Explore the vast range of titles available.

Caloric restriction slows or prevents Alzheimer’s disease in animal models. Calorie restriction is typically implemented in rodents through feeding once per day; as the animals quickly consume their food, they are subject to a prolonged self-imposed fasting period between meals. Here, we examine the distinct contributions of fasting and reduced calories to the beneficial effects of calorie restriction on Alzheimer’s disease by placing male and female 3xTg and non-transgenic control mice on a series of diet regimens enabling us to dissect the effects of calories and fasting. We find that reducing calories alone improves body weight and glucose tolerance. However, a prolonged fast between meals is necessary for many of the benefits of calorie restriction, including improved insulin sensitivity, reduced Alzheimer’s pathology, improved neuroprotective signaling, and improved cognition. Overall, our results suggest that both when and how much we eat may influence the development and progression of Alzheimer’s disease. Caloric restriction improves Alzheimer’s Disease outcomes in mice, but this diet not only reduces calories, but imposes a prolonged fast between meals. Here, the authors show this fast is essential to improve Alzheimer’s pathology and cognition.

Dietary protein is a key regulator of healthy aging in both mice and humans. In mice, reducing dietary levels of the branched‐chain amino acids (BCAAs) recapitulates many of the benefits of a low protein diet; BCAA‐restricted diets extend lifespan, reduce frailty, and improve metabolic health, while BCAA supplementation shortens lifespan, promotes obesity, and impairs glycemic control. Recently, high protein diets have been shown to promote cellular senescence, a hallmark of aging implicated in many age‐related diseases, in the liver of mice. Here, we test the hypothesis that the effects of high protein diets on metabolic health and on cellular senescence are mediated by BCAAs. We find that reducing dietary levels of BCAAs protects male mice from the negative metabolic consequences of both normal and high protein diets. Further, we identify tissue‐specific effects of BCAAs on cellular senescence, with restriction of all three BCAAs—but not individual BCAAs—protecting from hepatic cellular senescence while potentiating cellular senescence in white adipose tissue. We also find that these effects are sex‐specific. We find that the effects of BCAAs on hepatic cellular senescence are cell‐autonomous, with lower levels of BCAAs protecting cultured cells from antimycin‐A induced senescence. Our results demonstrate a direct effect of a specific dietary component on a hallmark of aging and suggest that cellular senescence may be highly susceptible to dietary interventions. Restriction of dietary BCAAs protects male mice from the metabolic consequences of both normal‐ and high‐protein diets. BCAA restriction also protects from hepatic cellular senescence in vivo and in vitro, especially in the context of mitochondrial stress.

Dietary protein is a critical regulator of metabolic health and aging. Low protein diets are associated with healthy aging in humans, and dietary protein restriction extends the lifespan and healthspan of mice. In this study, we examined the effect of protein restriction (PR) on metabolic health and the development and progression of Alzheimer’s disease (AD) in the 3xTg mouse model of AD. Here, we show that PR promotes leanness and glycemic control in 3xTg mice, specifically rescuing the glucose intolerance of 3xTg females. PR induces sex-specific alterations in circulating and brain metabolites, downregulating sphingolipid subclasses in 3xTg females. PR also reduces AD pathology and mTORC1 activity, increases autophagy, and improves the cognition of 3xTg mice. Finally, PR improves the survival of 3xTg mice. Our results suggest that PR or pharmaceutical interventions that mimic the effects of this diet may hold promise as a treatment for AD. There is growing need for ways to slow or prevent Alzheimer’s disease (AD). Here, the authors demonstrate that a low protein diet can protect against metabolic dysfunction, slow AD progression, and preserve cognitive function in a mouse model of AD.

Dietary protein regulates metabolic health and aging, with many benefits of a low protein diet resulting from reduced consumption of the three branched‐chain amino acids (BCAAs), leucine, isoleucine, and valine. Each BCAA has distinct physiological and molecular effects, and while restriction of protein or all three BCAAs improves cognition in mouse models of Alzheimer's disease (AD), the role of each individual BCAA on AD is unknown. Here, we investigate the impact of restricting leucine, isoleucine, or valine on metabolism, AD pathology, molecular signaling, and cognition in male and female 3xTg AD mice. Mice were fed BCAA‐restricted diets for nine months starting at six months of age. Restriction of either isoleucine or valine, but not leucine, improved metabolic health. We observed distinct, BCAA‐specific effects on AD pathology, molecular signaling, and gene expression in both sexes as well as shared molecular responses in males. Restricting any BCAA improved short‐term memory in males, with isoleucine having the strongest effect, while valine restriction led to the greatest cognitive benefits for females. These findings suggest that targeted BCAA restriction, particularly of isoleucine or valine, may form the basis of a novel sex‐specific approach to prevent or delay AD. Protein restriction (PR) slows Alzheimer's disease (AD) in mice, and other benefits of PR are due to decreased branched‐chain amino acids (BCAAs). We show that restricting any BCAA has benefits, with sex‐ and BCAA‐specific impacts on pathology, molecular signaling, and cognition. These findings highlight dietary composition as critical in the development and progression of AD, and could guide future therapies.

Caloric restriction (CR) extends the health and lifespan of diverse species. When fed once daily, CR‐treated mice rapidly consume their food and endure a prolonged fast between meals. As fasting is associated with a rise in circulating ketone bodies, we investigated the role of ketogenesis in CR using mice with whole‐body ablation of Hmgcs2, the rate‐limiting enzyme producing the main ketone body β‐hydroxybutyrate (βHB). Here, we report that Hmgcs2 is largely dispensable for many metabolic benefits of CR, including CR‐driven changes in adiposity, glycemic control, liver autophagy, and energy balance. Although we observed sex‐specific effects of Hmgcs2 on insulin sensitivity, fuel selection, and adipocyte gene expression, the overall physiological response to CR remained robust in mice lacking Hmgcs2. To gain insight into why the deletion of Hmgcs2 does not disrupt CR, we measured fasting βHB levels as mice initiated a CR diet. Surprisingly, as mice adapt to CR, they no longer engage in high levels of ketogenesis during the daily fast. Our work suggests that the metabolic benefits of long‐term CR are not mediated by ketogenesis. In this study, we demonstrated that metabolic responses to a daily‐fed caloric restriction (CR) protocol remain robust in mice that cannot engage in canonical ketogenesis. This surprising finding is due to mice physiologically adapting to the daily bouts of fasting during CR by downregulating ketone production.

Treatment with rapamycin, an inhibitor of the mechanistic Target Of Rapamycin Complex One (mTORC1) protein kinase, has been repeatedly demonstrated to extend lifespan and prevent or delay age-related diseases in diverse model systems. Concerns over the risk of potentially serious side effects in humans, including immunosuppression and metabolic disruptions, have cautiously limited the translation of rapamycin and its analogs as a treatment for aging associated conditions. During the last decade, we and others have developed a working model that suggests that while inhibition of mTORC1 promotes healthy aging, many of the negative side effects of rapamycin are associated with “off-target” inhibition of a second mTOR complex, mTORC2. Differences in the kinetics and molecular mechanisms by which rapamycin inhibits mTORC1 and mTORC2 suggest that a therapeutic window for rapamycin could be exploited using intermittent dosing schedules or alternative rapalogs that may enable more selective inhibition of mTORC1. However, the optimal dosing schedules and the long-term efficacy of such interventions in humans are unknown. Here, we highlight ongoing or upcoming clinical trials that will address outstanding questions regarding the safety, pharmacokinetics, pharmacodynamics, and efficacy of rapamycin and rapalogs on several clinically oriented outcomes. Results from these early phase studies will help guide the design of phase 3 clinical trials to determine whether rapamycin can be used safely to inhibit mTORC1 for the treatment and prevention of age-related diseases in humans.

Age is the greatest risk factor for Alzheimer’s disease (AD) as well as for other disorders that increase the risk of AD such as diabetes and obesity. There is growing interest in determining if interventions that promote metabolic health can prevent or delay AD. Acarbose is an anti-diabetic drug that not only improves glucose homeostasis, but also extends the lifespan of wild-type mice. Here, we test the hypothesis that acarbose will not only preserve metabolic health, but also slow or prevent AD pathology and cognitive deficits in 3xTg mice, a model of AD, fed either a Control diet or a high-fat, high-sucrose Western diet (WD). We find that acarbose decreases the body weight and adiposity of WD-fed 3xTg mice, increasing energy expenditure while also stimulating food consumption, and improves glycemic control. Both male and female WD-fed 3xTg mice have worsened cognitive deficits than Control-fed mice, and these deficits are ameliorated by acarbose treatment. Molecular and histological analysis of tau and amyloid pathology identified sex-specific effects of acarbose which are uncoupled from the dramatic improvements in cognition in females, suggesting that the benefits of acarbose on AD may be largely driven by improved metabolic health. In conclusion, our results suggest that acarbose may be a promising intervention to prevent, delay, or even treat AD, especially in individuals consuming a WD.

