Role of the CAG repeat polymorphism of the androgen receptor gene in polycystic ovary syndrome (PCOS)

BACKGROUND

Polycystic ovary syndrome (PCOS) is a frequent heterogenic disorder with a familial background. Androgenic effects, determining the clinical features of the syndrome, are mediated by the androgen receptor (AR), whose activity is modulated by a genetic polymorphism. We investigated the role of the CAG repeat polymorphism of the androgen receptor in PCOS.

METHODS

In the infertility unit of a university clinic, 72 PCOS patients were compared with 179 ovulatory controls undergoing a standardized diagnostic work-up. The number of CAG repeats was determined by PCR, labelling with IR-800 and PAGE. X-chromosome inactivation was assessed by a methylation-sensitive assay.

RESULTS

Compared to controls, PCOS patients displayed a shorter mean CAG repeat length, encoding for higher AR activity (P=0.001). CAG repeat length correlated inversely with oligomenorrhea, a central androgen dependent feature of the syndrome (P=0.005). In a binomial regression analysis including BMI, LH and free testosterone, CAG repeat length was identified as an independent risk factor for PCOS (P=0.002).

CONCLUSIONS

The CAG repeat polymorphism could constitute one of the genetic factors modulating the syndrome's phenotype, contributing to its clinical heterogeneity and associated metabolic consequences.

The functional anatomy of semantic retrieval is influenced by gender, menstrual cycle, and sex hormones

This study examines the neurobiology of semantic retrieval and describes the influence of gender, menstrual cycle, and sex hormones on semantic networks. Healthy right-handed subjects (12 men, 12 women) were investigated with 3T-fMRI during synonym generation. Behavioral performance and sex hormone levels were assessed. Women were examined during the early follicular and midluteal cycle phase. The activation pattern in all groups involved left frontal and temporal as well as bilateral medial frontal, cingulate, occipital, basal ganglia, and cerebellar regions. Men showed greater left frontal activation than women in both menstrual cycle phases. Women yielded high correlations of left prefrontal activation with estradiol in the midluteal phase and with progesterone in both phases. Testosterone levels correlated highly with left prefrontal activation in all three groups. In all, we describe a cerebral network involved in semantic processing and demonstrate that it is significantly affected by gender and sex steroid hormones.

Functional anatomy of visuo-spatial working memory during mental rotation is influenced by sex, menstrual cycle, and sex steroid hormones

Recent observations indicate that sex and level of steroid hormones may influence cortical networks associated with specific cognitive functions, in particular visuo-spatial abilities. The present study probed the influence of sex, menstrual cycle, and sex steroid hormones on 3D mental rotation and brain function using 3-T fMRI. Twelve healthy women and 12 men were investigated. Menstrual cycle and hormone levels were assessed. The early follicular and midluteal phase of the menstrual cycle were chosen to examine short-term cyclical changes. Parietal and frontal areas were activated during mental rotation in both sexes. Significant differences between men and women were revealed in both phases of menstrual cycle. In men we observed a significant correlation of activation levels with testosterone levels in the left parietal lobe (BA 40). In women, a cycle-dependent correlation pattern was observed for testosterone: brain activation correlated with this male hormone only during the early follicular phase. In both cycle phases females' brain activation was significantly correlated with estradiol in frontal and parietal areas. Our study provides evidence that fMRI-related activity during performance of cognitive tasks varies across sex and phases of the menstrual cycle. The variation might be partly explained by better task performance in men, but our results indicate that further explanations like basic neuronal or neurovascular effects modulated by steroid hormones must be considered. Both estradiol and testosterone levels may influence fMRI signals of cognitive tasks, which should affect selection of subjects for future fMRI studies.

A common single nucleotide polymorphism in exon 10 of the human follicle stimulating hormone receptor is a major determinant of length and hormonal dynamics of the menstrual cycle

CONTEXT

FSH is essential for follicular maturation. Data from ovarian hyperstimulation cycles suggest that FSH action is attenuated by a frequent single nucleotide polymorphism of the FSH receptor gene exchanging Asn for Ser at codon 680.

OBJECTIVE

We hypothesized that the FSH receptor genotype influences menstrual cycle dynamics.

DESIGN

Menstrual cycle was monitored from the midluteal phase through ovulation until the consecutive menstruation.

SETTING

The study was conducted at the University research center.

