 (cortex, hippocampe, thalamus) [...]. En revanche, l’halopéridol, un antipshychotique typique n’a pas d’effet. A l’inverse, les antipsychotiques typiques et atypiques induisent une augmentation significative des ARNm de VGLUT2 dans des structures sous-corticales (noyaux thalamiques médians) et des protéines (cortex prélimbique, striatum limbique), alors que les antidépresseurs n’ont quant à eux, aucun effet. Les données obtenues avec les souris DAT-KO montrent une légère diminution de l’expression des ARNm de VGLUT1 dans le cortex et des protéines de VGLUT1 dans le striatum comparée aux souris sauvages. En revanche, aucune variation dans l’expression de VGLUT2 n’a été observée entre les deux génotypes. [...] Ce travail permet de proposer les VGLUTs comme marqueurs spécifiques pour l’étude de certaines pathologies neuropsychiatriques comme la dépression ou la schizophrénie et ainsi de développer de nouvelles stratégies thérapeutiques ciblant le système glutamatergique / Glutamate is the major excitatory neurotransmitter in the central nervous system of mammals. The molecular characterization and functional three carriers vesicular glutamate, appointed VGLUT-3, allowed an experimental approach more specific glutamatergic neurotransmission. Thus, the objective of this thesis was to study in mice glutamatergic neurotransmission in pharmacological and genetic models of psychiatric diseases like depression or schizophrenia. The results obtained after chronic treatment by various psychotropic show that the molecules with an antidepressant activity increases VGLUT1 and those with an antipsychotic increase VGLUT2. The data obtained with mice invaided for the dopamine transporter (DAT-KO) show that agents proglutamatergiques reduce behavioral deficits in these mice. All these data reinforces the idea that VGLUT1 and VGLUT2 define two subsystems regulated so differencial by two major classes of psychotropic drugs and can offer the VGLUTs as specific markers for the study of certain neuropsychiatric disorders

