Exploring the aetiology of pre-motor Parkinson's disease and the efficacy of potential neuroprotective therapies

The present thesis aimed at providing insight into the aetiology and treatment of Parkinson’s disease (PD), which symptomatology consists of both motor and non-motor symptoms (NMSs). The latter have been linked to a loss of neurotransmitters other than dopamine and they have been shown to be modulated by treatments that do not act directly on the dopaminergic system, such as the glucagon-like peptide-1 receptor agonist exendin-4 (EX-4). Nevertheless, the aetiology of NMs, alongside with their potential treatments, has yet to be fully investigated. In this study, through injections of the neurotoxins N-N-ethyl-2-bromobenzylamine (DSP-4) and 6-hydroxydopamine (6-OHDA), a rat model of early-stage PD was developed and validated. Animals displayed the NMS hyposmia and memory impairments in the absence of motor symptoms, suggesting the PD model is representative of an early stage of the disease. Next, the effect of partial noradrenergic and dopaminergic denervation in several brain regions within the olfactory pathway was investigated using immunohistochemical techniques. Surprisingly, the combined denervation led to a reduction in the expression of interneuronal calcium binding proteins (CBPs) in the primary olfactory cortex and prefrontal cortex, whilst the expression in the olfactory bulbs was found to be increased, alongside with dopaminergic expression. Additionally, GABAergic cells in CA2 of the PD model were found to be decreased compare with controls. Interestingly, the observed structural changes were partially prevented following treatment with EX-4. Additionally, two preliminary studies were conducted using the early-stage PD model to test two potential new treatments, a novel viral vector and probiotics, and their effectiveness in preventing neuronal loss in the Substantia Nigra. Overall, this rat model of early-stage PD offers a useful means for research into early diagnosis as well as early intervention of PD, possibly resulting in a delay of disease progression together with improved patient’s quality of life

Protein Deimination Signatures in Plasma and Plasma-EVs and Protein Deimination in the Brain Vasculature in a Rat Model of Pre-Motor Parkinson’s Disease

The identification of biomarkers for early diagnosis of Parkinson’s disease (PD) is of pivotal importance for improving approaches for clinical intervention. The use of translatable animal models of pre-motor PD therefore offers optimal opportunities for novel biomarker discovery in vivo. Peptidylarginine deiminases (PADs) are a family of calcium-activated enzymes that contribute to protein misfolding through post-translational deimination of arginine to citrulline. Furthermore, PADs are an active regulator of extracellular vesicle (EV) release. Both protein deimination and extracellular vesicles (EVs) are gaining increased attention in relation to neurodegenerative diseases, including in PD, while roles in pre-motor PD have yet to be investigated. The current study aimed at identifying protein candidates of deimination in plasma and plasma-EVs in a rat model of pre-motor PD, to assess putative contributions of such post-translational changes in the early stages of disease. EV-cargo was further assessed for deiminated proteins as well as three key micro-RNAs known to contribute to inflammation and hypoxia (miR21, miR155, and miR210) and also associated with PD. Overall, there was a significant increase in circulating plasma EVs in the PD model compared with sham animals and inflammatory and hypoxia related microRNAs were significantly increased in plasma-EVs of the pre-motor PD model. A significantly higher number of protein candidates were deiminated in the pre-motor PD model plasma and plasma-EVs, compared with those in the sham animals. KEGG (Kyoto encyclopedia of genes and genomes) pathways identified for deiminated proteins in the pre-motor PD model were linked to “Alzheimer’s disease”, “PD”, “Huntington’s disease”, “prion diseases”, as well as for “oxidative phosphorylation”, “thermogenesis”, “metabolic pathways”, “Staphylococcus aureus infection”, gap junction, “platelet activation”, “apelin signalling”, “retrograde endocannabinoid signalling”, “systemic lupus erythematosus”, and “non-alcoholic fatty liver disease”. Furthermore, PD brains showed significantly increased staining for total deiminated proteins in the brain vasculature in cortex and hippocampus, as well as increased immunodetection of deiminated histone H3 in dentate gyrus and cortex. Our findings identify EVs and post-translational protein deimination as novel biomarkers in early pre-motor stages of PD

Single prazosin infusion in prelimbic cortex Fosters extinction of amphetamine-induced conditioned place preference

