Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Evidence links cocaine abuse and Parkinson’s disease

14.12.2005


Laboratory studies show that cocaine causes changes in brain that increase vulnerability to environmental toxins in both adults and in offspring who were exposed to cocaine before birth, according to St. Jude



Adults who abuse cocaine might increase their risk of developing Parkinson’s disease (PD), and pregnant women who abuse cocaine could increase the risk of their children developing PD later in life, according to results of laboratory studies performed by investigators at St. Jude Children’s Research Hospital.

The study’s findings are important because there are currently more than 2 million cocaine abusers in the US today, the researchers said. Many individuals who abused the drug during the height of the cocaine abuse epidemic of the 1970s and 1980s are now entering their older years, when symptoms of PD are likely to emerge.


A report on this work appears in the online, prepublication edition of Neuroscience.

The St. Jude team showed in laboratory models of both the adult and fetal brains that exposure to cocaine alters the nerve bodies in the region of the brain called the substantia nigra. This damage made the neurons more susceptible to MPTP, a toxin known to cause symptoms of PD.

The nigrostriatal system is a pathway of nerves that originates in the area called the substantial nigra pars compacta (SNpc) and spreads out into certain other parts of the brain. The neurons in the SNpc make the neurotransmitter dopamine, and degeneration of this area and the nigrostriatal system is one of the major hallmarks of PD, according to Richard Smeyne, Ph.D., an associate member of the St. Jude Department of Developmental Neurobiology.

"Our findings suggest that cocaine makes the SNpc in adults susceptible to further damage from environmental toxins that can cause Parkinson’s disease," Smeyne said "The findings also strongly suggest that women who abuse cocaine during pregnancies put their children at an increased risk for developing Parkinson’s disease."

Cocaine is also known to disrupt the normal function of the dopamine transporter, a protein that sweeps up dopamine from the synapse after it stimulates its target nerve, he added. Disruption of this process causes an abnormal rise in the concentration of dopamine in the synapse. This poses a threat to the brain because dopamine can interact with other chemicals to become a free radical--a highly reactive molecule that can damage tissue. "So the increase in the amount of dopamine in the synapse can lead to high levels of destructive free radicals that damage this area of the brain," Smeyne said.

The St. Jude team studied the effect of cocaine in laboratory models that are resistant to a toxin called MPTP, which is known to cause PD-like damage in the brain. The investigators used this model to determine if cocaine altered the nigrostriatal system so it became sensitive to MPTP.

Exposure to cocaine did not affect the number of cells in the SNpc of adult and fetal models but did make them more susceptible to damage from MPTP, the researchers reported. Furthermore, in both the adult and fetal models, cocaine exposure disrupted the balance between the proteins that sweep up dopamine from the synapses and bring them into the pre-synaptic cell and the sacs that sequester (package) them in those neurons. Specifically, the ratio of transporter proteins to the sacs increased by 27 percent in the fetal models and by 28 percent in adult models, the investigators reported.

"This means that the transporter proteins were pumping more dopamine back into the pre-synaptic nerves than could be repackaged in those sacs," Smeyne explained. "And that was allowing dopamine to accumulate freely inside the cell, where it can produce free radicals. That kind of stress can make the nerve susceptible to other environmental toxins. Smeyne theorizes that toxins that enter the body could then cause damage in the substantia nigra that leads to Parkinson’s disease.

The study also found that cocaine exposure decreased the number of certain dopamine receptors called D2 autoreceptors. These autoreceptors control the production and/or release of dopamine; when they are in short supply, the level of dopamine in the synapse rises. This in turn leaves the synapse (connection between nerves) vulnerable to free radical damage, according to Smeyne.

"Based on these findings it might not be surprising to see a rise in the number of cases of Parkinson’s disease in the next 10 or 20 years or so," said Steven A. Lloyd, Ph.D. the first author of the article. Lloyd was a graduate student in Smeyne’s laboratory during this work and is now an assistant professor of psychology at Rhodes College in Memphis.

Smeyne’s team previously published their findings that exercise confers protection on mice that otherwise would have developed PD following treatment with MPTP; and that the rise in the level of GDNF appeared to be key to that protection. The article appeared in the special October 2004 issue of Molecular Brain Research called "Molecular Aspects of Parkinson’s Disease."

Carrie Strehlau | EurekAlert!
Further information:
http://www.stjude.org

More articles from Health and Medicine:

nachricht Team discovers how bacteria exploit a chink in the body's armor
20.01.2017 | University of Illinois at Urbana-Champaign

nachricht Rabies viruses reveal wiring in transparent brains
19.01.2017 | Rheinische Friedrich-Wilhelms-Universität Bonn

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

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

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Helmholtz International Fellow Award for Sarah Amalia Teichmann

20.01.2017 | Awards Funding

An innovative high-performance material: biofibers made from green lacewing silk

20.01.2017 | Materials Sciences

Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery

20.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>