Correlation of Estrous cycle with estrogen and leptin levels in ob/ob and Agouti mice

Abstract

Gonadal hormones like estrogen acts as a metabolic signal of energy sufficiency and also regulates the stage of reproductive cycle. Apart from hormonal changes, feeding circuits also affects the estrous cycle. Estrogen, a hormone secreted by the ovaries regulates reproductive cycle and has a negative effect on food intake. Leptin, a hormone secreted by the adipose tissue has an inhibitory effect on food intake. In this study we tried to analyze the estrous cycle in relation with leptin and estrogen levels in two mouse lines ob/ob and Ay/a, both of which are obese, hypometabolic and infertile but with contrasting leptin levels. To assess the progression of estrous cycle, vaginal smears was performed on female WT, ob/ob and Ay/a (n=4) mice. In WT mice at proestrous; nucleated cells were round to hexagonal shaped, estrous; cornified cells and metaestrous; leukocytes with many nucleated cells, diestrous; the cells were all scattered leukocytes. We found that both ob/ob and Ay/a mice were not cycling and were at a persistent estrous phase with cornified cells. The number of cornified cells however was not similar at all stages. Quantitization of beta‐estradiol showed both ob/ob and Ay/a compared to WT had same or higher b‐estradiol levels. Thus, this study leads us to believe the estrous cycle of these mouse models is not only dependent on estrogen levels but interplay of gonadal hormones and feeding circuits.