Effects of estrogen and progestin on hypothalamic blood flow autoregulation

Emese Szelke, Szabolcs Varbiro, Tamas Mersich, Ferenc Banhidy, Bela Szekacs, Peter Sandor, Katalin Komjati

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

OBJECTIVES: The consequences of female sex hormone deficiency and the effects of hormone replacement therapy are controversial because individual hormones and their derivates can result in partially antagonistic activities. This intricate system involving cerebral autoregulatory mechanisms caused by ovariectomy and female sex hormone replacement was studied in rats. METHODS: The lower limit of cerebral blood flow autoregulation was determined by stepwise reduction of systemic arterial pressure while simultaneously measuring the changes of the hypothalamic blood flow (HBF) using the hydrogen gas-clearance method. RESULTS: In ovariectomized rats resting HBF decreased substantially and the threshold of cerebrovascular autoregulation decreased to 40 mm Hg. Estrogen replacement prevents the former change and shifts the latter upwards. Similarly, progestin replacement restores autoregulation to the physiological levels found in control animals, whereas it has no influence on the ovariectomy-induced reduction of resting blood flow. CONCLUSIONS: Steady-state HBF and compensatory changes of regional cerebral vascular autoregulation are altered significantly following ovariectomy. Estrogen or progestin replacement has an opposite effect on these cerebral circulatory parameters. Our observations highlight the essential role of female sex hormones in hypothalamic autoregulation during hypotensive stress.

Original languageEnglish
Pages (from-to)604-609
Number of pages6
JournalJournal of the Society for Gynecologic Investigation
Volume12
Issue number8
DOIs
Publication statusPublished - Dec 1 2005

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Keywords

  • Autoregulation
  • Estrogen
  • Hypothalamic blood flow
  • Ovariectomy
  • Progestin

ASJC Scopus subject areas

  • Obstetrics and Gynaecology

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