It has long been known that psychostimulant drugs have the paradoxical effect of reducing hyperactivity. [Psychostimulant drugs include methylphenidate – known by the trade names Ritalin, Concerta, and Methylin – and methamphetamine]. Since the mid-1950s, millions of children and adults have been prescribed stimulant medications to control attention deficit hyperactivity disorder (ADHD). But for more than seven decades, since the first experiment that gave an amphetamine drug to children diagnosed with behavioral problems, scientists have not known how stimulants work to control hyperactivity.
Now, a researcher at SUNY Downstate Medical Center, working with colleagues in Mexico, has identified the probable mechanism by which certain stimulants accomplish this paradoxical reduction of motor activity. David Erlij, MD, PhD, professor of physiology and pharmacology at SUNY Downstate, and fellow researchers have identified a network of nerve terminals where stimulation of dopamine D4 receptors depresses motor activity. "This network is localized deep in the brain, in the basal ganglia and the thalamus," says Dr. Erlij, "and its responses explain the reduction in motor activity caused by psychostimulants."
The findings were published in a recent edition of the journal, Neuropharmacology, and were conducted in an animal model. Dr. Erlij notes, "When, in 1937, Dr. Charles Bradley administered Benzedrine to a group of children with hyperactivity and learning disorders and discovered that 'fourteen children responded in a spectacular fashion,' a new era of psychopharmacology was inaugurated. Bradley showed, for the first time, that taking a pill could successfully treat a behavioral abnormality. Eventually, this discovery led to the widespread use of psychostimulant drugs in the treatment of ADHD."
"Despite their well established beneficial effects, it was not understood why psychostimulant drugs, which normally amplify the stimulatory responses of dopamine signals, reduce hyperactivity," says Dr. Erlij. "Our results suggest that enhancing dopamine D4 transmission in the basal ganglia and the thalamus is likely part of the mechanism of the therapeutic effects of psychostimulants on ADHD."
Dr. Erlij adds that the therapeutic action of psychostimulants in ADHD suggests that this condition is caused by abnormalities of dopamine signaling in the brain, and that, in ADHD patients, the dopamine D4 receptor gene is abnormal. He concludes, "Now that we know with some precision where calming of hyperactivity is likely taking place in the brain, it may be possible to develop new and better treatment modalities."
SUNY Downstate Medical Center, founded in 1860, was the first medical school in the United States to bring teaching out of the lecture hall and to the patient's bedside. A center of innovation and excellence in research and clinical service delivery, SUNY Downstate Medical Center comprises a College of Medicine, Colleges of Nursing and Health Related Professions, a School of Graduate Studies, a School of Public Health, University Hospital of Brooklyn, and an Advanced Biotechnology Park and Biotechnology Incubator.
SUNY Downstate ranks ninth nationally in the number of alumni who are on the faculty of American medical schools. More physicians practicing in New York City have graduated from SUNY Downstate than from any other medical school.
Ron Najman | EurekAlert!
Could this protein protect people against coronary artery disease?
17.11.2017 | University of North Carolina Health Care
Microbial resident enables beetles to feed on a leafy diet
17.11.2017 | Max-Planck-Institut für chemische Ökologie
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
17.11.2017 | Physics and Astronomy
17.11.2017 | Health and Medicine
17.11.2017 | Studies and Analyses