The effects of dexamethasone on experimental brain tumors: I. Transcapillary transport and blood flow in RG-2 rat gliomas

Peter Molnar, Gregory D. Lapin, Dennis R. Groothuis

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

Dexamethasone dramatically improves cerebral edema associated with malignant gliomas. Although the pathophysiology of this effect is not clearly understood, many investigators have postulated that tumor capillary permeability is reduced by dexamethasone. We studied blood-to-tissue transport and blood flow in 178 RG-2 transplanted gliomas in a control group and four groups given dexamethasone at doses of 3, 6, 9, and 12 mg/kg for four days.14C-α aminoisobutyric acid (AIB) was used to study blood-to-tissue transport in 31 animals; in an additional 27 animals14C-AIB and131I-iodoantipyrine (IAP) were used in double label experiments to study blood-to-tissue transport and blood flow. Regional measurements of the transfer constant (K) of AIB and blood flow (F) were made with quantitative autoradiography. There were significant differences between the control and dexamethasone-treated groups with regard to weight loss and plasma glucose. However, there was no significant effect of dexamethasone on values of K or F, regardless of the tumor or brain region examined, and regardless of the dose of dexamethasone administered. Analysis of the profiles of the transfer constant of AIB in the brain around tumor showed that the K of AIB decreased within 0.5 mm of the tumor edge in direct relationship to the dexamethasone dose. These results do not support the hypothesis that dexamethasone reduces brain tumor capillary permeability, and suggest that dexamethasone may decrease tumor-associated cerebral edema by effects on bulk flow away from the tumor margin.

Original languageEnglish
Pages (from-to)19-28
Number of pages10
JournalJournal of Neuro-Oncology
Volume25
Issue number1
DOIs
Publication statusPublished - Feb 1 1995

Keywords

  • blood-brain barrier
  • brain tumors
  • capillary permeability
  • cerebral edema
  • dexamethasone
  • steroids

ASJC Scopus subject areas

  • Oncology
  • Neurology
  • Clinical Neurology
  • Cancer Research

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