Placental PFAS concentrations are associated with perturbations of placental DNA methylation at loci with important roles on cardiometabolic health.

The placenta is crucial for fetal development, is affected by PFAS toxicity, and evidence is accumulating that gestational PFAS perturb the epigenetic activity of the placenta. Gestational PFAS exposure is can adversely affect offspring, yet individual and cumulative impacts of PFAS on the placental epigenome remain underexplored. Here, we conducted an epigenome-wide association study (EWAS) to examine the relationships between placental PFAS levels and DNA methylation in a cohort of mother-infant dyads in Arkansas. We measured 17 PFAS in human placental tissues and quantified placental DNA methylation levels via the Illumina EPIC Microarray. We tested for differential DNA methylation with individual PFAS, and with mixtures of multiple PFAS. Our results demonstrated that numerous epigenetic loci were perturbed by PFAS, with PFHxS exhibiting the most abundant effects. Mixture analyses suggested cumulative effects of PFOA and PFOS, while PFHxS may act more independently. We additionally explored whether sex-specific effects may be present and concluded that future large studies should explicitly test for sex-specific effects. The genes that are annotated to our PFAS-associated epigenetic loci are primarily involved in growth processes and cardiometabolic health, while some genes are involved in neurodevelopment. These findings shed light on how prenatal PFAS exposures affect birth outcomes and children's health, emphasizing the importance of understanding PFAS mechanisms in the in-utero environment.

Satellite-based time-series of sea-surface temperature since 1980 for climate applications.

A 42-year climate data record of global sea surface temperature (SST) covering 1980 to 2021 has been produced from satellite observations, with a high degree of independence from in situ measurements. Observations from twenty infrared and two microwave radiometers are used, and are adjusted for their differing times of day of measurement to avoid aliasing and ensure observational stability. A total of 1.5 × 1013 locations are processed, yielding 1.4 × 1012 SST observations deemed to be suitable for climate applications. The corresponding observation density varies from less than 1 km-2 yr-1 in 1980 to over 100 km-2 yr-1 after 2007. Data are provided at their native resolution, averaged on a global 0.05° latitude-longitude grid (single-sensor with gaps), and as a daily, merged, gap-free, SST analysis at 0.05°. The data include the satellite-based SSTs, the corresponding time-and-depth standardised estimates, their standard uncertainty and quality flags. Accuracy, spatial coverage and length of record are all improved relative to a previous version, and the timeseries is routinely extended in time using consistent methods.

Promoting a more diverse and inclusive research workforce through the research scholars program.

BACKGROUND: Novel and comprehensive approaches are needed to address shortcomings in the diversity and inclusiveness of the scientific workforce. In response to this need and informed by multiple programs and data sources, we created the Research Scholars Program (RSP). The RSP is a yearlong program for early-career faculty with an overall objective to overcome barriers to the academic success, retention, progression, and promotion of groups underrepresented in biomedical and behavioral research. The goal of the RSP is to increase research confidence and productivity, build a supportive research community, and reduce isolation by providing personal and group research enrichment to junior faculty through professional development, mentorship, and networking. METHODS: We adapted evidence-based approaches for our institutional context and vetted the RSP across our campus. The resulting RSP consists of three main elements: (1) five levels of Mosaic Mentorship; (2) group and tailored professional development programming; and (3) scientific and social networking. To determine the potential of the RSP to improve research confidence critical to success, we used a modified shortened version of the Clinical Research Appraisal Inventory (CRAI-12) to assess participants' confidence in performing a variety of research tasks before and after program participation. We collected information about retention, promotion, and grants submitted and awarded. Additionally, we conducted semi-structured exit interviews with each scholar after program participation to identify programmatic strengths and areas for improvement. Data for Cohorts 1 and 2 (N = 12) were analyzed. RESULTS: Our assessment finds, with one exception, increasing confidence in participants' research skills across all items, ranging from 0.4 (4.7%) to 2.6 (40.6%). In their exit interviews, the Research Scholars (RS) described their improved productivity and increased sense of belonging and support from others. Research Scholars noted numerous components of the RSP as strengths, including the Mosaic Mentorship model, professional development programming, and opportunities for both informal and formal interactions. Respondents identified time pressure, a lack of feedback, and unclear expectations of the various mentorship roles as areas in which the program can improve. CONCLUSION: Preliminary findings indicate that the RSP is successful in building the research confidence of underrepresented and disadvantaged early-career faculty. While this report focuses on the development and protocol of the RSP, additional cohorts and data will provide the evidence base to support dissemination as a national model of research professional development. Such programming is critical to ensure sustainable support structures, institutional networks, infrastructure, and resources that will improve discovery and equity through inclusive excellence.

