University of Macau / Institute of Chinese Medical Sciences

Parkinson's disease (PD) is one of the most common motor neurodegenerative diseases, affecting 1-2% of the world's population over the age of 65. It is characterised by a loss of dopamine neurons within the substantia nigra, which is an integral part of the basal ganglia (BG) where dopamine is the most important modulating neurotransmitter. As the BG is primarily involved with the execution of movement, the lack of dopamine input results in dysfunctional motor control. The current PD treatment, L-DOPA, improves these motor symptoms, however only provides patients 5 to 10 years of improved quality of life before debilitating side effects, often worse than the original symptoms, begin. The neuropeptide substance P (SP) is found in high concentration in the substantia nigra, and BG in general, where it is involved in dopamine release. In the late stages of PD, SP content within the substantia nigra and BG is decreased, thus implicating SP in the pathophysiology of PD. However, SP production has not been examined in the early stages of PD when dopaminergic degeneration is first initiated. This thesis therefore sought to characterise the role of SP in dopaminergic degeneration in an experimental model of early PD, the 6-hydroxydopamine model in rats. In contrast to the prevailing dogma that a decline in SP is associated with neurodegeneration in PD, this thesis demonstrates that SP is actually increased within the striatum in early PD, particular in perivascular tissue and within surviving dopaminergic neurons during the degenerative process. Increasing exposure of the dopaminergic neurons to SP, either by inhibition of substance P breakdown with Captopril or by direct injection with SP, exacerbated the disease progression as indicated by more profound neurogenic inflammation, functional deficits and increased dopaminergic cell death. However, when SP was inhibited by treatment with a SP NK₁ receptor antagonist, dopaminergic neurons were conserved, the inflammatory response was reduced and motor function was returned to near normal levels. We conclude that SP is increased in early PD, and that increased SP plays an important role in the degenerative process, specifically, in the genesis of BBB breakdown and initiation of neurogenic inflammation. Treatment with an NK1 antagonist may thus represent a novel therapeutic approach to early stage Parkinson’s disease. / Thesis (Ph.D.) -- University of Adelaide, School of Medical Sciences, 2009

Parkinson's disease (PD) is one of the most common motor neurodegenerative diseases, affecting 1-2% of the world's population over the age of 65. It is characterised by a loss of dopamine neurons within the substantia nigra, which is an integral part of the basal ganglia (BG) where dopamine is the most important modulating neurotransmitter. As the BG is primarily involved with the execution of movement, the lack of dopamine input results in dysfunctional motor control. The current PD treatment, L-DOPA, improves these motor symptoms, however only provides patients 5 to 10 years of improved quality of life before debilitating side effects, often worse than the original symptoms, begin. The neuropeptide substance P (SP) is found in high concentration in the substantia nigra, and BG in general, where it is involved in dopamine release. In the late stages of PD, SP content within the substantia nigra and BG is decreased, thus implicating SP in the pathophysiology of PD. However, SP production has not been examined in the early stages of PD when dopaminergic degeneration is first initiated. This thesis therefore sought to characterise the role of SP in dopaminergic degeneration in an experimental model of early PD, the 6-hydroxydopamine model in rats. In contrast to the prevailing dogma that a decline in SP is associated with neurodegeneration in PD, this thesis demonstrates that SP is actually increased within the striatum in early PD, particular in perivascular tissue and within surviving dopaminergic neurons during the degenerative process. Increasing exposure of the dopaminergic neurons to SP, either by inhibition of substance P breakdown with Captopril or by direct injection with SP, exacerbated the disease progression as indicated by more profound neurogenic inflammation, functional deficits and increased dopaminergic cell death. However, when SP was inhibited by treatment with a SP NK₁ receptor antagonist, dopaminergic neurons were conserved, the inflammatory response was reduced and motor function was returned to near normal levels. We conclude that SP is increased in early PD, and that increased SP plays an important role in the degenerative process, specifically, in the genesis of BBB breakdown and initiation of neurogenic inflammation. Treatment with an NK1 antagonist may thus represent a novel therapeutic approach to early stage Parkinson’s disease. / Thesis (Ph.D.) -- University of Adelaide, School of Medical Sciences, 2009

