Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0030567 (Parkinson's disease)
 63,064 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The dopamine transporter (DAT) operates via facilitated diffusion, harnessing an inward Na(+) gradient to drive dopamine from the extracellular synaptic cleft to the neuron interior. The DAT is relevant to central nervous system disorders such as Parkinson disease and attention-deficit hyperactivity disorder and is the primary site of action for the abused psychostimulants cocaine and amphetamines. Crystallization of a DAT homolog, the bacterial leucine transporter LeuT, provided the first reliable 3-D DAT template. Here, the LeuT crystal structure and the DAT molecular model have been combined with their respective substrates, leucine and dopamine, in lipid bilayer molecular dynamics simulations toward tracking substrate movement along the protein's substrate/ion permeation pathway. Specifically, movement of residue pairs that comprise the "external gate" was followed as a function of substrate presence. The transmembrane (TM) 1 arginine-TM 10 aspartate strut formed less readily in DAT compared with LeuT, with or without substrate present. For LeuT but not DAT, the addition of substrate enhanced the chances of forming the TM 1-10 bridge. Also, movement of the fourth extracellular loop EL-4 in the presence of substrate was more pronounced for DAT, the EL-4 unwinding to a degree. The overall similarity between the LeuT and DAT molecular dynamics simulations indicated that LeuT was a legitimate model to guide DAT structure-function predictions. There were, nevertheless, differences significant enough to allow for DAT-unique insights, which may include how cocaine, methylphenidate (Ritalin, NIDA Drug Supply, Rockville, MD), and other DAT blockers are not recognized as substrates even though they can access the primary substrate binding pocket. Proteins 2010. (c) 2009 Wiley-Liss, Inc.
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PMID:Molecular dynamics of leucine and dopamine transporter proteins in a model cell membrane lipid bilayer. 1989 68

Oral methylphenidate (Ritalin, Novartis) has been reported to alleviate symptoms of benign essential blepharospasm in an off-label application. This series presents 3 patients with refractory periorbital and facial dystonias, including blepharospasm, apraxia of eyelid opening, and oromandibular dystonia unresponsive to standard treatments who experienced a response to oral methylphenidate therapy. While the mechanisms for facial dystonias have not been elucidated, there is evidence to suggest that they are on the spectrum with Parkinson disease. Given the role of dopamine loss in the pathogenesis of Parkinson, the authors' speculate that methylphenidate may be acting on the pathway directly involved in facial dystonias. To the authors' knowledge, this is the first report of a case of successful treatment of blepharospasm refractory to upper eyelid myectomy with methylphenidate monotherapy.
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PMID:Oral methylphenidate for the treatment of refractory facial dystonias. 2595 Nov 77