a-hyperandrogenic-mouse-model-to-study-polycystic-ovary-syndrome

A Hyperandrogenic Mouse Model to Study Polycystic Ovary Syndrome

Hyperandrogenemia plays a critical role in reproductive and metabolic function in females and is the hallmark of polycystic ovary syndrome. Developing a ...

Johns Hopkins University School of Medicine

Previous findings are inconsistent; yet, converging evidence suggests an association between schizophrenia (SZ) and the impairment of posttranscriptional regulation of brain development through microRNA (miRNA) systems.

Converging evidence implicates the abnormal microRNA system in schizophrenia.

Androgen and its receptor (AR) play a critical role in reproductive function under both physiological and pathophysiological conditions. Female AR global knockout mice are subfertile due to both neuroendocrine and ovarian defects. Female offspring from prenatally androgenized heterozygous AR pregnant mice showed rescued estrous cyclicity and fertility. Ar is expressed in granulosa cells, theca interstitial cells, and oocytes in the ovary. We created mice with theca-specific deletion of Ar (ThARKO) by crossing Cyp17-iCre mice that express Cre recombinase under cytochrome P450 17A1 (Cyp17) promoter with Arfl/fl mice. ThARKO mice exhibited no significant differences in pubertal onset or fertility compared with control littermates, and neither estrogen or testosterone levels were different between these groups. Therefore, Ar expression in theca cells likely does not influence fertility nor androgen levels in female mice. We then tested the role of AR in theca cells under hyperandrogenemic condition. After treatment with a pathophysiological level of dihydrotestosterone (DHT), control mice (control-DHT) showed acyclicity and infertility. However, estrous cycles and fertility were altered to a significantly less degree in ThARKO-DHT mice than in control-DHT mice. Messenger RNA (mRNA) levels of Lhcgr (luteinizing hormone receptor) and Timp1 (tissue inhibitor of metalloproteinase 1, and inhibitor of matrix metalloproteinase) were significantly lower in control-DHT ovary compared with control-no DHT ovaries, whereas mRNA levels of Fshr (follicle-stimulating hormone receptor) were significantly higher. Timp1 gene expression was comparable in the ThARKO-DHT and the control-no DHT ovary. We speculate that the preserved level of Timp1 in ThARKO-DHT mice contributes to retained reproductive function.

Androgen Receptor in the Ovary Theca Cells Plays a Critical Role in Androgen-Induced Reproductive Dysfunction.

Female offspring of many species exposed to high doses of androgens in utero experience endocrine dysfunction during adulthood. The phenotype of offspring from females with prepregnancy hyperandrogenemia and impaired ovulation, however, has not been examined. We developed a mouse model of hyperandrogenemia by implanting a low-dose dihydrotestosterone (DHT) pellet 15 days before conception. Female offspring born to dams with hyperandrogenemia (DHT daughters) had delayed puberty (P < 0.05) with first estrus on postnatal day (PND) 41 compared with daughters from dams with physiological levels of DHT (non-DHT daughters, PND37.5). Serum follicle-stimulating hormone (FSH) levels in the DHT daughters were fourfold higher (P < 0.05) on PND21, and anti-Müllerian hormone levels were higher (P < 0.05) on PND26 than in non-DHT daughters (controls). DHT daughters showed an extended time in metestrus/diestrus and a shorter time in the proestrus/estrus phase compared with non-DHT daughters (P < 0.05). To examine ovarian response to gonadotropins, superovulation was induced and in vitro fertilization (IVF) was performed. Fewer numbers of oocytes were retrieved from the DHT daughters compared with non-DHT daughters (P < 0.05). At IVF, there was no difference in rates of fertilization or cleavage of oocytes from either group. There were fewer (P < 0.01) primordial follicles (6.5 ± 0.8 vs 14.5 ± 2.1 per ovary) in the ovaries of DHT daughters compared with non-DHT daughters. Daughters from hyperandrogenemic females exhibited elevated prepubertal FSH levels, diminished ovarian response to superovulation, impaired estrous cyclicity, delayed onset of puberty, and reduced ovarian reserve, suggesting that fetal androgen exposure had lasting effects on female reproductive function.

Zhiqiang Wang

Department of Pediatrics

Johns Hopkins University School of Medicine

A Hyperandrogenic Mouse Model to Study Polycystic Ovary Syndrome

Zhiqiang Wang

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Department of Pediatrics

Johns Hopkins University School of Medicine

A Hyperandrogenic Mouse Model to Study Polycystic Ovary Syndrome

Department of Pediatrics