Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Ritalin packs punch by elevating norepinephrine, suppressing nerve signal transmissions

31.05.2006


Methylphenidate (Ritalin) elevates norepinephrine levels in the brains of rats to help focus attention while suppressing nerve signal transmissions in the sensory pathways to make it easier to block out extraneous stimuli, a Philadelphia research team has found.



Their report in the Journal of Neurophysiology helps explain how a stimulant aids people with attention deficit and hyperactivity disorders to improve their focus without increasing their motor activity. Methylphenidate, prescribed under the brand name Ritalin, has been used for more than 20 years, mostly in children, to treat attention deficit hyperactivity disorder (ADHD) and attention deficit disorder (ADD). The drug can also help people who don’t suffer either disorder to attend better to a cognitive task.

Despite its wide use, little is known about how the drug, a chemical cousin of amphetamines, produces its therapeutic effects. Researchers want to unlock the mystery of why the drug has the paradoxical effect of decreasing hyperactive behavior and increasing the ability to focus, even though it is a stimulant, said Barry Waterhouse, the study’s senior author.


"We’re developing a series of behavioral and electrophysiological assays for examining the actions of drugs like methylphenidate," Waterhouse said. "If we can show exactly how methylphenidate works, we may be able to produce even more effective drugs and provide a better understanding of the physiology underlying ADHD."

The study, using rats, is the first to document the increase in norepinephrine and suppression of the neuronal response in this sensory pathway of the brain. "Methylphenidate enhances noradrenergic transmission and suppresses mid- and long-latency sensory responses in the primary somatosensory cortex of awake rats," by Philadelphia-based researchers Candice Drouin, University of Pennsylvania; Michelle Page, Thomas Jefferson University; and Barry Waterhouse, Drexel University College of Medicine appears online in the Journal of Neurophysiology, published by The American Physiological Society.

From whiskers to brain

The researchers stimulated rats’ whiskers while recording the activity of the neurons in the sensory pathways that convey this sensation from the whiskers to the cerebral cortex. They compared the rat’s sensory pathway response to the whisker stimulation when receiving two different doses of methylphenidate. They found that both the low and moderate doses of methylphenidate:

  • Elevated norepinephrine in the area of the brain that processes information related to whisker movement. Norepinephrine helps transmit sensory information from the periphery to the brain.
  • Suppressed the long latency phase of the brain’s neuronal response to whisker-related sensory stimuli. Suppression of the sensory neuronal response in this way is believed to help filter extraneous stimuli, Waterhouse explained. With the extraneous stimuli out of the way, the individual is better able to attend to the important stimuli.

In addition, the researchers found that the higher dose caused the rats to increase motor activity, while the lower dose did not.

Scientists still have much to learn about methylphenidate, which has an impact on neural circuits throughout the entire brain, not just the sensory pathway studied in this paper, Waterhouse noted. The changes that occur in this sensory pathway may affect other areas of the brain and changes in other areas of the brain may affect this pathway. In addition to sensory pathways, other scientists are studying how the drug affects cognitive and emotional areas of brain.

Next steps

"This experiment adds to our knowledge of what the drug is doing at the cellular level and gives us a springboard to other studies," Waterhouse said. "One question now is, how does the individual’s perception of what is an important stimulus factor into the equation?"

Researchers in this area keep in touch and share their results, Waterhouse said. One group, for example, is looking at the drug’s effects on dopamine and norepinephrine in the prefrontal cortex, he noted. These results will eventually have to be combined, as changes in one area of the brain are likely to affect other areas.

"We’ve been thinking about this for a long time," Waterhouse said of his research. "We hope to have a good idea of the drug’s action when we put it all together."

One broad question that intrigues researchers is whether ADHD traces back to the same area of the brain as attention deficit disorder, a similar condition but one in which hyperactivity isn’t a symptom.

They also want to know whether Ritalin has any toxic or long-lasting effects, not only for ADHD patients, but also for individuals taking the drug who do not suffer from ADHD or ADD. Methylphenidate use is on the rise among college students who solicit prescriptions from friends or siblings diagnosed with ADHD and use the drug to postpone fatigue and stay alert and focused while studying for exams or completing projects, Waterhouse said.

Christine Guilfoy | EurekAlert!
Further information:
http://www.the-aps.org

More articles from Health and Medicine:

nachricht Biofilm discovery suggests new way to prevent dangerous infections
23.05.2017 | University of Texas at Austin

nachricht Another reason to exercise: Burning bone fat -- a key to better bone health
19.05.2017 | University of North Carolina Health Care

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: Strathclyde-led research develops world's highest gain high-power laser amplifier

The world's highest gain high power laser amplifier - by many orders of magnitude - has been developed in research led at the University of Strathclyde.

The researchers demonstrated the feasibility of using plasma to amplify short laser pulses of picojoule-level energy up to 100 millijoules, which is a 'gain'...

Im Focus: Can the immune system be boosted against Staphylococcus aureus by delivery of messenger RNA?

Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.

Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....

Im Focus: A quantum walk of photons

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....

Im Focus: Turmoil in sluggish electrons’ existence

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...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

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...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

New insights into the ancestors of all complex life

29.05.2017 | Earth Sciences

New photocatalyst speeds up the conversion of carbon dioxide into chemical resources

29.05.2017 | Life Sciences

NASA's SDO sees partial eclipse in space

29.05.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>