by Cheng Wai Ming. / Thesis submitted in: October, 1998. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves 54-68 (2nd gp.)). / Abstracts in English and Chinese. / ACKNOWLEDGEMENTS --- p.iv / ABSTRACT --- p.v / ABSTRACT (Chinese) --- p.vii / Chapter CHAPTER 1 --- LITERATURE REVIEW --- p.1 / Chapter 1.1 --- Ionotropic glutamate receptors --- p.1 / Chapter 1.1.1 --- AMP A receptor --- p.3 / Chapter 1.1.1.1 --- Structure of AMP A receptor --- p.3 / Chapter 1.1.1.2 --- Electrophysiological properties of AMPA receptor --- p.4 / Chapter 1.1.1.3 --- Pharmacology of AMPA receptors --- p.6 / Chapter 1.1.1.4 --- Kinetics of AMPA receptors --- p.8 / Chapter 1.1.2 --- NMDA receptor --- p.9 / Chapter 1.1.2.1 --- Structure of NMDA receptor --- p.9 / Chapter 1.1.2.2 --- Electrophysiological properties of NMDA receptor --- p.10 / Chapter 1.1.2.3 --- Pharmacology of NMDA receptor --- p.11 / Chapter 1.1.2.4 --- Kinetics of NMDA receptor --- p.12 / Chapter 1.2. --- The basal ganglia and the SNR --- p.12 / Chapter 1.3 --- Excitatory glutamatergic inputs on SNR --- p.16 / Chapter 1.4 --- Aim of study --- p.17 / Chapter CHAPTER 2 --- Electrophysiological properties of SNR neurones --- p.18 / Chapter 2.1 --- Introduction --- p.18 / Chapter 2.2 --- Methods --- p.19 / Chapter 2.2.1 --- In vitro slice preparation and maintenance --- p.19 / Chapter 2.2.2 --- Whole-cell patch-clamp recording --- p.20 / Chapter 2.2.3 --- Solutions and drugs --- p.21 / Chapter 2.2.4 --- Histological methods --- p.21 / Chapter 2.2.5 --- Data analysis --- p.22 / Chapter 2.3 --- Results --- p.22 / Chapter 2.3.1 --- Passive membrane properties of SNR neurones --- p.22 / Chapter 2.3.2 --- Firing rate and action potential characteristics --- p.23 / Chapter 2.3.3 --- Firing patterns --- p.23 / Chapter 2.3.4 --- Weak hyperpolarization activated inward rectification --- p.24 / Chapter 2.3.5 --- Slow aflerhyperpolarization --- p.25 / Chapter 2.3.6 --- Current-frequency relationship --- p.25 / Chapter 2.3.7 --- Morphology of labelled SNR neurones --- p.25 / Chapter 2.4 --- Discussion and conclusion --- p.26 / Chapter CHAPTER 3 --- AMPA and NMDA induced membrane responses --- p.30 / Chapter 3.1 --- Introduction --- p.30 / Chapter 3.2 --- Methods --- p.31 / Chapter 3.2.1 --- In vitro slice preparation and maintenance --- p.31 / Chapter 3.2.2 --- Whole-cell patch-clamp recording --- p.31 / Chapter 3.2.3 --- Solutions and drugs --- p.31 / Chapter 3.2.4 --- Drug application --- p.32 / Chapter 3.2.5 --- Immunocytochemistry --- p.32 / Chapter 3.2.6 --- Data analysis --- p.33 / Chapter 3.3 --- Results --- p.33 / Chapter 3.3.1 --- AMPA induced responses in SNR GABA neurones --- p.33 / Chapter 3.3.1.1 --- AMPA induced membrane depolarization --- p.33 / Chapter 3.3.1.2 --- AMPA induced membrane current --- p.34 / Chapter 3.3.1.3 --- Current-voltage relationship --- p.34 / Chapter 3.3.1.4 --- Effect of NBQX --- p.35 / Chapter 3.3.1.5 --- Effects of JSTX and spermine --- p.35 / Chapter 3.3.2 --- NMDA-induced response in SNR GABA neurones --- p.36 / Chapter 3.3.2.1 --- NMDA induced membrane depolarization --- p.36 / Chapter 3.3.2.2 --- NMDA induced membrane current --- p.36 / Chapter 3.3.2.3 --- APV blocked NMDA-induced current --- p.36 / Chapter 3.3.2.4 --- Effect of glycine on NMDA induced response --- p.37 / Chapter 3.3.2.5 --- Mg2+-sensitivity --- p.37 / Chapter 3.3.2.6 --- Current-voltage relationship --- p.38 / Chapter 3.3.3 --- GluR2 subunit immunostaining --- p.38 / Chapter 3.4 --- Discussion and conclusion --- p.39 / Chapter 3.4.1 --- AMPA receptors in SNR neurones --- p.39 / Chapter 3.4.2 --- NMDA receptors in SNR neurones --- p.41 / Chapter 3.4.3 --- Functional significance --- p.41 / Chapter CHAPTER 4 --- Glutamate-mediated synaptic currents in SNR --- p.43 / Chapter 4.1 --- Introduction --- p.43 / Chapter 4.2 --- Methods --- p.44 / Chapter 4.2.1 --- In vitro slice preparation and maintenance --- p.44 / Chapter 4.2.2 --- Electrophysiological recordings --- p.44 / Chapter 4.2.3 --- Electrical stimulation --- p.45 / Chapter 4.2.4 --- Solutions and drugs --- p.45 / Chapter 4.2.5 --- Data analysis --- p.46 / Chapter 4.3 --- Results --- p.46 / Chapter 4.3.1 --- Characteristics of spontaneous EPSCs --- p.46 / Chapter 4.3.1.1 --- General characteristics --- p.46 / Chapter 4.3.1.2 --- Kinetics --- p.47 / Chapter 4.3.1.3 --- Pharmacology --- p.47 / Chapter 4.3.2 --- Characteristics of evoked EPSCs --- p.48 / Chapter 4.3.2.1 --- General characteristics --- p.48 / Chapter 4.3.2.2 --- Pharmacological characterization --- p.49 / Chapter 4.3.2.3 --- Effects of bicuculline --- p.50 / Chapter 4.4 --- Discussion and conclusion --- p.50 / Chapter 4.4.1 --- Excitatory transmission onto SNR neurones --- p.50 / Chapter 4.4.2 --- Source of excitatory drive --- p.51 / Chapter 4.4.3 --- Interaction with GABA inputs --- p.52 / Chapter 4.4.4 --- Functional significance --- p.52 / REFERENCES --- p.54

INTRODUÇÃO: A presença e extensão da perda neuronal no encéfalo dos idosos ainda é controversa. A substância negra (SN) é uma região localizada no mesencéfalo e caracterizada macroscopicamente pela coloração escura, devido à presença neuromelanina. O envelhecimento da SN ainda é um mistério, mas existem grandes quantidades de estudos relativos às modificações sofridas por essa região com o passar dos anos. Alguns estudos detectaram perda neuronal na SN durante o envelhecimento, enquanto outros afirmam que não há alteração significativa durante esse processo. OBJETIVO: Caracterizar as alterações que ocorrem na SN durante o envelhecimento humano, em indivíduos sem sintomas da doença de Parkinson, do ponto de vista citoarquitetônico em 3D. CASUÍSTICA E METODOLOGIA:O presente projeto faz parte do Projeto Envelhecimento Cerebral (PEC) do Grupo de Estudos em Envelhecimento