This Article Full Text (PDF) References Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Saved Citations Download to citation manager Request Permissions Request Reprints Add to My Marked Citations Citing Articles Citing Articles via Google Scholar Citing Articles via Scopus Google Scholar Articles by Szelke, E. Articles by Komjati, K. Search for Related Content PubMed PubMed Citation Articles by Szelke, E. Articles by Varbiro, S. Articles by Mersich, T. Articles by Banhidy, F. Articles by Szekacs, B. Articles by Sandor, P. Articles by Komjati, K. Pubmed/NCBI databases Compound via MeSH Substance via MeSH Hazardous Substances DB CARBON DIOXIDE ESTRADIOL OXYGEN Social Bookmarking                   What's this?

Effects of Estrogen and Progrestin on Hypothalamic Blood Flow Autoregulation

Institute of Human Physiology and Experimental Research; Second Department of Obstetrics and Gynecology; Second Department of Internal Medicine-Department of Geriatry, Faculty of Medicine, Semmelweis University Budapest, Hungary; Inotek Pharmaceutical Corporation, Beverly, Massachusetts, USA

Szabolcs Varbiro, MD, PhD

Institute of Human Physiology and Experimental Research; Second Department of Obstetrics and Gynecology; Second Department of Internal Medicine-Department of Geriatry, Faculty of Medicine, Semmelweis University Budapest, Hungary; Inotek Pharmaceutical Corporation, Beverly, Massachusetts, USA; varbiro{at}noi2.sote.hu

Tamas Mersich, MD

Ferenc Banhidy, MD, PhD

Bela Szekacs, MD, PhD, DMSc

Peter Sandor, MD, PhD, DMSc

Katalin Komjati, MD, PhD

Institute of Human Physiology and Experimental Research; Second Department of Obstetrics and Gynecology; Second Department of Internal Medicine-Department of Geriatry, Faculty of Medicine, Semmelweis University Budapest, Hungary; Inotek Pharmaceutical Corporation, Beverly, Massachusetts, USA

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 antagonisti activities. This intricate system involving cerebral autoregulatory mechanisms caused by ovariectomy and female sex horomne 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 chanes 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.

Key Words: Ovariectomy • estrogen • progestin • hypothalamic blood flow • autoregulation

Journal of the Society for Gynecologic Investigation, Vol. 12, No. 8, 604-609 (2005)
DOI: 10.1016/j.jsgi.2005.08.004


CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?