Progress 10/01/10 to 09/30/14
Outputs
Target Audience: The following 1200 scientists, students and community members - locally, nationally and internationally - learned about this research project: 170 UNH undergraduate students in NUTR 750 and NUTR 401; 20 UNH graduate students and faculty attending Integrative Physiology seminar; 150 attendees at the UNH Undergraduate Research Conference; 150 attendees at the UNH Graduate Research Conference; and some 700 scientists, graduate students and undergraduate students at regional, national and international professional meetings. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? Both undergraduate and graduate research training was provided by this project. This one-on-one training with a mentor included proposal writing, learning laboratory skills and techniques, methods development and trouble-shooting, data and statistical analysis, report writing and oral presentation skills. How have the results been disseminated to communities of interest? Information from these projects was disseminated to the academic and lay communities through six presentations: (1) invited presentation by Gale Carey on “Meal-feeding Rodents and Toxicology Research: Time Matters” at the annual meeting of the Swiss Laboratory Animal Meeting, Lausanne, Switzerland; (2) invited presentation by Gale Carey on “Metabolic Disruption by Flame Retardants: A Fat and Liver Story” to the Universite´ Paris Decartes, Paris, France; (3) presentation by Kylie Cowens at UNH’s Integrative Physiology seminar series, “Use of transcriptome profiling for the study of environmental chemicals”; (4) presentation by Kylie Cowens at the UNH Graduate Research Conference, “Polybrominated Diphenyl Ether (PBDE) disruption of liver metabolism”, (5) presentation by Kylie Cowens at the 31st annual New England Endocrine Conference, “Flame retardants disrupt adipose tissue PEPCK activity and (6) presentation by Kylie Cowens at the 14th annual workshop on Brominated and Other Flame Retardants, “Polybrominated Diphenyl Ether (PBDE) disruption of liver metabolism”. Information from these projects was disseminated to the scientific community via two abstracts. Seven undergraduates and one graduate student were involved in this project, and the results were incorporated into two UNH courses: NUTR 401 and NUTR 750. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
The global obesity epidemic continues to escalate. Although diet and exercise play a role in this epidemic, scientists admit that there may be other factors involved. One possibility is environmental chemicals that are not intended to enter the human body, but do. Indeed, a growing body of evidence suggests certain chemicals could disrupt the body’s metabolism and contribute to the obesity epidemic. For the past 4 years, our laboratory comprising over fifteen undergraduate and graduate students, has collaborated with researchers from 6 universities/industries across the country, to examine persistent organic environmental chemicals that could impact human health. We’ve learned that many of these chemicals, like DDT and PCBs, are present in the blood of our undergraduate students. We’ve also learned that one class of flame retardants – polybrominated diphenyl ethers, or PBDEs – affect blood levels of glucose and fat metabolites in the laboratory rat, suggesting a significant disruption in liver metabolism. Looking deeper, our findings suggest that a key metabolic enzyme named phosphoenolpyruvate carboxykinase, or PEPCK, could be the source of this disruption. We’ve learned that PBDEs suppress liver PEPCK activity by about 40%, reduce the amount of PEPCK protein by about 25% and reduce the activity of a specialized liver metabolic pathway by about 40%. Taken together, the impact of these findings is a change in knowledge: our presentations to undergraduate students, graduate students, scientists, and the public, have raised awareness of the potential for environmental chemicals to impact human health. Four projects were conducted this year. The first project tested the hypothesis that PBDEs perturbed serum physiological markers of glucose and lipid metabolism. To test this hypothesis, male Wistar rats were administered 14mg PBDEs/ kg BW or corn oil alone (n=8 per group). After 28 days and a 48-hour fast, blood from PBDE-treated rats had significantly higher ketones, but lower glucose and triglycerides, compared to controls. This suggested that livers of PBDE-treated rats were unable to maintain glucose and lipid homeostasis. The second project tested the hypothesis that the messenger RNA for liver PEPCK – a key enzyme in glucose and lipid metabolism – is reduced by PBDE-treatment. Liver samples taken from project one rats was subjected to transcriptome profiling and PEPCK messenger was found to be no different between control and treated rat liver. This suggested that the amount of PEPCK protein, not the amount of PEPCK messenger RNA, must be responsible for the suppression in PEPCK activity noted by Nash et al (2013). The third project validated this suspicion by testing the hypothesis that hepatic PEPCK protein levels and glyceroneogenesis rates were lower in PBDE-treated rats compared to controls. Male Wistar rats were administered 14mg PBDEs/ kg BW or corn oil alone (n=6 per group). After 28 days and a 48-hour fast, livers were removed for Western blot analysis of PEPCK protein and in vitro measurement of glyceroneogenesis. Both PEPCK protein and glyceroneogeneis rates were reduced by 25% and 42%, respectively, suggesting that a suppression in PEPCK protein reduces PEPCK activity, which reduces metabolic flow through glyceroneogenesis. The fourth project explored whether the induction in the drug-metabolizing enzyme CYP3A, which detoxifies PBDEs but also inactivates Vitamin D, could promote a Vitamin D deficiency. We showed that PBDEs induce liver CYP3A activity some 30-fold, but didn’t know if this induction would alter Vitamin D status. To test this hypothesis, young rats were fed a marginally-Vitamin D deficient diet. After 28 days, rats were divided into 2 groups: one group was given 7 mg/kg PBDE, while the other group was given corn oil as control. After 28 days, serum levels of Vitamin D metabolites was measured. No differences were found in Vitamin D metabolites, suggesting that PBDEs do not promote Vitamin D deficiency in the rat model. Our work continues to establish the possible health consequences of environmental chemical exposure, which includes a liver-centered perturbation in glucose and lipid metabolism. The findings from this work not only increase public awareness about environmental chemicals and human health but have the capacity to impact future policy on environmental chemicals.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2014