Introdução: A doença de Parkinson (DP) é uma doença neurodegenerativa cujo quadro clínico é essencialmente motor, no entanto as manifestações não motoras frequentemente estão presentes e muitas vezes são negligenciadas. Dentre as manifestações não motoras o declínio cognitivo tem ganhado destaque sendo causa de maior morbidade e mortalidade. A prevalência da demência na doença de Parkinson (DDP) varia de acordo com a população estudada e no momento do diagnóstico até 20% dos pacientes já apresentam algum grau de declínio cognitivo e com a evolução da doença até 80% dos pacientes apresentaram um quadro demencial associado a DP. Como A DP apresenta características clinico e patológicas sobrepostas à Doença de Alzheimer (DA) e a Apolipoproteína (ApoE) é o principal preditor de risco para desenvolvimento de demência na DA aventou-se a hipótese de que o alelo ?4 da ApoE pudesse ter relação com o risco de o paciente com DP desenvolver quadro demencial. Objetivo: analisar a relação entre o polimorfismo do gene ApoE com o desempenho cognitivo, avaliado pela MoCA, de pacientes com doença de Parkinson e descrever prevalência de cada alelo do gene em uma amostra de pacientes com DP da população brasileira. Método: estudo transversal onde foram analisados 186 pacientes em seguimento nos ambulatórios especializados em Distúrbios do Movimento do Hospital das Clínicas de Ribeirão Preto - HCFMRP e do Hospital São Paulo da Universidade Federal de São Paulo - UNIFESP, no período entre os anos de 2007 e 2014. Foi realizada a genotipagem dos alelos da ApoE e a avaliação cognitiva foi realiza através do MoCA. Para análise da amostra os pacientes foram classificados em portadores ou não do alelo ?4. Os grupos foram comparados utilizando o teste do Qui-quadrado para a variável sexo e o teste nãoparamétrico de Mann-Whitney para idade, tempo de doença e anos de estudo. Resultados: A análise dos escores da MoCA nos grupos com e sem o alelo ?4 não revelou diferença estatisticamente significativa entre os grupos (p=0,20). A frequência genotípica foi semelhante à descrita nos demais estudos sobre o assunto. Conclusão: a presença do alelo ?4 não está associada, em nossa amostra, a um pior desempenho cognitivo, quando este é avaliado pela escala cognitiva global MoCA. / Introduction: The Parkinson\'s disease (DP) is a neurodegenerative disorder where clinical findings are primarily motor however non-motor manifestations are often present and are frequently neglected. Among the non-motor events cognitive decline has gained prominence because it is cause of increased morbidity and mortality. The prevalence of Parkinson\'s disease dementia (PDD) varies depending on the population studied but at the time of diagnosis about 20% of patients already have some degree of cognitive decline and the progression of the disease up to 80% of patients demonstrated PDD. As DP has overlapping clinical and pathological features with Alzheimer\'s disease (DA) and apolipoprotein (ApoE) is the main predictor of risk for developing dementia in AD the hypothesis has suggested that the allele ?4 of ApoE could be related to the risk of the patient with PD develop dementia. Objective: analyze the relationship between ApoE gene polymorphism with the cognitive performance of patients with Parkinson\'s disease and describe prevalence of each allele of the gene in a sample of with PD in a Brazilian population. Method: cross-sectional study which analyzed 186 patients in follow-up in specialized of Hospital das Clínicas de Ribeirão Preto - HCFMRP and Hospital São Paulo of Universidade Federal de São Paulo - UNIFESP, between the years 2007 and 2014. Was made the genotyping for assessing the ApoE allele and cognitive assessment was carried out through the MoCA. For sample analysis, patients were classified as carriers or not allele ?4. The groups were compared using the chi-square test for gender and non-parametric Mann-Whitney test for age, disease duration and years of study. Results: The analysis of MoCA scores in the groups with and without the ?4 allele revealed no statistically significant difference between groups (p = 0.20). The genotypic frequency was similar to that described in other studies

Text in Afrikaans / Individuals can be deemed weaklings within the family relations by social discourse that claims that the value of a human being is measured by his productivity and mobility. Parkinson's disease in its turn has a paralysing effect on the mobility of the physical body. The above-mentioned social discourse on the one hand and Parkinson's disease on the other hand become a dominant story that "paralyses" the individual. During research someone who has been diagnosed with Parkinson's disease, related how she wrote an alternative story. This person, who practices a reformed spirituality, wrote an alternative story by using Christian faith language, which, in the end, halted the marginalising effect of Parkinson's disease. In this study the concerned participant had the opportunity to share her genuine experiences and her application of Christian language of faith to manage Parkinson's disease. / Practical Theology / M. Th.

