A G-Protein-Coupled Estrogen Receptor Is Involved in Hypothalamic Control of Energy Homeostasis

Abstract

Estrogens are involved in the hypothalamic control of multiple homeostatic functions including reproduction, stress responses, energy metabolism, sleep cycles, temperature regulation, and motivated behaviors. The critical role of 17β-estradiol (E₂) is evident in hypoestrogenic states (e.g., postmenopause) in which many of these functions go awry. The actions of E₂in the brain have been attributed to the activation of estrogen receptors α and β through nuclear, cytoplasmic, or membrane actions. However, we have identified a putative membrane-associated estrogen receptor that is coupled to desensitization of GABA_Band μ-opioid receptors in guinea pig and mouse hypothalamic proopiomelanocortin neurons. We have synthesized a new nonsteroidal compound, STX, which selectively targets the Gαq-coupled phospholipase C–protein kinase C–protein kinase A pathway, and have established that STX is more potent than E₂in mediating this desensitization in an ICI 182, 780-sensitive manner in both guinea pig and mouse neurons. Both E₂and STX were fully efficacious in estrogen receptor α,β knock-out mice. Moreover,in vivotreatment with STX, similar to E₂, attenuated the weight gain in hypoestrogenic female guinea pigs. Therefore, this membrane-delimited signaling pathway plays a critical role in the control of energy homeostasis and may provide a novel therapeutic target for treatment of postmenopausal symptoms and eating disorders in females.