Small extracellular vesicles in follicular fluids for predicting reproductive outcomes in assisted reproductive technology.

BACKGROUND: Assisted reproductive technology accounts for an increasing proportion of infertility treatments, and assessments to predict clinical pregnancy outcomes are desired. Extracellular vesicles exist in follicular fluid, and small non coding RNAs in extracellular vesicles underline the possibility of reflecting pregnancy potential. METHODS: Follicular fluid samples are collected from 20 ovarian follicles of 15 infertile patients undergoing assisted reproductive technology. Extracellular vesicles are isolated by serial centrifugation and small RNA sequencing is performed to investigate the profiles of microRNAs and P-element-induced wimpy testis-interacting RNAs. RESULTS: Small extracellular vesicles with a size range of approximately 100 nm are successfully isolated, and the small non coding RNA profiles of pregnant samples (n = 8) are different from those of non-pregnant samples (n = 12). Fourteen dysregulated small non coding RNAs are selected to identify the independent candidates [mean read count >100, area under the curve >0.8]. Among them, we find that a specific combination of small non coding RNAs (miR-16-2-3p, miR-378a-3p, and miR-483-5p) can predict the pregnant samples more precisely using a receiver operating characteristics curves analysis (area under the curve: 0.96). Furthermore, even in the same patients, the three microRNAs are differentially expressed between pregnant and non-pregnant samples. CONCLUSIONS: Our results demonstrate that small non coding RNAs derived from small extracellular vesicles in follicular fluid can be potential non-invasive biomarkers for predicting pregnancy, leading to their probable application in assisted reproductive technology. Further large-scale studies are required to validate the clinical usefulness of these small non coding RNAs.

Assisted reproductive technologies (ART) are medical procedures used to address infertility. Follicular fluid (FF)is a liquid that surrounds the immature egg cells (oocytes) and provides hormones and nutrients necessary for their maturation and eventual development into embryos. We analyzed genetic components within the FF as a potential predictor of reproductive outcomes following ART. Here, we show that a specific combination of genetic elements produced by the FF in successful pregnancies did not occur in unsuccessful pregnancies. Our findings may help to provide a non-invasive approach to determining reproductive outcomes during ART procedures.

Serum miRNA as a predictive biomarker for ovarian reserve after endometrioma-cystectomy.

Ovarian endometrioma (OE) is a common gynecological disease that is often treated with surgery and hormonal treatment. However, ovarian cystectomy can impair the ovarian reserve (OR). Previously, we showed that perioperative administration of dienogest (DNG) is an effective option for OR preservation. However, there were differences in the extent of OR preservation among patients following perioperative DNG treatment. In the current study, we performed a global examination of serum microRNAs (miRNAs) to identify accurate biomarkers that predict post-operative restoration of OR following perioperative DNG treatment. We also sought to identify specific miRNAs related to the anti-Müllerian hormone (AMH). miRNA sequencing was performed on serum samples obtained from twenty-seven patients who received perioperative DNG treatment. Candidate miRNAs were selected by comparing patients whose ORs were restored postoperatively (responder group, n = 7) with those whose ORs were not (non-responder group, n = 7). miR-370-3p and miR-1307-3p were significantly upregulated in the responder group, whereas miR-27b-3p was upregulated in the non-responder group. The pretreatment value of each miRNA could predict DNG responsiveness for OR following ovarian cystectomy (area under the curve [AUC] > 0.8). The quantitative polymerase chain reaction (qPCR) revealed only miR-1307-3p was found to be significantly upregulated in the responder group (P < 0.05). In addition, we identified miR-139-3p, miR-140-3p, and miR-629-5p as AMH-associated miRNAs. The transition of AMH showed a correlation with miR-139-3p (P < 0.05, r = -0.76). The miRNAs identified herein represent potential serum biomarkers of clinical value in predicting OR prior to DNG treatment.

Unkeito promotes follicle development by restoring reduced follicle-stimulating hormone responsiveness in rats with polycystic ovary syndrome.

Background: Polycystic ovary syndrome (PCOS) is a common disorder resulting in irregular menstruation and infertility due to improper follicular development and ovulation. PCOS pathogenesis is mediated by downregulated follicle-stimulating hormone receptor (FSHR) expression in granulosa cells (GCs); however, the underlying mechanism remains elusive. Unkeito (UKT) is a traditional Japanese medicine used to treat irregular menstruation in patients with PCOS. In this study, we aimed to confirm the effectiveness of UKT in PCOS by focusing on follicle-stimulating hormone (FSH) responsiveness. Methods: A rat model of PCOS was generated by prenatal treatment with 5α-dihydrotestosterone. Female offspring (3-week-old) rats were fed a UKT mixed diet or a normal diet daily. To compare the PCOS phenotype in rats, the estrous cycle, hormone profiles, and ovarian morphology were evaluated. To further examine the role of FSH, molecular, genetic, and immunohistological analyses were performed using ovarian tissues and primary cultured GCs from normal and PCOS model rats. Results: UKT increased the number of antral and preovulatory follicles and restored the irregular estrous cycle in PCOS rats. The gene expression levels of FSHR and bone morphogenetic protein (BMP)-2 and BMP-6 were significantly decreased in the ovarian GCs of PCOS rats compared to those in normal rats. UKT treatment increased FSHR staining in the small antral follicles and upregulated Fshr and Bmps expression in the ovary and GCs of PCOS rats. There was no change in serum gonadotropin levels. In primary cultured GCs stimulated by FSH, UKT enhanced estradiol production, accompanied by increased intracellular cyclic adenosine monophosphate levels, and upregulated the expression of genes encoding the enzymes involved in local estradiol synthesis, namely Cyp19a1 and Hsd17b. Furthermore, UKT elevated the expression of Star and Cyp11a1, involved in progesterone production in cultured GCs in the presence of FSH. Conclusions: UKT stimulates ovarian follicle development by potentiating FSH responsiveness by upregulating BMP-2 and BMP-6 expression, resulting in the recovery of estrous cycle abnormalities in PCOS rats. Restoring the FSHR dysfunction in the small antral follicles may alleviate the PCOS phenotype.

Upregulated Ribosomal Pathway Impairs Follicle Development in a Polycystic Ovary Syndrome Mouse Model: Differential Gene Expression Analysis of Oocytes.

Polycystic ovary syndrome (PCOS), a common endocrine disorder, is associated with impaired oocyte development, leading to infertility. However, the pathogenesis of PCOS has not been completely elucidated. This study aimed to determine the differentially expressed genes (DEGs) and epigenetic changes in the oocytes from a PCOS mouse model to identify the etiological factors. RNA-sequencing analysis revealed that 90 DEGs were upregulated and 27 DEGs were downregulated in mice with PCOS compared with control mice. DNA methylation analysis revealed 30 hypomethylated and 10 hypermethylated regions in the PCOS group. However, the DNA methylation status did not correlate with differential gene expression. The pathway enrichment analysis revealed that five DEGs (Rps21, Rpl36, Rpl36a, Rpl37a, and Rpl22l1) were enriched in ribosome-related pathways in the oocytes of mice with PCOS, and the immunohistochemical analysis revealed significantly upregulated expression levels of Rps21 and Rpl36. These results suggest that differential gene expression in the oocytes of mice in PCOS is related to impaired folliculogenesis. These findings improve our understanding of PCOS pathogenesis.

Predictive factors for massive hemorrhage in women with retained products of conception: a prospective study.

Retained products of conception (RPOC) is a common cause of postpartum bleeding, which may be life-threatening; however, no evidence-based guidelines exist to assist in evaluating the risk of massive hemorrhage in women with RPOC. In this prospective study, we aimed to evaluate the predictive factors for massive hemorrhage in women with RPOC. The primary and secondary endpoints were to validate the usefulness of power Doppler color scoring (PDCS) in evaluating hypervascularity and to identify other predictive factors (such as maximum RPOC diameter and serum ßhCG and Hb level at first visit), respectively. Among the 51 women with RPOC included in this study, 16 (31.5%) experienced massive hemorrhage during follow-up. None of the women with PDCS 1 or 2 (18) experienced massive hemorrhage, whereas 16 (48.5%) women with PDCS 3 or 4 (33) did. Multiple logistic regression analysis showed that the odds ratio [95% confidence interval] (P value) for PDCS, assisted reproductive technology (ART), and low serum hemoglobin (Hb) levels were 22.39 [2.25 - 3087.92] (P = 0.004), 5.72 [1.28 - 33.29] (P = 0.022), and 4.24 [0.97 - 22.99] (P = 0.056), respectively. Further, the decision tree method identified PDCS, ART, and low serum Hb levels as potential predictive factors for massive hemorrhage. This study identified PDCS as useful predictor of massive hemorrhage in women with RPOC. With additional inclusion of factors such as ART and low serum Hb levels, the risk of massive hemorrhage may be effectively evaluated, leading to better management of women of reproductive age.

