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Institute of Physiology and Pathophysiology

Research Areas

Hypoxia in the Brain

Our research group investigates the effects of hypoxia in the brain. Tissue hypoxia in the brain is a central problem in a number of disorders such as ischemia, tumors, brain injury, high altitude sickness and epilepsy. The insufficient availability of oxygen to the cells can be caused by reduced supply or increased consumption. Therefore our interest is focused on the neurovascular interplay which also includes glial cells. We study two hypoxia-related processes in particular: 1) the activation of endogenous factors which protect neurons against cell death or which induce their regeneration (neuroprotection and neurogenesis), and 2) the opening of the blood-brain barrier leading to cerebral oedema formation. We utilise various in vivo experimental models (hypoxia chamber, ischemia models), including transgenic animals, and combine these with modern molecular biology techniques. By analysing and characterising this endogenous protective response we hope to find clues for new therapies for human diseases.

1) Neuroprotection and Neurogenesis


Tissue hypoxia is detected via various oxygen sensors (polylhydoxylases, PHD), which activate specific transcription factors (hypoxia-inducible factors, HIF), which, in turn, lead to the induction of neurogenic and neuroprotective factors such as vascular endothelial growth factor (VEGF) or erythropoietin (Epo). It is the aim of our research to understand in detail the underlying mechanisms and to manipulate them in a positive way.




Brain-specific overexpression of VEGF reduces infarct (pale area) size. Infarct size quantification on cresyl violet-stained brain tissue sections revealed a significant 40% reduction in VEGF transgenic mice (VEGF-tg) as compared with non transgenic littermate controls (ntg).

 

from Wang et al.; Brain (2005); 128: 52-63

2) Blood-Brain Barrier


Besides its positive properties (neuroprotection, neurogenesis, angiogenesis) VEGF has one negative effect on the blood-brain barrier (BBB), which complicates its immediate therapeutic use:  VEGF leads to the opening of the BBB and, as a consequence, to the formation of a cerebral oedema. We investigate the molecular mechanisms of this opening by characterising the processes at the endothelial cell-cell contacts (tight junctions) and at the extracellular matrix. It is our goal to reduce oedema formation by intervention without affecting the neuroprotective properties.

 


Hypoxia causes rearrangement and gap formation of the tight junction protein occludin. Mice were exposed for 48 h to 20% (control) or 8% oxygen (hypoxia). Coronal brain sections were
stained immunohistochemically for occludin (green) and CD31 (red), and nuclei were stained with DAPI (blue). Three-dimensional reconstruction after confocal microscopy demonstrates occludin rearrangement and gap formation (arrowheads) after hypoxia, as compared to the continuous, sharp linear staining (arrows) in controls.

 

from Bauer et al.; J Cereb Blood Flow Metab (2010); 30: 837-848.





24.10.2017       13:30   /   INF 327, Seminar Room 1

 

Hypoxia and uterine contractions: Something old and something new

Prof. Dr. Susan Wray

Dept. of Cellular and Molecular Physiology, University of Liverpool, United Kingdom

  

24.10.2017       18:00   /   INF 410 (Med. Clinic), Auditorium

 

Calcium in the heart: in and out of control

Prof. Dr. David Eisner

Manchester Institute for Collaborative Research on Ageing, University of Manchester, United Kingdom


(seminar of Heidelberg University Hospital and German Center for Cardiovascular Disease (DZHK); host: Prof. Dr. M. Hecker, Inst. of Physiology and Pathophysiology, Heidelberg University)

  

Recent Publications

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Allosteric inhibition of carnosinase (CN1) by inducing a conformational shift. J Enzyme Inhib Med Chem. 2017 Dec;32(1):1102-1110. doi: 10.1080/14756366.2017.1355793.

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Transcription factor decoy technology: a therapeutic update. Biochem Pharmacol. 2017 Nov 15;144:29-34. doi: 10.1016/j.bcp.2017.06.122. Epub 2017 Jun 19. Review.

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Heteromeric channels formed by TRPC1, TRPC4 and TRPC5 define hippocampal synaptic transmission and working memory. EMBO J. 2017 Sep 15;36(18):2770-2789. doi: 10.15252/embj.201696369. Epub 2017 Aug 8

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NO-sGC Pathway Modulates Ca2+ Release and Muscle Contraction in Zebrafish Skeletal Muscle. Front Physiol. 2017 Aug 23;8:607. doi: 10.3389/fphys.2017.00607. eCollection 2017.


Institute of
Physiology and Pathophysiology

Heidelberg University

Im Neuenheimer Feld 326

69120 Heidelberg

Germany

Phone:+49 6221 54-4056
Fax:+49 6221 54-6364
E-mail:susanne.bechtel@
physiologie.uni-heidelberg.de