PROJECT SUMMARY Dramatic decline in circulating 17β-estradiol (E2) in post-menopausal women has been associated with development of obesity and glucose dysregulations. While E2 administration in post-menopausal women may correct these issues, the estrogen therapy is often associated with side effects, including reproductive endocrine toxicity and breast cancer. Targeting specific estrogen receptors (ERs) and ER-expressing populations may produce anti-obesity and anti-diabetes benefits with fewer side effects. We demonstrated that estrogen receptor-α (ERα) in the ventrolateral subdivision of the ventromedial hypothalamus (vlVMH) is essential to maintain body weight and glucose balance. Here we seek to unravel the molecular and neurocircuitry mechanisms for these ERα neurons by testing a general hypothesis that E2-sensitive ERαvlVMH neurons detect nutritional/glycemic fluctuations, and recruit multiple downstream neural circuits to maintain energy and glucose homeostasis. The first objective is to determine the glucose and energy-regulatory effects of the ERαvlVMH-originated projections to a few brain regions, including the dorsal Raphe nuclei (DRN) and medial posterior arcuate nucleus of the hypothalamus (mpARH). The second objective is to determine whether two ionic channel genes, namely, Abcc8 and Ano4, regulate the firing responses of ERαvlVMH neurons to various alterations in blood glucose and/or feeding states; we will also examine the physiological functions of these channels on whole-body energy/glucose balance. The third objective is to establish Clic1 as a novel ERα target gene, and to determine whether Clic1 in ERαvlVMH neurons mediates actions of E2 to maintain energy and glucose balance. Accomplishment of these studies will unravel ionic mechanisms by which ERαvlVMH neurons detect dynamic changes in energy and glucose balance, and reveal the ERαvlVMH-originated neural networks that respond to these changes and therefore restore energy/glucose homeostasis. We will also delineate molecular mechanisms by which E2 regulates ERαvlVMH neuron functions and energy/glucose balance, and may identify potential targets for treatment of metabolic disorders associated with menopause.