Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 201-220).

ARCA2 est une ataxie récessive qui se caractérise par une atrophie du cervelet et un léger déficit en coenzyme Q10. Des mutations dans le gène ADCK3 ont été récemment identifiées comme étant la cause d’ARCA2. ADCK3 code pour une kinase mitochondriale atypique, qui pourrait être impliquée dans la biosynthèse du coenzyme Q10. L’objectif de mon projet de thèse était d’élucider la physiopathologie d’ARCA2 en utilisant le modèle murin knockout pour Adck3. J’ai ainsi pu montrer que les souris Adck3-/- reproduisent de nombreux symptômes associés à ARCA2 et constituent un bon modèle pour étudier ARCA2. Au niveau du cervelet, les cellules de Purkinje sont spécifiquement touchées et présentent des anomalies morphologiques et fonctionnelles. Un léger défaut mitochondrial a été observé dans les muscles squelettiques des souris Adck3-/-. Enfin, une analyse transcriptomique de ces deux tissus a révélé des altérations de nombreuses voies, impliquant ADCK3 dans de nouveaux processus cellulaires. / ARCA2 is a form of recessive ataxia characterized by a slow progression of the ataxic phenotype, cerebellar atrophy and mild deficit in Coenzyme Q10. ARCA2 was recently found associated with mutations in the ADCK3 gene that encodes a putativemitochondrial kinase homologous to the yeast Coq8 and the bacterial UbiB proteins, which are required for Coenzyme Q biosynthesis. In order to elucidate the pathophysiology of ARCA2, a constitutive knockout mouse for Adck3 was generated.Adck3-/- mice reproduce many ARCA2 symptoms such as slow progression of the ataxic phenotype and mild Coenzyme Q deficit, suggesting that Adck3-/- mice are a good model to study ARCA2. Strikingly, a morphological and functional impairmentwas found in cerebellar Adck3-/- Purkinje cells, whereas a mild mitochondrial defect was observed in the skeletal muscle of Adck3-/- mice. Interestingly, transcriptomic analyses revealed alteration in a number of molecular pathways implicating ADCK3in novel cellular processes.

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How do we learn to establish associations between arbitrary visual cues (like a red light) and movements (like braking the car)? We investigated the neural correlates of visuomotor association learning in the mid-lateral cerebellum. Although cerebellum has been considered to be a motor control center involved in monitoring and correcting the motor error through supervised learning, in this thesis, we show that its role can also be extended to non-motor learning. Specifically, when primates learned to associate arbitrary visual cues with well-learned stereotypic movements, the simple spikes of the mid-lateral cerebellar Purkinje cells reported the monkey’s most recent decision’s outcome during learning. The magnitude of this reinforcement error signal changed with learning, finally disappearing when the association had been overlearned. We modeled this change in neural activity through a drift diffusion-reinforcement learning based model. The concurrent complex spikes, contrary to traditional theories, did not play the role of teaching signal, but encoded the probability of error as a function of the state of learning. They also encoded features that indicate the beginning of a trial. Inactivating the mid-lateral cerebellum significantly affected the monkey’s learning performance while it did not affect motor performance. This is because the mid-lateral cerebellum is in a loop with other cognitive processing centers of the brain including the prefrontal cortex and the basal ganglia. Finally, we verified that the features we identified in primate experiments can also be extended to humans, by studying the visuomotor association learning in humans through functional magnetic resonance imaging. In summary, through electrophysiological and causal experiments in monkeys, imaging in humans, computational models and an anatomical framework, we delineate mechanisms through which the cerebellum can be involved in reinforcement learning and specifically, learning new visuomotor associations.

Phenylethanolamine-N-methyltransferase (Pnmt) is the enzyme that catalyzes the conversion of noradrenaline to adrenaline. These catecholamines are synthesized in the medulla of the adrenal gland and by some neurons of the central nervous system. The precise location of Pnmt action in the brain and its physiological significance are unknown. Prior studies led by Aaron Owji, a graduate student in Dr. Ebert’s laboratory, showed that mice with selectively ablated Pnmt cells show signs of neurological defects such as abnormal gait, weakened grip strength, lack of balance, reduced movement, and defective reflexes during tail suspension tests. The cerebellum is a small section of the brain that is responsible for fine-tuning motor commands. Since the Purkinje cells of the cerebellum act as the sole source of output from the cerebellar cortex, impairment of these cells could possibly account for the motor deficits seen in the mice models. The purpose of this project is to determine if there is indeed a change in Purkinje cells between wild type mice and Pnmt-ablated mice. The first aim is to identify quantitative differences in cell count between both genotypes. The second aim is to determine any morphological changes in the Purkinje cells. The main technique used in this project is immunohistochemistry in which cerebellum tissue from mice models are stained with Calbindin (a cellular marker for Purkinje neurons) and imaged with a confocal microscope. Results showed a slight reduction in the Purkinje cells of the ablated mice compared to the control genotype, accompanied with observable differences in cell structure. Understanding catecholamine pathway mechanisms in the nervous system is imperative for elucidating and targeting key players in neurodegenerative disorders.

