Navigation Links
Low Doses Of Arsenic Have Broad Impact On Hormone Activity – Says A Researc

Dartmouth Medical School investigators are learning more about how low doses of arsenic, such as the levels found in drinking water in many areas of the United States//, affect human physiology. In a paper published online on Dec. 2 in the journal Chemical Research in Toxicology, the researchers report that three different steroid hormones all show similar responses to arsenic, suggesting a broader effect and a common mechanism of arsenic on how these hormones function.

"Since most of the health consequences of exposure to arsenic - various cancers, diabetes, heart and vascular disease, reproductive and developmental effects, etc. - involve these same steroid receptors, we think that disruption of their normal function could explain, in large part, how arsenic can influence so many disease risks," says Joshua Hamilton, one of the authors on this study and the director of the Center for Environmental Health Sciences at Dartmouth and Dartmouth's Superfund Basic Research Program on Toxic Metals.

Hamilton's laboratory had earlier found that arsenic disrupts the activity of the glucocorticoid receptor, and this follow up study considered the progesterone and mineralocorticoid receptors, which regulate a wide range of biological processes. This work was done in collaboration with Jack Bodwell, the lead author on this paper and a research associate professor of physiology at Dartmouth Medical School.

Hamilton, Bodwell, and their team found that arsenic appears to suppress the ability of all three of these critical receptors to respond to their normal hormone signals. Chemicals that disrupt steroid hormone receptor signaling are called endocrine disruptors, and this study provides further evidence that arsenic, a metal, does not behave like other endocrine disruptors such as pesticides.

"Arsenic does not activate these receptors, as some endocrine disruptors do, by mimicking the natural hormone, nor does it block the ability of the n ormal hormones to activate their specific receptor, as most other endocrine disruptors do," says Hamilton, who is also a professor of pharmacology and toxicology at Dartmouth Medical School. "Nor does it affect the ability of the hormone-activated receptor to move to the nucleus of the cell or to bind to DNA to initiate gene expression. Yet, somehow arsenic still strongly affects the ability of these hormone-activated receptors to regulate gene expression. There's still a lot more to learn."

The study also looked into the effects of different levels of arsenic on these receptors. At very low doses (comparable to what is found in drinking water at the current and previous U.S. regulatory limits, in the range of 5-50 ppb) arsenic enhances hormone-stimulated gene expression, by two- to three-fold. At slightly higher doses (in the range of 50-200 ppb, commonly found in drinking water from contaminated wells in New Hampshire and elsewhere in the U.S.) arsenic has the exact opposite effect, strongly and almost completely inhibiting hormone-stimulated gene expression by these receptors. This non-conventional dose-response suggests that arsenic might have very different biological effects at the lower and higher doses.

"Elucidating these complex biological effects of arsenic on hormone signaling at different doses will be critical to our overall understanding of how arsenic influences human health, and should be considered as an important component of determining the overall disease risk of people who are exposed to arsenic in their drinking water, " says Hamilton.

The work is funded by grants to Dartmouth collaborators Hamilton and Bodwell from the National Institute of Environmental Health Sciences, a component of the National Institutes of Health. Both researchers are members of the NIEHS-funded Superfund Basic Research Program at Dartmouth and Dartmouth's Center for Environmental Health Sciences. Co-authors on the study include Julie A. Go sse, and Athena P. Nomikos, both of Dartmouth and both recipients of training fellowships from Dartmouth's Superfund Basic Research Program.



Source-Eurekalert
SRI
'"/>




Related medicine news :

1. India To Procure 1 Million Doses Of Tamiflu
2. Small Doses Of Radiation Can Help Certain Lung Cancer Patients
3. Polyphenols in Green Tea Cause Liver Damage At High Doses
4. Pre-eclampsia Pronounced With Intake of Vitamins in Large Doses
5. Stronger Doses Fewer Administration for Breast Cancer
6. High Doses Of Common Pain killers Can Double The Chances Of Heart attack
7. Even Normal Doses Of Tylenol Could Damage Liver
8. Allergic Individuals Should Carry Two Doses Of EpiPen Says Quebec Coroner
9. Reduced Doses of Medication Beneficial to Preschoolers with ADHD
10. Low Doses of Anti-Depressant May Help PMS
11. High Doses of Lithium-Like Drugs May Impair Neuronal Function
Post Your Comments:
*Name:
*Comment:
*Email:


(Date:2/12/2016)... ... ... CDRH Enforcement Trends: , Back to the Future , Feb. 25, 2016 — 11:00 a.m. ... “Those who don’t learn from history are doomed to repeat it.” , An analysis of ... year. But that takes time. , Take a close look at the warning letters ...
(Date:2/12/2016)... ... February 12, 2016 , ... T.E.N., ... have closed for the ISE Southeast Awards 2016. Finalists and winners of the ... ISE® Southeast Executive Forum and Awards Gala on March 15, 2016 at the ...
(Date:2/12/2016)... ... February 12, 2016 , ... AssureVest Insurance Group, a locally owned insurance firm ... that will raise funds earmarked to purchase computers and software for Mrs. Harrison’s 2nd ... school is in a low-income area and has more than 60 2nd and 3rd ...
(Date:2/12/2016)... , ... February 12, 2016 , ... Donor Network West, ... California and Nevada, announced a partnership with San Ramon Regional Medical Center. Under the ... hospital’s facilities as a way to accommodate a more certain time frame for donor ...
(Date:2/12/2016)... ... February 12, 2016 , ... ... foods choices that promote eye health. These articles generally list between five and ... health advocate Sharon Kleyne endorses every one of these lists and believes that ...
Breaking Medicine News(10 mins):
(Date:2/11/2016)... -- Walgreens has committed to provide drug disposal kiosks ... D.C. as part of a program to combat ... advocacy organization As You Sow. Conrad MacKerron , ... on to unneeded drugs because they lack easily accessible collection ... --> Conrad MacKerron , Senior Vice President at As ...
(Date:2/11/2016)... Feb. 11, 2016 Potrero Medical, Inc., the developer ... announce the appointment of George M. Rapier, III , ... Antonio, TX , WellMed is one of the nation,s ... and HMO members in Texas and ... out of his own internal medicine practice, he has been ...
(Date:2/11/2016)... WILMINGTON, N.C. , Feb. 11, 2016 /PRNewswire/ ... a leading provider of custom manufacturing and development ... announces expanded sterile fill-finish capabilities and capacity in ... Substantial growth in demand has driven several recent ... in 2001 it had one filling line with ...
Breaking Medicine Technology: