Kalthur, Guruprasad

Context Women with obesity or polycystic ovary syndrome (PCOS) often require repeated ovulation induction (OI) due to ovulatory dysfunction and infertility. However, the cumulative effects of repeated stimulation on ovarian function and embryo development remain poorly understood. Aims The present study aimed to understand the consequences of repeated OI and/or repeated superovulation (SO) on preimplantation embryonic development in obese (high-fat diet-induced) and PCOS (high-fat diet and dehydroepiandrosterone-induced) mouse models. Methods Control (without any metabolic disorder), obese, and PCOS mice were divided into three experimental groups. The mice in one round of superovulation (SO1) were injected with 5 IU intraperitoneal (i.p.) injection of pregnant mare serum gonadotropin, followed by 10 IU of human chorionic gonadotropin 48 h later. In the repeated superovulation (SO3) group, mice were subjected to three rounds of superovulation with a gap of 9 days between each superovulation. Mice in the OI3 + SO3 group were administered with three doses of CC (50 mg/kg body weight, i.p., gap of 9 days between each CC injection), followed by three rounds of superovulation. Key results Both single and three rounds of superovulation resulted in decrease in primordial follicles and a moderate increase in atretic follicles in obese and PCOS mice. Reduction in the number of ovulated oocytes, increased rate of abnormal fertilization, decrease in blastocyst rate and elevated DNA damage in blastocysts were observed in in vitro fertilization-derived embryos. Conclusions These findings demonstrate compromised embryonic development following repeated ovarian stimulation. Implications The study highlights need for mild ovarian stimulation strategies in metabolically compromised patients undergoing infertility treatments.

Abstract Polycystic ovarian syndrome (PCOS) is a complex health condition associated with metabolic disturbances and infertility. Recent data suggest that the prevalence of PCOS is increasing among women globally, although the etiology of these trends is undefined. Consequently, preclinical models that better reflect the biology of PCOS are urgently needed to facilitate research that can lead to the discovery of prevention strategies or improved management. The existing animal models have several limitations as they do not reflect all the PCOS features metabolically and/or phenotypically. Therefore, there is no clear consensus on the use of appropriate animal model and selection of the most appropriate PCOS-inducing agent. To that end, we have established a Swiss albino mouse model of PCOS based on 3 weeks of daily treatment with letrozole (50 μg/day; intraperitoneal) and dehydroepiandrosterone (DHEA, 6 mg/100 g body weight; subcutaneous) in 5-week-old female mice fed on normal or high-fat diet (HFD). Mice were regularly assessed for body weight, blood glucose, and estrous cycle. Three weeks after drug administration, mice were sacrificed and assessed for blood-based metabolic parameters as well as ovarian function. Our results indicate that DHEA combined with HFD produces changes mimicking those of clinical PCOS, including elevated serum testosterone and luteinizing hormone, dyslipidemia, poor ovarian microenvironment, and development of multiple ovarian cysts, recapitulating cardinal features of PCOS. In comparison, normal diet and/or letrozole produced fewer features of PCOS. The data from the experimental models presented here can improve our understanding of PCOS, a growing concern in women’s health.