Aging is associated with loss of beneficial effects of estrogen on leptin responsiveness in mice fed high fat diet: Role of estrogen receptor α and cytokines.

Aging causes changes in body composition and energy balance. Estrogen plays an important role in body's metabolism. The aim of this study was to determine whether estrogen has beneficial effects on leptin responsiveness in aged mice. Young 4 months and aged 19-21 female mice fed High Fat Diet (HFD) or Standard Diet (SD) for 12 weeks and following received estrogen for 4 weeks. Responsiveness to leptin was compared by measuring energy balance parameters. Results showed that HFD caused weight gain compared to SD in young, but had no effect on aged animals. Estrogen reduced body weight, energy intake and visceral fat in young, while none of these parameters was affected in aged animals. Although there was leptin sensitivity in aged compared to ovariectomized animals, estrogen only improved the sensitivity of young to leptin. Estrogen prevented increase in TNF-α and a decrease in IL-10 in HFD young and aged animals. Response to estrogen depended on age, and estrogen increased leptin sensitivity only in young animals. Determining the exact mechanism of this action is suggested in future studies.