Citation:
Polybrominated diphenyl ether (PBDE) disruption of liver metabolism , 14th annual workshop on Brominated and Other Flame Retardants, Indianapolis, IN
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2013
Citation:
Flame retardants disrupt adipose tissue PEPCK activity , 31st New England Endocrinology Conference, Durham, NH
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2014
Citation:
Polybrominated diphenyl ether (PBDE) disruption of liver metabolism , UNH Graduate Research Conference, Durham, NH
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Progress 10/01/12 to 09/30/13
Outputs
Target Audience: The following scientists, students and community members learned about this research project: over 300 medical professionals attending the NH Medical Society meeting, 80 community members attendingpresentation to the community, 80 undergraduate students in NUTR 750, 40 students attending the Honors Night PechaKucha, and 30 graduate, undergraduate and faculty attending the Integrative Physiology seminar. Changes/Problems: An additional objective has been added: toevaluate the potential for PBDEs to promote Vitamin D deficiency. This objective grew from our observation that PBDEs induced CYP3A, a drug-metabolizing enzyme that also is responsible for inactivating Vitamin D. What opportunities for training and professional development has the project provided? Both undergraduate and graduate research training was provided by this project. This one-on-one training with a mentorincluded proposal writing, learning laboratory skills and techniques, methods development and trouble-shooting, data and statistical analysis, and report writing. How have the results been disseminated to communities of interest? Information from these projects was disseminated to the academic and lay communities through four presentations: (1) invited presentation by Gale Carey on “Environment and Obesity: Maybe it’s not just what we eat” at the annual meeting of the NH Medical Society, Portsmouth, NH; (2) invited presentation by Gale Carey to the RiverWoods Retirement Community, “Environmental Chemicals, Obesity and Diabetes”; (3) presentation at UNH’s Integrative Physiology seminar series by Kylie Cowens, “A tale of two PEPCKs”; (4) invited presentation by Gale Carey at UNH’s PechaKucha Honors Night. Information from these projects was disseminated to the scientific community via one peer-reviewed publication. Two undergraduates and one graduate student were involved in this project, and the results were incorporated into two UNH courses: NUTR 401 and NUTR 750. What do you plan to do during the next reporting period to accomplish the goals? We plan to evaluate the consequences of the PBDE administration on rat physiology, metabolism, Vitamin D status and gene expression in liver and adipose tissue.
Impacts
What was accomplished under these goals?
Obesity is a global, growing epidemic recognized by the USDA.At the biochemical level there is a growing body of experimental evidence suggesting certain environmental chemicals - or "obesogens" -could disrupt the body's metabolism and contribute to the obesity epidemic. Because disruptions in glucose metabolism and increases in oxidative stress are associated with weight gain, the proposed research will assess the role of putative obesogens in the obesity epidemic. Three projects were conducted this year. The first project tested the hypothesis that one class of brominated flame retardants – polybrominated diphenyl ethers, or PBDEs – suppress the activity of PEPCK in adipose tissue, which could lead to insulin resistance. To test this hypothesis, male Wistar rats were administered 14mg PBDEs/ kg BW or corn oil alone (n=8 per group). After 28 days, PEPCK was measured and found to be significantly suppressed by 16% (first study) and 25% (second study) in adipose tissue from PBDE-treated vs. controls. The second project validated that liver CYP3A, a cytochrome P450 drug-metabolizing enzyme responsible for detoxifying PBDEs, is induced by in vivo PBDE treatment. Twenty-eight days of PBDE treatment caused a 30-fold induction of liver CYP3A activity compared to corn oil treatment. The third project tested the hypothesis that the induction of CYP3A by PBDEs promotes the inactivation of Vitamin D, thereby promoting Vitamin D deficiency. Livers from control and PBDE-treated rats were removed and their ability to metabolize Vitamin D to its inactive form is currently being assessed. Our work continues to establish the possible health consequences of environmental chemical exposure. Our findings in rats suggest that PBDEs suppress a key enzyme in glucose and lipid metabolism is adipose tissue as well as liver. The findings from these three projects not only increase public awareness about environmental chemicals and human health but have the capacity to impact future policy on environmental chemicals.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Nash, Jessica T., Szabo, D.T., Carey, Gale B. (2013) Polybrominated Diphenylethers alter hepatic phosphoenolpyruvate carboxykinase inzyme kinetics in male Wistar rats: Implications for lipid and glucose metabolism. J. Toxicol. Env. Health, Part A., 76:142-156.