Exposure to drug-associated cues to induce extinction is a useful strategy to contrast cue-induced drug seeking. Norepinephrine (NE) transmission in medial prefrontal cortex has a role in the acquisition and extinction of conditioned place preference induced by amphetamine. We have reported recently that NE in prelimbic cortex delays extinction of amphetamine-induced conditioned place preference (CPP). A potential involvement of α1-adrenergic receptors in the extinction of appetitive conditioned response has been also suggested, although their role in prelimbic cortex has not been yet fully investigated. Here, we investigated the effects of the α1-adrenergic receptor antagonist prazosin infusion in the prelimbic cortex of C57BL/6J mice on expression and extinction of amphetamine-induced CPP. Acute prelimbic prazosin did not affect expression of amphetamine-induced CPP on the day of infusion, while in subsequent days it produced a clear-cut advance of extinction of preference for the compartment previously paired with amphetamine (Conditioned stimulus, CS). Moreover, prazosin-treated mice that had extinguished CS preference showed increased mRNA expression of brain-derived neurotrophic factor (BDNF) and post-synaptic density 95 (PSD-95) in the nucleus accumbens shell or core, respectively, thus suggesting that prelimbic α1-adrenergic receptor blockade triggers neural adaptations in subcortical areas that could contribute to the extinction of cue-induced drug-seeking behavior. These results show that the pharmacological blockade of α1-adrenergic receptors in prelimbic cortex by a single infusion is able to induce extinction of amphetamine-induced CPP long before control (vehicle) animals, an effect depending on contingent exposure to retrieval, since if infused far from or after reactivation it did not affect preference. Moreover, they suggest strongly that the behavioral effects depend on post-treatment neuroplasticity changes in corticolimbic network, triggered by a possible “priming” effect of prazosin, and point to a potential therapeutic power of the antagonist for maladaptive memories

Differential behaviour of normal, transformed and Fanconi's anemia lymphoblastoid cells to modeled microgravity

Background: Whether microgravity might influence tumour growth and carcinogenesis is still an open issue. It is not clear also if and how normal and transformed cells are differently solicited by microgravity. The present study was designed to verify this issue.Methods: Two normal, LB and HSC93, and two transformed, Jurkat and 1310, lymphoblast cell lines were used as representative for the two conditions. Two lymphoblast lines from Fanconi's anemia patients group A and C (FA-A and FA-C, respectively), along with their isogenic corrected counterparts (FA-A-cor and FA-C-cor) were also used. Cell lines were evaluated for their proliferative ability, vitality and apoptotic susceptibility upon microgravity exposure in comparison with unexposed cells. Different parameters correlated to energy metabolism, glucose consumption, mitochondrial membrane potential (MMP), intracellular ATP content, red-ox balance and ability of the cells to repair the DNA damage product 8 OHdG induced by the treatment of the cells with 20 mM KBrO3 were also evaluated.Results: Transformed Jurkat and 1310 cells appear resistant to the microgravitational challenge. On the contrary normal LB and HSC93 cells display increased apoptotic susceptibility, shortage of energy storages and reduced ability to cope with oxidative stress. FA-A and FA-C cells appear resistant to microgravity exposure, analogously to transformed cells. FA corrected cells did shown intermediate sensitivity to microgravity exposure suggesting that genetic correction does not completely reverts cellular phenotype.Conclusions: In the light of the reported results microgravity should be regarded as an harmful condition either when considering normal as well as transformed cells. Modeled microgravity and space-based technology are interesting tools in the biomedicine laboratory and offer an original, useful and unique approach in the study of cellular biochemistry and in the regulation of metabolic pathways

O cuidado com o idoso frente a polifarmácia: uma revisão de Literatura / Care for the elderly front polypharmacy: a literature review

INTRODUÇÃO: Considerando o aumento da expectativa de vida mundial e, o Brasil acompanha a mesma, com idosos que, possuem pelo menos uma patologia crônica, sendo que destes, 56% necessitam de tratamento farmacológico a polifarmácia faz-se presente, visto é frequente a utilização de cinco ou mais medicamentos. OBJETIVO: Identificar as publicações científicas acerca do cuidado com o idoso frente a polifarmácia.  METODOLOGIA: Revisão de literatura do tipo narrativa, com coleta de dados na Biblioteca Virtual em Saúde nas bases de dados Literatura Latino-Americana e do Caribe em Ciências da Saúde, Base de Dados de Enfermagem e, Medline utilizando-se os Descritores de Ciências da Saúde idoso, cuidado, polifarmácia com o operador booleano “AND”. RESULTADOS E DISCUSSÃO: Foram encontrados 643 artigos, selecionados 21 estudos, sendo a seleção final de 10 artigos. Foram construídas duas categorias temáticas: O envelhecimento como fator desencadeante da polifarmácia e a fragilidade na comunicação e acompanhamento do idoso no tratamento medicamentoso. CONCLUSÃO: Considera-se relevante a qualificação das equipes de cuidado gerontológico, com foco no tema deste estudo, bem como a abordagem holística no processo de cuidar e, assim será possível rever as condutas medicamentosas e não medicamentosas que oportunizem aos idosos a vivência da velhice com qualidade de vida