Sex differences in type 2 diabetes: an opportunity for personalized medicine.

Over the past several decades, substantial ground has been gained in understanding the biology of sex differences. With new mandates to include sex as a biological variable in NIH-funded research, greater knowledge is forthcoming on how sex chromosomes, sex hormones, and social and societal differences between sexes can affect the pathophysiology of health and disease. A detailed picture of how biological sex impacts disease pathophysiology will directly inform clinicians in their treatment approaches and challenge canonical therapeutic strategies. Thus, a profound opportunity to explore sex as a variable in personalized medicine now presents itself. While many sex differences are apparent in humans and have been described at length, we are only beginning to see how such differences impact disease progression, treatment efficacy, and outcomes in obesity, type 2 diabetes, and cardiovascular disease. Here, we briefly present the most salient and convincing evidence of sex differences in type 2 diabetes detection, diagnostics, disease course, and therapeutics. We then offer commentary on how this evidence can inform clinicians on how to approach the clinical workup and management of different patients with diabetes. Finally, we discuss some gaps that remain in the literature and propose several research questions to guide basic and translational researchers as they continue in this growing area of scientific exploration.

For decades, most research in the laboratory and clinical settings focused primarily on males. However, more recently, grant-funding agencies, including the National Institutes of Health, have prioritized research that studies both males and females. This has dramatically improved our understanding of how biological sex impacts whether a person is at higher risk for developing a particular disease and what treatment options may be best to achieve the healthiest outcomes. This article offers the perspectives of practicing physicians and scientists on how our knowledge about biological sex may impact disease incidence, progression, treatment options, and outcomes in obesity, diabetes, and heart disease. The piece will offer a broad overview of the current science and personalized medicine approaches in these areas. It then discusses gaps in our knowledge and proposes several questions to guide future research.

Exposure to PCB126 during the nursing period reversibly impacts early-life glucose tolerance.

Polychlorinated biphenyls (PCBs) are persistent environmental organic pollutants known to have detrimental health effects. Using a mouse model, we previously demonstrated that PCB126 exposure before and during pregnancy and throughout the perinatal period adversely affected offspring glucose tolerance and/or body composition profiles. The purpose of this study was to investigate the glucose tolerance and body composition of offspring born to dams exposed to PCB126 during the nursing period only. Female ICR mice were bred, and half of the dams were exposed to either vehicle (safflower oil) or 1 µmole PCB126 per kg of body weight via oral gavage on postnatal days (PND) 3, 10, and 17 (n = 9 per group). Offspring body weight, lean and fat mass, and glucose tolerance were recorded every three weeks. PCB126 treatment did not alter dam nor offspring body weight (p > 0.05). PCB126-exposed male and female offspring displayed normal body composition (p > 0.05) relative to vehicle-exposed offspring. However, both male and female offspring that were exposed to PCB126 during the nursing period had significantly impaired glucose tolerance at 3 and 9 weeks of age (p < 0.05). At 6 and 12 weeks of age, no impairments in glucose tolerance existed in offspring (p > 0.05). Our current study demonstrates that exposure to PCB126 through the mother's milk does not affect short- or long-term body composition but impairs glucose tolerance in the short-term.

Maternal polychlorinated biphenyl 126 (PCB 126) exposure modulates offspring gut microbiota irrespective of diet and exercise.

