Sleep disturbances represent an important clinical feature in different neurodegenerative disorders. Insomnia, hypersomnia, parasomnia, loss of specific sleep stages and alterations in circadian rhythms characterize synucleinopathies, prionpathies and tauopathies. Recent evidences highlight that, in many instances, sleep alterations could disclose the onset of a neurodegenerative disorder. In particular, it has been shown that the idiopathic form of the REM sleep Behavior Disorder (iRBD) could be a prognostic factor for the development of a future synucleinopathy. The use of animal models is very common in biomedical research and is essential to develop new and more effective methods for diagnosis and treating disease that affecting both humans and animals. The first aim of this thesis is to verify if murine models of neurodegenerative disorders with different aetiology show sleep alterations similar to those observed in humans. Secondly, the availability of a murine model at different stages of the disease’s course allowed us to investigate whether the sleep alterations precede (or not) the development of other features of the disease. To this purpose, the sleep-wake cycle was poligraphically recorded and analyzed in the murine models of three neurodegenerative disorders: i) Fatal Familial Insomnia (FFI), ii) Creutzfeldt-Jakob disease (CJD) and iii) Alzheimer’s disease (AD). In the first experiment we analyzed the sleep-wake cycle of transgenic mice expressing the murine homolog of the D178N/M129 human mutation at the Prnp gene, encoding for prion protein (PrP). This kind of mutation is associated in human with FFI. We compared the sleep-wake cycle of these animals with two control mice strains: i) wild-type mice (C57BL/6J, WT mice) and ii) PrP knock-out mice (KO mice). In the second experiment we analyzed the sleep-wake cycle in mice expressing the murine homolog of the D178N/V129 human mutation, associated with a familial form of Creutzfeldt-Jakob disease (CJD178). We compared the sleep of these mice with WT and KO mice. In order to evaluate the course of sleep alterations and their onset, each mice strain was recorded at three different ages: 6, 12 and 18 months of age. At these ages animals can be considered as young, adult and old, respectively. In the third experiment, we considered an acute mice model of Alzheimer’s disease (AD). C57BL/6J mice were intracerebroventricularly injected with three different solutions: i) synthetic oligomers of amyloid-β (A-β1-42); ii) phosphate buffer saline, PBS (vehicle); iii) synthetic monomers of amyloid-β (A-β1-42). A-β1-42 oligomers are the main elements of A-β plaques, observed in AD patients. The other two solutions were administered as control condition. All mice received all the three injections (within design) at the light onset. Hereafter, the sleep-wake cycle was polygraphically recorded during the next 24 hours in baseline conditions. We compared the sleep-wake cycle of mice following the injection of A-β1-42 oligomers with that followed the administration of the control conditions. In all three experiments the murine models showed marked sleep-wake alterations, in particular a reduction of the amount of REM sleep. The loss of REM sleep was due to a reduction of the number of REM sleep bouts. In other words, the murine models showed a difficulty in entering REM sleep. The reduction of the time spent in REM sleep was combined with a decrease of EEG theta power during REM sleep bouts. Moreover, the EEG activity of murine models was characterized by bursts of polyphasic complexes, peaking at around 7 Hz. At last, analyses of the murine model of CJD at different ages revealed that sleep alterations were already present at 12 months of age, before any other evidence of clinical signs. As well as in humans, sleep alterations are have been described in animal models of neurodegenerative disorders, including those in which sleep disturbance is not considered a main feature. Moreover, in the murine model of CJD, the alteration of the normal sleep-wake cycle seems to precede the onset of other clinical signs of the disease. These data suggest the existence of a relationship between sleep-wake cycle alterations and some neurodegenerative disorders and suggest to pay more attention to sleep disturbances, in clinic and diagnostic field. Sleep alterations seem to represent an important feature of numerous neurodegenerative disorders and could be considered a prognostic factor for the evolution of these disorders and something to be taken into account in the evaluation of the clinical picture. In the future, it would be useful considering the enhancement of sleep quality and/or the normalization of sleep-wake cycle as a new tool to prevent the evolution of neurodegeneration and the onset of several neurodegenerative disorder, or at least represent a palliative care in course of the disorders.