Effectiveness of NLRP3 Inhibitor as a Non-Hormonal Treatment for ovarian endometriosis.

BACKGROUND: Endometriosis is a complex syndrome characterized by an estrogen-dependent chronic inflammatory process that affects 10% of women of reproductive age. Ovarian endometriosis (OE) is the most common lesion in endometriosis and may cause infertility, in addition to dysmenorrhea. Hormonal treatments, which are the conventional treatment methods for endometriosis, suppress ovulation and hence are not compatible with fertility. The inflammasome is a complex that includes Nod-like receptor (NLR) family proteins, which sense pathogen-associated molecular patterns and homeostasis-altering molecular processes. It has been reported that the nucleotide-binding oligomerization domain, leucine-rich repeat, and pyrin domain-containing (NLRP) 3 inflammasome, which contributes to the activation of interleukin-1 beta (IL-1ß), might be related to the progression of endometriosis. Therefore, the aim of the present study was to evaluate non-hormonal therapies for OE, such as inhibitors of the NLRP3 inflammasome. METHODS: The expression of NLRP3 was measured in the eutopic endometrium (EM) of patients with and without endometriosis and OE samples, as well as stromal cells derived from the endometrium of patients with and without endometriosis and OE samples (endometrial stromal cells with endometriosis [ESCs] and cyst-derived stromal cells [CSCs]). The effects of an NLRP3 inhibitor (MCC950) on ESCs and CSCs survival and IL-1ß production were evaluated. We then administered MCC950 to a murine model of OE to evaluate its effects on OE lesions and ovarian function. RESULTS: NLRP3 gene and protein expression levels were higher in OE and CSCs than in EM and ESCs, respectively. MCC950 treatment significantly reduced the survival of CSCs, but not that of ESCs. Moreover, MCC950 treatment reduced the co-localization of NLRP3 and IL-1ß in CSCs, as well as IL-1ß concentrations in CSCs supernatants. In the murine model, MCC950 treatment reduced OE lesion size compared to phosphate-buffered saline treatment (89 ± 15 vs. 49 ± 9.3 mm3 per ovary; P < 0.05). In the MCC950-treated group, IL-1ß and Ki67 levels in the OE-associated epithelia were reduced along with the oxidative stress markers of granulosa cells. CONCLUSIONS: These results indicated that NLRP3/IL-1ß is involved in the pathogenesis of endometriosis and that NLRP3 inhibitors may be useful for suppressing OE and improving the function of ovaries with endometriosis.

Tamoxifen Activates Dormant Primordial Follicles in Mouse Ovaries.

Our previous study found that 17ß-estradiol (E2) suppresses primordial follicle activation and growth in cultured mouse ovaries. In this study, we administered tamoxifen, an estrogen receptor antagonist, into the abdominal cavity of mice to clarify the relationship between primordial follicle activation and the physiological concentration of E2 in mouse ovaries. The results showed that tamoxifen promoted primordial follicle activation. Administration of tamoxifen promoted degradation of the extracellular matrix surrounding primordial follicles in the ovaries. Furthermore, tamoxifen decreased the expression of stefin A, an inhibitor of cathepsins that digest some proteins and extracellular matrix, in the ovaries. Mechanical stress produced by the extracellular matrix reportedly suppresses the activation of primordial follicles. The collective results show that tamoxifen can promote primordial follicle activation through the degradation of the extracellular matrix surrounding primordial follicles. Our results indicate that E2 suppresses primordial follicle activation in vivo and that tamoxifen may be useful as a therapeutic agent against infertility.

Functional Lactotrophs in Induced Adenohypophysis Differentiated From Human iPS Cells.

