Document Detail


Effects of ionizing radiation on the blood brain barrier permeability to pharmacologically active substances.
MedLine Citation:
PMID:  2262385     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Ionizing radiation can impair the integrity of the blood brain barrier (BBB). Data on early and late damage after brain irradiation are usually reported separately, yet a gradual transition between these two types has become evident. Signs appearing within 3 weeks after irradiation are considered to be early manifestations. The mechanism of radiation-effected integrity impairment of the BBB is discussed in relation to changes in morphological structures forming the BBB, the endothelium of intracerebral vessels, and in the surrounding astrocytes. Alterations in the function of the BBB are manifested in the endothelium by changes in the ultra-structural location of the activity of phosphatases and by the activation of pinocytotic vesicular transport, and in astrocyte cytoplasm by glycogen deposition. The changes in ultrastructure were critically surveyed with regard to increasing doses of radiation to the brain in the range of 5 Gy to 960 Gy. The qualitative as well as the semiquantitative and quantitative observations on the passage of substances across the damaged BBB were treated separately. Qualitative changes are based mainly on findings of extravasation of vital stains and of labelled proteins. The quantitative studies established differences in radiation-induced changes in the permeability of the BBB depending on the structure and physico-chemical properties of the barrier penetrating tracers. Indirect evaluation of radiation-induced BBB changes is based on studies of pharmacological effects of substances acting on the CNS. In conclusion, radiation impairs significantly the integrity of the BBB following single irradiation of the brain with a dose exceeding 10-15 Gy. The response of the BBB to ionizing radiation is dependent both on the dose to which the brain is exposed and on specific properties of the tracer. Either an increase or a decrease of BBB permeability, or both, occurring in a certain time sequence, was observed. The mechanism of hyperpermeability after irradiation is not fully understood, but the activation of vesicular transport offers one possible explanation. Even less understood is the mechanism of decreased permeability. The response of the BBB to ionizing radiation is most probably nonspecific and its nature may be assumed to be similar to its responses to other physical or chemical noxious factors.
Authors:
T Trnovec; Z Kállay; S Bezek
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Publication Detail:
Type:  Journal Article; Review    
Journal Detail:
Title:  International journal of radiation oncology, biology, physics     Volume:  19     ISSN:  0360-3016     ISO Abbreviation:  Int. J. Radiat. Oncol. Biol. Phys.     Publication Date:  1990 Dec 
Date Detail:
Created Date:  1991-02-01     Completed Date:  1991-02-01     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  7603616     Medline TA:  Int J Radiat Oncol Biol Phys     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1581-7     Citation Subset:  IM    
Affiliation:
Institute of Experimental Pharmacology, Slovak Academy of Sciences, Bratislava.
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MeSH Terms
Descriptor/Qualifier:
Blood-Brain Barrier / radiation effects*
Humans
Permeability
Radiation Dosage
Radiation, Ionizing

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