This thesis documents three main projects performed during my PhD. Chapter 3 describes a published project in which detailed behavioral analysis based on machine learning approaches for pose-estimation were used to characterize a novel sensorimotor transformation in which mice use whisker information to rapidly modify their gait in order to rapidly avoid an obstacle in their path (Warren et al., 2021). I contributed to designing experiments, data collection and analysis related to this project spanning roughly from Aug. 2018 to Aug. 2019. Appendix 1 describes a follow-up study in which I performed multi-site silicon probe recordings and anatomical reconstruction of recording sites across the deep cerebellar nuclei in head-fixed mice performing the same obstacle avoidance behavior mentioned above. Data collection for this project spanned roughly from May 2019 to Jan. 2021. This data was initially analyzed in collaboration with Richard Warren and is currently being analyzed in collaboration with Ramin Kajeh in Dr. Larry Abbott’s group. Finally, Chapter 2 reports on the major independent work undertaken as part of my thesis, spanning from Sept. 2021 to present. As such, the Introduction relates solely to Chapter 2. The goal of this ongoing project is to extend the Sawtell laboratory studies of the mechanisms for sensory prediction and cancellation in the cerebellum-like circuitry of the electrosensory lobe (ELL) of electric fish to a cerebellum-like circuit in mammals, the dorsal cochlear nucleus (DCN) in the auditory brainstem. In particular, my work provides initial insights into the function of the cartwheel cell (CWC), a previously enigmatic cell type that occupies a similar place in the circuitry of the dorsal cochlear nucleus as the Purkinje cell of the cerebellum and the medium ganglion (MG) cell of the ELL. We have demonstrated that CWCs convey tonotopically-specific signals that are well-suited for canceling self-generated auditory responses in fusiform cells (FCs), the principal output cells in the DCN. Additionally, our findings reveal that the two characteristic types of spikes observed in CWCs—the axonal simple spikes (comparable to simple spikes in Purkinje cells and narrow spikes in MG cells) and dendritic complex spikes (similar to complex spikes in Purkinje cells and broad spikes in MG cells)—are distinctly modulated by both self-generated behavior and external acoustic stimuli, suggesting that these two types of spikes serve separate functional roles in the processing of the cancellation signal, as well as auditory information, within the DCN circuitry. This finding is consistent with the reported distinct functions of narrow and broad spikes in MG cells within the circuitry of the ELL, suggesting an evolutionarily conserved role of Purkinje-like cells in cerebellum-like circuits.

