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From the National Institute on Drug Abuse, National Institutes of Health : Recent research at Brookhaven National Laboratory may begin to explain how methylphenidate helps people with ADHD. The researchers used positron emission tomography (PET - a noninvasive brain scan) to confirm that administering normal therapeutic doses of methylphenidate to healthy, adult men increased their dopamine levels. The researchers speculate that methylphenidate amplifies the release of dopamine, a neurotransmitter, thereby improving attention and focus in individuals who have dopamine signals that are weak, such as individuals with ADHD. "Dopamine, while an essential neurotransmitter, is also a known neurotoxin that potentially plays a role in several neurodegenerative diseases. Dopamine metabolism and oxidation readily produce reactive oxygen species and dopamine can also be oxidized to a reactive quinone via spontaneous, enzyme-catalyzed or metal-enhanced reactions. These results suggest that dopamine toxicity is tightly linked to intracellular oxidant/antioxidant levels, and that environmental factors, such as excessive Mn exposure, may modulate cellular sensitivity to dopamine."(1) References (1) Dopamine toxicity in neuroblastoma cells: role of glutathione depletion by L-BSO and apoptosis. (2) Neuropharmacology 1996 May;35(5):571-8 (3) Exp Brain Res 1998 Dec;123(3):263-8
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