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Apoptosis And Excitotoxicity In The Death of Cultured And Grafted Dopaminergic Neurones

Schierle, Gabriele LU (1999)
Abstract (Swedish)
Popular Abstract in Swedish

Under de senaste två decennierna har transplantation av embryonal vävnad från ventrala mesencephalon, mitthjärnan, utvecklats till en möjlig terapi för Parkinson’s sjukdom. Ju bättre transplantatet återställer den dopaminerga neurotransmissionen, desto större blir den motoriska förbättringen hos patienten. Dessvärre dör över 90% av de dopaminerga nervcellerna under transplantations processen. Om cellöverlevnaden i transplantaten kunde ökas skulle detta underlätta och utvidga användandet av metoden. Syftet med denna avhandling var att karaktärisera celldöden som sker under transplantationen, samt att finna och utvärdera metoder för att skydda de embryonala dopaminerga nervcellerna. Ca2+... (More)
Popular Abstract in Swedish

Under de senaste två decennierna har transplantation av embryonal vävnad från ventrala mesencephalon, mitthjärnan, utvecklats till en möjlig terapi för Parkinson’s sjukdom. Ju bättre transplantatet återställer den dopaminerga neurotransmissionen, desto större blir den motoriska förbättringen hos patienten. Dessvärre dör över 90% av de dopaminerga nervcellerna under transplantations processen. Om cellöverlevnaden i transplantaten kunde ökas skulle detta underlätta och utvidga användandet av metoden. Syftet med denna avhandling var att karaktärisera celldöden som sker under transplantationen, samt att finna och utvärdera metoder för att skydda de embryonala dopaminerga nervcellerna. Ca2+ överbelastning i nervcellen resulterar i en kaskad av händelser som slutligen leder till celldöd. Ca2+ inflöde orsakas huvudsakligen av aktivering av excitatoriska aminosyre-receptorer (EAA-receptorer) eller via spänningsberoende Ca2+ kanaler (VDCC). I avhandlingen visar vi att en kraftfull hämmare av EAA-receptorerna kan skydda embryonala dopaminerga nervceller i odling mot stress inducerad av serum-deprivering. Dock kunde vi inte se någon ökning av överlevnaden när hämmaren användes i transplantations studier. Detta indikerar att excitotoxicitet spelar en underordnad roll vid död av dopaminerga nervceller. Å andra sidan kunde Flunarizine, en effektiv blockerare av VDCC, öka överlevnaden av transplanterade dopaminerga nervceller till nästan 300% jämfört med kontroller. Bcl-2 är ett anti-apoptotiskt (mot programmerad celldöd) protein som har betydelse vid nervcells död. I denna avhandling visar vi att Bcl-2 överuttryck skyddar ytterligare forskning kring dopaminerga nervceller i odling. Emellertid kunde inte Bcl-2 överuttryck skydda de dopaminerga nervcellerna i transplantations paradigmen. Inte alla former av apoptos är känsliga för Bcl-2, och därför undersökte vi Bcl-2 oberoende mekanismer närmare. Kaspaser är en familj proteaser som främjar apoptos, och vissa av kaspaserna är nära bundna till en Bcl-2 oberoende mekanism. I en intressant studie såg vi en potent kaspas-hämmare öka antalet överlevande dopaminerga nervceller i transplantat 3-4 gånger, vilket innebär att den effektivt blockerade apoptos. Poly (ADP-ribose) polymerase (PARP) är ett substrat för kaspaser och har nyligen associerats med nervcells död. Emellertid är dess roll i apoptos fortfarande oklar. I denna avhandling visar vi att PARP inte har betydelse för nigral celldöd. Ytterligare forskning kring de nya, lovande neuroprotektiva strategierna för ökad överlevnad av embryonala dopaminerga nervceller är befogad före klinisk applikation kan ske. (Less)
Abstract
Over the past two decades, grafting of embryonic nigral tissue has developed into a feasible therapeutic strategy for Parkinson's disease (PD). It has become apparent that the degree of restoration of dopaminergic neurotransmission by the transplanted cells is highly correlated to the symptomatic relief. However, the efficacy of the treatment is still far from optimal: More than 90% of the grafted dopaminergic neurones die during the transplantation procedure and the immediate period (first one to four days) after graft injection. Improvement in the survival of transplanted cells would increase the potential of this therapeutic approach and facilitate a more widespread use. This background provided the motivation of the research described... (More)
Over the past two decades, grafting of embryonic nigral tissue has developed into a feasible therapeutic strategy for Parkinson's disease (PD). It has become apparent that the degree of restoration of dopaminergic neurotransmission by the transplanted cells is highly correlated to the symptomatic relief. However, the efficacy of the treatment is still far from optimal: More than 90% of the grafted dopaminergic neurones die during the transplantation procedure and the immediate period (first one to four days) after graft injection. Improvement in the survival of transplanted cells would increase the potential of this therapeutic approach and facilitate a more widespread use. This background provided the motivation of the research described in the present thesis. The focus here was 1), to characterise cell death occurring during nigral transplantation, and, 2), to find and evaluate novel neuroprotective strategies. In the neurone an overload of Ca2+ effects a cascade of events ultimately leading to cell death. Ca2+ entry is mainly mediated either via excitatory amino acid (EAA) receptor activation or via voltage-dependent Ca2+ channels (VDCCs). In the present work, it could be shown that a potent inhibitor of the EAA receptor N-methyl-D-aspartate (NMDA) was able to protect cultured embryonic dopaminergic neurones against stress induced by serum-deprivation. On the other hand, when this compound was applied during mesencephalic grafting, no increase in dopaminergic neurone survival was observed. This indicates that excitotoxicity plays a subordinate role in death of transplanted dopaminergic neurones. In contrast, effective inhibition of VDCCs increased the survival of grafted dopaminergic neurones