Comparative Analysis of Letrozole and Estradiol Valerate PCOS Models: Reproductive and Metabolic Outcomes with and Without High-Fat Diet

Polycystic ovary syndrome (PCOS) is a prevalent endocrine disorder in reproductive-aged women, characterized by hyperandrogenism, oligoanovulation, and polycystic ovarian morphology. Despite its classification as a reproductive disorder, PCOS is closely associated with metabolic dysregulation, including insulin resistance and obesity. An ideal animal model for PCOS should replicate both reproductive and metabolic features of the condition. In this study, we compared two widely used postnatal PCOS models (letrozole and estradiol valerate [EV]) administered alone or in combination with a high-fat diet (HFD), assessing their ability to induce both the reproductive and metabolic features. Letrozole treatment led to significant weight gain and increased visceral adiposity, effects that were amplified by HFD. Conversely, EV treatment showed a tendency toward reduced body mass. While neither model significantly altered fasting glucose levels, letrozole combined with HFD impaired glucose tolerance, supporting its role in metabolic dysfunction. Hyperandrogenism was more consistently induced by letrozole compared to EV, aligning with clinical PCOS phenotypes. Both treatments disrupted estrous cyclicity and induced polycystic ovarian morphology, though metabolic disturbances were more pronounced in the letrozole model. These findings suggest that letrozole, particularly in combination with HFD, provides a more consistent model for studying both the reproductive and metabolic facets of PCOS.