High-fat diet exposure from pre-pubertal age induces polycystic ovary syndrome (PCOS) in rats

Abstract

Polycystic ovary syndrome (PCOS) is associated with hyperandrogenism, oligo-anovulation, polycystic ovaries and metabolic syndrome. Many researchers reported that PCOS often starts with menarche in adolescents. Presently available animal model focuses on ovarian but not metabolic features of PCOS. Therefore, we hypothesized that high-fat diet feeding to pre-pubertal female rats results in both reproductive and metabolic features of PCOS. Pre-pubertal female rats were divided into two groups: group I received normal pellet diet and group II received high-fat diet (HFD). In the letrozole study, adult female rats were divided into two groups: group I received 1% carboxy methyl cellulose and group II received 1 mg/kg letrozole orally. Oral glucose tolerance test, lipid profile, fasting glucose, insulin, estrus cycle, hormonal profile, ovary weight, luteinizing hormone (LH) receptor and follicle-stimulating hormone receptor expression were measured. Polycystic ovarian morphology was assessed through histopathological changes of ovary. Feeding of HFD gradually increase glucose intolerance and fasting insulin levels. Triglyceride level was higher in HFD study while total cholesterol level was higher in the letrozole study. Alteration in testosterone and estrogen levels was observed in both studies. LH receptor expression was upregulated only in HFD study. Histopathological changes like increase cystic follicle, diminished granulosa cell layer and thickened theca cell layer were observed in letrozole as well as HFD study. High-fat diet initiated at pre-puberty age in rats produces both metabolic disturbances and ovarian changes similar to that observed clinically in PCOS patients. Letrozole on the other hand induces change in ovarian structure and function.