Estrogen-based drug therapy in cardiovascular diseases has been difficult because it has not been possible to separate the wanted vasculoprotective effect from the unwanted effects of the hormone to the reproductive system. Here, we demonstrate that, after endothelial denudation of rat carotid artery, the mRNA of the classical estrogen receptor (ER␣) is constitutively expressed at a low level whereas the expression of the novel ER␤ mRNA increases >40-fold. Under in situ hybridization and immunohistochemistry, ER␤ mRNA and protein colocalize with the smooth muscle cells in the media and neointima. Treatment of ovariectomized female rats with the isof lavone phytoestrogen genistein, which shows 20-fold higher binding affinity to ER␤ than to ER␣, or with 17␤-estradiol, which does not differentiate between the two receptors, provides similar dosedependent vasculoprotective effect in rat carotid injury model. In addition in concentrations <10 M, both ligands are equally inhibitory to the replication and migration of smooth muscle cells in vitro. However, only treatment with 17␤-estradiol, but not with genistein, is accompanied with a dose-dependent uterotrophic effect. The results suggest that preferential targeting to ER␤ will provide vasculoprotective estrogen analogs devoid of effects to the reproductive system. Vascular intimal dysplasia and remodeling are characteristic features of injury after percutaneous transluminal coronary angioplasty (1) and in chronic allograft rejection (2, 3). The initial response to injury is inflammatory and involves the attraction of lymphocytes, macrophages, and thrombocytes to the site of injury and the secretion of cytokines, eicosanoids, and growth factors (4). Under the influence of growth factors and cytokines, smooth muscle cells (SMCs) proliferate and migrate into the intima and contribute to intimal hyperplasia and vascular stenosis.Estrogen has several protective effects on the vascular wall. Some of these are rapid, presumably direct membrane effects whereas others require transcriptional activation of genes (5, 6). The inhibitory effect of estrogen on the replication, migration, and extracellular matrix deposition by vascular SMC, the key events in vascular fibroproliferative dysplasias, is presumably a genomic effect mediated through a variety of mechanisms, including regulation of several growth factors and͞or their receptors and possibly by a direct antiproliferative effect of estrogen on SMC (5, 7).The development of vasculoprotective drug therapies based on the protective effect of estrogen has been difficult, as it has not been possible to differentiate the desired vasculoprotective effect of estrogen from its effects on the reproductive system. In this communication, we demonstrate that this is possible by preferential targeting to the novel estrogen receptor ␤ (ER␤). MATERIALS AND METHODSCarotid Denudation Injury. Carotid denudations were made to Wistar rats purchased from the Laboratory Animal Center (University of Helsinki). The details of the operation...

Our previous studies have shown that transgenic male mice expressing human P450 aromatase (AROM+) are infertile. In the present study, we followed the testis phenotype up to 15 months of age in these mice. The testes of the old AROM+ mice showed Leydig cell hypertrophy and hyperplasia, as indicated by the staining for steroidogenic enzymes and androgen and estrogen receptors. However, the Leydig cell adenomas did not show signs of malignization. In contrast, we observed a marked increase in the number of activated macrophages in the testicular interstitium of the aging AROM+ mice. The macrophages were further shown to express high levels of CD68 (a monocyte/macrophage marker) and secrete TNFalpha, indicating strong activation, presumably by estrogen exposure. The increased activity of the macrophages was associated with Leydig cell depletion (analyzed at the age of 9 and 15 months) and an increased number of mast cells and fibrosis in the testicular interstitium. Interestingly, similar findings have been made in testes of infertile men. Hence, the aging AROM+ males present with a phenocopy of inflammation-associated infertility in men, providing a model for further studies on the putative link among estrogens, orchitis, and infertility.