Cerebral (GEEC) da Faculdade de Medicina da Universidade de São Paulo (FMUSP). Foram utilizados 18 casos, classificados em quatro faixas etárias. Quinze casos foram analisados estereológicamente e recontruídos tridimensionalmente. Para estes, foram determinados número de neurônios, volume da SN e densidade neuronal e submetidos à testes estatísticos não paramétricos. Três casos foram imunocorados com quatro diferentes anticorpos: anti tirosina-hidroxilase (TH), anti proteína tau hiperfosforilada, anti proteína alfa-sinucleína e anti calbindina D28k (Calb) e analisados qualitativamente. RESULTADOS: As lâminas imunocoradas com anticorpo anti -sinucleína e anti-tau, foram negativas. As lâminas imunocoradas com anticorpo anti- TH e anti-Calb D28k foram positivas. Dos quinze casos analisados estereologicamente, Para o número de neurônios, encontrou-se: mediana de 504.575 células, valor mínimo de 348.662 células e valor máximo de 672.172 células. Para o volume, encontrou-se mediana de 190,8mm3; valor mínimo de 134,1 mm3 e valor máximo de 267,3mm3. Para a densidade total média, encontrou-se a mediana de 2.517,4 cel/mm3, valor mínimo de 1.603,1 cel/mm3 e valor máximo de 5.015,7 cel/mm3. Realizou-se o teste de correlação de Spearman para as três variáveis neuronais, correlacionando hemisfério direito e esquerdo, encontrou-se uma correlação moderada para número de neurônios e volume, e correlação forte para densidade. Com o mesmo teste, realizou-se análise das variáveis neuronais em função da idade, e não houve alteração estatisticamente significativa. Apenas uma tendência à diminuição no volume total da SN em relação à idade. Também verificou-se a relação entre as variáveis neuronais, por gênero em função da idade e não houve alteração estatisticamente significativa. Nas reconstruções tridimensionais, verificou-se uma grande variabilidade interpessoal entre as 15 SN reconstruídas. DISCUSSÃO: Diversos estudos estereológicos foram feitos, mas poucos deles com análise estereológica sem viés e a maior parte deles demonstra diminuição no número de neurônios, discordando dos achados atuais. A reconstrução tridimensional também não descreve alterações decorrentes do envelhecimento, mas aparentemente modificações interpessoais. CONCLUSÃO: As características da substância negra se mantém ao longo dos anos, porém, ainda devem ser muito mais estudadas / INTRODUTION: Some aspects about maco and micro braischanges are suffering modifications along the years. The presence and extension of neuronal lost in elderly still a big and polemic issue. The SUBSTANTIA NIGRA (SN) is located at the midbrain and characterized by the dark color due to the pigmented neurons, which contain neuromelanin. The SNs aging is still a mystery, nevertheless, there are great researches related to these changes suffered in this region by the years. Some of the researches noticed that neuronal lost in SN during the aging, while others claim that there are no significant modifications through this process.OBJECTIVE: Describing SN changes during the human aging in individuals with no Parkinsons disease symptoms, from the 3D cytoarchitectonic point of view. METHODS: This project is part of the Brain Aging Project of Brain Aging Study Group, in University of São Paulo Medical School. Eighteen cases had been analyzed and classified into four ages groups. Fifteen cases had been analyzed with stereological methos and 3D reconstructed. During the stereological analysis, were determinate the neuronal number, SN volume, neuronal density and submitted to nonparametric statistics test. Three cases had been immunostained with 4 different antibodies anti tyrosine-hydroxylase (TH), anti hyperphosphorylated tau (anti-tau), anti alfa-synuclein (alpha-syn) e anti calbindin D28k (Calb) and qualitatively analyzed. RESULTS: The immunostained slices with the anti alpha-syn and anti-tau antibodies were negative. The immunostained slices with anti TH and anti calb D28K antibodies were positive. From the 15 cases estereologically analyzed, 53,3% were female and 46,7% male. Had been analyzed neuron numbers, SN volume and neuronal density. For the neural numbers were found median of 504.575 cells, minimum value of 348.662 cells and maximum value of 672.172 cells. For the volume were found median of 190,8mm³; minimum value of 134,1mm³ and maximum value of 267,3mm³. For the total density, was found median of de 2.517,4 cel/mm³, minimum value of 1603,1 cel/mm³ , maximum value of 5015,7 cel/mm³. The Spearmans correlation test had been done to the three neuronal variable correlating the right and left hemispheres and was a moderated correlation between neuron numbers and neuron volume and strong correlation to density. Using the same test, the rate neuron by the age analysis had been concluded and there was no significant change.There was noticed just one trend to the reduction in the SN total volume related to aging. It was also checked the relation between the neurons variety by gender considering aging and there was no significant changes. In the 3D reconstruction, was possible to notice a great interpersonal variability between the 15 SN rebuilt. DISCUSSION: Many stereological researches had been done, however, a few of them used the unbiased stereological analysis and most of them show a reduction in the neuron number, disagreeing from the current conclusions. The 3D reconstruction also dont describe changes as aging result, but apparently interpersonal changes. CONCLUSION: The Substantia Nigra maintain the same characteristics along the years, however, it must be much more explored

