Polybrominated Diphenyl Ethers as Endocrine Disruptors of Adipocyte Metabolism

Abstract

HOPPE, ANDREA A., AND GALE B. CAREY. Polybrominated diphenyl ethers as endocrine disruptors of adipocyte metabolism. Obesity. 2007;15:2942-2950. Objective: Obesity is thought to result from poor diet and insufficient exercise. An additional factor may be endocrine-disrupting environmental chemicals that contaminate the air, water, and food supply. We tested the hypothesis that a class of lipid-soluble flame retardant chemicals known to accumulate in adipose tissue, polybrominated diphenyl ethers (PBDEs), disrupts insulin and isoproterenol sensitivity of isolated rat adipocytes. Research Methods and Procedures: Six-week-old Sprague-Dawley rats were gavaged daily with 14 mg/kg body weight (BW) pentabrominated diphenyl ether (penta-BDE) in corn oil (n ϭ 24) or corn oil alone (n ϭ 24). At 2 and 4 weeks of treatment, epididymal fat pad adipocytes were isolated, and isoproterenol-stimulated lipolysis, insulin-stimulated glucose oxidation, and adipocyte size were measured. Results: There was no alteration in adipocyte metabolism after 2 weeks of in vivo penta-BDE treatment, but after 4 weeks of treatment, adipocytes averaged a 30% increase in isoproterenol-stimulated lipolysis and a 59% decrease in insulin-stimulated glucose oxidation, compared with control. There were no differences in average rat BW and adipocyte size between treated and control rats, but plasma total thyroxine level in 2-and 4-week treated rats was 30% of control. Discussion: Daily exposure of rats to 14 mg/kg BW penta-BDE for 4 weeks has no effect on animal or adipocyte size but significantly alters insulin and isoproterenol-stimulated metabolism of isolated adipocytes. These alterations, hallmark features of metabolic obesity, suggest the need for further research on the contribution of lipid-soluble, endocrine-disrupting environmental chemicals to the obesity epidemic.

Chronic zebrafish low dose decabrominated diphenyl ether (BDE-209) exposure affected parental gonad development and locomotion in F1 offspring

“…In general, undernourished or thin fish have a K value of less than 1, and adequately fed fish have a K value of greater than 1. Increased condition factor after chronic exposure to low level of PBDE in our study also suggest a possible link between PBDE developmental exposure and obesity as indicated by earlier studies on rats (Hoppe and Carey 2007). Our observation is also consistent with a recent report on the effect of natural mixtures of persistent organic pollutants (PBDE, PCB, and DDT) on zebrafish development, where increased weight gain and induced expression of steroid hormone and Fig.…”

Endocrine disruptive chemicals: mechanisms of action and involvement in metabolic disorders

“…The investigators conclude that brominated POPs stored in adipose tissue, may be involved in the pathogenesis of diabetes and MetS. In rats, exposure to penta-BDE in vivo for at least 4 weeks increased lipolysis and decreased glucose oxidation, both symptoms characteristic of diabetes and obesity (Hoppe & Carey 2007). …”

Conceptual heuristic models of the interrelationships between obesity and the occupational environment

“…Fat-soluble xenobiotics, such as benzo(a)pyrene (104) and polybrominated diphenyl esters (105), deposit in adipose tissue and have been shown to affect lipolysis and thyroid function in rodents. A complex causal relationship between polychlorinated biphenyls and obesity has been theorized with varying impact of factors, such as degree of chlorination, and time course of exposure as well as gender, in analyses of US and Swedish cohorts (37).…”