Model: ob/ob and Ovariectomized Mice
Estrous cycle is the recurring physiological changes occurring in the endometrium of the uterus during the reproductive cycle. There is a known impact of hormones like estrogen and leptin on the regulation of the estrous cycle. Estrous cycle in mice is a 4-5 day cycle characterized by proestros, estrous, metaestrous and diestrous, which can be determined by the cell types obtained from the vaginal smear. Analyzes of estrous cycle is an important tool as female mice are considered to be an excellent model for the study of neuroendocrine mechanism underlying a wide variety of normal functions and pathophysiological conditions in human. Estrogen, a hormone secreted mainly by the ovaries not only regulates the reproductive cycle but also has a negative effect on food intake. Leptin, a hormone secreted by the fat cells 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 ovariectomized (OVX) female mice, both of which are infertile, increased body weight, with low or no estrogen but with contrasting leptin levels.
Model: C57Bl/6J female mice
Obesity causes several health complications along with disruption in the reproductive system. The aim of the current study is to determine how long term intake of very high fat diet (VHFD) changes the hormonal milieu affecting the cellular morphology and reproductive cycle in female mice. Mice fed on VHFD showed a significant increase in weight gain, reduction in food intake and increase in energy intake compared to animals fed on ND indicating that it is the caloric-density of the diet that is responsible for the differences in the weight gain. Hormonal analysis showed hyperleptinemia, hyperinsulinemia and increases in estrogen levels along with increases in size of the islet of Langerhans and adipocytes. After 25-27 weeks all animals fed on VHFD showed complete acyclicity; elongation of phases (e.g diestrous), skipping of phases (e.g. metaestrous), or a combination of both indicating disruption in the reproductive cycle. Quantitative analysis showed that in the diestrous phase there was 70% increase in cell count in VHFD compared to animals fed on ND.