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!
Atomic-level motion may drive bacteria's ability to evade immune system defenses
24.04.2017 | Indiana University
Two-dimensional melting of hard spheres experimentally unravelled after 60 years
24.04.2017 | University of Oxford
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
24.04.2017 | Physics and Astronomy
24.04.2017 | Materials Sciences
24.04.2017 | Life Sciences