The gut microbiota plays an important role throughout the lifespan in maintaining host health, and several factors can modulate microbiota composition including diet, exercise, and environmental exposures. Maternal microbiota is transferred to offspring during early life; thus, environmental exposures before gestation may also modulate offspring microbiota. Here we aimed to investigate the effects of maternal exposure to dioxin-like polychlorinated biphenyls (PCBs) on the microbiota of aged offspring and to determine if lifestyle factors, including maternal exercise or offspring high-fat feeding alter these associations. To test this, dams were exposed to PCB 126 (0.5 µmole/kg body weight) or vehicle oil by oral gavage during preconception, gestation, and during lactation. Half of each group was allowed access to running wheels for ≥ 7 days before and during pregnancy and up through day 14 of lactation. Female offspring born from the 4 maternal groups (PCB exposure or not, with/without exercise) were subsequently placed either on regular diet or switched to a high-fat diet during adulthood. Microbiota composition was quantified in female offspring at 49 weeks of age by 16 S rRNA sequencing. Maternal exposure to PCB 126 resulted in significantly reduced richness and diversity in offspring microbiota regardless of diet or exercise. Overall compositional differences were largely driven by offspring diet, but alterations in specific taxa due to maternal PCB 126 exposure, included the depletion of Verrucomicrobiaceae and Akkermansia muciniphila, and an increase in Anaeroplasma. Perturbation of microbiota due to PCB 126 may predispose offspring to a variety of chronic diseases later in adulthood.

PCB126 exposure during pregnancy alters maternal and fetal gene expression.

Polychlorinated biphenyls (PCBs) are organic pollutants that can have lasting impacts on offspring health. Here, we sought to examine maternal and fetal gene expression differences of aryl hydrocarbon receptor (AHR)-regulated genes in a mouse model of prenatal PCB126 exposure. Female mice were bred and gavaged with 1 µmole/kg bodyweight PCB126 or vehicle control on embryonic days 0 and 14, and maternal and fetal tissues were collected on embryonic day 18.5. Total RNAs were isolated, and gene expression levels were analyzed in both maternal and fetal tissues using the NanoString nCounter system. Interestingly, we found that the expression levels of cytochrome P450 (Cyp)1a1 and Cyp1b1 were significantly increased in response to PCB exposure in the tested maternal and fetal tissues. Furthermore, PCB exposure altered the expression of several other genes related to energy balance, oxidative stress, and epigenetic regulation in a manner that was less consistent across tissue types. These results indicate that maternal PCB126 exposure significantly alters gene expression in both developing fetuses and pregnant dams, and such changes vary in intensity and expressivity depending on tissue type. The altered gene expression may provide insights into pathophysiological mechanisms by which in utero PCB exposures contribute to PCB-induced postnatal metabolic diseases.

Effects of maternal controlled exercise on offspring adiposity and glucose tolerance.

While metabolic disorders such as obesity and diabetes are costly and deadly to the current population, they are also extremely detrimental to the next generation. Much of the current literature focuses on the negative impact of poor maternal choices on offspring disease, while there is little work examining maternal behaviors that may improve offspring health. Research has shown that voluntary maternal exercise in mouse models improves metabolic function in offspring. In this study, we hypothesized that controlled maternal exercise in a mouse model will effect positive change on offspring obesity and glucose homeostasis. Female mice were separated into three groups: home cage, sedentary, and exercise. The sedentary home cage group was not removed from the home cage, while the sedentary wheel group was removed from the cage and placed in an immobile wheel apparatus. The exercise group was removed from the home cage and run on the same wheel apparatus but with the motor activated at 5-10 m/min for 1 h/d prior to and during pregnancy. Offspring were subjected to oral glucose tolerance testing and body composition analysis. There was no significant difference in offspring glucose tolerance or body composition as a consequence of the maternal exercise intervention compared to the sedentary wheel group. There were no marked negative consequences of the maternal controlled exercise intervention. Further research should clarify the potential advantages of the controlled exercise model and improve experimental techniques to facilitate translation of this research to human applications.

Elevated lipid oxidation is associated with exceeding gestational weight gain recommendations and increased neonatal anthropometrics: a cross-sectional analysis.