The approaches available for unlocking a neural circuit – deciphering its algorithm’s means and ends – are restricted by the biological characteristics of both the circuit in question and the organism in which it is studied. The cerebellum has long appealed to circuits neuroscientists in this regard because of its simple yet evocative structure and physiology. Decades of efforts to validate theories inspired by its distinctive characteristics have yielded intriguing but highly equivocal results. In particular, the general spirit of David Marr and James Albus’s models of cerebellar involvement in associative learning, now almost 50 years old, continues to shape much research, and yet the resulting data indicates that the Marr-Albus theories cannot, in their original incarnations, be the whole story. In efforts to resolve these mysteries of the cerebellum, researchers have pushed the advantages of its simple circuit even further by studying it in model organisms with complimentary methodological advantages. Much early work for example was conducted in monkeys and humans taking advantage of the mechanically simple and precise oculomotor behaviors at which these foveates excel. Then, as genetic tools entered the scene and became increasingly powerful, neuroscientists began porting what had been learned into mouse, a model system in which these tools can be deployed with great sophistication. This was effective in part because cerebellum is highly conserved across vertebrates so complimentary insights can be made across different model systems. Today genetic prowess has been further augmented by rapid advances in optical methods for visualizing and manipulating genetically targeted components. The promise of these new capabilities provides grounds for exploring additional model organisms with characteristics particularly suited to harnessing the power of modern methodology. In the following chapters I explore the promise and challenges of adding a new organism to the current pantheon of most commonly studied cerebellar model organisms. In chapter 1, I introduce the cerebellar circuit and a sampling of the historically equivocal outcomes met by efforts to test Marr-Albus theories in the context of a classical cerebellar learning paradigm: vestibulo-ocular reflex adaptation. In chapter 2, I detail my efforts to establish a method for population calcium imaging in cerebellar granule cells (GCs) of the weakly electric mormyrid fish, gnathonemus petersii. The unusual anatomical placement of GCs in this organism, directly on the surface of the brain, is ideal for optical methods, which require the ability to illuminate structures of interest. Furthermore, in the mormyrid, GCs play analogous role in two circuits -- the cerebellum and a purely sensory structure, the electrosensory lobe, which has a cerebellum-like structure. This latter circuit is unusually well-characterized and appears to employ a Marr-Albus style associative learning algorithm. This could provide a helpful context for interpreting the purpose of GC processing, shared by this circuit and the cerebellum proper. However, taking advantage of these qualities will require overcoming methodological hurdles presented by imaging in this as-yet not genetically tractable organism. While I was able to load and image evoked transients in these cells, and twice observed spontaneous transient, I did not find a loading method that allowed routine observation of spontaneous levels of activity. In chapter 3, I introduce the larval zebrafish, danio rerio, an organism in which optical and genetic methods are already quite established. The zebrafish is genetically tractable and orders of magnitudes smaller than other vertebrate model systems, making it extremely accessible to optical monitoring and manipulation of neural activity. However, in contrast to the mormyrid, very little is known about the physiology of the cerebellar circuit components in this organism or the behaviors to which they contribute. In chapter 4 I detail my efforts to contribute to this modest foundational knowledge by characterizing the electrophysiological activity of Purkinje cells of larval zebrafish during the optomotor response (OMR)—a behavior with similarities to cerebellar-dependent visual stabilization behaviors that have been studied extensively in mammals. I observe a diversity of structured motor and visual activity that suggests that Purkinje cells could contribute to adjusting swim speed during the OMR and other behaviors. In chapter 5, I outline some of the upfront work that remains before cerebellar researchers are likely to fully harness the power of optical and genetic methods in the zebrafish as well as the types of experiments that may become possible if we do.