Influence of fluctuations of plasma large neutral amino acids with normal diets on the clinical response to levodopa
Open accessAbstract
Plasma large neutral amino acids (LNAAs) compete with levodopa for entry into the brain. Fluctuations in plasma LNAA concentrations could therefore contribute to variability in clinical response to levodopa. The hourly plasma levodopa, plasma LNAAs and clinical response were investigated in 11 fluctuating Parkinsonian patients on a regular hospital diet. The fluctuations in plasma levodopa were 2 to 3 times greater than the fluctuations of plasma LNAAs. The correlation between clinical response and plasma levodopa was substantially improved in only one patient by considering plasma LNAAs and calculating relative levodopa flux into brain. Although plasma LNAAs significantly increased during the day, the patients' clinical status did not uniformly deteriorate and mean afternoon clinical scores correlated better with mean plasma levodopa and levodopa flux than with mean plasma LNAAs. Minimum effective concentrations of levodopa for clinical response did not correlate with 9 am LNAA concentrations. It is concluded that in most patients, the relatively small variation in plasma LNAAs in comparison with the large variations in plasma levodopa indicates that fluctuations in LNAA are not an important contributor to the fluctuating response to levodopa.
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Many symptoms and signs associated with Parkinson's disease demonstrate diurnal variations in intensity and frequency.
“Many symptoms and signs associated with PD demonstrate diurnal variations in its intensity and frequency.”
From Circadian dysregulation in Parkinson's disease (2017) · cites this paper as Nutt et al., 1989
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- Authors
- Nutt, J. G., Woodward, W. R., Carter, J. H., & Trotman, T. L.
- Affiliations
- Oregon Health & Science University (US)
- Venue
- Journal of Neurology, