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!
Discovery of a Key Regulatory Gene in Cardiac Valve Formation
24.05.2017 | Universität Basel
Carcinogenic soot particles from GDI engines
24.05.2017 | Empa - Eidgenössische Materialprüfungs- und Forschungsanstalt
Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.
In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...
24.05.2017 | Event News
23.05.2017 | Event News
22.05.2017 | Event News
24.05.2017 | Physics and Astronomy
24.05.2017 | Physics and Astronomy
24.05.2017 | Event News