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Progress 10/01/11 to 09/30/12
Outputs
OUTPUTS: Three projects were conducted this year. The first project tested the hypothesis that one class of brominated flame retardants - polybrominated diphenyl ethers, or PBDEs - promote the accumulation of lipids in liver tissue. The second project extended these findings by examining if adipose tissue contributes to fatty liver by its inability to esterify fatty acids due to low activity of phosphoenolpyruvate carboxykinase (PEPCK). The assay for PEPCK in adipose tissue was set up and optimized in the Carey lab after a visit to the Hansen lab at Case Western Reserve University. The third project explored the relationship between serum levels of persistent organic pollutants and biochemical, clinical, and anthropometric health markers in college students. Six mL of blood was drawn from each of 19 female students and analyzed for DDT, DDE, PCBs and dioxins via mass spectrometer. Health markers including blood cholesterol, glucose and triglyceride levels, blood pressure, height, weight, BMI and waist circumference were also measured. Information from these projects was disseminated to the academic and lay communities through four presentations: (1) invited presentation by Gale Carey on "Environmental Chemicals, Obesity and Diabetes" at the NH Dietetics Association annual meeting, Rochester, NH; (2) poster presentation by Michaela Barhite at the UNH Undergraduate Research Conference "Do Environmental Chemicals Predict Weight Status in College-Aged Females"; (3) poster presentation by Whit Durant at the UNH Undergraduate Research Conference "The Effect of PBDEs on Lipid Accumulation in Liver Tissue", and (4) poster presentation by Jessica Nash at Experimental Biology meetings, San Diego 2012, "The effect of in vivo PBDE treatment on hepatic phosphoenolpyruvate carboxykinase (PEPCK) enzyme kinetics in male Wistar rats". Information from this project was disseminated to the scientific community via one abstract, one senior thesis, one Honors Thesis, and two peer-reviewed publications. Two undergraduates and one graduate student were involved in this project, and the results were incorporated into two UNH courses: NUTR 401 and NUTR 720. PARTICIPANTS: The following students, collaborators and industries participated in this project: undergraduates Michaela Barhite and Whit Durant; graduate student Kylie Cowens; collaborator Dr. David Szabo, PhD. (EPA); collaborator Phil Bassignani and Fluid Management Systems, Inc., Watertown, MA; the Richard Hansen laboratory at Case Western Reserve University for training in measuring adipose tissue PEPCK. TARGET AUDIENCES: The following scientists, students and community members learned about this research project: hundreds of scientists attending Experimental Biology meetings in San Diego, CA; 400 students in NUTR 400 class as a result of Michael Barhite describing her research project and recruiting student participation; 400 attendees at the UNH Undergraduate Research Conference to view 2 undergraduate posters about this project; 70 undergraduate students in NUTR 720 and 50 dietitians attending the annual NH Dietetics Association meeting, to hear about "Environmental Chemicals, Obesity and Diabetes". PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Our work continues to establish the possible health consequences of environmental chemical exposure, highlights the fact that college students have significant body burdens of these chemicals, and underscores the need for continued research. Our findings in rats suggest that PBDEs may contribute to fatty liver. Rats were tube fed with 14mg PBDEs/ kg BW or corn oil alone (n=8 per group). After 28 days, the percentage of total liver lipids was 20% higher (p<0.05) in livers of treated rats compared to controls. Our findings in college students revealed a significant inverse relationship between serum PCB levels and triglycerides (p<0.05) and warrants future research on the role of environmental chemicals in altering health status of college students. The findings from these three projects not only increase public awareness about environmental chemicals and human health but have the capacity to impact future policy on environmental chemicals.
Publications
- Carey, Gale B. and Merrill, Lisa C. (2012) Meal-feeding rodents and toxicology research. Chem. Res. Toxicol. 25:1545-1550.
- Nash, Jessica T., Szabo, D.T., Carey, Gale B. (2012) Polybrominated Diphenylethers alter hepatic phosphoenolpyruvate carboxykinase inzyme kinetics in male Wistar rats: Implications for lipid and glucose metabolism. J. Toxicol. Env. Health, Part A., in press.