Text in Afrikaans / Individuals can be deemed weaklings within the family relations by social discourse that claims that the value of a human being is measured by his productivity and mobility. Parkinson's disease in its turn has a paralysing effect on the mobility of the physical body. The above-mentioned social discourse on the one hand and Parkinson's disease on the other hand become a dominant story that "paralyses" the individual. During research someone who has been diagnosed with Parkinson's disease, related how she wrote an alternative story. This person, who practices a reformed spirituality, wrote an alternative story by using Christian faith language, which, in the end, halted the marginalising effect of Parkinson's disease. In this study the concerned participant had the opportunity to share her genuine experiences and her application of Christian language of faith to manage Parkinson's disease. / Philosophy, Practical and Systematic Theology / M. Th.

The effect of concurrent music on gait was investigated amongst Parkinson‟s disease (PD) patients and age-matched control subjects. Ten people (mean age 66.6 ± 6.5 years) with idiopathic Parkinson‟s disease and ten healthy age-matched (mean age 65.4 ± 6.3 years) control subjects completed steady state gait, dual task and obstacle negotiation trials in two differing test conditions; no music and whilst listening to music. Testing conditions were counterbalanced between subjects. The gait performance of PD patients was detrimentally affected by concurrently listening to music during steady state gait and obstacle negotiation, an effect that was further compounded in the dual task context. These findings imply that listening to music concurrent to gait may increase the attentional cost for PD patients. The findings of these studies have implications for patients, who may be at greater risk of falls in multi-task situations. / xi, 113 leaves ; 29 cm. --

A suite of signal processing algorithms designed for extracting information from brain electrophysiology and movement signals, along with new insights gained by applying these tools to understanding parkinsonism, were presented in this dissertation. The approach taken does not assume any particular stimulus, underlying activity, or synchronizing event, nor does it assume any particular encoding scheme. Instead, novel signal processing applications of complex continuous wavelet transforms, cross-frequency-coupling, feature selection, and canonical correlation were developed to discover the most significant electrophysiologic changes in the basal ganglia and cortex of parkinsonian rhesus monkeys and how these changes are related to the motor signs of parkinsonism. The resulting algorithms effectively characterize the severity of parkinsonism and, when combined with motor signal decoding algorithms, allow technology-assisted multi-modal grading of the primary pathological signs. Based on these results, parallel data collection algorithms were implemented in real-time embedded software and off-the-shelf hardware to develop a new system to facilitate monitoring of the severity of Parkinson's disease signs and symptoms in human patients. Off -line analysis of data collected with the system was subsequently shown to allow discrimination between normal and simulated parkinsonian conditions. The main contributions of the work were in three areas: 1) Evidence of the importance of optimally selecting multiple, non-redundant features for understanding neural information, 2) Discovery of signi ficant correlations between certain pathological motor signs and brain electrophysiology in different brain regions, and 3) Implementation and human subject testing of multi-modal monitoring technology.

The midbrain dopamine system is involved in many aspects of purposeful behaviour and, when compromised, can have devastating effects on movement and cognition as seen in diseases like Parkinson's. In the healthy brain, dopamine neurons are thought to play particularly important roles in learning by signalling errors in reward prediction. The objective of this thesis was to investigate the diversity in the functional properties of the midbrain dopamine system, and how this is altered through genetic variation of relevance to Parkinson's and development of cell phenotype. This objective was addressed with a combination of behavioural experiments, in vivo single-cell recording and labelling (both in anaesthetised as well as awake rodents), immunofluorescence labelling, retrograde tracing and stereology. In a first set of experiments, it was demonstrated that chronic as well as acute genetic challenges can alter the firing patterns of midbrain dopamine neurons. Using a novel bacterial artificial chromosome-transgenic rat model, it was shown that the R1441C mutation in human leucine-rich repeat kinase 2, which is linked to Parkinson's, leads to motor deficits and an age-dependent reduction in the in vivo firing variability and burst firing of substantia nigra pars compacta (SNc) dopamine neurons. These findings help reveal processes of early, pre-degenerative dysfunction in dopamine neurons in Parkinson's. Similar effects on firing variability and burst firing of SNc dopamine neurons were found in a mouse model with conditional knock- out of the transcription factors Forkhead box A1 and A2 (FoxA1/2) in midbrain dopamine neurons. These findings indicate that FoxA1/2 are not only crucial for the early development of dopamine neurons, but also their function in the mature brain. In a second set of experiments in wildtype mice, it was demonstrated that midbrain dopamine neurons (located in SNc and ventral tegmental area) show diverse expression of the molecular markers Calbindin, Calretinin, Aldh1a1, Sox6, Girk2, SatB1 and Otx2. It was found that selective expression of these markers is of use for discriminating between midbrain dopamine neurons that project to dorsal striatum or nucleus accumbens. To elucidate whether the diverse molecular marker expression would map onto dopamine neurons whose firing correlates with distinct behavioural events, midbrain dopamine neurons were recorded and labelled in head-fixed awake mice either exposed to neutral sensory stimuli or performing a classical conditioning paradigm. The population activity of midbrain dopamine neurons was not modulated by neutral sensory stimuli. Interestingly, fewer than 50% of identified dopamine neurons showed phasic firing increases following reward- predicting cue and/or reward delivery, despite the common assumption that most (if not all) midbrain dopamine neurons signal reward prediction errors. Instead, firing was modulated by other explanatory factors, such as licking, or showed no modulation during the task. Response types of midbrain dopamine neurons were not correlated with their anatomical location nor the selective or combinatorial expression of the markers Aldh1a1, Calbindin and Sox6. In conclusion, the first set of experiments identified how different genetic burdens can alter the in vivo firing of midbrain dopamine neurons, and provide new insights into how circuits can change in pathological or compensatory ways at early disease stages in Parkinson's. The second set of experiments revealed striking heterogeneity of midbrain dopamine neurons in the intact system, and established further a functional diversity in the response types of identified midbrain dopamine neurons that is only partially consistent with canonical reward prediction error signalling.