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Lesões sistêmicas peri e pré-natais alteram o desenvolvimento do SNC, levando a problemas cognitivos e motores em crianças que podem perdurar por toda a vida. Um tipo particular de lesão é a hipóxia-isquemia (HI), caracterizada pela interrupção momentânea ou permanente do fluxo sanguíneo. Um dos mecanismos propostos para as lesões decorrentes da HI é a excitotoxicidade glutamatérgica. O uso de inibidores da neurotransmissão glutamatérgica tem sido estudados em diversos modelos de HI. Neste trabalho, avaliamos os efeitos morfofuncionais da administração de um antagonista não-competitivo do receptor de glutamato NMDA sobre o desenvolvimento do cerebelo. Ratas no 18 dia de gestação foram anestesiadas, os cornos uterinos expostos e as 4 artérias uterinas obstruídas por 45 minutos (Grupo H). Animais controle tiveram os úteros expostos, sem a obstrução (Grupo S). Após a cirurgia a gestação prosseguiu. Somente animais nascidos a termo foram utilizados. Um dia após o nascimento, metade de cada ninhada foi designada para receber MK801, 0,3mg/kg/dia, (grupos SM e HM) e a outra metade recebeu solução salina (grupos SS e HS), por 5 dias. Após anestesia e perfusão-fixação com paraformaldeído 4% aos 9, 23, 30 e 60 dias pós-natais, cortes parassagitais do cerebelo foram obtidos em criótomo e submetidos à imunohistoquímica para calbindina, GFAP, GLAST, PDGFRα e MBP. A partir de 45 dias de vida, os animais foram testados em vários de testes comportamentais: labirinto em cruz elevado (LCE), campo vazado (CV), ROTAROD, teste de caminhada sobre barras (ladder test) e teste do comprimento da passada (stride length). Aos 9 dias, a espessura da árvore dendrítica era menor nos animais SM, HS/HM, demonstrando efeitos deletérios tanto do MK801 quanto da HI. Menor número de células PDGFRα+ foi observado nos animais HS/HM, sem efeitos da administração de MK801. Aos 23 dias, maior número de células PDGFRα+ foi observado nos animais HM comparado aos outros 3 grupos, indicando efeito neuroprotetor do MK801. Nessa idade, menor número de fibras mielinizadas (MBP+) foi observada nos animais HS, e a administração de MK801 parece reverter estes efeitos. Aos 9 dias a distribuição de GLAST estava alterada nos animais HS, com os efeitos da HI parcialmente revertidos pelo MK801. Não foram observados efeitos da HI ou do MK801 sobre comportamentos relacionados a ansiedade pelo LCE, assim como na latência de queda no ROTAROD. HI piora a performance motora no ladder test. No teste do CV, não observamos efeitos da HI sobre a busca por novidade assim como sobre a atividade locomotora espontânea. No entanto, MK801 diminui comportamentos de autolimpeza e a atividade locomotora espontânea. Menor variação das passadas foi observada em decorrência da administração de MK801 no stride length, com nenhum efeito da HI. Nossos resultados demonstram que a inibição do receptor NMDA tem um efeito neuroprotetor sobre os progenitores de oligodendrócitos e mielinização, provavelmente pela manutenção da capacidade proliferativa por um período maior. A atividade do receptor NMDA exerce importante papel na diferenciação das células de Purkinje, assim como na distribuição do transportador GLAST, corroborando a importância deste receptor na gênese das lesões causadas pela HI. / Peri and prenatal systemic lesions alter CNS development leading to motor and cognitive problems in children that might persist throughout life. A particular kind of injury, the hypoxic ischemic (HI), is characterized by a permanent or temporary blockage of blood flow. One of the proposed mechanisms downstream from a HI event is called glutamatergic excitotoxicity. The administration of glutamate inhibitors has been studied in HI models for several years. In this work, we evaluated the effects of administration of a non-competitive antagonist of glutamate receptor, NMDA, on cerebellar development and behavioral tests of HI animals. Pregnant rats in the 18th gestational day were anesthetized, the uterine horns were exposed and the four uterine arteries were clamped for 45 minutes (group H). Sham controls had the uterine horns exposed, but no arteries were clamped (group S). Gestation proceeded after surgery. Only full term animals were used. One day after birth half the animals was assigned to receive either SALINE (groups SS and HS) or MK801 (groups SM and HM). Animals were anesthetized and perfused with 4% paraformaldehyde at 9, 23, 30 and 60 days of age. Parasagittal cerebellar sections were submitted to Calbindin, GFAP, GLAST, PDGFRα and MBP immunohistochemistry. Beginning at P45 animals were subjected to a battery of behavioral tests: elevated plus maze (EPM), hole board (HB), ROTAROD, ladder test and stride length. At P9 the dendritic tree of Purkinje cells were thinner in SM, HS/HM animals, indicating that both HI and MK801 are deleterious regarding this Purkinje cell differentiation. A lower number of PDGFRα+ cells was observed in HS/HM animals, with no effects of MK801 administration. At P23 a greater number of PDGFRα+ cells was found in HM animals when compared to the other 3 groups, demonstrating a neuroprotector effect of MK801. A lower number of myelinated fibers (MBP+) was observed in HS animals at P9, and MK801 administration reverse this effect. At P9, GLAST distribution was altered in HS animals, and MK801 partially reverse this altered distribution. No effects of HI and MK801 were observed in the EPM and ROTAROD tests. HI decreased motor performance of hind limbs in the ladder test, though no effect of MK801 was noted. In the HB test, we do not observe HI effects regarding the novelty seeking behavior and locomotor activity, otherwise the administration of MK801 decreased the number of grooming and locomotor activity. In the stride length test, we do not observed effects of HI although MK801 augmented the length variation of the fore limbs. Our results show that inhibition of NMDA receptors exerts a neuroprotector effect on oligodendrocyte progenitor cells and myelination, probably by temporarily inhibiting differentiation of those, providing more time to proliferate. NMDA activity exerts a crucial role in Purkinje cell differentiation as well as in GLAST distribution. Taken together our results lead us to conclude that NMDA receptor activity has an important role in the genesis of lesions caused by HI events.

