Thesis supervisor: Tamás Dóczi
Location of studies (in Hungarian): PTE ÁOK Pécs, Szigeti u. 12. Abbreviation of location of studies: ÁOK
Description of the research topic:
The precise adjustment of cerebral water content and brain volume is of critical importance for the normal functioning of the central nervous system (CNS). The brain, surrounded by the bony cranium is highly sensitive to any increase in intracranial volume. Failure of the compensatory mechanisms may result in decreased cerebral blood flow and mechanical tissue damages, the most dangerous of them being cerebral herniation. Although numerous investigations have been performed to elucidate intracranial volume buffering, little is known about the cellular and molecular mechanisms of the volume regulation of the nervous tissue. Constant volume of the nervous tissue is a requirement of action potentials and synaptic activities of neurons. The leader of this program has put forward the concept that brain water and electrolyte content is regulated by a central neuro-endocrine system that is independent of systemic regulation. It has been shown, that the endothelium of the brain vasculature is not freely permeable to water, in fact it exhibits similar water permeability properties as epithelial membranes known to regulate membrane water permeability (e.g. kidney collecting duct epithel. Arginine vasopressin (AVP) and atrial natriuretic peptide (ANP), peptide hormones important in the volume homeostasis of extracerebral tissues, have been suggested to play similar regulatory role in the CNS. These hormones and their receptors have been demonstrated in significant concentration in the brain and it has been shown, that they enter the CSF directly from the brain and not from the systemic circulation, thus plasma vasopressin and ANP levels may not actually reflect their central activity. Vasopressin antagonists and atriopeptin analogues may be useful in combatting raised intracranial pressure. Recent introduction of MRI and proton MR spectroscopy enabled the non-invasive investigation of physiological and also physical water compartments in the nervous tissue. Quantitative clinical measurements of brain water content and that of the free and bound tissue water fraction have opened a new world for the study of brain volume regulation. Participants will be well-worsed also in the theory and practice of MRI.
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