No abstract

Aging is the greatest risk factor for most chronic diseases. Metabolic dysfunction underlies several chronic diseases, which are further exacerbated by obesity. Dietary interventions can reverse metabolic declines and slow aging processes, although compliance issues remain paramount due to adverse effects on quality of life.17α-estradiol treatment improves metabolic parameters and slows aging in male mice. The mechanism by which 17α-E2 elicits benefits remain unknown, which has led speculation that an uncharacterized receptor is involved. Herein, we show that 17α-estradiol and 17β-estradiol elicit similar genomic binding and transcriptional activation of ERα and that the ablation of ERα in male mice completely attenuates the beneficial effects of 17α-estradiol. Our findings also suggest that 17α-E2 acts primarily through the liver and/or hypothalamus to elicit benefits, and that 17α-E2 also improves metabolic parameters in male rats. Collectively, these data suggest ERα is a relevant drug target for mitigating chronic diseases in male mammals. KEYWORDS17α-estradiol, aging, estrogen receptor, hypothalamus, liver, metabolism, obesity Aging is the leading risk factor for most chronic diseases, many of which are associated with declines in metabolic homeostasis [1]. Metabolic detriments associated with advancing age are further exacerbated by obesity [2,3], which has risen substantially in the older population (> 65 years) over the past several decades [4,5]. Moreover, obesity in mid-life has been shown to accelerate aging mechanisms and induce phenotypes more commonly observed in older mammals [6][7][8][9][10][11][12]. These observations have led many to postulate that obesity may represent a mild progeria syndrome [13][14][15][16][17]. Although it is well established that dietary interventions, including calorie restriction, can reverse obesity-related metabolic sequelae, many of these strategies are not well tolerated in older patients due to concomitant comorbidities [2,18]. Compliance issues across all age groups also remain a paramount hurdle due to calorie restriction adversely affecting mood, thermoregulation, and musculoskeletal mass [19]. These adverse health outcomes demonstrate the need for pharmacological approaches aimed at curtailing metabolic perturbations associated with obesity and aging.17α-estradiol (17α-E2) is one of the more recently studied compounds to demonstrate efficacy for beneficially modulating obesity-and age-related health outcomes. The NIA Interventions Testing Program (ITP) found that long-term administration of 17α-E2 extends median lifespan of male mice in a dose-dependent manner [20,21]. Our group has been exploring potential mechanisms by which 17α-E2 may improve healthspan and extend lifespan in a sex-specific manner. We have found that 17α-E2 administration reduces food intake and regional adiposity in combination with significant improvements in a multitude of systemic metabolic parameters in both middle-aged obese and old male mice without inducing deleterious effects [22][23...