Η νόσος του Πάρκινσον χαρακτηρίζεται από την προοδευτική εκφύλιση της μελαινοραβδωτής ντοπαμινεργικής οδού που οδηγεί σε κινητικές διαταραχές. Θεωρείται πολυπαραγοντική νόσος, η αιτιολογία της οποίας παραμένει άγνωστη. Με δεδομένο ότι η διαθέσιμη φαρμακευτική αγωγή της νόσου στηρίζεται στη συμπτωματολογία της και έχει σοβαρές παρενέργειες, η νευροπροστασία από τα πρώϊμα στάδια της νόσου αποτελεί τομέα έντονης έρευνας. Τα τελευταία χρόνια, ένα ευρύ φάσμα παραγόντων ερευνήθηκε ως προς το νευροπροστατευτικό τους ρόλο σε νευροτοξικά μοντέλα οξείας ντοπαμινεργικής εκφύλισης. Ο μεταλλαγμένος μυς “weaver” αποτελεί ένα μοναδικό γενετικό μοντέλο μελαινοραβδωτής νευροεκφύλισης, η οποία λαμβάνει χώρα ενδογενώς και προοδευτικά, αρχίζοντας μετά την 7η μετεμβρυϊκή ημέρα (Ρ7) και προσεγγίζοντας το 50% την 21η μετεμβρυϊκή ημέρα (Ρ21). Στην παρούσα μελέτη, προκειμένου να διερευνηθούν νευροπροστατευτικοί μηχανισμοί κατά τα πρώτα στάδια της νευροεκφυλιστικής διαδικασίας στο μυ “weaver”, και να επιτευχθεί μία πλειοτροπική θεραπευτική δράση, χορηγήθηκαν τρεις φαρμακευτικοί νευροπροστατευτικοί παράγοντες με διαφορετικούς μηχανισμούς δράσης καθώς και ένα σχήμα συνδυασμού τους. Συγκεκριμένα, χορηγήθηκαν, μεμονωμένα και σε συνδυασμό, στους μυς “weaver” N-ακετυλοκυστεΐνη (ΝAC) (αντιοξειδωτική δράση), ασπιρίνη (αντιφλεγμονώδης δράση) και 17β οιστραδιόλη [Ε2] (αντιοξειδωτική, αντιαποπτωτική, νευροτροφική δράση) σε καθημερινή βάση από την Ρ1 μέχρι την Ρ21. Το νευροπροστατευτικό αποτέλεσμα αξιολογήθηκε με ανοσοϊστοχημικό προσδιορισμό των ντοπαμινεργικών νευρώνων της συμπαγούς μοίρας της μέλαινας ουσίας (SNpc) των μυών στους οποίους χορηγήθηκαν τα παραπάνω φάρμακα. Η χορήγηση των NAC και ασπιρίνης δεν επηρέασε την επιβίωση των ντοπαμινεργικών νευρώνων (DA) των weaver μυών. Αντίθετα η χορήγηση της 17β οιστραδιόλης οδήγησε σε σημαντική επιβίωση των DA νευρώνων της SNpc, της τάξης του 48%, στους weaver μυς που έλαβαν την αγωγή, συγκριτικά με τους weaver μυς που έλαβαν φυσιολογικό ορό. Επιπλέον η χορήγηση του συνδυασμού των τριών φαρμάκων (cocktail) προώθησε σε ακόμα μεγαλύτερο βαθμό την επιβίωση των DA νευρώνων της SNpc, σε ποσοστό 86%. Οι weaver μύες που έλαβαν το cocktail εμφάνισαν 26% περισσότερους DA νευρώνες σε σύγκριση με τους weaver μυς που έλαβαν μεμονωμένα 17β οιστραδιόλη προτείνοντας πιθανή συνεργιστική δράση μεταξύ 17β οιστραδιόλης και NAC. Η διερεύνηση του μηχανισμού της νευροεκφύλισης στην SNpc και της παρεχόμενης νευροπροστασίας από τη χορήγηση της 17β οιστραδιόλης και του cocktail πραγματοποιήθηκε σε δύο επίπεδα. Αρχικά με τον προσδιορισμό μιας σειράς δεικτών οξειδωτικού στρες όπως η υπεροξείδωση λιπιδίων και δείκτες της θειολικής κατάστασης του κυττάρου (GSH, GSSG, CSH NPSSC, PSH, PSSP, NPSH, NSPSSR). Ο προσδιορισμός της υπεροξείδωση λιπιδίων πραγματοποιήθηκε στο μεσεγκέφαλο και το ραβδωτό σώμα των φυσιολογικών και weaver μυών που έλαβαν φυσιολογικό ορό (saline +/+ και saline wv/wv), 17 β οιστραδιόλη (17β +/+ και 17β wv/wv) cocktail (cocktail +/+ και cocktail wv/wv). Τα επίπεδα της υπεροξείδωσης λιπιδίων, στο μεσεγκέφαλο, αυξήθηκαν περίπου κατά 98% στους saline wv/wv μυς συγκριτικά με τους saline +/+ δείχνοντας παρουσία έντονου οξειδωτικού στρες στην παθολογική κατάσταση των weaver μυών. Ήταν ενδιαφέρον όμως το γεγονός ότι η λιπιδική υπεροξείδωση ανεστάλη σε ποσοστό 27% στους 17β wv/wv ενώ επανήλθε στα φυσιολογικά επίπεδα στους cocktail wv/wv μύες. Από τους υπόλοιπους δείκτες που εξετάστηκαν μόνο το NPSSC έδειξε διαφορές μεταξύ saline +/+ και saline wv/wv, ενώ οι GSSG, PSSP και PSH ακολούθησαν παρόμοια αύξηση στους cocktail +/+ και cocktail wv/w. Οι παρατηρήσεις αυτές δείχνουν ότι οι συγκεκριμένοι δείκτες από μόνοι τους δεν μπορούν να δώσουν σαφή εικόνα της οξειδωτικής κατάστασης, καθώς αποτελούν ταχέως μεταβαλλόμενα συστατικά αντιοξειδωτικών κύκλων. Στη συνέχεια διερευνήθηκε η έκφραση των γονιδίων Lasp1, Supt14h, Nr4a2 (nurr1), Dlg4 και του γονιδίου του μεταφορέα της σεροτονίνης (SERT), τα οποία φαίνονται να εμπλέκονται στα μονοπάτια της νευροεκφύλισης, στη μεσεγκεφαλική περιοχή και στο ραβδωτό σώμα των weaver μυών. Δεν παρατηρήθηκαν διαφορές στα επίπεδα έκφρασής τους με χρήση της τεχνικής RT-PCR σε καμία από τις υπό εξέταση περιοχές. Τα αποτελέσματα της παρούσας εργασίας οδηγούν στο συμπέρασμα ότι η 17β-οιστραδιόλη παρείχε σημαντική νευροπροστασία στους ντοπαμινεργικούς νευρώνες, για πρώτη φορά, ενός μοντέλου in vivo, ενδογενούς, προοδευτικής μελαινοραβδωτής νευροεκφύλισης, του μοντέλου weaver. Στο μηχανισμό της νευροπροστατευτικής δράσης της Ε2 φαίνεται να παίζει σημαντικό ρόλο η αντιοξειδωτική της δράση αφού η χορήγησή της αναστέλλει τη λιπιδική υπεροξείδωση. Επιπλέον η νευροπροστατευτική δράση της Ε2 ενδυναμώθηκε σημαντικά κατά τη συγχορήγηση του NAC, προτείνοντας την ύπαρξη συνέργειας μεταξύ της Ε2 και της GSH, για πρώτη φορά σε ένα in vivo μοντέλο νευροεκφύλισης. Η ενίσχυση του νευροπροστατευτικού αποτελέσματος από το cocktail δίνει ένα πρόσθετο επιχείρημα στην υπόθεση του αντιοξειδωτικού τρόπου δράσης της Ε2 αφού παράλληλα το cocktail επαναφέρει την υπεροξείδωση των λιπιδίων στα φυσιολογικά επίπεδα. Οι παρατηρήσεις αυτές προτείνουν την Ε2 ως μια μελλοντική υποψήφια φαρμακευτική αγωγή για νευροεκφυλιστικές καταστάσεις, όπως είναι η νόσος του Πάρκινσον, για τα θηλυκά βέβαια άτομα. Eπιπλέον προτείνουν ότι ο συνδυασμός της Ε2 και του NAC μπορεί να οδηγήσει σε εφαρμογή μικρότερων και κατά συνέπεια λιγότερο επιβαρυντικών, από άποψη παρενεργειών, δόσεων που θα οδηγεί σε ίδιο ή και μεγαλύτερο νευροπροστατευτικό αποτέλεσμα με τη μεμονωμένη χορήγηση της 17β-οιστραδιόλης. / Parkinson’s disease (PD) is characterized by the progressive degeneration of the nigrostriatal dopaminergic innervation that leads to motor disturbances. It is considered to be a multifactor disease, the etiology of which still remains unknown. Since currently available treatments are only symptomatic, having severe side-effects, neuroprotection from the early stages of the disease has been given much