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May 18, 2005

Contact: Jim Tobin

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Low Doses of Endocrine-Disrupting Chemicals Impair

Glucagon-Releasing Alpha Cells

Report in Environmental Health Perspectives finds

disruption from bisphenol A, others, may lead to

obesity

[RESEARCH TRIANGLE PARK, NC] Even at very low doses,

endocrine-disrupting chemicals (EDCs) that mimic the

action of naturally occurring estrogens impair the

body's secretion of glucagon, according to a study

accepted for publication today by the peer-reviewed

journal Environmental Health Perspectives.

Glucagon is released by alpha cells in the pancreas.

It provides the major counter-regulatory mechanism for

insulin by stimulating the liver to produce glucose

and maintaining proper glucose levels in the blood. It

also has a crucial role in inducing the breakdown of

fat and the release of fatty acids from tissue when

blood glucose is low. Glucose is needed by the body to

produce energy; when glucose metabolism is impaired,

obesity and type 2 diabetes mellitus may result.

Earlier studies found that insulin-releasing beta

cells were affected by low concentrations of the EDCs

bisphenol A (BPA) and diethylstilbestrol (DES); the

present study found a similar impact on

glucagon-releasing alpha cells. The study found that

the EDCs binds to a nonclassical membrane estrogen

receptor and acts the same as naturally occurring

estrogens.

BPA is found in polycarbonate plastic, the lining of

food cans, and dental sealants. A bill introduced

recently in the California legislature seeks to ban

the use of BPA in plastic products made for babies and

toddlers, while the plastics industry maintains that

it is safe. DES is a synthetic estrogen used between

the 1940s and the 1970s to prevent miscarriages. This

study shows the first evidence of a disruption of

pancreatic alpha cells by these endocrine disruptors.

In the study, researchers collected freshly isolated

whole islets of Langerhans, which are the

physiological unit of the endocrine pancreas that

produces both insulin and glucagon. The researchers

evaluated the islets with fluorescent

calcium-sensitive dye using laser scanner confocal

microscopy. While the tests were done in vitro using

extracted cells, the researchers expect the same

levels of BPA and DES to have similar response in

vivo.

This suggests that glucagon levels in the bloodstream

could be affected by low levels of BPA and DES, which

in turn may " connect BPA with obesity through the

disruption of alpha cells, " said study coauthor Angel

Nadal.

The lead author of the study was Paloma

Alonso-Magdalena of the Institute of Bioengineering at

University in Alicante, Spain. Other

authors included Nadal, Ouahiba Laribi, Ana B. Ropero,

Esther Fuentes, Cristina Ripoll, and Bernat Soria.

Funding sources for the research as reported by the

authors included grants from the Spanish Ministry of

Education and Science and the Instituto de Salud

III. The article is available free of charge at

http://ehp.niehs.nih.gov/docs/2005/8002/abstract.html.

EHP is published by the National Institute of

Environmental Health Sciences, part of the U.S.

Department of Health and Human Services. EHP is an

Open Access journal. More information is available

online at http://www.ehponline.org/.

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