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- Andsberg, Gunnar
(författare)
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Experimental Stroke and Neurotrophins: Regulation, function and gene transfer of neurotrophins in rat and mouse models of focal cerebral ischemia
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Stroke caused by focal cerebral ischemia is a major cause of death and neurological disability in humans. The forebrain region most commonly affected by ischemic incidents is that supplied by the middle cerebral artery. In this thesis, neuronal cell death has been investigated using immunohistochemistry for identification of specific neurons and unbiased counting methods after transient occlusion of the middle cerebral artery (MCAO). Our studies show that striatal projection neurons and parvalbumin-containing interneurons are vulnerable, whereas cholinergic and NOS-containing interneurons are highly resistant to MCAO. The high potency of the neurotrophin family of neurotrophic factors to inhibit neuronal death in immature cell systems and the widespread expression of these factors throughout the adult brain, suggest that the neurotrophins might be critical regulators of neuronal survival. Rapid and profound increase of BDNF gene expression has been shown in the frontal and cingulate cortices after MCAO. We show here that also the BDNF protein levels are elevated in the same cortical regions after the ischemic insult, but also further dynamic changes in subcortical regions strongly suggesting anterograde transport of BDNF in forebrain neurons. In our further studies, the ability of the neurotrophins to change the vulnerability of striatal neurons to ischemic damage was investigated in the MCAO model. First, the resistant cholinergic interneurons in striatum respond to MCAO with expression of the p75 neurotrophin receptor (p75NTR). However, the vulnerability of the cholinergic interneurons to MCAO was not increased in a mice strain mutant for the P75NTR, which strongly argue against a major role of this receptor for the prominent resistance of these interneurons to ischemic insults. In order to directly investigate the neuroprotective properties of the neurotrophins, the vulnerability of striatal neurons to focal cerebral ischemia was determined after increasing the levels of BDNF and NGF by gene transfer to the striatum. Increased survival of striatal projection neurons was found after intrastriatal grafting of NGF-secreting genetically modified neural stem cells and after direct transfer of the BDNF gene to striatal cells using an adenoassociated viral (AAV) vector. Furthermore, viral transfer of the BDNF or NGF gene to striatal cells increased survival of parvalbumin-containing interneurons after MCAO. Our data support a role for the neurotrophins as a protective factor against ischemic damage. To assess the functional significance of increased neuronal survival in striatum after focal cerebral ischemia, we utilized different behavioral tests for striatal motor function. We found a strong correlation between scores from these behavioral tests and the extent of striatal damage, and in particular skilled forelimb use in the staircase paradigm was the best predictor of damage. Viral delivery of the neurotrophins lead to improvements in ischemia-induced motor impairments, which appeared to be due to increase in the survival of striatal neurons treated with BDNF. In conclusion, this thesis shows that focal cerebral ischemia causes dynamic changes of the BDNF and p75NTR levels. Gene transfer-induced elevation of neurotrophin levels increases the survival of striatal neurons to ischemic damage, which indicates a neuroprotective role for these factors in the mature brain.
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| 2. |
- Andsberg, Gunnar, et al.
(författare)
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Neuropathological and behavioral consequences of adeno-associated viral vector-mediated continuous intrastriatal neurotrophin delivery in a focal ischemia model in rats.
- 2002
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Ingår i: Neurobiology of Disease. - : Elsevier BV. - 0969-9961. ; 9:2, s. 187-204
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Tidskriftsartikel (refereegranskat)abstract
- Nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) were continuously delivered to the striatum at biologically active levels via recombinant adeno-associated viral (rAAV) gene transfer 4-5 weeks prior to 30 min of middle cerebral artery occlusion (MCAO). The magnitude of the deficits in a battery of behavioral tests designed to assess striatal function was highly correlated to the extent of ischemic damage determined by unbiased stereological estimations of striatal neuron numbers. The delivery of neurotrophins lead to mild functional improvements in the ischemia-induced motor impairments assessed 3-5 weeks after the insult, in agreement with a small but significant increase of the survival of dorsolateral striatal neurons. Detailed phenotypic analysis demonstrated that the parvalbumin-containing interneurons were spared to a greater extent by the neurotrophin treatment as compared to the projection neurons, which agreed with the specificity for interneuron transduction by the rAAV vector. These data show the advantage of the never previously performed combination of precise quantification of the ischemia-induced neuropathology along with detailed behavioural analysis for assessing neuroprotection after stroke. We observe that intrastriatal delivery of NGF and BDNF using a viral vector system can mitigate, albeit only moderately, neuronal death following stroke, which leads to detectable functional sparing. (c)2002 Elsevier Science (USA).
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| 3. |
- Andsberg, Gunnar, et al.
(författare)
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Upregulation of p75 neurotrophin receptor after stroke in mice does not contribute to differential vulnerability of striatal neurons
- 2001
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Ingår i: Experimental Neurology. - : Elsevier BV. - 0014-4886. ; 169:2, s. 351-363
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Tidskriftsartikel (refereegranskat)abstract
- The survival of different neuron types and the expression of the p75 neurotrophin receptor (p75(NTR)) after focal cerebral ischemia were studied in the mouse striatum using immunocytochemical and histochemical techniques and stereological procedures. As assessed at 1 week after 30 min of middle cerebral artery occlusion, the order of vulnerability was projection neurons > parvalbumin-expressing interneurons > nitric oxide synthase-containing interneurons > cholinergic interneurons. Within the ischemic lesion, projection neurons were almost completely lost whereas cholinergic interneurons were spared. Calretinin-immunoreactive interneurons also seemed resistant to the insult. Expression of p75(NTR) was induced in cholinergic interneurons within the lesioned area, raising the possibility of a protective action. However, the number of cholinergic interneurons was unaffected in p75(NTR) knockout mice subjected to the same ischemic insult. These quantitative data demonstrate that striatal neurons in the mouse are differentially susceptible to ischemic damage and argue against a significant role of p75(NTR) for the high resistance of cholinergic interneurons.
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| 4. |
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| 5. |
- Gustafsson, Elin, et al.
(författare)
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Anterograde delivery of brain-derived neurotrophic factor to striatum via nigral transduction of recombinant adeno-associated virus increases neuronal death but promotes neurogenic response following stroke.
- 2003
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Ingår i: European Journal of Neuroscience. - : Wiley. - 1460-9568 .- 0953-816X. ; 17:12, s. 2667-2678
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Tidskriftsartikel (refereegranskat)abstract
- o explore the role of brain-derived neurotrophic factor for survival and generation of striatal neurons after stroke, recombinant adeno-associated viral vectors carrying brain-derived neurotrophic factor or green fluorescent protein genes were injected into right rat substantia nigra 4–5 weeks prior to 30 min ipsilateral of middle cerebral artery occlusion. The brain-derived neurotrophic factor–recombinant adeno-associated viral transduction markedly increased the production of brain-derived neurotrophic factor protein by nigral cells. Brain-derived neurotrophic factor was transported anterogradely to the striatum and released in biologically active form, as revealed by the hypertrophic response of striatal neuropeptide Y-positive interneurons. Animals transduced with brain-derived neurotrophic factor-recombinant adeno-associated virus also exhibited abnormalities in body posture and movements, including tilted body to the right, choreiform movements of left forelimb and head, and spontaneous, so-called 'barrel' rotation along their long axis. The continuous delivery of brain-derived neurotrophic factor had no effect on the survival of striatal projection neurons after stroke, but exaggerated the loss of cholinergic, and parvalbumin- and neuropeptide Y-positive, γ-aminobutyric acid-ergic interneurons. The high brain-derived neurotrophic factor levels in the animals subjected to stroke also gave rise to an increased number of striatal cells expressing doublecortin, a marker for migrating neuroblasts, and cells double-labelled with the mitotic marker, 5-bromo-2'-deoxyuridine-5'monophosphate, and early neuronal (Hu) or striatal neuronal (Meis2) markers. Our findings indicate that long-term anterograde delivery of high levels of brain-derived neurotrophic factor increases the vulnerability of striatal interneurons to stroke-induced damage. Concomitantly, brain-derived neurotrophic factor potentiates the stroke-induced neurogenic response, at least at early stages.
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