to 260% compared to control. Bcl-2 is a protein which has proven effective in the prevention of apoptosis in related contexts. Here it could be shown that it protected dopaminergic neurones in cultures subjected to serum-deprivation or staurosporine (STS) insult. However, Bcl-2 overexpression did not increase dopaminergic neurone survival when embryonic ventral mesencephalic tissue from transgenic mice was xenotransplanted into rats. The caspase family of proteases promotes apoptosis and some of its members are closely linked to a Bcl-2-independent pathway. In part of the current thesis, treatment with a caspase inhibitor was found to lead to a remarkable three-to-fourfold increase in the number of surviving implanted dopaminergic neurones, and thus efficiently blocked apoptosis. Activation of poly (ADP-ribose) polymerase (PARP) which is a substrate of caspases has recently been linked to neuronal death. However, its role in the context of apoptosis is still matter of debate. In the final part of the present thesis, it was shown that PARP does not play a role in nigral cell death. The presented research sheds further light on the mechanisms leading to cell death in nigral transplantation and led to the discovery of novel neuroprotective strategies which justify further exploration regarding their relevance for clinical application. (Less)
Please use this url to cite or link to this publication:
author
opponent
  • Prof Schapira, Anthony
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Ac-YVAD-cmk, MK-801, flunarizine, N-methyl-D-aspartate, voltage-dependent calcium channels, Bcl-2, caspase, excitotoxicity, apoptosis, tyrosine hydroxylase, dopamine, Parkinson's disease, intracerebral transplantation, Poly (ADP-ribose) polymerase, Neurology, neuropsychology, neurophysiology, Neurologi, neuropsykologi, neurofysiologi
pages
125 pages
publisher
Department of Physiological Sciences, Lund University
defense location
Segerfalkssalen, WNC
defense date
1999-06-09 10:15
external identifiers
  • Other:ISRN: LUMEDW/MEFF--1026--SE
ISBN
91-628-3506-8
language
English
LU publication?
yes
id
4ca5bda8-fdc8-407d-b6fd-611c6883c5c6 (old id 39685)
date added to LUP
2007-06-21 11:23:12
date last changed
2016-09-19 08:45:03
@phdthesis{4ca5bda8-fdc8-407d-b6fd-611c6883c5c6,
  abstract     = {Over the past two decades, grafting of embryonic nigral tissue has developed into a feasible therapeutic strategy for Parkinson's disease (PD). It has become apparent that the degree of restoration of dopaminergic neurotransmission by the transplanted cells is highly correlated to the symptomatic relief. However, the efficacy of the treatment is still far from optimal: More than 90% of the grafted dopaminergic neurones die during the transplantation procedure and the immediate period (first one to four days) after graft injection. Improvement in the survival of transplanted cells would increase the potential of this therapeutic approach and facilitate a more widespread use. This background provided the motivation of the research described in the present thesis. The focus here was 1), to characterise cell death occurring during nigral transplantation, and, 2), to find and evaluate novel neuroprotective strategies. In the neurone an overload of Ca2+ effects a cascade of events ultimately leading to cell death. Ca2+ entry is mainly mediated either via excitatory amino acid (EAA) receptor activation or via voltage-dependent Ca2+ channels (VDCCs). In the present work, it could be shown that a potent inhibitor of the EAA receptor N-methyl-D-aspartate (NMDA) was able to protect cultured embryonic dopaminergic neurones against stress induced by serum-deprivation. On the other hand, when this compound was applied during mesencephalic grafting, no increase in dopaminergic neurone survival was observed. This indicates that excitotoxicity plays a subordinate role in death of transplanted dopaminergic neurones. In contrast, effective inhibition of VDCCs increased the survival of grafted dopaminergic neurones to 260% compared to control. Bcl-2 is a protein which has proven effective in the prevention of apoptosis in related contexts. Here it could be shown that it protected dopaminergic neurones in cultures subjected to serum-deprivation or staurosporine (STS) insult. However, Bcl-2 overexpression did not increase dopaminergic neurone survival when embryonic ventral mesencephalic tissue from transgenic mice was xenotransplanted into rats. The caspase family of proteases promotes apoptosis and some of its members are closely linked to a Bcl-2-independent pathway. In part of the current thesis, treatment with a caspase inhibitor was found to lead to a remarkable three-to-fourfold increase in the number of surviving implanted dopaminergic neurones, and thus efficiently blocked apoptosis. Activation of poly (ADP-ribose) polymerase (PARP) which is a substrate of caspases has recently been linked to neuronal death. However, its role in the context of apoptosis is still matter of debate. In the final part of the present thesis, it was shown that PARP does not play a role in nigral cell death. The presented research sheds further light on the mechanisms leading to cell death in nigral transplantation and led to the discovery of novel neuroprotective strategies which justify further exploration regarding their relevance for clinical application.},
  author       = {Schierle, Gabriele},
  isbn         = {91-628-3506-8},
  keyword      = {Ac-YVAD-cmk,MK-801,flunarizine,N-methyl-D-aspartate,voltage-dependent calcium channels,Bcl-2,caspase,excitotoxicity,apoptosis,tyrosine hydroxylase,dopamine,Parkinson's disease,intracerebral transplantation,Poly (ADP-ribose) polymerase,Neurology,neuropsychology,neurophysiology,Neurologi,neuropsykologi,neurofysiologi},
  language     = {eng},
  pages        = {125},
  publisher    = {Department of Physiological Sciences, Lund University},
  school       = {Lund University},
  title        = {Apoptosis And Excitotoxicity In The Death of Cultured And Grafted Dopaminergic Neurones},
  year         = {1999},
}