by Staff Writers
New York NY (SPX) Mar 05, 2012
Exposure to lead wreaks havoc in the brain, with consequences that include lower IQ and reduced potential for learning. But the precise mechanism by which lead alters nerve cells in the brain has largely remained unknown.
New research led by Tomas R. Guilarte, PhD, Leon Hess Professor and Chair of Environmental Health Sciences at Columbia University Mailman School of Public Health, and post-doctoral research scientist Kirstie H. Stansfield, PhD, used high-powered fluorescent microscopy and other advanced techniques to painstakingly chart the varied ways lead inflicts its damage.
They focused on signaling pathways involved in the production of brain-derived neurotropic factor, or BDNF, a chemical critical to the creation of new synapses in the hippocampus, the brain's center for memory and learning.
The study appears online in the journal Toxicological Sciences.
Once BDNF is produced in the nucleus, explains Dr. Stansfield, it is transported as cargo in a railroad-car-like vesicle along a track called a microtubule toward sites of release in the axon and dendritic spines. Vesicle navigation is controlled in part through activation (phosphorylation) of the huntingtin protein, which as its name suggests, was first identified through research into Huntington's disease.
By looking at huntingtin expression, the researchers found that lead exposure, even in small amounts, is likely to impede or reverse the train by altering phosphorylation at a specific amino acid.
The BDNF vesicle transport slowdown is just one of a variety of ways that lead impedes BDNF's function. The researchers also explored how lead curbs production of BDNF in the cell nucleus. One factor, they say, may be a protein called methyl CpG binding protein 2, or MeCP2, which has been linked with RETT syndrome and autism spectrum disorders and acts to "silence" BDNF gene transcription.
The paper provides the first comprehensive working model of the ways by which lead exposure impairs synapse development and function.
"Lead attacks the most fundamental aspect of the brain-the synapse. But by better understanding the numerous and complex ways this happens we will be better able to develop therapies that ameliorate the damage," says Dr. Guilarte.
Study co-authors include J. Richard Pilsner from the University of Massachusetts, Amherst; and Quan Lu and Robert O. Wright of the Harvard School of Public Health.
Columbia University's Mailman School of Public Health
Our Polluted World and Cleaning It Up
Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.
China says most cities fail to meet new air standard
Beijing (AFP) March 2, 2012
China said Friday that two-thirds of its cities currently fail to meet new air-quality standards introduced this week that are based on the pollutants most harmful to health. Under pressure from a worried Chinese public, the government this week issued revised air-quality targets based on the smallest particulates, which make up much of the country's air pollution. Cities will have four ... read more
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2012 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement|