steroids 73 ( 2 0 0 8 ) 88–95 available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/steroids Activities of steroid metabolic enzymes in secretory endometria from untreated women with Polycystic Ovary Syndrome Luis Leon a,b , Ketty Bacallao a,b , Fernando Gabler c , Carmen Romero b , Luis Valladares d , Margarita Vega a,b,∗ a Institute of Maternal and Child Research, School of Medicine, University of Chile, Chile b Department of Obstetrics and Gynecology, School of Medicine, University of Chile Clinical Hospital, Chile c Department of Pathology, School of Medicine, University of Chile, San Borja Arriaran Clinical Hospital, Chile d Institute of Nutrition and Food Technology, University of Chile, Chile article info Article history: Received 13 June 2007 Received in revised form 10 September 2007 Accepted 11 September 2007 Published on line 16 September 2007 Keywords: Polycystic Ovary Syndrome Endometria Steroid-metabolic enzymes Estrogens abstract Polycystic Ovary Syndrome (PCOS) is an endocrine-metabolic pathology related with infer- tility and recurrent miscarriage. We have previously shown that the endometrium of these patients can exhibit a potentially higher sensitivity to estrogen action, being estrogens important regulators of the cell cycle and tissue homeostasis. The effect of estrogens on tissues depends on their in situ availability, which is in part regulated by the activity of steroid metabolic enzymes within the tissues. Therefore, the objective of the present study was to analyze if the activity and/or expression of steroid metabolic enzymes in endometria from women with PCOS differ from controls. For this purpose, the activity of the enzymes was determined by using radiometric assays and the mRNA levels mea- sured by semi-quantitative RT-PCR. Both assays were assessed in endometria obtained during mid secretory phase from control (CE, n = 12) and PCOS women (PCOSE, n = 11). For the statistical analyses, Mann–Whitney and Student’s t-tests were used to compare CE and PCOSE, considering a p value <0.05 significantly different. The results showed an increase in the sulfatase activity in PCOS respect to control endometria (200 ± 28 pmol/mg vs. 115 ± 13 pmol/mg prot h; p < 0.05), in agreement with the higher mRNA levels found for the enzyme in PCOSE. In addition, a PCOSE exhibited lower activity of sulfotransferase respect to the control group (50 ± 21 pmol/mg vs. 124 ± 10 pmol/mg prot h; p < 0.05), whereas a higher level of 17-hydroxysteroid dehydrogenase type 1 mRNA was found in PCOSE compared with the control tissues (p < 0.05). The activity of 17-hydroxysteroid dehydrogenase type 2 and the mRNA levels of sulfotransferase were similar in both groups; meanwhile, the expression of aromatase was undetectable. These data indicate that the sulfatase pathway could play an important role in the local production of estrogens in PCOSE from secretory phase. This potentially higher bioavailability of estrogens in endometria from PCOS women could influ- ence the deregulation of tissue homeostasis that we have previously reported, and could partially explain the poor reproductive performance observed in this group of patients. © 2007 Elsevier Inc. All rights reserved. ∗ Corresponding author at: Department of Obstetrics and Gynecology, School of Medicine, University of Chile Clinical Hospital, Santos Dumont # 999, Santiago, Chile. Tel.: + 56 2 9788304; fax: +56 2 7374555. E-mail address: mvega@redclinicauchile.cl (M. Vega). 0039-128X/$ – see front matter © 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.steroids.2007.09.003