Polycystic ovary syndrome (PCOS) is the most common ovulatory defect in women. Although most PCOS patients are obese, a subset of PCOS women are lean but show similar risks for adverse fertility outcomes. A lean PCOS mouse model was created using prenatal androgen administration. This developmentally programmed mouse model was used for this study. Our objective was to investigate if mitochondrial structure and functions were compromised in oocytes obtained from lean PCOS mouse. The lean PCOS mouse model was validated by performing glucose tolerance test, HbA1c levels, body weight and estrous cycle analyses. Oocytes were isolated and were used to investigate inner mitochondrial membrane potential, oxidative stress, lipid peroxidation, ATP production, mtDNA copy number, transcript abundance and electron microscopy. Our results demonstrate that lean PCOS mice have similar weight to that of the controls but exhibit glucose intolerance and hyperinsulinemia along with dysregulated estrus cycle. Analysis of their oocytes show impaired inner mitochondrial membrane function, elevated reactive oxygen species (ROS) and increased RNA transcript abundance. Electron microscopy of the oocytes showed impaired mitochondrial ultrastructure. In conclusion, the lean PCOS mouse model shows a decreased oocyte quality related to impaired mitochondrial ultrastructure and function.

Background: Hyperandrogenemia in an obese polycystic ovary syndrome (PCOS) mouse model results in altered glucose/insulin metabolism and mitochondrial structure and function in the oocytes, in part explaining adverse outcomes and inheritance patterns seen in PCOS.Objective: To study the oocyte quality by means of mitochondrial structure and function in a well-established classic PCOS mouse model. Design: Animal study using an obese PCOS mouse model compared with control.Setting: Animal research facility in a tertiary care university hospital setting. Animals: C57/B6J mice. Intervention(s): Three-week-old mice had subdermal implants of dihydrotestosterone controlled release pellet or placebo for 90 days. Main Outcome Measure(s): The mouse model was validated by performing glucose tolerance test and glycated hemoglobin level, body weight, and estrous cycle analyses. Oocytes were subsequently isolated and were used to investigate mitochondrial membrane potential, oxidative stress, lipid peroxidation, adenosine triphosphate production, mitochondrial DNA copy number, transcript abundance, histology, and mitochondrial ultrastructure. Result(s): Results showed glucose intolerance and hyperinsulinemia along with dysregulated estrus cycle. Analysis of the oocytes indicated impaired inner mitochondrial membrane function, increased adenosine triphosphate production and mitochondrial DNA copy number, altered RNA transcript abundance, and aberrant ovarian histology. Electron microscopy of the oocytes revealed severely impaired mitochondrial ultrastructure. Conclusion(s):The obese PCOS mouse model shows a decreased oocyte quality related to impaired mitochondrial function. (Fertil Steril Sci Ò 2021;2:101-12. Ó2020 by American Society for Reproductive Medicine.

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