Effects of estrogen on cerebral blood flow and pial microvasculature in rabbits

M. T. Littleton-Kearney, D. M. Agnew, R. J. Traystman, P. D. Hurn

Research output: Contribution to journalArticlepeer-review

Abstract

We tested the hypothesis that intracarotid estrogen infusion increases cerebral blood flow (CBF) in a concentration-dependent manner and direct application of estrogen on pial arterioles yields estrogen receptor-mediated vasodilation. Rabbits of both genders were infused with estrogen via a branch of the carotid artery. Estrogen doses of 20 or 0.05 μg·ml-1·min-1 were used to achieve supraphysiological or physiological plasma estrogen levels, respectively. CBF and cerebral vascular resistance were determined at baseline, during the infusion, and 60-min postinfusion, and effects on pial diameter were assessed via a cranial window. Pial arteriolar response to estrogen alone and to estrogen after administration of tamoxifen (10-7), an antiestrogen drug that binds to both known estrogen receptor subtypes, was tested. No gender differences were observed; therefore, data were combined for both males and females. Systemic estrogen infusion did not increase regional CBF. Estradiol dilated pial arteries only at concentrations ranging from 10-4-10-7 M (P ≤ 0.05). Pretreatment with tamoxifen alone had no effect on arteriolar diameter but inhibited estrogen-induced vasodilation (P < 0.001). Our data suggest that estrogen does not increase CBF under steady-state conditions in rabbits. In the pial circulation, topically applied estradiol at micromolar concentrations dilates vessels. The onset is rapid and dependent on estrogen receptor activation.

Original languageEnglish (US)
Pages (from-to)H1208-H1214
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume279
Issue number3 48-3
DOIs
StatePublished - 2000

Keywords

  • Cranial window
  • Microcirculation
  • Pial circulation
  • Precapillary vessels
  • Tamoxifen

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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