Prolactin (PRL), a hormone involved in lactation, is mainly produced and secreted by the lactotrophs of the anterior pituitary (AP) gland. We previously reported a method to generate functional adrenocorticotropic hormone-producing cells by differentiating the AP and hypothalamus simultaneously from human induced pluripotent stem cells (iPSCs). However, PRL-producing cells in the induced AP have not been investigated. Here, we confirmed the presence of PRL-producing cells and evaluated their endocrine functions. We differentiated pituitary cells from human iPSCs using serum-free floating culture of embryoid-like aggregates with quick reaggregation (SFEB-q) method and evaluated the appearance and function of PRL-producing cells. Secretion of PRL from the differentiated aggregates was confirmed, which increased with further culture. Fluorescence immunostaining and immunoelectron microscopy revealed PRL-producing cells and PRL-positive secretory granules, respectively. PRL secretion was promoted by various prolactin secretagogues such as thyrotropin-releasing hormone, vasoactive intestinal peptide, and prolactin-releasing peptide, and inhibited by bromocriptine. Moreover, the presence of tyrosine hydroxylase-positive dopaminergic nerves in the hypothalamic tissue area around the center of the aggregates connecting to PRL-producing cells indicated the possibility of recapitulating PRL regulatory mechanisms through the hypothalamus. In conclusion, we generated pituitary lactotrophs from human iPSCs; these displayed similar secretory responsiveness as human pituitary cells in vivo. In the future, this is expected to be used as a model of human PRL-producing cells for various studies, such as drug discovery, prediction of side effects, and elucidation of tumorigenic mechanisms using disease-specific iPSCs. Furthermore, it may help to develop regenerative medicine for the pituitary gland.

Impact of perioperative use of GnRH agonist or dienogest on ovarian reserve after cystectomy for endometriomas: a randomized controlled trial.

BACKGROUND: Ovarian endometrioma is a common gynecological disease that is often treated with surgery or hormonal treatment. Ovarian cystectomy, a surgical procedure for ovarian endometrioma, can result in impaired ovarian reserve. METHODS: We conducted a randomized controlled trial to evaluate the efficacy of hormonal treatment [gonadotropin-releasing hormone agonist (GnRHa) or dienogest (DNG)] for preserving ovarian reserve after cystectomy for ovarian endometrioma. The primary endpoint was the level of serum Anti-Müllerian hormone (AMH) as a marker of ovarian reserve. RESULTS: Before and after laparoscopic surgery, 22 patients in the GnRHa group and 27 patients in the DNG group were administered hormonal treatment for a total of 4 months. After 1-year follow-up, >60% of the patients in the DNG group retained over 70% of their pretreatment AMH levels, whereas no patient in the GnRHa group retained their AMH levels after cystectomy (P < 0.01). Interleukin-6 (IL-6) is a key cytokine involved in inflammation. Compared with the GnRHa group, patients in the DNG group had lower IL-6 levels at the end of treatment. CONCLUSIONS: Our data revealed that DNG is more effective than GnRHa in preserving ovarian reserve after cystectomy of ovarian endometrioma. This is achieved through the reduction of the inflammatory response during the perioperative period and other endometriosis-related inflammatory reactions. TRIAL REGISTRATION: The registration number of this trial is UMIN-CTR, UMIN000018569, registered 6 August 2015, https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000021492 , and Japan Registry of Clinical Trials, jRCTs041180140, registered 29 March 2019, https://jrct.niph.go.jp/en-latest-detail/jRCTs041180140 . This randomized controlled trial was conducted in accordance with the CONSORT guidelines.

Primate-specific POTE-actin gene could play a role in human folliculogenesis by controlling the proliferation of granulosa cells.

Patients with primary ovarian insufficiency (POI) often have a high prevalence of autoimmune disorders. To identify antigenic molecules associated with ovarian autoimmunity, we performed immunoprecipitation (IP) screening using serum from patients with POI and the established human granulosa cell line (HGrC1). POTE ankyrin domain family member E (POTEE) and POTE ankyrin domain family member F (POTEF), proteins specific to primates, were identified as candidate antigens. Using immunohistochemistry (IHC) with human ovarian tissue, POTEE or POTEF was weakly seen in the granulosa cells (GCs) of primordial follicles and primary follicles, and strongly in large antral follicles and luteal cells. Interestingly, no signals were detected in growing GCs in secondary, preantral, and small antral follicles. Thus, to explore the function of POTEE and POTEF in human folliculogenesis, we established HGrC1 cell lines with drug-inducible expression of POTEF. Expression of POTEF significantly suppressed cell proliferation in HGrC1 cells. Furthermore, chaperonin containing TCP-1 complex (CCT) components, which affect folding proteins required for cell proliferation, was bound to the actin domain of POTEF protein. Although CCT is normally localized only around the Golgi apparatus, TCP-1α, a component of CCT, co-migrated closer to the cell membrane when POTEF expression was induced. These data suggest that the interaction between POTEF and CCT components impairs the usual function of CCT during cell growth. In addition, over-accumulation of POTEF in HGrC1 cells leads to autophagic failure. It was recently reported that knockout of an autophagic gene in mice leads to a phenotype similar to human POI. These results suggested that a proper amount of POTEF is required for the maintenance of GCs in follicle pools, whereas POTEF overaccumulation might be involved in follicle atresia and the development of POI. We also showed the possibility that POTEF could be an antigen involved in ovarian autoimmunity.