I disturbi del sonno rappresentano una manifestazione clinica tipica di gran parte delle malattie neurodegenerative. Insonnia, ipersonnia, parasonnie, perdita di specifiche fasi del sonno e disorganizzazione del ciclo veglia-sonno sono alcune delle manifestazioni che caratterizzano le sinucleinopatie, le prionopatie e le taupatie. Recenti evidenze hanno rilevato che in molti casi i disturbi del sonno possono precedere l’insorgenza del quadro sintomatico tipico di queste patologie. In particolare, è stato osservato che la presenza di RBD (disturbo del comportamento durante il sonno REM) nella sua forma idiopatica (iRBD) sembra costituire un fattore predittivo per l’insorgenza di una futura sinucleinopatia. L’utilizzo di modelli animali è uno degli strumenti più utilizzati in campo biomedico per lo studio della patologia umana e lo sviluppo di nuovi metodi più efficaci per la diagnosi e il trattamento di malattie sia umane che animali. Scopo di questa tesi è stato quello di verificare se le alterazioni del sonno fossero presenti anche in modelli murini di alcune malattie neurodegenerative con diversa eziologia. Tra queste abbiamo preso in considerazione l’Insonnia Fatale Familiare (FFI), la malattia di Creutzfeldt-Jakob (CJD) e la malattia di Alzheimer (AD). In seconda istanza, la disponibilità di un modello murino a diversi stadi evolutivi, ha permesso di indagare l’ipotesi di una precoce insorgenza dei disturbi del sonno nella malattia di Creutzfeldt-Jakob. A questo scopo è stato registrato poligraficamente e analizzato il ciclo veglia-sonno in modelli murini delle tre patologie sopra citate. Nel primo esperimento è stato analizzato il ciclo veglia-sonno di topi transgenici che esprimevano l’omologo murino della mutazione (D178N/M129) al gene Prnp che codifica per la proteina prionica (PrP). Questa mutazione nell’uomo è associata a insonnia fatale familiare. Il ciclo veglia-sonno di questi animali è stato confrontato con due ceppi di topi di controllo: i) topi wild type (C57BL/6J) e ii) topi knock-out per la PrP. Nel secondo esperimento sono state analizzate le caratteristiche del sonno in topi transgenici recanti l’omologo murino della mutazione (D178N/V129) al gene Prnp, che nell’uomo porta a una forma familiare di Creutzfeldt-Jakob (CJD178). Il ciclo veglia-sonno di questi topi è stato confrontato con i ceppi di controllo già descritti per il primo esperimento. Ciascun ceppo di topi, inoltre, è stato analizzato a tre diverse età: 6, 12 e 18 mesi che rappresentano stadi evolutivi diversi (rispettivamente: giovani, adulti e anziani); questo al fine di valutare l’evoluzione delle alterazioni del sonno e la loro effettiva insorgenza. Nel terzo esperimento è stato preso in considerazione un modello, in acuto, di malattia di Alzheimer (AD). Il ciclo veglia-sonno di topi C57BL/6J è stato analizzato in seguito a somministrazione intracerebroventricolare (ICV), in acuto, di oligomeri sintetici di β-amiloide (A-β1-42). Questi sono i costituenti delle placche amiloidi riscontrate in pazienti affetti da AD. La somministrazione veniva eseguita all’inizio della fase di luce del ciclo luce-buio. In seguito, il ciclo veglia-sonno era registrato poligraficamente per le successive 24 ore in condizioni normali di laboratorio. Questa condizione è stata confrontata con il ciclo veglia-sonno degli stessi topi (disegno within) in seguito a somministrazione di due trattamenti di controllo: i) un veicolo (tampone fosfato salino, PBS) e ii) i monomeri sintetici di β-amiloide. In tutti e tre i modelli murini considerati si sono osservate marcate alterazioni del ciclo veglia-sonno, nei termini di una riduzione del sonno REM. La perdita di questa fase era essenzialmente dovuta a una diminuzione del numero dei suoi episodi. I modelli murini delle tre malattie neurodegenerative mostravano, infatti, una certa difficoltà nell’iniziare un episodio di sonno REM. La decurtazione di sonno REM era accompagnata, anche, da una riduzione del potere spettrale della banda theta durante gli episodi di sonno REM. L’analisi dei tracciati elettroencefalografici (EEG) ha, inoltre, messo in evidenza la presenza di attività EEG anomala, consistente in complessi polifasici di ampio voltaggio e con un picco di frequenza attorno ai 7 Hz. Le registrazioni del modello murino di CJD a diversi stadi evolutivi hanno evidenziato che le alterazioni del sonno in questo modello si presentano già a 12 mesi di età, ancora prima dell’insorgenza dei sintomi tipici della patologia. Le alterazioni del sonno sono, quindi, presenti anche in modelli murini di alcune malattie neurodegenerative, incluse quelle in cui il disturbo del sonno non rappresenta il sintomo principale. Nel modello murino di CJD, inoltre, l’alterazione del normale ciclo veglia-sonno sembra precedere la manifestazione del quadro sintomatico tipico della patologia. Questi dati suggeriscono una stretta relazione tra alterazioni del ciclo veglia-sonno e malattie neurodegenerative. Per questo motivo, in campo clinico e diagnostico, sarebbe opportuno porre una maggiore attenzione ai disturbi del sonno. Questi sembrano essere, infatti, parte integrante di molte malattie contraddistinte da degenerazione neuronale. L’alterazione del normale ciclo veglia-sonno potrebbe avere, inoltre, un valore predittivo per alcune delle patologie neurodegenerative o comunque essere un valido aiuto nel processo diagnostico. In futuro, il miglioramento della qualità del sonno e/o la normalizzazione del ciclo veglia-sonno potrebbero essere validi strumenti al fine di prevenire la neurodegenerazione e l’insorgenza di alcune malattie neurodegenerative, o almeno rappresentare un approccio palliativo in corso di malattia.