BACKGROUND: Deviations from gestational weight gain (GWG) recommendations are associated with unfavorable maternal and neonatal outcomes. There is a need to understand how maternal substrate metabolism, independent of weight status, may contribute to GWG and neonatal outcomes. The purpose of this study was to explore the potential link between maternal lipid oxidation rate, GWG, and neonatal anthropometric outcomes. METHODS: Women (N = 32) with a lean pre-pregnancy BMI were recruited during late pregnancy and substrate metabolism was assessed using indirect calorimetry, before and after consumption of a high-fat meal. GWG was categorized as follows: inadequate, adequate, or excess. Shortly after delivery (within 48 h), neonatal anthropometrics were obtained. RESULTS: Using ANOVA, we found that fasting maternal lipid oxidation rate (grams/minute) was higher (p = 0.003) among women with excess GWG (0.1019 ± 0.0416) compared to women without excess GWG (inadequate = 0.0586 ± 0.0273, adequate = 0.0569 ± 0.0238). Findings were similar when lipid oxidation was assessed post-meal and also when expressed relative to kilograms of fat free mass. Absolute GWG was positively correlated to absolute lipid oxidation expressed in grams/minute at baseline (r = 0.507, p = 0.003), 2 h post-meal (r = 0.531, p = 0.002), and 4 h post-meal (r = 0.546, p = 0.001). Fasting and post-meal lipid oxidation (grams/minute) were positively correlated to neonatal birthweight (fasting r = 0.426, p = 0.015; 2-hour r = 0.393, p = 0.026; 4-hour r = 0.540, p = 0.001) and also to neonatal absolute fat mass (fasting r = 0.493, p = 0.004; 2-hour r = 0.450, p = 0.010; 4-hour r = 0.552, p = 0.001). CONCLUSIONS: A better understanding of the metabolic profile of women during pregnancy may be critical in truly understanding a woman's risk of GWG outside the recommendations. GWG counseling during prenatal care may need to be tailored to women based not just on their weight status, but other metabolic characteristics.

Metabolic flexibility during late pregnancy is associated with neonatal adiposity.

The aim of this study was to determine the relationships between maternal metabolic flexibility during pregnancy and neonatal health outcomes. Percent change in lipid oxidation (before and after a high-fat meal) was calculated as the measure of "metabolic flexibility". Neonatal adiposity was assessed within 48 h of delivery by skinfold anthropometry. Metabolic flexibility (r = -0.271, p = 0.034), maternal HOMA-IR (r = 0.280, p = 0.030), and maternal body mass index (r = 0.299, p = 0.018) were correlated with neonatal subscapular skinfold (i.e., measure of neonatal adiposity). Clinical Trail Registration Number: NCT03504319. Novelty: This is the first study to link maternal metabolic flexibility, body mass index, and insulin resistance during pregnancy to neonatal adiposity at parturition.

Chronic Exposure to Cadmium Induces Differential Methylation in Mice Spermatozoa.

Cadmium exposure is ubiquitous and has been linked to diseases including cancers and reproductive defects. Since cadmium is nonmutagenic, it is thought to exert its gene dysregulatory effects through epigenetic reprogramming. Several studies have implicated germline exposure to cadmium in developmental reprogramming. However, most of these studies have focused on maternal exposure, while the impact on sperm fertility and disease susceptibility has received less attention. In this study, we used reduced representation bisulfite sequencing to comprehensively investigate the impact of chronic cadmium exposure on mouse spermatozoa DNA methylation. Adult male C57BL/J6 mice were provided water with or without cadmium chloride for 9 weeks. Sperm, testes, liver, and kidney tissues were collected at the end of the treatment period. Cadmium exposure was confirmed through gene expression analysis of metallothionein-1 and 2, 2 well-known cadmium-induced genes. Analysis of sperm DNA methylation changes revealed 1788 differentially methylated sites present at regulatory regions in sperm of mice exposed to cadmium compared with vehicle (control) mice. Furthermore, most of these differential methylation changes positively correlated with changes in gene expression at both the transcription initiation stage as well as the splicing levels. Interestingly, the genes targeted by cadmium exposure are involved in several critical developmental processes. Our results present a comprehensive analysis of the sperm methylome in response to chronic cadmium exposure. These data, therefore, highlight a foundational framework to study gene expression patterns that may affect fertility in the exposed individual as well as their offspring, through paternal inheritance.

Lack of Offspring Nrf2 Does Not Exacerbate the Detrimental Metabolic Outcomes Caused by In Utero PCB126 Exposure.