Very Low Levels of Serum Anti-Müllerian Hormone as a Possible Marker for Follicle Growth in Patients with Primary Ovarian Insufficiency Under Hormone Replacement Therapy.

Patients with primary ovarian insufficiency (POI) occasionally present with follicle growth; however, accurately predicting cycles accompanied by follicle growth is challenging. Early-stage follicles produce serum anti-Müllerian hormone (AMH), a useful marker of ovarian reserve. Therefore, serum AMH levels indicate growth of small follicles (which are difficult to detect ultrasonographically) and may predict follicle growth in patients with POI. Using an ultrasensitive enzyme-linked immunosorbent assay (ELISA) kit, we observed very low serum AMH levels in patients with POI. We further evaluated follicle growth in each patient during each cycle to determine the usefulness of measuring serum AMH levels as a predictor of follicle growth in patients with POI who receive hormone replacement therapy (HRT). We investigated 19 patients with POI in whom we analyzed 91 cycles; 14 cycles showed positive and 77 cycles showed negative results on serum AMH testing. The rate of cycles showing follicle growth in AMH-positive cycles was higher than that in AMH-negative cycles (64.3% vs. 6.5%, p = 0.0001). The median serum AMH level (7.7 pg/mL [25th and 75th percentiles 4.6 pg/mL and 22.3 pg/mL, respectively]) in AMH-positive cycles was lower than the lower limit of detection of conventional AMH ELISA kits. The positive predictive value of positive serum AMH levels for follicle growth was higher than that of follicle-stimulating hormone (< 10 mIU/mL). These results indicate that a very low level of serum AMH detected using picoAMH assays is a useful predictor of follicle growth in patients with POI receiving HRT.

Involvement of Transcription Factor 21 in the Pathogenesis of Fibrosis in Endometriosis.

Repeated tissue injury and repair and fibrosis play a pivotal role in endometriosis. Fibrotic tissue consists of extracellular matrix proteins, regulated by transcriptional factors promoting cell proliferation and survival. Periostin is one of the putative key extracellular matrix proteins. This study aimed to determine whether transcription factor 21 (TCF21) is involved in the development of endometriosis as an upstream regulatory gene of periostin. Formalin-fixed, paraffin-embedded tissue samples [normal endometrium of women without endometriosis; eutopic endometrium of women with endometriosis; ovarian endometriosis (OE); and deep infiltrating endometriosis (DIE)] and respective cells were analyzed. Basal, transiently stimulated, and knocked down periostin and TCF21 concentrations in stromal cells of women with or without endometriosis were examined. Periostin and TCF21 expressions were undetected in normal endometrium of women without endometriosis, weakly positive in eutopic endometrium of women with endometriosis, moderately positive in OE, and strongly positive in DIE. Type 2 helper T-cell cytokines (IL-4, IL-13, and transforming growth factor-ß1) increased the mRNA expression of periostin and TCF21. These cytokines, periostin, and TCF21 colocalized in the stroma of OE and DIE. siRNA against human TCF21 gene suppressed periostin expression. Transfection of TCF21 plasmid vector into stromal cells of women without endometriosis, which originally expressed neither periostin nor TCF21, resulted in TCF21 and periostin expression. TCF21 and periostin are involved in the regulation of fibrosis in endometriosis. TCF21 may be a promising therapeutic target and biomarker in endometriosis.

Molecular mechanism of FSHR expression induced by BMP15 in human granulosa cells.