attention as a promising approach to PD management. Indeed, a broad range of agents has been investigated for their neuroprotective role in neurotoxical models of acute dopaminergic degeneration. “Weaver” mutant mouse represents a unique genetic model, in which the nigrostriatal neurodegeneration occurs endogenously and progressively, starting after postnatal day 7 (P7) and reaching 50% at P21. In the present study, aiming to identify neuroprotective mechanisms in the early progression of the “weaver” degenerative process and to achieve a potentially pleiotropic therapeutic action, we applied three pharmaceutical agents with different mechanisms of action, as well as a scheme combining them. Specifically, “weaver” mice were treated, individually and in combination, with N-acetylcysteine (NAC) (antioxidant), aspirine (anti-inflammatory) and 17b-estradiol [E2] (antioxidant, antiapoptotic, neurotrophic) daily, from P1 to P21. The neuroprotective effect was evaluated by immunohistochemical detection of dopaminergic (DA) neurons in the substantia nigra (SNpc) of treated animals. The administration of ΝΑC and aspirine did not influence the survival of (DA) neurons of weaver mice. On the contrary, the administration of 17b estradiol led to significant survival of DA neurons of SNpc, approximately 48%, in weaver mice that received E2, comparatively with weaver mice that received saline. Moreover the administration of the combination of the three drugs (cocktail) promoted the survival of DA neurons of SNpc, approximately 86% to a higher degree. Weaver mice that received cocktail had 26% more DA neurons compared to weaver mice that received individually 17b estradiol, proposing a possible synergistic action between 17b estradiol and NAC. The investigation of mechanism of neurodegeneration in SNpc and provided neuroprotection by 17b estradiol and cocktail, was realised in two levels. Initiall, by determination of oxidative stress markers, like lipid peroxidation and markers of cellular thiol redox (GSH, GSSG, CSH NPSSC, PSH, PSSP, NPSH, NSPSSR). The determination of lipid peroxidation was realised in the midbrain and striatum of normal and weaver mice that received saline (saline +/+ and saline wv/wv), 17 b estradiol (17b +/+ and 17b wv/wv) cocktail (cocktail +/+ and cocktail wv/wv). Lipid peroxidation levels in the midbrain were increased about 98% in saline wv/wv mice comparatively with the saline +/+, showing the presence of intense oxidative stress in the weaver mutant mouse. It was interesting, however, the fact that lipid peroxidation was inhibited approximately 27% in 17b wv/wv mice, while it was reverted at the normal levels in cocktail wv/wv mice. Regarding to the other oxidative markers that were examined, only NPSSC showed differences between saline +/+ and saline wv/wv, while the GSSG, PSSP and PSH followed similar increasement in both cocktail +/+ and cocktail wv/w animals. This observation indicates that these markers alone cannot give a clear figure of oxidative situation, as they constitute rapidly altered components of antioxidant cycles. Afterwards, we investigated the expression of genes Lasp1, Supt14h, Nr4a2 (nurr1), Dlg4 and serotonin transporter’s gene (SERT), which appear to be involved in neurodegeneration pathways, in the midbrain ant striatum of normal and weaver mice. There were not observed differences in their expression levels (using the RT-PCR technique) in both regions investigated. The results of the present study, lead to the conclusion that 17b-estradiol provided important neuroprotection in the DA neurons, for the first time, in a model of in vivo, endogenous, progressive dopaminergic degeneration, the weaver model. The mechanism of E2’s neuroprotective effect appears to be antioxidant as the administration of E2 suspends lipid peroxidation. Moreover the E2’s neuroprotective effect was strengthened significantly by the co-treatment of NAC, proposing the existence of synergy between E2 and GSH, for the first time in an in vivo model of neurodegeneration. The reinforced cocktail’s result gives an additional argument in the hypothesis of antioxidant mechanism of E2’s action, as cocktail, at the same time, restores lipid peroxidation in normal levels. These observations propose E2 as a future candidate pharmaceutic treatment for neurodegenerative situations, like PD, of course for female individuals. Moreover they propose that the combined treatment of E2 and NAC, can lead to the application of lower and, in consequence, less aggravating doses, concerning the side effects, that will lead to same or even higher neuroprotective result with the individual administration of 17b-estradiol

Made available in DSpace on 2015-07-22T20:50:30Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-02-28. Added 1 bitstream(s) on 2015-08-11T03:26:35Z : No. of bitstreams: 1 Publico-Tese%20Doutorado%20Marcelo%20M%20S%20Lima%20A.pdf: 1921437 bytes, checksum: 137175d8ab4d8c8de55271aa236d3452 (MD5). Added 1 bitstream(s) on 2015-08-11T03:26:35Z : No. of bitstreams: 2 Publico-Tese%20Doutorado%20Marcelo%20M%20S%20Lima%20A.pdf: 1921437 bytes, checksum: 137175d8ab4d8c8de55271aa236d3452 (MD5) Publico-Tese%20Doutorado%20Marcelo%20M%20S%20Lima%20B.pdf: 706371 bytes, checksum: db83e739e4717c5c824c2f6fc42e637e (MD5). Added 1 bitstream(s) on 2015-08-11T03:26:35Z : No. of bitstreams: 3 Publico-Tese%20Doutorado%20Marcelo%20M%20S%20Lima%20A.pdf: 1921437 bytes, checksum: 137175d8ab4d8c8de55271aa236d3452 (MD5) Publico-Tese%20Doutorado%20Marcelo%20M%20S%20Lima%20B.pdf: 706371 bytes, checksum: db83e739e4717c5c824c2f6fc42e637e (MD5) Publico-Tese%20Doutorado%20Marcelo%20M%20S%20Lima%20C.pdf: 1231295 bytes, checksum: d4978d6d50480082f2f58a6e8c6317fc (MD5). Added 1 bitstream(s) on 2015-08-11T03:26:35Z : No. of bitstreams: 4 Publico-Tese%20Doutorado%20Marcelo%20M%20S%20Lima%20A.pdf: 1921437 bytes, checksum: 137175d8ab4d8c8de55271aa236d3452 (MD5) Publico-Tese%20Doutorado%20Marcelo%20M%20S%20Lima%20B.pdf: 706371 bytes, checksum: db83e739e4717c5c824c2f6fc42e637e (MD5) Publico-Tese%20Doutorado%20Marcelo%20M%20S%20Lima%20C.pdf: 1231295 bytes, checksum: d4978d6d50480082f2f58a6e8c6317fc (MD5) Publico-Tese%20Doutorado%20Marcelo%20M%20S%20Lima%20D.pdf: 946427 bytes, checksum: 54f4c0262b49f8ffbe3eedb7e56d115a (MD5). Added 1 bitstream(s) on 2015-08-11T03:26:35Z : No. of bitstreams: 5 Publico-Tese%20Doutorado%20Marcelo%20M%20S%20Lima%20A.pdf: 1921437 bytes, checksum: 137175d8ab4d8c8de55271aa236d3452 (MD5) Publico-Tese%20Doutorado%20Marcelo%20M%20S%20Lima%20B.pdf: 706371 bytes, checksum: db83e739e4717c5c824c2f6fc42e637e (MD5) Publico-Tese%20Doutorado%20Marcelo%20M%20S%20Lima%20C.pdf: 1231295 bytes, checksum: d4978d6d50480082f2f58a6e8c6317fc (MD5) Publico-Tese%20Doutorado%20Marcelo%20M%20S%20Lima%20D.pdf: 946427 bytes, checksum: 54f4c0262b49f8ffbe3eedb7e56d115a (MD5) Publico-Tese%20Doutorado%20Marcelo%20M%20S%20Lima%20E.pdf: 1159114 bytes, checksum: 70e61676ec1c583f9ac4fb6dd31c72b6 (MD5). Added 1 bitstream(s) on 2015-08-11T03:26:35Z : No. of bitstreams: 6 Publico-Tese%20Doutorado%20Marcelo%20M%20S%20Lima%20A.pdf: 1921437 bytes, checksum: 137175d8ab4d8c8de55271aa236d3452 (MD5) Publico-Tese%20Doutorado%20Marcelo%20M%20S%20Lima%20B.pdf: 706371 bytes, checksum: db83e739e4717c5c824c2f6fc42e637e (MD5) Publico-Tese%20Doutorado%20Marcelo%20M%20S%20Lima%20C.pdf: 1231295 bytes, checksum: d4978d6d50480082f2f58a6e8c6317fc (MD5) Publico-Tese%20Doutorado%20Marcelo%20M%20S%20Lima%20D.pdf: 946427 bytes, checksum: 54f4c0262b49f8ffbe3eedb7e56d115a (MD5) Publico-Tese%20Doutorado%20Marcelo%20M%20S%20Lima%20E.pdf: 1159114 bytes, checksum: 70e61676ec1c583f9ac4fb6dd31c72b6 (MD5) Publico-Tese%20Doutorado%20Marcelo%20M%20S%20Lima%20F.pdf: 1538781 bytes, checksum: 47d5cbd870c32fe12325305adebc81a5 (MD5). Added 1 bitstream(s) on 2015-08-11T03:26:35Z : No. of bitstreams: 7 Publico-Tese%20Doutorado%20Marcelo%20M%20S%20Lima%20A.pdf: 1921437 bytes, checksum: 137175d8ab4d8c8de55271aa236d3452 (MD5) Publico-Tese%20Doutorado%20Marcelo%20M%20S%20Lima%20B.pdf: 706371 bytes, checksum: db83e739e4717c5c824c2f6fc42e637e (MD5) Publico-Tese%20Doutorado%20Marcelo%20M%20S%20Lima%20C.pdf: 1231295 bytes, checksum: d4978d6d50480082f2f58a6e8c6317fc (MD5) Publico-Tese%20Doutorado%20Marcelo%20M%20S%20Lima%20D.pdf: 946427 bytes, checksum: 54f4c0262b49f8ffbe3eedb7e56d115a (MD5) Publico-Tese%20Doutorado%20Marcelo%20M%20S%20Lima%20E.pdf: 1159114 bytes, checksum: 70e61676ec1c583f9ac4fb6dd31c72b6 (MD5) Publico-Tese%20Doutorado%20Marcelo%20M%20S%20Lima%20F.pdf: 1538781 bytes, checksum: 47d5cbd870c32fe12325305adebc81a5 (MD5) Publico-Tese%20Doutorado%20Marcelo%20M%20S%20Lima%20G.pdf: 1816795 bytes, checksum: 633f9f17b5d6c0875287ad49d75cba1a (MD5) / Recentemente, a neurotransmissão dopaminérgica tem sido reconhecida por estar envolvida na geração de distúrbios de sono. Evidências crescentes mostram que os distúrbios de sono associados à doença de Parkinson (DP) são mais relacionados à doença per se, do que apenas fenômenos secundários. Dados apresentados pela literatura sugerem a hipótese de que o sistema dopaminérgico nigroestriatal esteja envolvido na regulação de padrões de sono. Demonstrou-se no presente trabalho que uma lesão de 50% dos neurônios dopaminérgicos residentes na substância negra pars compacta (SNpc) foi capaz de gerar um prejuízo em diversos parâmetros de sono em ratos. Essa redução neuronal provocou uma diminuição importante na porcentagem de sono paradoxal durante os três primeiros dias de registro de sono. Observou-se também uma forte correlação (r=0.91) entre o número de neurônios e a porcentagem de sono paradoxal. A partir disso, propomos que os neurônios dopaminérgicos presentes na SNpc possuem um papel fundamental para a regulação dos padrões de sono, particularmente na promoção de sono paradoxal. Em outro experimento, apresentamos evidências de que a proteína tirosina hidroxilase (TH) encontra-se com sua expressão reduzida no sistema dopaminérgico nigroestriatal após um período de 24 h de privação de sono paradoxal (PSP) em camundongos. De acordo com esses resultados, sugerese que a redução da expressão da TH, produzida pela (PSP), possa explicar em parte a existência da supersensibilidade dopaminérgica de receptores D2. As implicações dessas alterações podem reverberar diretamente sobre anormalidades motoras e de sono encontradas em pacientes portadores da DP. xiii Achados eletrofisiológicos demonstraram que o bloqueio dos receptores D2 (por haloperidol) produziu uma redução de sono paradoxal durante o período de rebote, realizado após 96 h de PSP. Essa redução foi acompanhada por um incremento de sono de ondas lentas, o que possivelmente tenha ocorrido em decorrência de um observado aumento de eficiência de sono. Os resultados também indicaram que a administração de piribedil não pôde gerar um aumento adicional de sono paradoxal. Sugerimos a existência de uma ação particular da neurotransmissão dopaminérgica recaindo sobre a ativação dos receptores D2. As evidências demonstradas no presente trabalho e na literatura permitem sugerir que os neurônios dopaminérgicos presentes na SNpc e na aérea tegmental ventral podem ser considerados essenciais para a regulação de sono, em particular no disparo e manutenção do sono paradoxal, respectivamente. Propõe-se que o paradigma que envolve a dopamina como sendo responsável apenas pela vigília, não é totalmente acurado. A teoria proposta nessa tese alega que esse neurotransmissor pode apresentar uma importante participação em ambos os estados: vigília e sono, e que cada estado deva ser