A poluição do ar é associada a diferentes patologias inclusive as que afetam o sistema nervoso central. O objetivo deste estudo foi avaliar o efeito do material particulado fino (PM2,5) da cidade de São Paulo nas células de Purkinje de embriões de galinha. Dose única de PM2,5 em suspensão (1,5 ou 20,0 Pg.100Pl-1) foi injetada em ovos fertilizados de galinha em E0 foram artificialmente incubados por 18 dias (E18). Análises morfométricas no cerebelo foram realizadas em material submetido à reação imuno-histoquímica com anticorpos dirigidos à calbindina (CB), ao fator neurotrófico derivado do encéfalo (BDNF) e à caspase 3 (CAS) para avaliação da densidade de células de Purkinje, de seus dendritos e da taxa de apoptose nestas células. A expressão do BDNF no cerebelo foi determinada pelo método de immunoblotting. A ocorrência de elementos traço e de peroxidação lipídica no cerebelo foi avaliada, assim como a atividade da superóxido dismutase (SOD) e da catalase. Não foram observadas diferenças no desenvolvimento geral e na taxa de mortalidade dos embriões submetidos ao PM2,5 em comparação aos controles. Embora o PM2.5 em suspensão tenha apresentado elevada quantidade de elementos traço, depleção na concentrações de elementos como Cu, Mg, Mn, Se e Zn foi observada no cerebelo dos animais. Comparados ao controle salina, animais submetidos às concentrações de PM2,5 apresentaram diminuição da densidade de células de Purkinje CB+ nos grupos PM2,5 (18% no PM2,51,5 Pg e 23% no grupo PM2,5 20,0 Pg). Aumento de 45% na densidade de dendritos das células de Purkinje no grupo exposto a PM2,5 20,0 Pg foi observado. Redução significativa na expressão de BDNF no cerebelo e também na densidade de células de Purkinje BDNF+ no grupo PM2,5 20,0 Pg foi observada em relação aos controles e ao grupo PM2,51,5 Pg. A ocorrência de células de Purkinje apoptóticas não variou entre os grupos deste estudo da mesma forma em que a peroxidação lipídica e a atividade de SOD também não variaram. Contudo, foi observada maior atividade da catalase no cerebelo dos animais expostos ao material particulado. Conclusão: O material particulado fino da cidade de São Paulo afetou o desenvolvimento embrionário das células de Purkinje no modelo empregado e promoveu a ativação de mecanismos antioxidantes. A composição elementar do material particulado da cidade de São Paulo pode estar associada à perturbação da poda dendrítica nas células de Purkinje / Air pollutants are associated to several diseases including those related to central nervous system. The aim of this work was to evaluate the effect of urban fine particles (PM2.5) in chicken embryo Purkinje cells. A single dose of PM2.5 suspension in two different concentrations (1.5 or 20.0 Pg.100Pl-1) was injected in fresh laid fertilized eggs on E0. Control groups were performed (intact and saline groups). After 18 days of embryo incubation (E18), no differences in general abnormal development and mortality ratio were found between groups. Cerebellar morphometrical analysis for neuronal density, dendritic outgrowth and cellular apoptosis were scored in anti-CB, anti-BDNF and anti-CAS immunelabeled Purkinje cells. Measurements of trace elements, lipid peroxidation, superoxide dismutase and catalase were performed as well. PM2.5 suspensions presented high amounts of metals but the cerebellar tissue presented metal depletion. Compared to control animals (saline group) both PM2.5 doses exposed embryos showed a decreased number of Purkinje cell CB+ (ca. 18% for PM2.5 1.5 Pg and 23% for PM2.5 20.0 Pg) and increased Purkinje cell dendritic branches density in the PM2.5 20.0Pg exposed embryos (ca. 45% for PM2.5 20.0Pg). Interestingly, a significant reduction of Purkinje cell BDNF expression was observed in the PM2.5 20 Pg group embryos when compared to those of the control and PM2.5 1.5Pg groups. No alterations in the number of Purkinje cells CAS+ were observed. The lipid peroxidation and SOD activity showed similar levels in the cerebellar tissue of all experimental groups, although significant higher levels of CAT were detected in PM2.5 20 Pg group cerebella. In conclusion, urban fine particles impair the embryonic development of Purkinje cells in chick embryo model as well promote the antioxidant defense activation. PM2.5 elemental compounds may disrupt the physiological dendritic pruning of Purkinje cells