PURPOSE: Follicle-stimulating hormone receptor (FSHR) expression in granulosa cells is critical in enabling follicles to achieve accelerated growth. Although FSHR expression has been reported to be epigenetically regulated, the mechanism is unclear. Cooperation between oocytes and granulosa cells is also essential for normal follicular growth. Among oocyte-derived factors, bone morphogenetic protein 15 (BMP15) promotes follicular growth and is suggested to have epigenetic effects. We examined the role of BMP15 in the acquirement of FSHR in human granulosa cells. METHODS: Immortalized non-luteinized human granulosa (HGrC1) cells were stimulated with trichostatin A (TSA) or BMP15 to analyze FSHR expression, histone modifications, and USF1/2 binding at the FSHR promoter region. Histone acetyl transferase (HAT) activity and phosphorylation of Smad 1/5/8 and p38 MAPK were examined with or without BMP15, SB203580, and LDN193189. CYP19A1 expression and estradiol production were also studied. RESULTS: TSA and BMP15 induced FSHR mRNA expression in a dose-dependent manner and histone modifications were observed with increased binding of USF1/2. BMP15 increased FSHR protein expression, which was suppressed by LDN193189. BMP15 increased phosphorylation of Smad 1/5/8 and significantly increased HAT activity, which was inhibited by LDN193189, but not by SB203580. BMP15 increased phosphorylation of p38 MAPK and USF1. LDN193189 suppressed BMP15-induced phosphorylation of both p38 MAPK and USF1, whereas SB203580 suppressed the phosphorylation of USF1. BMP15 increased CYP19A1 mRNA expression and estradiol production. CONCLUSION: BMP15 induced FSHR expression in human granulosa cells through Smad and non-Smad pathways. This mechanism of FSHR induction by BMP15 may be utilized for controlling follicular growth.

Effect of the neuropeptide phoenixin and its receptor GPR173 during folliculogenesis.

Folliculogenesis is a complex process, defined by the growth and development of follicles from the primordial population. Granulosa cells (GCs) play a vital role in every stage of follicular growth through proliferation, acquisition of gonadotropic responsiveness, steroidogenesis and production of autocrine/paracrine factors. A recently discovered hypothalamic neuropeptide phoenixin is involved in the regulation of the reproductive system. Phoenixin acts through its receptor, G protein-coupled receptor 173 (GPR173), to activate the cAMP/PKA pathway leading to the phosphorylation of CREB (pCREB). Here, we demonstrated the expression patterns of phoenixin and GPR173 in human ovary and explored its role in folliculogenesis. Phoenixin and GPR173 were both expressed in the human ovarian follicle, with increased expression in GCs as the follicle grows. Phoenixin treatment at 100 nM for 24 h induced the proliferation of human non-luteinized granulosa cell line, HGrC1 and significantly increased the expression levels of CYP19A1, FSHR, LHR and KITL, but decreased NPPC expression levels. These effects were suppressed by GPR173 siRNA. The expression level of CREB1, pCREB and estradiol (E2) production in the culture medium was significantly enhanced by phoenixin treatment in a concentration-dependent manner. Phoenixin also significantly increased the follicular area in a murine ovarian tissue culture model, leading to an increased number of ovulated oocytes with a higher level of maturation. Taken together, our data demonstrate that phoenixin is an intraovarian factor that promotes follicular growth through its receptor GPR173 by accelerating proliferation of GCs, inducing E2 production and increasing the expression of genes related to follicle development.

Animal models of polycystic ovary syndrome: A review of hormone-induced rodent models focused on hypothalamus-pituitary-ovary axis and neuropeptides.

BACKGROUND: Polycystic ovary syndrome (PCOS) is a common endocrine disorder among women of reproductive age and a major cause of infertility; however, the pathophysiology of this syndrome is not fully understood. This can be addressed using appropriate animal models of PCOS. In this review, we describe rodent models of hormone-induced PCOS that focus on the perturbation of the hypothalamic-pituitary-ovary (HPO) axis and abnormalities in neuropeptide levels. METHODS: Comparison of rodent models of hormone-induced PCOS. MAIN FINDINGS: The main method used to generate rodent models of PCOS was subcutaneous injection or implantation of androgens, estrogens, antiprogestin, or aromatase inhibitor. Androgens were administered to animals pre- or postnatally. Alterations in the levels of kisspeptin and related molecules have been reported in these models. CONCLUSION: The most appropriate model for the research objective and hypothesis should be established. Dysregulation of the HPO axis followed by elevated serum luteinizing hormone levels, hyperandrogenism, and metabolic disturbance contribute to the complex etiology of PCOS. These phenotypes of the human disease are recapitulated in hormone-induced PCOS models. Thus, evidence from animal models can help to clarify the pathophysiology of PCOS.