Human environmental exposures to toxicants, such as polychlorinated biphenyls (PCBs), increase oxidative stress and disease susceptibility. Such exposures during pregnancy and/or nursing have been demonstrated to adversely affect offspring health outcomes. Nuclear factor erythroid-2-related factor 2 (Nrf2) regulates the antioxidant response and is involved in the detoxification of coplanar PCBs, like PCB126. The purpose of this study was to investigate glucose tolerance and body composition in PCB-exposed offspring expressing or lacking Nrf2. We hypothesized that offspring lacking Nrf2 expression would be more susceptible to the long-term health detriments associated with perinatal PCB exposure. During gestation, whole-body Nrf2 heterozygous (Het) and whole-body Nrf2 knockout (KO) mice were exposed to vehicle or PCB126. Shortly after birth, litters were cross-fostered to unexposed dams to prevent PCB exposure during nursing. Offspring were weaned, and their body weight, body composition, and glucose tolerance were recorded. At two months of age, PCB exposure resulted in a significant reduction in the average body weight of offspring born to Nrf2 Het dams (p < 0.001) that primarily arose from the decrease in average lean body mass in offspring (p < 0.001). There were no differences in average body weight of PCB-exposed offspring born to Nrf2 KO dams (p > 0.05), and this was because offspring of Nrf2 KO dams exposed to PCB126 during pregnancy experienced a significant elevation in fat mass (p = 0.002) that offset the significant reduction in average lean mass (p < 0.001). Regardless, the lack of Nrf2 expression in the offspring themselves did not enhance the differences observed. After an oral glucose challenge, PCB-exposed offspring exhibited significant impairments in glucose disposal and uptake (p < 0.05). Offspring born to Nrf2 Het dams exhibited these impairments at 30 min and 120 min, while offspring born to Nrf2 KO dams exhibited these impairments at zero, 15, 30, 60 and 120 min after the glucose challenge. Again, the interactions between offspring genotype and PCB exposure were not significant. These findings were largely consistent as the offspring reached four months of age and demonstrate that the lack of offspring Nrf2 expression does not worsen the metabolic derangements caused by in utero PCB exposure as we expected. Future directions will focus on understanding how the observed maternal Nrf2 genotypic differences can influence offspring metabolic responses to in utero PCB exposure.

Widespread skeptic attitudes among people with epilepsy toward generic antiseizure drugs - A Swedish survey study.

PURPOSE: To explore associations between the characteristics of people with epilepsy (PWE) and their attitudes toward generic substitution of antiseizure drugs (ASDs) in epilepsy. METHODS: This was a cross-sectional survey study directed at adults with epilepsy using selected brand drugs: Keppra®, Lamictal®, Lyrica® or Topimax®. Symptoms of anxiety and depression, sense of self-efficacy, and beliefs about medicines were assessed. Caregivers were asked to answer for persons with intellectual or communicative difficulties. RESULTS: The total response rate was 41% (n = 178). Almost half (46%) of subjects stated that they would oppose generic substitution (Gen-NEG) if suggested by their neurologist, while 71% would worry about adverse effects and/or increased seizure frequency after a putative switch. Age ≥50 increased the odds of being Gen-NEG (adjusted OR: 2.20, 95% CI: 1.18-4.11). Negative associations with both Gen-NEG and worriers were found for education level of high-school diploma or above, employment/studies, and prior experience of generic ASD switch. The proportion of worriers was much higher among caregivers (21/22) compared to subjects with epilepsy (106/156). CONCLUSION: High proportions of PWE express concerns regarding generic substitution of ASDs. The elderly and caregivers seem to express particular concerns. Identifying ways to diminish negative outcomes and worries in connection with a switch is an important future field of research in order to ensure high quality, cost-effective health care for the most vulnerable people in our societies.

NQO1 protects obese mice through improvements in glucose and lipid metabolism.

Chronic nutrient excess leads to metabolic disorders and insulin resistance. Activation of stress-responsive pathways via Nrf2 activation contributes to energy metabolism regulation. Here, inducible activation of Nrf2 in mice and transgenesis of the Nrf2 target, NQO1, conferred protection from diet-induced metabolic defects through preservation of glucose homeostasis, insulin sensitivity, and lipid handling with improved physiological outcomes. NQO1-RNA interaction mediated the association with and inhibition of the translational machinery in skeletal muscle of NQO1 transgenic mice. NQO1-Tg mice on high-fat diet had lower adipose tissue macrophages and enhanced expression of lipogenic enzymes coincident with reduction in circulating and hepatic lipids. Metabolomics data revealed a systemic metabolic signature of improved glucose handling, cellular redox, and NAD+ metabolism while label-free quantitative mass spectrometry in skeletal muscle uncovered a distinct diet- and genotype-dependent acetylation pattern of SIRT3 targets across the core of intermediary metabolism. Thus, under nutritional excess, NQO1 transgenesis preserves healthful benefits.