La partie céphalique de notre corps est le siège de douleurs qui, comme la migraine, peuvent être très invalidantes. Le sous noyau caudal du trijumeau (Sp5C) assure le transfert des messages nociceptifs provenant de la face et des méninges vers les centres supérieurs. Ce transfert est modulé par des projections descendantes provenant de centres supraspinaux dont l'hypothalamus. Comment sont organisés les contrôles descendants hypothalamiques sur le Sp5C ? En utilisant le traceur retrograde, Fluorogold (FG), nous avons analysé les projections hypothalamiques sur le Sp5C. Elles proviennent du noyau paraventricular (PVN), de l'aire hypothalamique laterale (LH), de l'aire hypothalamique perifornicale (PFX), du noyau A11 et de l'aire retrochiasmatique (RCA). La zone ophtalmique V1 du Sp5C reçoit la plus forte densité de projections. Ces projections sont systématiquement bilatérales. Par double marquage immunohistochimique traceur/phénotype, nous avons précisé les phénotypes neurochimiques des neurones projetant du A11, LH et PFX vers le Sp5C. Dans le noyau A11, 60% environ de ces neurones sont dopaminergiques (DA) et 10% environ contiennent l'alpha-calcitonin gene related peptide (CGRP). De plus, 15% de ces neurones dans LH et 30% de ceux-ci dans PFX sont oréxinergiques. L'expression de Fos est augmentée dans le noyau A11 après stimulation nociceptive tonique inflammatoire (formol facial sous-cutané), indiquant que ce noyau contribue au traitement de l'information douloureuse. Cependant, ni les neurones DA ni les neurones FG expriment Fos. Par une approche comportementale et électrophysiologique, nous avons précisé le rôle des contrôles hypothalamiques dans la modulation de la nociception trigéminale. La lésion par acide kaïnique ou 6-OHDA d'un noyau A11 abaisse les réponses nociceptives comportementales (test au formol) chez le rat vigil. Pour tester l'hypothèse d'un contrôle hypothalamique orexinergique, nous avons enregistré les réponses électrophysiologiques de neurones trigéminaux à la stimulation électrique de leur champ récepteur. L'injection intracisternale (0.6 nmol dans 5μl) d'orexine A réduit (environ 50%) les réponses à l'activation sélectivement des fibres afférentes de type C sans modifier leur windup. Au total, plusieurs de nos résultats méritent d'être soulignés. (1) Les voies hypothalamiques descendantes semblent contrôler préférentiellement les inputs méningés. (2) Un dysfonctionnement prolongé du noyau A11 provoque un état d'hypoalgésie, suggérant que l'activation des afférences DA provoque un état d'hyperalgie. Or, les résultats d'injections locales de DA ou de manipulations aigues du noyau A11 suggèrent un contrôle DA inhibiteur sur l'information nociceptive. Le dysfonctionnement DA pourrait favoriser une plasticité dans le Sp5C. (3) Enfin, l'inhibition sélective des réponses C par l'orexine A, suggère l'existence d'un contrôle présynaptique inhibiteur du message nociceptif trigéminal. / Pain syndroms located in the head, such as migraine, can be particularly invalidating. Sensory inflow generated bynociceptors in the face and meninges activate neurons in the medullary dorsal horn (MDH), within the trigeminal system.There, a network of descending projections from cerebral structures enhance or inhibit the transfer of nociceptive informationto higher centers. However, the functional anatomy of such descending controls of nociceptive information are still ill-defined.Here, we investigated the descending hypothalamic projections to the MDH. Using the retrograde tracer, Fluorogold (FG), we analyzed the organization of hypothalamic projections to MDH. They originate from the paraventricular nucleus (PVN), lateral hypothalamic area (LH), perifornical hypothalamic area (PFX), A11 nucleus and retrochiasmatic area (RCA). Within MDH, the V1 area, where primary afferent fibers of the ophthalmic branch of the trigeminal nerve terminate, receives the strongest hypothalamic projections. Hypothalamic projections to MDH are bilateral. Using double-immunolabelling, we determined the molecular phenotype of A11 nucleus, LH and PFX projecting neurons to MDH. In A11 nucleus, about 60% of projecting neurons to MDH are dopaminergic (DA) and about 10% contain the alphacalcitonin gene related peptide (CGRP). Fifteen percent of LH projecting neurons to MDH and 30% of PFX ones contain orexin. Pain (facial formalin test) elevates Fos expression in A11 nucleus, suggesting that it contributes to pain processing. However, it is worth noting that Fos-immunoreactive neurons are neither DA nor projecting neurons. We combined behavioral and electrophysiological techniques to get further insights into the role of hypothalamic projections on trigeminal pain. Lesion of A11 nuclei, by locally injecting kainic acid or 6-OHDA, reduces spontaneous pain behavior (facial formalin test). To examine whether orexin descending hypothalamic projections control trigeminal pain, we examined the effect of intracisternally applied orexin A on electrophysiological responses of trigeminal neurons to electrical stimulation of their receptive field. Orexin A (0.6 nmol in 5μl) selectively reduces (about 50%) C-fiber-evoked responses but not the windup phenomenon. Several of these results are worth to note. (1) Descending hypothalamic projections predominantly control VI area of MDH, where primary afferent fibers innervating the meninges terminate. (2) The effect of long-lasting dysfunction of A11nucleus suggests that activation of descending DA projections produce a state of hyperalgesia. This is at odds with theconclusion of previous reports on the effects of local administration of DA or acute manipulations of A11 nuclei, suggestingthat descending DA projections rather inhibit nociceptive transmission. Long-lasting dysfunction of descending A11 DAprojections might enable plasticity changes in DH neuronal network. (3) That orexin A selectively inhibits C-fiber-evokedresponses suggests that orexin A selectively controls the transfer of nociceptive information via a presynaptic mechanism.

