Researchers Describe How Ritalin May Work
May have implications for treating attention-deficit/hyperactivity disorder
TUESDAY, May 30 (HealthDay News) -- Methylphenidate appears to work by elevating norepinephrine levels and suppressing nerve signal transmissions in the sensory cortex of awake rats, which could have implications for producing more effective drugs for treating attention-deficit/hyperactivity disorder, according to a study published online May 10 in the Journal of Neurophysiology.
Candice Drouin, Ph.D., from the University of Pennsylvania in Philadelphia, and colleagues stimulated the whiskers of freely-behaving rats and measured extracellular levels of the neurotransmitter norepinephrine in the somatosensory cortex. They recorded the activity of somatosensory cortical neurons before and after administration of either saline or methylphenidate.
The researchers found that 1 and 5 mg/kg methylphenidate increased the levels of norephinephrine by 64 percent and 101 percent, respectively. Both doses of methylphenidate also suppressed the post-excitatory inhibition and the long-latency phase excitation of somatosensory cortical neurons, which is believed to help filter out extraneous stimuli, according to the researchers. The highest methylphenidate dose caused an increase in locomotor activity.
"This experiment adds to our knowledge of what the drug is doing at the cellular level and gives us a springboard to other studies," co-author Barry D. Waterhouse, Ph.D., of Drexel University College of Medicine in Philadelphia, said in a statement.