Schizophrenia is a prevalent neurological disorder characterized by disrupted neuronal circuitry. Antipsychotic drugs (APDs) are capable of ameliorating the symptoms of schizophrenia with varying efficacy. Clozapine, the "gold-standard" for antipsychotic drug treatment, has been shown by this lab to induce the outgrowth of mediodorsal thalamic (MDT) dendritic arbor in rodents, a brain region which has altered function and decreased regional volume in schizophrenic patients. These studies further explored the ability of APD treatment to restructure dendrite arbor and the mechanisms of clozapine's ability to elaborate MDT arbor. Additionally, glutamate hypofunction is thought to contribute to the schizophrenic disease state. Using a novel model of perinatal glutamate hypofunction, we examined the long-term effects on dendritic architecture of developmental glutamate signaling disruption. MDT dysfunction is hypothesized to contribute to cognitive symptoms of schizophrenia. Clozapine has increased efficacy in ameliorating these symptoms. To further understand clozapine’s actions to remodel MDT dendritic architecture, we examined whether clozapine-induced morphological alterations are limited to the thalamus or if they also occur in additional regions associated with cognitive schizophrenic pathology, the hippocampus and striatum. We found that clozapine can induce dendritic remodeling in the hippocampus, but the not to the amplitude of remodeling seen in the thalamus, indicating that the MDT is uniquely altered by clozapine treatment and may be an important locus of clozapine's action. The mechanisms of clozapine's remodeling of MDT arbor, we examined changes to mRNA and miRNA expression and calcium dynamics in the MDT in response to APD treatment. Clozapine-treatment altered the expression of genes involved in cytoskeletal remodeling, external membrane receptors, and calcium dynamics, as well as increased the rate of calcium influx into thalamic neurons. Disruption to glutamate signaling has been hypothesized to contribute to schizophrenic pathology. Disruption to perinatal vesicular glutamate packaging along the corticolimbic axis has long term effects for neuronal morphology and function. Interestingly, we find that disruption along the corticolimbic axis also has downstream effects on MDT dendritic architecture. These studies show that the MDT is an important locus of action for clozapine and is capable of remodeling dendritic architecture in response to afferent circuitry dysfunction. / acase@tulane.edu

Abstract not available

Schizophrenia is a devastating psychiatric disorder that affects approximately 1% of the population. The main treatments for schizophrenia are antipsychotic drugs that target dopamine receptors, yet the underlying biological mechanisms through which they alleviate the symptoms of schizophrenia remain ill defined. In this study, we used microarray analysis to profile the expression changes of thousands of genes simultaneously, following antipsychotic drug treatment of mice. Mice were treated chronically (28 days), or for a novel intermediate time-point (7 days), with one of three antipsychotic drugs: clozapine, haloperidol or olanzapine. The use of three drugs enabled us to discern antipsychotic-specific effects co-regulated by multiple drugs, rather than the side effects of individual compounds. Transcript profiling and validation by quantitative PCR of whole brain tissue revealed antipsychotic drug regulation of genes in diverse biological pathways, including: dopamine metabolism, neuropeptide and second-messenger signalling, neurogenesis, synaptic plasticity, cell adhesion, myelination, and voltage-gated ion channels. The regulation of voltage-gated channels by antipsychotic drugs has been suggested previously by electrophysiological studies, although thorough analysis has not been undertaken in vivo. Therefore, the second aim of this study was to characterise the regional mRNA and protein expression of two genes altered by multiple APDs, the voltage-gated potassium channel ??-subunit (Kcna1) and voltage-gated potassium channel interacting protein (Kchip3). Regional characterisation and expression analyses were carried out by immunohistochemistry, in situ hybridisation, and Western blot analysis of mouse brain regions of interest to schizophrenia and its treatment. Following 7-day haloperidol treatment we observed up-regulation of Kcna1 in the striatum and dentate gyrus, with increased protein in the striatum, hippocampus and midbrain; and down-regulation of Kchip3 in the striatum, with decreased protein in the cortex, hippocampus and midbrain. These studies implicate voltage-gated potassium channels in the antipsychotic drug regulation of midbrain dopaminergic neuronal activity, adult neurogenesis and/or striatothalamic GABAergic neuronal inhibition. These findings indicate that regulation of potassium channels may underlie some of the mechanisms of action of antipsychotic drugs, and that voltage-gated ion channels may provide alternative drug targets for the treatment of schizophrenia.

Thesis (Ph. D.)--Memorial University of Newfoundland, 2005. / Restricted until May 2006. Includes bibliographical references (leaves 187-207).

