Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Read your shampoo’s label: Study finds common ingredient stunts developing neurons of rats

06.12.2004


An antimicrobial agent found in many shampoos and hand lotions and widely used in industrial settings inhibits the development of particular neuron structures that are essential for transmitting signals between cells, according to a University of Pittsburgh study presented today at Cell Biology 2004, the 44th annual meeting of the American Society for Cell Biology. The meeting is being held Dec. 4 – 8 at the Washington Convention Center.

Prolonged exposure to low levels of methylisothiazolinone (MIT) restricted growth of axons and dendrites of immature rat nerve cells in culture, apparently by disengaging the machinery of a key enzyme that is activated in response to cell-to-cell contact, and may have potentially damaging consequences to a developing nervous system, the researchers report. "While more research is needed to determine what effect MIT would have in rodent models, both at the cellular level and to a developing nervous system, our results thus far suggest there is potential that everyday exposure to the chemical could also be harmful to humans. I would be particularly concerned about occupational exposure in pregnant women and the possibility of risk to the fetus," said senior author Elias Aizenman, Ph.D., professor of neurobiology at the University of Pittsburgh School of Medicine.

Dr. Aizenman became interested in MIT as an offshoot to his primary area of research on the mechanisms of neuronal cell death. The first he heard of the chemical was when its name came up in a literature search for compounds with specific chemical properties that he thought would incite a particular cell death pathway he recently had identified. As it turned out, MIT activated a different, novel pathway, but Dr. Aizenman remained intrigued, in large part because of the considerable lack of scientific data about a compound that he came to realize was listed on numerous consumer product labels and was very widely used in industry.



As an antimicrobial agent, or biocide, MIT and related compounds kill harmful bacteria that like to grow near moisture or water. As such, they often are found in personal care products, as well as in water-cooling systems and at factories that require water for manufacturing. Since learning about MIT, Dr. Aizenman has not found any published neurotoxicity reports, or concrete data in any public documents filed with the Environmental Protection Agency.

The first set of studies he and his team published in 2002 in The Journal of Neuroscience involved acute exposure to mature rat neurons. They reported that 10-minute exposure at a high concentration – roughly 100 times the dose used in their current study – was lethal to these cells.

To understand what effect chronic exposure would have on immature, developing neurons, the researchers kept cells in a media solution containing low concentrations of MIT for 18 hours. In a standard culture, an immature neuron will in such time develop an axon, the extension from the cell body used for sending signals to other cells, and several dendrites, elaborate projections that receive incoming information. But after exposure to MIT, the cells had few, if any, axons and dendrites, with the inhibition of their growth being dose-dependent, reported Kai He, Ph.D., a postdoctoral fellow working with Dr. Aizenman who presented the data at Cell Biology 2004.
Additional studies revealed that MIT significantly hindered tyrosine phosphorylation, a process that initiates molecular events during cell-to-cell contact, and that a particular protein enzyme was its target. This enzyme, focal adhesion kinase (FAK), is known to be important for outgrowth of axons and dendrites as well as necessary for cell signaling. But to kick into action, FAK must undergo tyrosine phosphorylation, whereby collections of molecules called phosphate groups are added to FAK’s sequence of amino acids. Like all proteins, FAK is comprised of a unique sequence of some 20 amino acids, including tyrosine, so any change, such as through phosphorylation, essentially changes its function. To pinpoint the exact site along FAK’s sequence where tyrosine phosphorylation was being inhibited, the researchers had to determine which of its tyrosines were targeted by MIT. Digging further, they found that one tyrosine in particular (amino acid 576 in the protein sequence) was more substantially affected by MIT, an indication that this particular amino acid residue is important for axon and dendrite growth and development.

"Since we know FAK to be highly expressed in the nerve tissue during brain development, this study suggests that phosphorylation of tyrosine 576 may be critical for axon and dendrite outgrowth," Dr. He reported.

The authors, who also included Carl F. Lagenaur, Ph.D., associate professor of neurobiology at the University of Pittsburgh School of Medicine, plan additional research to further understand the molecular mechanisms underlying MIT’s neurotoxic effect on cells, as well as studies involving whole animals. They are hopeful that their work will stimulate additional research by other groups as well as bring heightened awareness about the potential risks from human exposure.

"This chemical is being used more and more extensively, yet there have been no neurotoxicity studies in humans to indicate what kind and at what level exposure is safe. I realize it’s a big leap to suggest there may be a parallel between environmental exposure and the noticeably higher rates of diagnosed childhood developmental disabilities, but I would caution that based on our data, there very well could be neurodevelopmental consequences from MIT. Clearly, more study is needed, with both scientists and government regulators equally engaged," added Dr. Aizenman.

Lisa Rossi | EurekAlert!
Further information:
http://www.upmc.edu

More articles from Studies and Analyses:

nachricht Innovative genetic tests for children with developmental disorders and epilepsy
11.07.2018 | Christian-Albrechts-Universität zu Kiel

nachricht Oxygen loss in the coastal Baltic Sea is “unprecedentedly severe”
05.07.2018 | European Geosciences Union

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

A smart safe rechargeable zinc ion battery based on sol-gel transition electrolytes

20.07.2018 | Power and Electrical Engineering

Reversing cause and effect is no trouble for quantum computers

20.07.2018 | Information Technology

Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern

20.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>