SUBJECTS

Women homozygous for the Asn680 (n = 12) and Ser680 (n = 9) variants with normal menstrual cycles volunteered for the study.

INTERVENTIONS

There were no interventions.

MAIN OUTCOME MEASUREMENTS

Follicular growth, serum LH, FSH, estradiol, progesterone, inhibin A, inhibin B and antimullerian hormone were measured.

RESULTS

During the luteo-follicular transition, serum levels of estradiol, progesterone, and inhibin A were significantly lower, and FSH started to rise earlier in the Ser680/Ser680 group. FSH levels were steadily and significantly higher, and the mean area under the FSH curve was 31% greater in this group (P < 0.002). No differences were observed in estradiol, inhibin B, and growth velocities of dominant follicles. The time from luteolysis to ovulation was significantly longer in women with the Ser680/Ser680 (13.6 +/- 1.01 d) compared with Asn680/Asn680 (11.3 +/- 0.61 d, P < 0.05) genotype with a significant difference in total menstrual cycle length (29.3 vs. 27.0 d, respectively; P < 0.05).

CONCLUSIONS

The FSH receptor Ser680/Ser680 genotype is associated with higher ovarian threshold to FSH, decreased negative feedback of luteal secretion to the pituitary during the intercycle transition, and longer menstrual cycles.

Enhanced oestradiol secretion briefly after embryo transfer in conception cycles from IVF

The hypothesis was tested that conception cycles (CC) resulting from IVF can be distinguished from non-conception cycles (NC) by differences in corpora lutea function that are detectable at the earliest stage of embryo implantation. Luteal oestradiol secretion was analysed retrospectively in 409 ovarian stimulation cycles of 296 patients from the day of embryo transfer until 14 days after embryo transfer (ET+14) in IVF/intracytoplasmic sperm injection (ICSI) cycles. Human chorionic gonadotrophin (HCG) was administered in 330 of 409 cycles in addition to vaginal progesterone in all cycles. Differences in serum oestradiol concentrations between CC and NC increased from day ET+1 onward and became statistically significant on days ET+4 through ET+14, with higher oestradiol concentrations in CC compared with NC. Even though exogenous HCG administration prevented the fall in luteal oestradiol concentrations after ET+4 both in CC and NC, increasing differences in oestradiol concentrations between CC and NC after embryo transfer were observed in both groups of HCG-supplemented and non-supplemented cycles. It is concluded that luteal oestradiol secretion is affected at the earliest stage of embryo implantation. The putative early signal to the corpus luteum associated with embryo attachment and early implantation appears to be superimposed onto the effect of exogenous luteal HCG administration and is clearly distinguishable as early as 4 days after embryo transfer in conception cycles.

Localization in tissues and secretion of eotaxin by cells from normal endometrium and endometriosis

Our laboratories have focused recently on the production and localization of eotaxin, a C-C-chemokine of 8.4 kDa, whose major biological activity is the chemoattraction of eosinophils. Given evidence of autoimmune activity in the endometriosis syndrome, we hypothesized that eosinophil chemoattractants might be expressed in endometriosis. In histological sections, we observed eotaxin protein localized mainly in epithelial cells, with only very faint immunostaining in the surrounding stromal cells. Prominent eotaxin accumulation was noted in the luminal epithelium of secretory endometrium. Eotaxin distribution in endometriosis was similar to that seen in eutopic endometrium but with higher levels of eotaxin staining in the glandular epithelium. Peritoneal fluid concentrations of eotaxin were significantly higher in women with moderate or severe endometriosis than in women with minimal or mild endometriosis or no disease. The treatment of isolated human endometriosis epithelial cells with estradiol, medroxyprogesterone acetate, tumor necrosis factor-alpha, and interferon-gamma stimulated measurable eotaxin secretion into the conditioned media. The results indicate that eotaxin is produced in epithelial cells of normal endometrium and endometriosis tissues, varies across the menstrual cycle, and is elevated in women with endometriosis. We postulate that eotaxin, interacting with other known cytokines and immune cells, contributes to an inflammatory reproductive tract environment, leading to endometrial or blastocyst dysfunction.

Vascular endothelial growth factor A (VEGF-A) mRNA expression levels decrease after menopause in normal breast tissue but not in breast cancer lesions

We hypothesized that the regulation of microvascular functions and angiogenesis in breast tissue, a well known target of ovarian steroid action, is dependent on the hormonal exposure of the breast. Relative expression levels of VEGF-A (vascular endothelial growth factor A), a putative key regulator of angiogenesis in breast cancer, were analysed in the tumour and the adjacent non-neoplastic breast tissue of 19 breast cancer patients by quantitative reverse transcriptase polymerase chain reaction. In non-neoplastic breast specimens the expression levels of all detected VEGF-A-isoforms (189, 165, 121) were significantly higher in premenopausal compared to post-menopausal women (P = 0.02) and were inversely correlated with the patient's age (P = 0.006). In contrast, in cancerous tissues menopausal status had no influence on VEGF-A-expression levels. Benign and malignant tissues exhibited a similar expression pattern of VEGF-A-isoforms relative to each other. Thus, the regulation of the vasculature in normal breast tissue, as opposed to breast cancer tissue, appears to be hormonally dependent. Endogenous and therapeutically used hormonal steroids might, therefore, cause clinically relevant changes of the angiogenic phenotype of the human breast.

Disparate actions of mifepristone (RU 486) on glands and stroma in the primate endometrium

Besides being an antiprogestin, mifepristone (RU 486) was recently shown to antagonize oestrogen-dependent growth in the endometrium. To explore the molecular mechanisms for this phenomenon, we investigated whether or not the morphological effects of mifepristone are mediated by the progesterone receptor (PR) and whether mifepristone has disparate effects on the glandular epithelium and stroma. Six groups of hypogonadal, oestrogen-primed cynomolgus monkeys were treated for 2 weeks with: vehicle only (group I); mifepristone (group II); mifepristone plus progesterone at 0.2 mg/kg (group III), 1.0 mg/kg (group IV) or 5.0 mg/kg (group V); and progesterone only (5.0 mg/kg) (group VI). Histomorphological evaluation showed strikingly compacted stroma in the mifepristone-exposed endometria (group II), which was partially reversible by additional progesterone treatment (groups III-V). Glandular proliferation (pseudostratification, glandular mitoses) in mifepristone-treated monkeys was not significantly different from that in vehicle (oestradiol)-treated monkeys, but was inhibited by progesterone-only treatment. Cells containing vacuoles were scarce in the mifepristone-exposed endometrium, but detected frequently in progesterone-exposed endometria, indicating the strong antisecretory effect of mifepristone on glands. We conclude that oestrogen-dependent oedema in the stroma is antagonized by mifepristone. The reversal of this effect by progesterone suggests a PR-mediated mechanism. In glands, mifepristone is antiprogestogenic, but not antioestrogenic. Thus, stromal cells may be the target of antiprogestin-induced inhibition of oedema and endometrial growth.

Vascular endothelial growth factor in primate endometrium is regulated by oestrogen-receptor and progesterone-receptor ligands in vivo

We investigated hormonal regulation of endometrial angiogenesis in menstruating primates. This study was designed to demonstrate: (i) that cell-specific vascular endothelial growth factor (VEGF) production and expression in monkey endometrium are regulated by steroid receptor ligands; and (ii) mifepristone (RU 486) alters VEGF production even in the absence of a progestin agonist. Endometrial VEGF production was compared by computer-assisted immunohistochemical analysis during induced hypoestrogenism and after oestradiol, progestin, or antiprogestin (mifepristone) treatment. VEGF gene expression was estimated by quantitative reverse-transcriptase polymerase chain reaction (RT-PCR) in endometrial samples from castrate cynomolgus monkeys, from intact monkeys in the luteal phase, and from monkeys treated for 20 days with levonorgestrel (LNG) or mifepristone. VEGF staining intensities in glandular epithelium and VEGF mRNA expression were highest in hypoestrogenic monkeys. Progestin treatment induced intense VEGF staining in the stroma. Gene expression of VEGF-189, but not other isoforms, was higher in progesterone- and progestin (LNG)-exposed endometria compared to mifepristone-exposed endometria or endometria from anovulatory cycles (P < 0.04). Mifepristone abolished VEGF staining in glandular epithelium almost completely. We conclude that VEGF protein and VEGF mRNA expression levels in primate endometrium depend on the steroidal milieu. Anti-angiogenic effects of mifepristone via suppression of VEGF production might represent a mechanism for its quelling effects on endometrium.