O cuidado com o idoso frente a polifarmácia: uma revisão de literatura / Care for the elderly front polypharmacy: a literature review

INTRODUÇÃO: Considerando o aumento da expectativa de vida mundial e, o Brasil acompanha a mesma, com idosos que, possuem pelo menos uma patologia crônica, sendo que destes, 56% necessitam de tratamento farmacológico a polifarmácia faz-se presente, visto é frequente a utilização de cinco ou mais medicamentos. OBJETIVO: Identificar as publicações científicas acerca do cuidado com o idoso frente a polifarmácia.  METODOLOGIA: Revisão de literatura do tipo narrativa, com coleta de dados na Biblioteca Virtual em Saúde nas bases de dados Literatura Latino-Americana e do Caribe em Ciências da Saúde, Base de Dados de Enfermagem e, Medline utilizando-se os Descritores de Ciências da Saúde idoso, cuidado, polifarmácia com o operador booleano “AND”. RESULTADOS E DISCUSSÃO: Foram encontrados 643 artigos, selecionados 21 estudos, sendo a seleção final de 10 artigos. Foram construídas duas categorias temáticas: O envelhecimento como fator desencadeante da polifarmácia e a fragilidade na comunicação e acompanhamento do idoso no tratamento medicamentoso. CONCLUSÃO: Considera-se relevante a qualificação das equipes de cuidado gerontológico, com foco no tema deste estudo, bem como a abordagem holística no processo de cuidar e, assim será possível rever as condutas medicamentosas e não medicamentosas que oportunizem aos idosos a vivência da velhice com qualidade de vida

Psychosocial Aspects of Suicide on Elderly People and Perceptions of Survivors

Suicide among older adults has become a relevant topic for public health in the last decades. Regarding suicidal rates in older adults, literature estimates that although they have smaller numbers of attempts compared to other age ranges, the rates for accomplished suicides are higher. The objective of the research was to investigate the psychosocial circumstances of death caused by suicide in older ages which occurred in a city in northwest Rio Grande do Sul (RS), through a script of semistructured interview of the tool “Psychological and psychosocial autopsy about suicides in older adults”, with qualitative approach. A collective case study was conducted, where six psychosocial autopsies of older adults who committed suicide were carried out. The participants were family members and people who had some meaningful bond with the ones who committed suicide, and the information from the interviews was analyzed using thematic analysis. From the research, it was possible to investigate the psychosocial circumstances involved in the death caused by suicide of older adults. Concerning psychosocial factors, it is possible to list the diseases, the presence of mental disorders, the existence of family conflicts and the history of losses as factors found in this population correlated with suicide

Dopamine neuronal loss contributes to memory and reward dysfunction in a model of Alzheimer's disease

Alterations of the dopaminergic (DAergic) system are frequently reported in Alzheimer’s disease (AD) patients and are commonly linked to cognitive and non-cognitive symptoms. However, the cause of DAergic system dysfunction in AD remains to be elucidated. We investigated alterations of the midbrain DAergic system in the Tg2576 mouse model of AD, overexpressing a mutated human amyloid precursor protein (APPswe). Here, we found an age-dependent DAergic neuron loss in the ventral tegmental area (VTA) at pre-plaque stages, although substantia nigra pars compacta (SNpc) DAergic neurons were intact. The selective VTA DAergic neuron degeneration results in lower DA outflow in the hippocampus and nucleus accumbens (NAc) shell. The progression of DAergic cell death correlates with impairments in CA1 synaptic plasticity, memory performance and food reward processing. We conclude that in this mouse model of AD, degeneration of VTA DAergic neurons at pre-plaque stages contributes to memory deficits and dysfunction of reward processing

Structural Changes Observed in the Piriform Cortex in a Rat Model of Pre-motor Parkinson’s Disease

Early diagnosis of Parkinson’s disease (PD) offers perhaps, the most promising route to a successful clinical intervention, and the use of an animal model exhibiting symptoms comparable to those observed in PD patients in the early stage of the disease, may facilitate screening of novel therapies for delaying the onset of more debilitating motor and behavioral abnormalities. In this study, a rat model of pre-motor PD was used to study the etiology of hyposmia, a non-motor symptom linked to the early stage of the disease when the motor symptoms have yet to be experienced. The study focussed on determining the effect of a partial reduction of both dopamine and noradrenaline levels on the olfactory cortex. Neuroinflammation and striking structural changes were observed in the model. These changes were prevented by treatment with a neuroprotective drug, a glucagon-like peptide-1 (GLP1) receptor agonist, exendin-4 (EX-4)