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

Schizophrenia is a devastating psychiatric disorder that affects approximately 1% of the population. The main treatments for schizophrenia are antipsychotic drugs that target dopamine receptors, yet the underlying biological mechanisms through which they alleviate the symptoms of schizophrenia remain ill defined. In this study, we used microarray analysis to profile the expression changes of thousands of genes simultaneously, following antipsychotic drug treatment of mice. Mice were treated chronically (28 days), or for a novel intermediate time-point (7 days), with one of three antipsychotic drugs: clozapine, haloperidol or olanzapine. The use of three drugs enabled us to discern antipsychotic-specific effects co-regulated by multiple drugs, rather than the side effects of individual compounds. Transcript profiling and validation by quantitative PCR of whole brain tissue revealed antipsychotic drug regulation of genes in diverse biological pathways, including: dopamine metabolism, neuropeptide and second-messenger signalling, neurogenesis, synaptic plasticity, cell adhesion, myelination, and voltage-gated ion channels. The regulation of voltage-gated channels by antipsychotic drugs has been suggested previously by electrophysiological studies, although thorough analysis has not been undertaken in vivo. Therefore, the second aim of this study was to characterise the regional mRNA and protein expression of two genes altered by multiple APDs, the voltage-gated potassium channel ??-subunit (Kcna1) and voltage-gated potassium channel interacting protein (Kchip3). Regional characterisation and expression analyses were carried out by immunohistochemistry, in situ hybridisation, and Western blot analysis of mouse brain regions of interest to schizophrenia and its treatment. Following 7-day haloperidol treatment we observed up-regulation of Kcna1 in the striatum and dentate gyrus, with increased protein in the striatum, hippocampus and midbrain; and down-regulation of Kchip3 in the striatum, with decreased protein in the cortex, hippocampus and midbrain. These studies implicate voltage-gated potassium channels in the antipsychotic drug regulation of midbrain dopaminergic neuronal activity, adult neurogenesis and/or striatothalamic GABAergic neuronal inhibition. These findings indicate that regulation of potassium channels may underlie some of the mechanisms of action of antipsychotic drugs, and that voltage-gated ion channels may provide alternative drug targets for the treatment of schizophrenia.

<p>Allosteric modulators are a newly emerging concept in the field of drug discovery which have shown remarkable success in their ability to alter G-protein coupled receptor (GPCR) activity in a precise and subtle manner. A GPCR of particular interest for allosteric targeting is the dopamine D2 receptor. This receptor has repeatedly been implicated in the etiology of complex neurological and neuropsychiatric disorders including Parkinson’s disease and schizophrenia. Previous studies from our lab have effectively developed allosteric modulators targeting the D2 receptor based on the pharmacophore of the endogenous tripeptide L-prolyl-L-leucyl-glycinamide (PLG). PLG and its potent peptidomimetics, particularly 3(R)-[(2(S)-pyrrolidinylcarbonyl)amino]-2-oxo-1-pyrrolidineacetamide (PAOPA) (PCT/CA2011/000968), have shown robust preclinical efficacy in treating models of Parkinson’s disease, depression, tardive dyskinesia and schizophrenia. These ligands modulate agonist binding to the D2 receptor in a biphasic manner, although further information on their mechanisms of action are currently unknown. Therefore, the overarching objective of this thesis was to enhance our knowledge on the mechanisms of action of the promising D2 allosteric ligands PLG and PAOPA. Results of the studies presented here show PAOPA to cause significant upregulation of D2 regulatory proteins and downstream signaling kinases, as well as cause an increase in D2 internalization. Additionally, the PLG allosteric binding site was narrowed down to be localized between transmembrane domains 5 and 6 on the D2 receptor. The collection of work presented here enhance our understanding of the mechanisms of action of the potentially therapeutic D2 allosteric ligands PLG and PAOPA, progressing them closer to helping clinically affected populations. The findings of these studies prove globally significant as they highlight the diverse cellular pathways which could be affected by allosteric modulators, and bring to light the importance of studying these candidate ligands for eventual improvements in the treatment of human health.</p> / Doctor of Philosophy (Medical Science)