- Nash, Jessica T. and Carey, Gale B. (2012) The effect of in vivo PBDE treatment on hepatic phosphoenolpyruvate carboxykinase (PEPCK) enzyme kinetics in male Wistar rats. FASEB J. 26:567.2 (abstract).
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Progress 10/01/10 to 09/30/11
Outputs
OUTPUTS: The metabolic effects of two classes of brominated flame retardants - polybrominated diphenyl ethers (PBDEs) and hexobromocyclododecane (HBCDs) - were evaluated in the rat model. In the first study, the effects of PBDEs on the activity of a key gluconeogenic enzyme, phosphoenolpyruvate carboxykinase (PEPCK), were examined. Forty-eight, one month-old, male Wistar rats were gavaged daily with corn oil or corn oil containing 14 mg/kg DE-71 (a commercial mixture of PBDEs) for 3, 14 or 28 days (N = 8 per group). At each time point, fasting plasma glucose, insulin and C-peptide were measured and hepatic PEPCK and cytochrome P450 (CYP) enzyme activities were assayed. PBDE treatment significantly decreased PEPCK Vmax (micromol/min/g liver weight) by 22% (3 days) to 44% (28 days). CYP1A, -2B and -3A Vmax were increased by 6-, 6- and 30-fold, respectively, in treated rats compared to control. There was a significant inverse and temporal correlation (r = -0.74) between CYP3A and PEPCK Vmax for the treatment group. Fasting plasma glucose, insulin and C-peptide levels were unaffected by treatment, but the glucose:insulin ratio tended (P=0.07) to be higher in treated compared to control rats. Data from the first study suggest that 3 days of in vivo PBDE treatment is sufficient to compromise liver glucose metabolism and 28 days of treatment may influence insulin sensitivity. In the second study, two groups of female rats (n=6 per group) were gavaged with 100 mg mixed diastereomer HBCD in corn oil/kg BW/day; the control group was gavaged with an equivalent volume of corn oil each day. Treatment continued for 4 weeks. After four weeks, rats were euthanized, livers removed, and hepatocytes isolated. Hepatocytes were incubated either in buffer, alanine (20 mM), glycerol (20 mM), or lactate (20 mM) and pyruvate (2 mM) for 60 minutes and glucose production measured.Results from the second experiment revealed that HBCD treatment of rats caused a 30% increase in liver weight (7.0 vs. 9.1 g, for control vs. treatment, n=6, P<0.05) and a 22% increase in liver weight as a percent of final body weight (3.92 vs. 4.79%, for control vs. treatment, n=6, P<0.05). Gluconeogenesis with alanine as a precursor tended to be higher in hepatocytes from treated rats (0.44 vs. 1.16 nmol glucose/mg cells, control vs. treatment, n=4, P=0.11) while gluconeogenesis from lactate/pyruvate metabolic precursors tended to be lower in hepatocytes from treated rats (1.40 vs. 1.20 nmol glucose/mg cells, control vs. treatment, n=4, P=0.17)/ Outputs from this project include an undergraduate Honors Thesis, a Masters Thesis, and a poster presentation "Does hexabromocyclododecane decrease gluconeogenesis in rat liver" at the 12th Brominated Flame Retardant Workshop, Boston, MA, June 2011. PARTICIPANTS: Two undergraduate students, Allison McQueen and Christina Auger, and one graduate student, Masters candidate Jessica Nash, participated in this research over the past year. Allison presented her research findings at the UNH Undergraduate Research Conference and at the 10th Brominated Flame Retardant workshop. Jessica successfully defended her MS research to the UNH Department of Molecular, Cellular and Biomedical Sciences. TARGET AUDIENCES: Ninety students in an undergraduate nutrition class, twenty students in a public health class, and one hundred fifty attendees of the 10th Brominated Flame Retardant workshop were informed about this research. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The finding that gluconeogenesis from lactate/pyruvate tended to be lowered by HBCD treatment is consistent with published findings using phenobarbital. However, the finding that gluconeogenesis from alanine tended to increase in hepatocytes from HBCD-treated rats contrasts with published findings. These data suggest that the modes of action of phenobarbital and HBCD on liver gluconeogenesis may be distinct; however, they suggest that HBCD may affect the gluconeogenesis pathway in the liver.
Publications
- Nash, Jessica (2011) The effect of in vivo PBDE treatment on hepatic phosphoenolpyruvate carboxykinase (PEPCK) enzyme kinetics in male Wistar rats, MS Thesis.
- McQueen,Allison B. and Carey, Gale B.(2011) The effect of hexabromododecane treatment of rats on hepatocyte gluconeogenesis. 12th Workshop on Brominated and Other Flame Retardants Boston, MA
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