VASCULAR DISTRIBUTION OF ESTROGEN RECEPTOR SUBTYPES
Research field:Endocrinology
Authors:Nilsson B-O, Andersson C, Fernö M, Gustafsson J-Å, Idvall I, Lydrup M-L.
Address of presenting
author:		Bengt-Olof Nilsson
Department of Physiological Sciences,
Lund University,
Sölvegatan 19,
S-223 62 Lund
Sweden
E-mail:Bengt-Olof.Nilsson@mphy.lu.se
Phone:+46-46-2227769
Fax:+46-46-2224546
Text of abstract Introduction
Estrogen protects postmenopausal women from cardiovascular disease partly via a direct effect on cardiovascular function. In cultured endothelial cells estrogen, in physiological concentrations (nM), acutely induces eNOS expression, while estrogen, in these concentrations, has no acute effect on vascular contractility. Higher concentrations (mM) of estrogen cause, however, vascular relaxation. A new estrogen receptor (ERb) was cloned from rat prostate in 1996 (Kuiper et al. 1996). Estrogen receptors (ER) involved in regulation of vascular function have not been identified. The purpose of the present study was to determine vascular expression of ER subtypes a and b.

Methods
ER subtypes were determined in uterine artery, aorta and tail artery of sexually mature female rats using immunocytochemistry and enzyme-immuno assay. Staining with antibodies against ERa and b was performed on transverse and longitudinal sections of formalin fixed and paraffin embedded vascular tissues. Enzyme-immuno assay was performed on tissue homogenates. Uterine and breast tissues were used as positive controls.

Results
By using immunocytochemistry, we found immunoreactivity against ERa in smooth muscle cells of the fine branches of uterine artery while no immunoreactivity against ERa was observed in either transverse or longitudinal sections of the tail arterial wall. Quantitative determination of ERa by enzyme-immuno assay supported findings obtained by immunocytochemistry. High amounts (112 fmol/mg protein) of ERa, comparable to those observed in breast cancer tissue, were detected in uterine tissue, while in 4 out of 5 preparations of tail artery no ERa was detected. In aorta, a low (3 fmol/mg protein) level of ERa was observed.

Conclusions
Data presented in this study suggest that ER subtypes are regionally distributed in the vascular system.

References
Kuiper, G.G.J.M., Enmark, E., Pelto-Huikko, M., Nilsson, S. & Gustafsson, J.-Å. 1996. Proc Natl Acad Sci USA 93, 5925-5930.

Keywords:estrogen receptors, immunocytochemistry, vascular tissue

Created 2000-04-29