Thesis (DMed (Psychiatry))--University of Stellenbosch, 2007. / This study reports on the effect of seminar education by studying changes in knowledge, attitude and behaviour to haloperidol prescribing patterns of psychiatrists who In summary, this study demonstrated a direct relationship between seminar attendance and changes to selected minimum effective haloperidol dose and duration of treatment. However, seminar attendance did not appear to be a significant factor in changes to antipsychotic class used for treatment and changes in optimal effective haloperidol dose: rather a change in the level of “background” knowledge of participants was most likely responsible. This study also found individual participant characteristic differences in those who did change treatment duration and minimum effective dose. In conclusion, this study showed that the successful integration of international treatment recommendations into daily psychiatric practise could be facilitated by the use of appropriate educational seminars. Not all attendees benefit i.e. “learn”, but those needing to “learn” most do - i.e. those who need to change their prescribing habits most to meet internationally accepted guidelines. The peer exposure provided allows a format for informed discussion and the practise of evidence-based medicine. The judicious use of such seminars should result in better treatment options and outcomes for patients.attended evidence-based schizophrenia seminars presented by the Lundbeck Institute in Denmark. The objectives of the study were two-fold. Firstly, it set out to determine whether changes actually occurred in the post-seminar haloperidol prescribing behaviour of participants. This was done by analysing changes in choice of optimal haloperidol dose (both in acute treatment i.e. most effective dose and maintenance treatment i.e. minimum effective dose), selected duration of treatment (for first- and multi-episode schizophrenia patients) and drug-class used (conventional versus new generation antipsychotic). The study then investigated whether these changes (if they occurred) could be ascribed wholly or in part to the effect of schizophrenia seminar attendance, or whether other factors e.g. scientific progress over time in understanding schizophrenia and its treatment (“background” knowledge) and differences between participant datasets studied (only paired pre- and post-seminar data were used in this study) also played a role. Secondly, it attempted to identify factors predictive of seminar participants changing their haloperidol prescribing behaviour post-seminar i.e. what were the factors that predisposed some attendees to change their prescribing behaviour? This was done by analysing the effect that pre-seminar prescribing behaviour, participant nationality, patient caseload, work experience and workplace environment had on post-seminar behaviour. Results show that changes did occur in post-seminar haloperidol prescribing behaviour, but that they were not always due to an effect of seminar attendance. Only the changes in the minimum effective haloperidol dose and duration of treatment for first- and multi-episode schizophrenia patients could validly be ascribed to the effects of schizophrenia seminar attendance. Furthermore, multivariate analysis of the factors relating to these changes found that a participant was most likely to change their selected minimum effective haloperidol dose to be more in line with internationally accepted standards if they i) selected above the target dose pre-seminar, ii) had a relatively low caseload comprised mainly of schizophrenia patients and iii) came from either Greece, Germany, Britain, Spain, Italy or some other Eastern European country. The single most important factor related to changes in duration of treatment was found to be pre-seminar behaviour: respondents below the recommended duration of treatment increased their duration of treatment significantly.

<p>This thesis is based on two independent studies, the first in Stockholm County (index year 1984; n=302), and the second, a replication and validation study, in Uppsala County (index year 1991; n=455).</p><p>The general aim was to study all individuals with Long-term Functional Psychosis (LFP) within the two counties of Sweden from an epidemiological perspective and to perform specific studies on a subgroup of individuals with schizophrenia. In the Stockholm study, the total one-year LFP prevalence was 5.3/1 000; in the the rural, suburban and urban areas it was 3.4, 5.6 and 6.6/1 000, respectively. The total one-year prevalence of LFP in Uppsala was 7.3/1 000; in the rural, peripheral city and central city areas it was 6.0, 7.0, and 8.7/1 000, respectively.</p><p>Within the non-schizophrenic subpopulation, a pronounced difference was demonstrated between the two studies with substantially higher prevalence rates in the Uppsala study. The schizophrenic subgroup in Uppsala was re-diagnosed using parallel diagnostic systems (DSM-III, DSM-III-R, DSM-IV and ICD-10), and reasonably comparable prevalence estimates were obtained.</p><p>In both studies antipsychotic drugs were most frequently prescribed for the patients with schizophrenia, and the doses were considered as low to moderate. In the Uppsala study the doses of antipsychotic drugs decreased with a longer duration of illness, while the opposite was found in the Stockholm study.</p><p>The increased mortality rate among patients with schizophrenia was mainly due to unnatural causes of death and cardiovascular diseases, particularly among males.</p><p>The main methodological differences between the two studies were in the sampling procedures. In the Uppsala study, a larger number of care facilities were screened, and a broader set of diagnostic criteria were used for identifying cases from different registers.</p>

This thesis is based on two independent studies, the first in Stockholm County (index year 1984; n=302), and the second, a replication and validation study, in Uppsala County (index year 1991; n=455). The general aim was to study all individuals with Long-term Functional Psychosis (LFP) within the two counties of Sweden from an epidemiological perspective and to perform specific studies on a subgroup of individuals with schizophrenia. In the Stockholm study, the total one-year LFP prevalence was 5.3/1 000; in the the rural, suburban and urban areas it was 3.4, 5.6 and 6.6/1 000, respectively. The total one-year prevalence of LFP in Uppsala was 7.3/1 000; in the rural, peripheral city and central city areas it was 6.0, 7.0, and 8.7/1 000, respectively. Within the non-schizophrenic subpopulation, a pronounced difference was demonstrated between the two studies with substantially higher prevalence rates in the Uppsala study. The schizophrenic subgroup in Uppsala was re-diagnosed using parallel diagnostic systems (DSM-III, DSM-III-R, DSM-IV and ICD-10), and reasonably comparable prevalence estimates were obtained. In both studies antipsychotic drugs were most frequently prescribed for the patients with schizophrenia, and the doses were considered as low to moderate. In the Uppsala study the doses of antipsychotic drugs decreased with a longer duration of illness, while the opposite was found in the Stockholm study. The increased mortality rate among patients with schizophrenia was mainly due to unnatural causes of death and cardiovascular diseases, particularly among males. The main methodological differences between the two studies were in the sampling procedures. In the Uppsala study, a larger number of care facilities were screened, and a broader set of diagnostic criteria were used for identifying cases from different registers.