Parkinson’s disease (PD) is a debilitating movement disorder. The cardinal symptoms of PD are bradykinesia, resting tremors and rigidity. PD is characterized by degeneration of dopaminergic neurons of A9 region, substantia nigra pars compacta (SNpc) and loss of dopaminergic terminals in striatum while the dopaminergic neurons of A10 region, ventral tegmental area (VTA) are relatively protected. Putative mechanisms, such as mitochondrial dysfunction, dysregulation of the ubiquitin proteasome system and increased oxidative stress have been hypothesized to mediate PD pathology. However, precise mechanisms that underlie selective vulnerability of SNpc dopaminergic neurons to degeneration are unknown. The aim of this thesis was to evaluate the pathological mechanisms that may contribute to degeneration of SNpc dopaminergic neurons in PD. Dopaminergic neurons of SNpc are pacemakers and constant calcium entry through L-type calcium channel, Cav1.3 has been reported in these neurons during pacemaking. In addition, these neurons have poor calcium buffering capacity. Together, this leads to dysregulation of calcium homeostasis in the SNpc dopaminergic neurons leading to increased oxidative stress. Gene expression of the full length channel and the variant was investigated in the mouse midbrain and further their presence was verified in mouse SNpc and VTA and also in SNpc and VTA in the MPTP mouse model of PD. Gene expression of Cav1.3 -42 and its variant was also studied in SNpc from autopsy tissue from PD patients and age matched controls. Having studied differential expression of the calcium channels, global changes in gene expression in SNpc from the MPTP mouse model of PD and PD autopsy tissues were next examined. This is the first report of transcriptome profile alterations from SNpc in mouse model and PD tissue performed using RNA-seq. Gene expression profiles were examined from SNpc 1 day post single exposure to MPTP, in which case there is no neuronal death and 14 days after daily MPTP treatment where SNpc has undergone ~50% cell death. Further, RNA- seq was performed to study gene expression alterations in SNpc from human PD patients and age- matched controls. The RNA-seq data was taken through extensive analyses; analysed for differential gene expression, gene-set enrichment analysis, pathway analysis and network analysis. Glutaredoxin 1 (Grx1) is a thiol disulfide oxidoreductase that catalyses the deglutathionylation of proteins and is important for regulation of cellular protein thiol redox homeostasis. Down-regulation of Grx1 has been established to exacerbate neurodegeneration through impairment of cell survival signalling. Previous work from our laboratory has demonstrated that perturbation of protein thiol redox homeostasis through diamide injection into SNpc leads to development of PD pathology and motor deficits. It was therefore investigated if Grx1 down-regulation in vivo, leading to increased glutathionylation and protein thiol oxidation, could result in PD pathology. This work is thus the first study of RNA-seq based transcriptomic profile alterations in SNpc from human PD patients. This work also highlights several differences between mouse model and human PD tissue indicating that the underlying mechanisms of PD pathogenesis differ from mouse to humans in addition to developing a novel model for PD.