Doctor of Philosophy / Entomology / Yoonseong Park / Tick salivary secretion is crucial for survival and for successful feeding. Tick saliva includes excretory water/ions and bioactive components for compromising the hosts' immune responses, and provides a direct route for pathogen transmission. Control of the tick salivation involves autocrine/paracrine dopamine, the most potent stimulator of tick salivation. Our research group reported the presence of two dopamine receptors in the salivary glands of the blacklegged tick (Ixodes scapularis): dopamine receptor (D1) and invertebrate specific D1-like dopamine receptor (InvD1L). Dopamine-induced salivary secretion was orchestrated by two distinct physiological roles via activation of the two dopamine receptors (Chapter 2). Low concentration of dopamine activated D1 receptor on epithelial cells of salivary gland acini leading inward fluid transport. High concentration of dopamine activated InvD1L receptors on axonal projections innervating myoepithelial cells modulating pumping/gating actions for emptying luminal saliva into the main duct. Thus, ticks coordinated salivary secretion with duo dopamine receptors. Dopamine-mediated saliva production involves an important downstream component, Na/K-ATPase (Chapter 3). Na/K-ATPase was found in the epithelial cells of all types of acini. However, Na/K-ATPase had two different functions in salivary secretion in different acini: 1) dopamine-mediated production of primary saliva in distally located salivary gland acini type-2/- 3, and 2) dopamine-independent resorption in proximally located salivary gland acini type-1. Type-1 acini were also found to function in direct water absorption of off-host ticks, which could be a potential route for delivery of acaricides. Chapter 4 investigated the comparative transcriptomics of the lone star tick underlying the processes of pathogen acquisition. Differential expression analyses in pathogen-exposed ticks revealed a number of transcripts that are important in the tick-pathogen interaction. These included genes for tick immunity against pathogen and for modulation of tick physiology facilitating a pathogen’s invasion and proliferation. My study expanded the understanding of physiological mechanisms controlling tick salivation. In addition, transcriptomics of ticks in interaction with pathogen identified several genes that are relevant in vector/pathogen interactions. The knowledge obtained in my study will facilitate to the development of novel methods for the disruption of tick feeding and pathogen transmission.

Attention deficit hyperactivity disorder (ADHD) is a heritable disorder, which has detrimental effects on childhood development and is associated with maladaptive functioning in adulthood. Despite this, we are far from an understanding of the etiology and possible trajectories of ADHD, possibly due to investigations focusing on the contribution of single genes. In fact, single genes are likely not influential enough to alter behavior, but the additive effect of many genes may predispose an individual toward certain behaviors. Further, environmental input can activate or suppress genetic expression, thereby leading to vast individual differences in both normative behavior and psychopathological illness, including ADHD. This study investigated the effect of cumulative genetic sensitivity across three dopaminergic polymorphisms (DRD2 A1, DRD4 7R, and DAT1 10R) on ADHD symptomatology in very young children. In addition, we were interested in the G x E associations with ADHD symptomatology. Findings provide novel evidence regarding the effects of dopamine polymorphisms on inattention, and thus ADHD, symptomatology in very young children. Specifically, the findings suggest that the cumulative effect of genetic sensitivity across several dopamine polymorphisms predicts severity of symptomatology, particularly in males. In addition, a robust G x E interaction emerged, whereby a specific genetic predisposition moderated the effect of family context on behavior. This finding, lending support to the BSC model and the differential susceptibility hypothesis, suggests that genetic sensitivity can moderate environmental influence, for better and for worse.

<p>Background: Organophosphate (OP) pesticides are well-known developmental neurotoxicants that have been linked to abnormal cognitive and behavioral endpoints through both epidemiological studies and animal models of behavioral teratology, and are implicated in the dysfunction of multiple neurotransmitters, including dopamine. Chemical similarities between OP pesticides and organophosphate flame retardants (OPFRs), a class of compounds growing in use and environmental relevance, have produced concern regarding whether developmental exposures to OPFRs and OP pesticides may share behavioral outcomes, impacts on dopaminergic systems, or both. Methods: Using the zebrafish animal model, we exposed developing fish to two OPFRs, TDCIPP and TPHP, as well as the OP pesticide chlorpyrifos, during the first 5 days following fertilization. From there, the exposed fish were assayed for behavioral abnormalities and effects on monoamine neurochemistry as both larvae and adults. An experiment conducted in parallel examined how antagonism of the dopamine system during an identical window of development could alter later life behavior in the same assays. Finally, we investigated the interaction between developmental exposure to an OPFR and acute dopamine antagonism in larval behavior. Results: Developmental exposure to all three OP compounds altered zebrafish behavior, with effects persisting into adulthood. Additionally, exposure to an OPFR decreased the behavioral response to acute D2 receptor antagonism in larvae. However, the pattern of behavioral effects diverged substantially from those seen following developmental dopamine antagonism, and the investigations into dopamine neurochemistry were too variable to be conclusive. Thus, although the results support the hypothesis that OPFRs, as with OP pesticides such as chlorpyrifos, may present a risk to normal behavioral development, we were unable to directly link these effects to any dopaminergic dysfunction.</p> / Dissertation

Binge eating disorder (BED) is the most prevalent of all eating disorders and is characterized by recurrent episodes of eating a large amount of food in the absence of control. There have been various kinds of research of BED, but the phenomenon remains poorly understood. This thesis reviews the results of research on BED to provide a synthetic view of the current general understanding on BED, as well as the neural correlates of the disorder and treatments. Research has so far identified several risk factors that may underlie the onset and maintenance of the disorder, such as emotion regulation deficits and body shape and weight concerns. However, neuroscientific research suggests that BED may characterize as an impulsive/compulsive disorder, with altered reward sensitivity and increased attentional biases towards food cues, as well as cognitive dysfunctions due to alterations in prefrontal, insular, and orbitofrontal cortices and the striatum. The same alterations as in addictive disorders. Genetic and animal studies have found changes in dopaminergic and opioidergic systems, which may contribute to the severities of the disorder. Research investigating neuroimaging and neuromodulation approaches as neural treatment, suggests that these are innovative tools that may modulate food-related reward processes and thereby suppress the binges. In order to predict treatment outcomes of BED, future studies need to further examine emotion regulation and the genetics of BED, the altered neurocircuitry of the disorder, as well as the role of neurotransmission networks relatedness to binge eating behavior.

Thesis advisor: Rebekah Levine Coley / Substance abuse and dependence are among the nation's leading health issues, leading to more illnesses, disabilities, and deaths than any other modifiable health condition. Substance use among youth is of particular concern, as rates are higher than among any other age group and because early use is associated with a higher risk of later abuse and dependence and a higher incidence of related risk-taking behavior. Thus, a better understanding of the causes of substance use problems is a central issue. The primary goal of this study was to examine genetic and environmental predictors of youth alcohol and drug abuse and dependence. This study expands upon extant research by being the first to utilize a genetic risk score (GRS) approach to examine the joint effect of four dopaminergic genetic polymorphisms on substance abuse and dependence, by incorporating cumulative measures of environmental risk and promotive factors, and by examining gene-environment interactions (GxEs) and gender differences in substance use predictors, thus allowing for a more comprehensive assessment of environmental and genetic influences than has previously been attempted. Analyses were conducted on a national longitudinal sample of 1,396 Caucasian youth who participated in surveys and DNA sampling in the National Longitudinal Study of Adolescent Health, with individuals followed from adolescence (ages 12-18) into early adulthood (ages 24-32). Logistic regression analyses examined main and interactive effects of cumulative environmental risk and promotive factors and genetic risk scores on clinically significant alcohol and drug abuse and dependence in early adulthood. Analyses were conducted separately for males and females to examine gender differences in substance use predictors. Results show that a dopaminergic GRS index significantly predicted the likelihood that female, but not male, youth will meet clinical criteria for substance abuse and dependence, even after accounting for cumulative environmental influences. No evidence of GxE was found. These results provide a better understanding of the etiology of substance abuse and dependence and provide evidence of the utility of GRS methods for studying genetic influences on substance use behaviors. / Thesis (PhD) — Boston College, 2012. / Submitted to: Boston College. Lynch School of Education. / Discipline: Counseling, Developmental, and Educational Psychology.

ABSTRACT The current study documents the findings from immunohistochemical examination of the brains of microbats and megabats (Chiroptera) using antibodies for cholineacetyltransferase (cholinergic neurons), tyrosine hydroxylase (dopaminergic, adrenergic and noradrenergic neurons), and serotonin (serotonergic neurons). The objective of the study was firstly to describe the anatomical organization and morphology of the neuromodulatory systems (nuclear complement) in both microbats and megabats, as there is no literature on these systems in the brains of chiropterans. Secondly, we aimed to investigate whether or not there are differences in these systems between the two suborders of chiroptera in hopes to shed some light on the phylogeny of the two, which is a controversial subject. The two groups were found to possess clear differences in their respective neuromodulatory nuclear complements. The differences observed between the two groups include a dorsal division of the locus coeruleus (A6d), which was absent in microbats but present in megabats, also the absence of an A4 in microbats but clear presence in megabats, and the parabigeminal (PBg) nucleus that was absent in microbats but clearly visible in megabats. The microbats were found to possess a complement that appeared similar to that of insectivores; whereas megabats had a complement resembling that of primates, carnivores and rodents. The differences found between the two groups suggest a diphyletic origin for the two groups.

Thesis advisor: Michael Numan / Postpartum female rats immediately respond to biological or foster offspring with the display of maternal behavior. In contrast, females that are hysterectomized and ovariectomized on day 15 of pregnancy (15HO) and presented with pups 48 hours later show maternal behavior after 2-3 days of pup exposure. The natural onset of maternal behavior in postpartum females is mediated, in part, by the rise in estradiol just prior to birth. When 15HO rats are administered estradiol benzoate (EB) at the time of HO surgery, 48 hours prior to pup presentation, they show an almost immediate onset of maternal behavior. Presumably, EB administration functions to prime neural circuits which regulate maternal behavior such that these circuits respond to pup presentation with increased maternal responsiveness. Two important neural regions which have been shown to interact in order to promote responsiveness toward infant stimuli are the medial preoptic area (MPOA) and the nucleus accumbens (NA). The following series of studies were undertaken to examine how dopamine (DA) activity within these two important neural sites substitutes for the facilitatory effects of chronic (48 hours) EB stimulation of maternal behavior in 15HO rats. Study 1 investigates whether, in the absence of EB treatment, microinjection of dopamine receptor agonists into either NA or MPOA at the time of pup presentation stimulate maternal behavior in 15HO rats. Study 2 examines the underlying mechanism by which DA receptor stimulation of NA promotes the onset of maternal behavior in 15HO rats. Finally, Study 3 examines the relationship between DA receptor stimulation and estradiol stimulation in the facilitation of maternal responsiveness in 15HO rats. / Thesis (PhD) — Boston College, 2009. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Psychology.

Stroke is a widespread condition, which often leaves survivors with lasting deficits in motor function, however, physical rehabilitation is the only treatment available after the acute period. A large body of preclinical literature suggests dopamine-augmenting drugs, could enhance motor recovery following stroke. Unfortunately, mixed clinical results have prevented the implementation of such treatments, possibly due to the wide variety of G protein-coupled receptors these drugs can activate. Using a mouse photothrombosis stroke model and a battery of motor and sensorimotor behavioural tests, the current study aims to demonstrate proof of principle for the use of D1-class dopamine receptor agonists to enhance poststroke motor recovery and to evaluate the role of aerobic exercise rehabilitation in an asynchronous study design. The effect of light-dark cycle on behavioural outcome (horizontal ladder test, adhesive removal test, cylinder test) and histological outcome (infarct size) in photothrombotic stroke was evaluated in order to optimize the stroke model, but no there was no evidence of differences between strokes occurring during the light or dark period of a mouse’s circadian rhythm. A bioactive, suboptimal dose of D1-agonist dihydrexidine, was determined by evaluating its effect on locomotor activity and its ability to increase expression of immediate early gene c-fos. Using the determined dose, studies evaluating the efficacy of 7-days and 2-days of dihydrexidine administration on poststroke motor recovery, were performed, indicating efficacy of a 7-days, but not of a 2-days, course of treatment. The 7-days dihydrexidine treatment resulted in accelerated recovery as compared to a control group receiving saline. This work demonstrates, for the first time, proof of principle for the use of specific activation of D1-class dopamine receptors to enhance motor recovery following stroke.