Dietary protein intake mediates healthy aging in diverse species, with consumption of a low protein (LP) diet improving metabolic health in both humans and mice. In mice, the benefits of LP diets are sex-specific, with males exhibiting a stronger response to a LP diet than females. The reason for this sexually dimorphic response is unknown, but we hypothesized that sex hormones might be responsible for this difference. Here, we tested the role of sex hormones in the response to a LP diet by feeding intact and gonadectomized mice of both sexes either a Control (21% of calorie from protein) or LP (7% of calories from protein) diet, and assessing the effects on weight, body composition, glycemic control, and energy balance over the course of three months, followed by molecular and histological analysis of tissues from each group. We confirm that males show a stronger metabolic response to an LP diet than females, but that ovariectomy sensitizes female mice to the metabolic effects of an LP diet, making them respond more similarly to males; conversely, castration does not substantially impact the response of males to an LP diet. Molecularly, we find that gonadectomy and sex are important interactors that mediate the response of mechanistic target of rapamycin (mTOR) signaling, lipid homeostasis, and thermogenesis to an LP diet. Together, this data shows that the resistance of female mice to an LP diet is mediated by ovarian hormones and suggests the possibility that older female humans might receive enhanced benefits from LP diet feeding.

Dietary protein is a critical regulator of metabolic health and aging in diverse species. Recent discoveries have determined that many benefits of a low protein diet are the result of reduced consumption of the three branched-chain amino acids (BCAAs), leucine, isoleucine, and valine. Intriguingly, each BCAA has distinct physiological and molecular effects, with restriction of isoleucine alone being sufficient to improve metabolic health and extend the lifespan of mice. While restriction of protein or all three BCAAs improves cognition in mouse models of Alzheimer's disease (AD), the impact of restricting each individual BCAA on the progression and development of AD is unknown. Here, we investigate the effect of restricting each individual BCAA on metabolic health, AD pathology, molecular signaling, and cognition in the 3xTg mouse model. We find that restriction of isoleucine and valine, but not leucine, promotes metabolic health. Restriction of each BCAA had distinct effects on AD pathology and molecular signaling, with transcriptomic analysis of the brain revealing both distinct and shared, and highly sex-specific, molecular impacts of restricting each BCAA. Restricting any of the three BCAAs improved short-term memory in males, with isoleucine restriction having the strongest effect, while restricting valine had the greatest cognitive benefits in females. We identify a set of significantly altered pathways strongly associated with reduced AD pathology and improved cognitive performance in males. Our findings suggest that restricting any of the BCAAs, particularly isoleucine or valine, may form the basis of a novel sex-specific approach to prevent or delay the progression of AD.

Caloric restriction (CR) robustly extends the health and lifespan of diverse species. When fed once daily, CR-treated mice rapidly consume their food and endure a prolonged fast between meals. As fasting is associated with a rise in circulating ketones, we decided to investigate the role of ketogenesis in CR using mice with whole-body ablation of , the rate-limiting enzyme producing the main ketone body β-hydroxybutyrate (βHB). Here, we report that is largely dispensable for many metabolic benefits of CR, including CR-driven changes in adiposity, glycemic control, liver autophagy, and energy balance. Although we observed sex-specific effects of on insulin sensitivity, fuel selection, and adipocyte gene expression, the overall physiological response to CR remains robust in mice lacking . To gain insight into why deletion of does not disrupt CR, we measured fasting βHB levels as mice began a CR diet. Surprisingly, as CR-fed mice adapt to CR, they no longer engage high levels of ketogenesis during the daily fast. Our work suggests that the benefits of long-term CR in mice are not mediated by ketogenesis.