SONNO E MALATTIE NEURODEGENERATIVE IN MODELLI ANIMALI
DEL GALLO, FEDERICO
2014
Abstract
Sleep disturbances represent an important clinical feature in different neurodegenerative disorders. Insomnia, hypersomnia, parasomnia, loss of specific sleep stages and alterations in circadian rhythms characterize synucleinopathies, prionpathies and tauopathies. Recent evidences highlight that, in many instances, sleep alterations could disclose the onset of a neurodegenerative disorder. In particular, it has been shown that the idiopathic form of the REM sleep Behavior Disorder (iRBD) could be a prognostic factor for the development of a future synucleinopathy. The use of animal models is very common in biomedical research and is essential to develop new and more effective methods for diagnosis and treating disease that affecting both humans and animals. The first aim of this thesis is to verify if murine models of neurodegenerative disorders with different aetiology show sleep alterations similar to those observed in humans. Secondly, the availability of a murine model at different stages of the disease’s course allowed us to investigate whether the sleep alterations precede (or not) the development of other features of the disease. To this purpose, the sleep-wake cycle was poligraphically recorded and analyzed in the murine models of three neurodegenerative disorders: i) Fatal Familial Insomnia (FFI), ii) Creutzfeldt-Jakob disease (CJD) and iii) Alzheimer’s disease (AD). In the first experiment we analyzed the sleep-wake cycle of transgenic mice expressing the murine homolog of the D178N/M129 human mutation at the Prnp gene, encoding for prion protein (PrP). This kind of mutation is associated in human with FFI. We compared the sleep-wake cycle of these animals with two control mice strains: i) wild-type mice (C57BL/6J, WT mice) and ii) PrP knock-out mice (KO mice). In the second experiment we analyzed the sleep-wake cycle in mice expressing the murine homolog of the D178N/V129 human mutation, associated with a familial form of Creutzfeldt-Jakob disease (CJD178). We compared the sleep of these mice with WT and KO mice. In order to evaluate the course of sleep alterations and their onset, each mice strain was recorded at three different ages: 6, 12 and 18 months of age. At these ages animals can be considered as young, adult and old, respectively. In the third experiment, we considered an acute mice model of Alzheimer’s disease (AD). C57BL/6J mice were intracerebroventricularly injected with three different solutions: i) synthetic oligomers of amyloid-β (A-β1-42); ii) phosphate buffer saline, PBS (vehicle); iii) synthetic monomers of amyloid-β (A-β1-42). A-β1-42 oligomers are the main elements of A-β plaques, observed in AD patients. The other two solutions were administered as control condition. All mice received all the three injections (within design) at the light onset. Hereafter, the sleep-wake cycle was polygraphically recorded during the next 24 hours in baseline conditions. We compared the sleep-wake cycle of mice following the injection of A-β1-42 oligomers with that followed the administration of the control conditions. In all three experiments the murine models showed marked sleep-wake alterations, in particular a reduction of the amount of REM sleep. The loss of REM sleep was due to a reduction of the number of REM sleep bouts. In other words, the murine models showed a difficulty in entering REM sleep. The reduction of the time spent in REM sleep was combined with a decrease of EEG theta power during REM sleep bouts. Moreover, the EEG activity of murine models was characterized by bursts of polyphasic complexes, peaking at around 7 Hz. At last, analyses of the murine model of CJD at different ages revealed that sleep alterations were already present at 12 months of age, before any other evidence of clinical signs. As well as in humans, sleep alterations are have been described in animal models of neurodegenerative disorders, including those in which sleep disturbance is not considered a main feature. Moreover, in the murine model of CJD, the alteration of the normal sleep-wake cycle seems to precede the onset of other clinical signs of the disease. These data suggest the existence of a relationship between sleep-wake cycle alterations and some neurodegenerative disorders and suggest to pay more attention to sleep disturbances, in clinic and diagnostic field. Sleep alterations seem to represent an important feature of numerous neurodegenerative disorders and could be considered a prognostic factor for the evolution of these disorders and something to be taken into account in the evaluation of the clinical picture. In the future, it would be useful considering the enhancement of sleep quality and/or the normalization of sleep-wake cycle as a new tool to prevent the evolution of neurodegeneration and the onset of several neurodegenerative disorder, or at least represent a palliative care in course of the disorders.File | Dimensione | Formato | |
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https://hdl.handle.net/20.500.14242/78740
URN:NBN:IT:UNIMI-78740