Effect of Evidence-Based Materials and Access to Local Resources on Physical Activity Levels, Beliefs, and Motivation During Pregnancy in a Rural Setting.

BACKGROUND: The purpose of this study was to determine the impact of evidence-based educational materials and access to local resources on physical activity (PA) levels, beliefs, and motivation (including self-efficacy) regarding PA during pregnancy in a rural setting. METHODS: Information on PA levels (step counts, Pregnancy Physical Activity Questionnaire) and beliefs and motivation regarding PA (main surveys: Exercise Beliefs Questionnaire, Protection Motivation Theory and Health Action Process Approach) were collected between 8 and 16 weeks gestation. Women from a rural community were randomly assigned to the PA group (PAG, n = 38) or control group (n = 32). The PAG participants received an evidence-based educational brochure and access (at no charge to them) to local fitness facilities. At approximately 34 to 37 weeks gestation, baseline assessments were repeated. RESULTS: Sedentary time was significantly different between groups over time, with control participants increasing sedentary time and PAG participants decreasing sedentary time (P = .04). Sixteen women (42%) in the PAG utilized the resources provided (prenatal yoga being utilized most). Postintervention, there was a significant group × time interaction for Perceived Self-Efficacy scores; scores in the PAG remained consistent with baseline values, whereas scores in the control group decreased (P = .03). CONCLUSIONS: The intervention reduced sedentary time and maintained self-efficacy scores during pregnancy.

Perinatal diet influences health and survival in a mouse model of leukemia.

The goal of the current study was to determine the role of maternal diet in the perinatal period on the health and survival of the offspring. AKR/J mice, a model described to be susceptible to leukemia development, was used where females were maintained on either standard diet (SD), high sucrose diet, Western diet, or calorie restriction (CR) as they were mated with SD-fed males. Body weights, pregnancy rates, litter size, and litter survival were used as markers of successful pregnancy and pup health. Data indicated that maternal diet had significant effects on litter size, early pup survival, and early pup body weights. As pups matured, the makeup of their respective maternal diet was a predictor of adult metabolic health and survival. Overall, these results suggest that perinatal maternal diet is an important determinant of the health and survival of the offspring and that these effects continue well into adulthood, strongly correlating with lifespan.

Metabolic flexibility is impaired in women who are pregnant and overweight/obese and related to insulin resistance and inflammation.

CONTEXT: Maternal obesity is a significant public health concern that contributes to unfavorable outcomes such as inflammation and insulin resistance. Women with obesity may have impaired metabolic flexibility (i.e. an inability to adjust substrate metabolism according to fuel availability). Impaired metabolic flexibility during pregnancy may mediate poor pregnancy outcomes in women with obesity. PURPOSE: The purposes of this study were to: 1) compare metabolic flexibility between overweight/obese and lean women; and 2) determine the relationships between metabolic flexibility, inflammation following a high-fat meal, and maternal metabolic health outcomes (i.e. gestational weight gain and insulin resistance). PROCEDURES: This interventional physiology study assessed lipid oxidation rates via indirect calorimetry before and after consumption of a high-fat meal. The percent change in lipid metabolism was calculated to determine 'metabolic flexibility.' Maternal inflammatory profiles (CRP, IL-6, IL-8, IL-10, IL-12, TNF-α) and insulin resistance (HOMA-IR) were determined via plasma analyses. MAIN FINDINGS: 64 women who were pregnant (lean = 35, overweight/obese = 29) participated between 32 and 38 weeks gestation. Lean women had significantly higher metabolic flexibility compared to overweight/obese women (lean 48.0 ±â€¯34.1% vs overweight/obese 29.3 ±â€¯34.3%, p = .035). Even when controlling for pre-pregnancy BMI, there was a negative relationship between metabolic flexibility and percent change in CRP among the overweight/obese group (r = -0.526, p = .017). Metabolic flexibility (per kg fat free mass) was negatively correlated with postprandial HOMA-IR (2 h: r = -0.325, p = .016; 4 h: r = -0.319, p = .019). CONCLUSIONS: Overweight and obese women who are pregnant are less 'metabolically flexible' than lean women, and this is related to postprandial inflammation and insulin resistance.

Deletion of Nrf2 shortens lifespan in C57BL6/J male mice but does not alter the health and survival benefits of caloric restriction.