A poluição do ar é associada a diferentes patologias inclusive as que afetam o sistema nervoso central. O objetivo deste estudo foi avaliar o efeito do material particulado fino (PM2,5) da cidade de São Paulo nas células de Purkinje de embriões de galinha. Dose única de PM2,5 em suspensão (1,5 ou 20,0 Pg.100Pl-1) foi injetada em ovos fertilizados de galinha em E0 foram artificialmente incubados por 18 dias (E18). Análises morfométricas no cerebelo foram realizadas em material submetido à reação imuno-histoquímica com anticorpos dirigidos à calbindina (CB), ao fator neurotrófico derivado do encéfalo (BDNF) e à caspase 3 (CAS) para avaliação da densidade de células de Purkinje, de seus dendritos e da taxa de apoptose nestas células. A expressão do BDNF no cerebelo foi determinada pelo método de immunoblotting. A ocorrência de elementos traço e de peroxidação lipídica no cerebelo foi avaliada, assim como a atividade da superóxido dismutase (SOD) e da catalase. Não foram observadas diferenças no desenvolvimento geral e na taxa de mortalidade dos embriões submetidos ao PM2,5 em comparação aos controles. Embora o PM2.5 em suspensão tenha apresentado elevada quantidade de elementos traço, depleção na concentrações de elementos como Cu, Mg, Mn, Se e Zn foi observada no cerebelo dos animais. Comparados ao controle salina, animais submetidos às concentrações de PM2,5 apresentaram diminuição da densidade de células de Purkinje CB+ nos grupos PM2,5 (18% no PM2,51,5 Pg e 23% no grupo PM2,5 20,0 Pg). Aumento de 45% na densidade de dendritos das células de Purkinje no grupo exposto a PM2,5 20,0 Pg foi observado. Redução significativa na expressão de BDNF no cerebelo e também na densidade de células de Purkinje BDNF+ no grupo PM2,5 20,0 Pg foi observada em relação aos controles e ao grupo PM2,51,5 Pg. A ocorrência de células de Purkinje apoptóticas não variou entre os grupos deste estudo da mesma forma em que a peroxidação lipídica e a atividade de SOD também não variaram. Contudo, foi observada maior atividade da catalase no cerebelo dos animais expostos ao material particulado. Conclusão: O material particulado fino da cidade de São Paulo afetou o desenvolvimento embrionário das células de Purkinje no modelo empregado e promoveu a ativação de mecanismos antioxidantes. A composição elementar do material particulado da cidade de São Paulo pode estar associada à perturbação da poda dendrítica nas células de Purkinje / Air pollutants are associated to several diseases including those related to central nervous system. The aim of this work was to evaluate the effect of urban fine particles (PM2.5) in chicken embryo Purkinje cells. A single dose of PM2.5 suspension in two different concentrations (1.5 or 20.0 Pg.100Pl-1) was injected in fresh laid fertilized eggs on E0. Control groups were performed (intact and saline groups). After 18 days of embryo incubation (E18), no differences in general abnormal development and mortality ratio were found between groups. Cerebellar morphometrical analysis for neuronal density, dendritic outgrowth and cellular apoptosis were scored in anti-CB, anti-BDNF and anti-CAS immunelabeled Purkinje cells. Measurements of trace elements, lipid peroxidation, superoxide dismutase and catalase were performed as well. PM2.5 suspensions presented high amounts of metals but the cerebellar tissue presented metal depletion. Compared to control animals (saline group) both PM2.5 doses exposed embryos showed a decreased number of Purkinje cell CB+ (ca. 18% for PM2.5 1.5 Pg and 23% for PM2.5 20.0 Pg) and increased Purkinje cell dendritic branches density in the PM2.5 20.0Pg exposed embryos (ca. 45% for PM2.5 20.0Pg). Interestingly, a significant reduction of Purkinje cell BDNF expression was observed in the PM2.5 20 Pg group embryos when compared to those of the control and PM2.5 1.5Pg groups. No alterations in the number of Purkinje cells CAS+ were observed. The lipid peroxidation and SOD activity showed similar levels in the cerebellar tissue of all experimental groups, although significant higher levels of CAT were detected in PM2.5 20 Pg group cerebella. In conclusion, urban fine particles impair the embryonic development of Purkinje cells in chick embryo model as well promote the antioxidant defense activation. PM2.5 elemental compounds may disrupt the physiological dendritic pruning of Purkinje cells