gerado por intermédio de diferentes graus de modulação dopaminérgica. A conclusão delineada a partir desses achados é que a dopamina apresenta implicações significantes na regulação de sono, e essa condição particular deve ser considerada em relação ao tratamento de pacientes com a DP. / Dopamine (DA) is critically involved in regulating neural processes responsible for complex movements and emotions. Alterations in central dopaminergic neurotransmission have been implicated in important neurological and psychiatric disorders such as Parkinson’s disease (PD) and schizophrenia. In addition, DA has recently been recognized as instrumental in the regulation of sleep-wake states. Herein, we present evidence that tyrosine hydroxylase (TH) is down-regulated in the nigrostriatal pathway after 24 h of sleep deprivation (SD) in mice. To identify the involvement of DA in SD and sleep rebound (R) we administered reserpine (1 mg/kg) associated to a-methyl-p-tyrosine (aMT) (250 mg/kg) to produce DA depletion, and rotenone (10 mg/kg) to increase striatal DA turnover. Behavioral tests (catalepsy, grasping and open-field) were conducted to evaluate muscular rigidity and motor alterations inflicted by the drugs immediately after SD and R. Western blot and immunohistochemistry demonstrated that SD alone produced important down-regulation on TH protein expression within the substantia nigra (SN), without affecting the number of dopaminergic neurons. Pharmacological depletion of DA or increase of its turnover affected the entire nigrostriatal pathway. We propose that downregulation of TH expression produced by SD greatly explains the existence of supersensitivity of dopaminergic D2 receptors, especially along the nigrostriatal pathway, and suggest a novel role of DA in the mediation of sleep-wake states as a consequence of the modulation of TH protein expression along that pathway. The implications of these alterations may directly reverberate in motor and sleep abnormalities found in patients with PD. / TEDE / BV UNIFESP: Teses e dissertações

Submitted by Eduardo Barros de Almeida Silva (eduardo.philippe@ufpe.br) on 2015-04-17T12:44:08Z No. of bitstreams: 2 Tese Henriqueta Dias Cardoso.pdf: 5265290 bytes, checksum: e2e8c3ba450de08f6e92ede26a203fc0 (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) / Made available in DSpace on 2015-04-17T12:44:08Z (GMT). No. of bitstreams: 2 Tese Henriqueta Dias Cardoso.pdf: 5265290 bytes, checksum: e2e8c3ba450de08f6e92ede26a203fc0 (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Previous issue date: 2013-02-26 / FACEPE / Os ácidos graxos essenciais (AGEs) têm sido indicados como potenciais agentes preventivos e terapêuticos em uma grande variedade de doenças neurodegenerativas assim como indispensáveis para o desenvolvimento cerebral. O principal objetivo deste trabalho foi investigar os mecanismos relacionados com a perda de neurônios dopaminérgicos induzida pela deficiência crônica em AGEs previamente detectada na substância negra (SN) de ratos Wistar jovens (J), estendendo a análise também a animais adultos (A). Para isso, foram utilizadas dietas balanceadas e que diferiram apenas na fonte lipídica, sendo óleo de soja para os grupos controles (C) e óleo de coco para os grupos experimentais (E). As dietas foram fornecidas às mães a partir do acasalamento e mantidas por uma (F1) ou duas (F2) gerações. Marcadores de insulto oxidativo: lipoperoxidação (LP), atividade das enzimas superóxido dismutase total (SOD-t), catalase (CAT) na SN e corpo estriado (CE) foram avaliados em animais AF1 e em JF2 e AF2. Indicadores de neurodegeneração na SN e CE destes animais foram avaliados utilizando a técnica de marcação com o fluoróforo, Fluoro Jade C. Análise quantitativa do tamanho e nº de neurônios dopaminérgicos e da distribuição de células imunorreativas ao fator neurotrófico derivado do cérebro (BDNF) foi realizada em animais AF2. Os níveis de nitrito, como indicador da produção de óxido nítrico na SN e CE, foram analisados em animais JF2 e AF2. A dieta experimental reduziu em ~28%, ~50% e ~60% os níveis de ácido docosahexaenóico (DHA) na SN dos grupos experimentais AF1, JF2 e AF2 respectivamente, comparado aos seus controles. Nos animais EAF1 um aumento em ~17% e ~45% na atividade da SOD-t foi observado na SN e CE comparado ao grupo controle, o evitou níveis danosos de lipoperoxidação. Por outro lado, um aumento nos níveis de lipoperoxidação (~34%) foi detectado na SN de animais EJF2, acompanhados de não reatividade da SOD-t e de uma redução em 4,8 vezes na atividade da CAT. Sinais de neurodegeneração foram evidenciados em neurônios dopaminérgicos e não dopaminérgicos da SN do grupo EJF2. No CE, o aumento da LP em ~39% foi acompanhado de redução em 3,8 vezes e 2,8 vezes da atividade da SOD-t e CAT, respectivamente, só foram observados nos animais do grupo EAF2. A dieta experimental não alterou os níveis de nitrito na SN, mas aumentou de forma significativa estes níveis no CE de animais jovens (30%) e adultos (1,8 vezes). A deficiência crônica em DHA até a idade adulta comprometeu o crescimento do corpo celular e aumentou a perda de neurônios dopaminérgicas na SN rostro-dorso-medial (~35%) afetando também aqueles localizados na região caudo-ventro-lateral deste núcleo. Uma redução de ~22% no número de células BDNF+ foi também observada na SN. Os resultados mostram que a restrição dietética em AGEs por duas gerações até a idade adulta é capaz de induzir lipoperoxidação na SN e CE devido a comprometimento na atividade das enzimas anti-oxidantes, perda de células BDNF+ na SN e aumentados níveis de óxido nítrico no CE. Tidos em conjunto, tais mecanismos podem estar atuando de forma sinérgica na degeneração de neurônios dopaminérgicos induzida pela deficiência em DHA.

INTRODUÇÃO: A presença e extensão da perda neuronal no encéfalo dos idosos ainda é controversa. A substância negra (SN) é uma região localizada no mesencéfalo e caracterizada macroscopicamente pela coloração escura, devido à presença neuromelanina. O envelhecimento da SN ainda é um mistério, mas existem grandes quantidades de estudos relativos às modificações sofridas por essa região com o passar dos anos. Alguns estudos detectaram perda neuronal na SN durante o envelhecimento, enquanto outros afirmam que não há alteração significativa durante esse processo. OBJETIVO: Caracterizar as alterações que ocorrem na SN durante o envelhecimento humano, em indivíduos sem sintomas da doença de Parkinson, do ponto de vista citoarquitetônico em 3D. CASUÍSTICA E METODOLOGIA:O presente projeto faz parte do Projeto Envelhecimento Cerebral (PEC) do Grupo de Estudos em Envelhecimento Cerebral (GEEC) da Faculdade de Medicina da Universidade de São Paulo (FMUSP). Foram utilizados 18 casos, classificados em quatro faixas etárias. Quinze casos foram analisados estereológicamente e recontruídos tridimensionalmente. Para estes, foram determinados número de neurônios, volume da SN e densidade neuronal e submetidos à testes estatísticos não paramétricos. Três casos foram imunocorados com quatro diferentes anticorpos: anti tirosina-hidroxilase (TH), anti proteína tau hiperfosforilada, anti proteína alfa-sinucleína e anti calbindina D28k (Calb) e analisados qualitativamente. RESULTADOS: As lâminas imunocoradas com anticorpo anti -sinucleína e anti-tau, foram negativas. As lâminas imunocoradas com anticorpo anti- TH e anti-Calb D28k foram positivas. Dos quinze casos analisados estereologicamente, Para o número de neurônios, encontrou-se: mediana de 504.575 células, valor mínimo de 348.662 células e valor máximo de 672.172 células. Para o volume, encontrou-se mediana de 190,8mm3; valor mínimo de 134,1 mm3 e valor máximo de 267,3mm3. Para a densidade total média, encontrou-se a mediana de 2.517,4 cel/mm3, valor mínimo de 1.603,1 cel/mm3 e valor máximo de 5.015,7 cel/mm3. Realizou-se o teste de correlação de Spearman para as três variáveis neuronais, correlacionando hemisfério direito e esquerdo, encontrou-se uma correlação moderada para número de neurônios e volume, e correlação forte para densidade. Com o mesmo teste, realizou-se análise das variáveis neuronais em função da idade, e não houve alteração estatisticamente significativa. Apenas uma tendência à diminuição no volume total da SN em relação à idade. Também verificou-se a relação entre as variáveis neuronais, por gênero em função da idade e não houve alteração estatisticamente significativa. Nas reconstruções tridimensionais, verificou-se uma grande variabilidade interpessoal entre as 15 SN reconstruídas. DISCUSSÃO: Diversos estudos estereológicos foram feitos, mas poucos deles com análise estereológica sem viés e a maior parte deles demonstra diminuição no número de neurônios, discordando dos achados atuais. A reconstrução tridimensional também não descreve alterações decorrentes do envelhecimento, mas aparentemente modificações interpessoais. CONCLUSÃO: As características da substância negra se mantém ao longo dos anos, porém, ainda devem ser muito mais estudadas / INTRODUTION: Some aspects about maco and micro braischanges are suffering modifications along the years. The presence and extension of neuronal lost in elderly still a big and polemic issue. The SUBSTANTIA NIGRA (SN) is located at the midbrain and characterized by the dark color due to the pigmented neurons, which contain neuromelanin. The SNs aging is still a mystery, nevertheless, there are great researches related to these changes suffered in this region by the years. Some of the researches noticed that neuronal lost in SN during the aging, while others claim that there are no significant modifications through this process.OBJECTIVE: Describing SN changes during the human aging in individuals with no Parkinsons disease symptoms, from the 3D cytoarchitectonic point of view. METHODS: This project is part of the Brain Aging Project of Brain Aging Study Group, in University of São Paulo Medical School. Eighteen cases had been analyzed and classified into four ages groups. Fifteen cases had been analyzed with stereological methos and 3D reconstructed. During the stereological analysis, were determinate the neuronal number, SN volume, neuronal density and submitted to nonparametric statistics test. Three cases had been immunostained with 4 different antibodies anti tyrosine-hydroxylase (TH), anti hyperphosphorylated tau (anti-tau), anti alfa-synuclein (alpha-syn) e anti calbindin D28k (Calb) and qualitatively analyzed. RESULTS: The immunostained slices with the anti alpha-syn and anti-tau antibodies were negative. The immunostained slices with anti TH and anti calb D28K antibodies were positive. From the 15 cases estereologically analyzed, 53,3% were female and 46,7% male. Had been analyzed neuron numbers, SN volume and neuronal density. For the neural numbers were found median of 504.575 cells, minimum value of 348.662 cells and maximum value of 672.172 cells. For the volume were found median of 190,8mm³; minimum value of 134,1mm³ and maximum value of 267,3mm³. For the total density, was found median of de 2.517,4 cel/mm³, minimum value of 1603,1 cel/mm³ , maximum value of 5015,7 cel/mm³. The Spearmans correlation test had been done to the three neuronal variable correlating the right and left hemispheres and was a moderated correlation between neuron numbers and neuron volume and strong correlation to density. Using the same test, the rate neuron by the age analysis had been concluded and there was no significant change.There was noticed just one trend to the reduction in the SN total volume related to aging. It was also checked the relation between the neurons variety by gender considering aging and there was no significant changes. In the 3D reconstruction, was possible to notice a great interpersonal variability between the 15 SN rebuilt. DISCUSSION: Many stereological researches had been done, however, a few of them used the unbiased stereological analysis and most of them show a reduction in the neuron number, disagreeing from the current conclusions. The 3D reconstruction also dont describe changes as aging result, but apparently interpersonal changes. CONCLUSION: The Substantia Nigra maintain the same characteristics along the years, however, it must be much more explored

The aim of the current study was divided into two separate goals, (i) optimization of a number of PCR-based protocols employed for genotyping transgenic mouse lines and (ii) evaluating a protocol for co-detection of mRNA and its correlated protein in the mouse midbrain. The optimization was performed on PCR protocols for genotyping the following transgenic mouse lines; Dat-Cre, Vglut2-Lox, Vglut2-Cre and Vmat2-Lox. Also, two different polymerases were evaluated parallel to each other – KAPA and Maxima Hot Start. One of the main findings from the PCR optimizations were that for the Vglut2-Lox protocol. By decreasing the annealing temp and increasing the MgCl2 the bands appeared brighter.  For the second part of the project, in-situ hybridization (ISH) was used to detect the mRNA expression with a `non-radioactive in situ hybridization´ protocol, using digoxigenin or fluorescein labelled riboprobes (mRNA probes). To detect the correlated protein a basic immunohistochemistry (IHC) protocol with the use of primary and secondary antibodies was implemented. The combined protocol was tested with Nd6 and Grp markers. Before testing to combined the protocols the ISH protocol was performed alone with riboprobes for Girk2, Lpl and Fst. The combined protocol detected mRNA and protein for both the control marker Th and the Nd6 marker. In conclusions, the optimized PCR protocols were optimal when used with the Maxima Hot Start polymerase and the new combined ISH and IHC protocol worked for markers Th and Nd6.

The pesticide/neurotoxin, rotenone, has been shown to cause systemic inhibition of mitochondrial complex I activity, with consequent degeneration of the nigrostriatal pathway, as observed in Parkinson’s disease. A novel intrastriatal rotenone model of Parkinson’s disease was used to examine the neuroprotective effects of valproic acid (VPA) and melatonin, both of which are known to induce neurotrophic gene expression in the central nervous system via mechanisms which may involve epigenetic modulation. In these studies, sham or lesioned rats were treated with either vehicle, VPA (4mg/mL), or melatonin (4µg/mL) in drinking water. Results from a forelimb asymmetry test indicated a significant decrease in use of the contralateral forelimb in rotenone-infused animals, in the third week post-surgery, which was abolished by VPA treatment. Apomorphine administration resulted in significantly higher ipsilateral rotation in rotenone-lesioned (12µg) animals, as compared to controls, which was attenuated by melatonin treatment. Subsequent immunohistochemical examination revealed a decrease in tyrosine hydroxylase immunoreactivity within the striatum and substantia nigra of rotenone-infused animals. VPA or melatonin treatment prevented this decrease in tyrosine hydroxylase in the striatum and substantia nigra. Stereological cell counting indicated a significant decrease in dopamine neurons within the substantia nigra of rotenone-treated animals. Importantly, this loss of dopamine neurons in rotenone-infused animals was blocked by chronic VPA or melatonin treatment. A third study explored whether rotenone infusion into the medial forebrain bundle and substantia nigra in mice could provide a model of Parkinson's disease. Densitometric analysis revealed a significant depletion of tyrosine hydroxylase immunofluorescence within the ipsilateral striatum and substantia nigra of lesioned animals, and a significant bilateral overexpression of α-synuclein in the substantia nigra, as compared to control animals. These novel findings support the use of intracranial rotenone as a Parkinsonian model, and provide a solid platform for future combinatorial therapeutic approaches with VPA and melatonin. / Dissertation / Doctor of Philosophy (PhD)

Previous studies have shown that persons with Parkinson’s disease (pwPD) share specific deficits in learning new sequential movements, but the neural substrates of this impairment remain unclear. In addition, the degree to which striatal dopaminergic denervation in PD affects the cortico-striato-thalamo-cerebellar motor learning network remains unknown. We aimed to answer these questions using fMRI in 16 pwPD and 16 healthy age-matched control subjects while they performed an implicit motor sequence learning task. While learning was absent in both pwPD and controls assessed with reaction time differences between sequential and random trials, larger error-rates during the latter suggest that at least some of the complex sequence was encoded. Moreover, we found that while healthy controls could improve general task performance indexed by decreased reaction times across both sequence and random blocks, pwPD could not, suggesting disease-specific deficits in learning of stimulus-response associations. Using fMRI, we found that this effect in pwPD was correlated with decreased activity in the hippocampus over time. Importantly, activity in the substantia nigra (SN) and adjacent bilateral midbrain was specifically increased during sequence learning in pwPD compared to healthy controls, and significantly correlated with sequence-specific learning deficits. As increased SN activity was also associated (on trend) with higher doses of dopaminergic medication as well as disease duration, the results suggest that learning deficits in PD are associated with disease progression, indexing an increased drive to recruit dopaminergic neurons in the SN, however, unsuccessfully. Finally, there were no differences between pwPD and controls in task modulation of the cortico-striato-thalamo-cerebellar network. However, a restricted nigral-striatal model showed that negative modulation of SN to putamen connection was larger in pwPD compared to controls during random trials, while no differences between the groups were found during sequence learning. We speculate that learning-specific SN recruitment leads to a relative increase in SN- > putamen connectivity, which returns to a pathological reduced state when no learning takes place

O Colículo Superior (SC) é conhecido por apresentar diversas funções que modulam a caça predatória. Neste estudo, investigamos as funções do SC em ratos expostos a caça de insetos. Primeiramente, verificamos que o comportamento predatório induz uma distinta ativação da porção lateral do SC (SCl). Para entender as potenciais funções dessa região colicular, foi analisado o comportamento predatório antes e após lesões bilaterais iontoforéticas por NMDA do SCl. Animais com SCl lesados ficaram menos motivados a perseguirem as baratas, falharam para se orientarem na direção do movimento das presas e quando tentaram capturar as presas, eles apresentaram sérios déficits para capturá-las e segurá-las eficientemente. Por outro lado, animais com lesões da porção medial do SC (SCm) apresentaram apenas um aumento da latência para iniciar a caça, enquanto os outros parâmetros não diferiram significantemente dos animais intactos. Posteriormente, examinamos as conexões eferentes do SCl e do SCm usando como traçador anterógrado a leucoaglutinina do Phaseolus vulgaris. Notamos projeções densas do SCl para a região rostral da coluna lateral da matéria cinzenta periaquedutal (PAGl), um setor criticamente envolvido no controle dos aspectos motivacionais relacionados aos comportamentos de caça predatória e forrageamento. Além disso, o SCl se projeta densamente para o tálamo dorsal, especificamente para os núcleos ventral lateral, central medial e paracentral do tálamo, os quais sabemos que se projetam para setores estriatais ou para áreas motoras corticais, que provavelmente estão envolvidas no ajuste da ação motora durante a captura das presas. O SCm, por sua vez, aferenta densamente a coluna dorsolateral da PAG, núcleo cuneiforme, e núcleos reticulares mesencefálico e pontino, que são setores envolvidos na elaboração de respostas defensivas, além disso, o SCm se projeta esparsamente para os núcleos posterior lateral e suprageniculado do complexo geniculado medial / The superior colliculus is classically known to present a number of functions that fit hunting behavior. In the present study, we investigate the potential roles of the superior colliculus in rats displaying insect hunting. First, we have found that predatory hunting induces a distinct activation of the lateral region of the intermediate layer of the superior colliculus (SCl). To understand the potential roles of this collicular region, we analyzed the hunting performance before and after iontophoretic NMDA lesions bilaterally placed into the SCl. Animals with SCl lesions were clearly less motivated to pursue the roaches, failed to orient themselves toward the moving prey, and whenever the SCl-lesioned rats tried to catch the roaches, they presented serious deficits to capture and hold them efficiently. Next, we examined the SCl efferents connections using Phaseolus vulgaris leucoagglutinin as an anterograde tracer. Of particular relevance, we noted that the SCl projects to the rostral lateral periaqueductal gray, a site critically involved in controlling motivational drive to chase prey and forage. In addition, the SCl also present particularly strong projections to the dorsal thalamus, aimed at the ventral lateral, ventral medial, central medial and paracentral nuclei of thalamus, all of which known to project either to striatal sites or to cortical motor areas, likely to be involved in adjusting the motor action during prey capture. Therefore, the SCl, which seems to present cells responding to prey displacement in the temporal field, presents important arms to the periaqueductal gray and dorsal thalamic sites, influencing, respectively, the motivational drive and the motor skills to hunt