Caloric restriction (CR) is the leading non-pharmaceutical dietary intervention to improve health- and lifespan in most model organisms. A wide array of cellular pathways is induced in response to CR and CR-mimetics, including the transcriptional activator Nuclear factor erythroid-2-related factor 2 (Nrf2), which is essential in the upregulation of multiple stress-responsive and mitochondrial enzymes. Nrf2 is necessary in tumor protection but is not essential for the lifespan extending properties of CR in outbred mice. Here, we sought to study Nrf2-knockout (KO) mice and littermate controls in male C57BL6/J, an inbred mouse strain. Deletion of Nrf2 resulted in shortened lifespan compared to littermate controls only under ad libitum conditions. CR-mediated lifespan extension and physical performance improvements did not require Nrf2. Metabolic and protein homeostasis and activation of tissue-specific cytoprotective proteins were dependent on Nrf2 expression. These results highlight an important contribution of Nrf2 for normal lifespan and stress response.

Effects of Aryl Hydrocarbon Receptor Deficiency on PCB-77-Induced Impairment of Glucose Homeostasis during Weight Loss in Male and Female Obese Mice.

BACKGROUND: Lipophilic polychlorinated biphenyls (PCBs) accumulate with obesity, but during weight loss, liberated PCBs act as ligands of the aryl hydrocarbon receptor (AhR) to negatively influence health. Previous studies demonstrated that PCB-77 administration to obese male mice impaired glucose tolerance during weight loss. Recent studies indicate higher toxic equivalencies of dioxin-like PCBs in exposed females than males. OBJECTIVES: We compared effects of PCB-77 on weight gain or loss and glucose homeostasis in male vs. female mice. We defined effects of AhR deficiency during weight gain or loss in male and female mice exposed to PCB-77. METHODS: Study design was vehicle (VEH) or PCB-77 administration while fed a high-fat (HF) diet for 12 wk, followed by weight loss for 4 wk. The following groups were examined: male and female C57BL/6 mice administered VEH or PCB-77, female [Formula: see text] and [Formula: see text] mice administered VEH or PCB-77, and male [Formula: see text] and [Formula: see text] mice administered PCB-77. Glucose tolerance was quantified during weight gain (week 11) and loss (week 15); liver and adipose AhR and IRS2 (insulin receptor substrate 2) mRNA abundance, and PCB-77 concentrations were quantified at week 16. RESULTS: PCB-77 attenuated development of obesity in females but not males. During weight loss, PCB-77 impaired glucose tolerance of males. AhR-deficient females (VEH) were resistant to diet-induced obesity. Compared with VEH-treated mice, HF-fed [Formula: see text] females treated with PCB-77 has less weight gain, and [Formula: see text] females had greater weight gain. During weight loss, [Formula: see text] females but not [Formula: see text] males treated with PCB-77 exhibited impaired glucose tolerance. In [Formula: see text] females administered PCB-77, IRS2 mRNA abundance was lower in adipose tissue compared with VEH-treated mice. CONCLUSION: Male and female mice responded differently to PCB-77 and AhR deficiency in body weight (BW) regulation and glucose homeostasis. AhR deficiency reversed PCB-77-induced glucose impairment of obese males losing weight but augmented glucose intolerance of females. These results demonstrate sex differences in PCB-77-induced regulation of glucose homeostasis of mice. https://doi.org/10.1289/EHP4133.

Benefits of Caloric Restriction in Longevity and Chemical-Induced Tumorigenesis Are Transmitted Independent of NQO1.

Caloric restriction (CR) is the most potent nonpharmacological intervention known to both protect against carcinogenesis and delay aging in laboratory animals. There is a growing number of anticarcinogens and CR mimetics that activate NAD(P)H:quinone oxidoreductase 1 (NQO1). We have previously shown that NQO1, an antioxidant enzyme that acts as an energy sensor through modulation of intracellular redox and metabolic state, is upregulated by CR. Here, we used NQO1-knockout (KO) mice to investigate the role of NQO1 in both the aging process and tumor susceptibility, specifically in the context of CR. We found that NQO1 is not essential for the beneficial effects of CR on glucose homeostasis, physical performance, metabolic flexibility, life-span extension, and (unlike our previously observation with Nrf2) chemical-induced tumorigenesis.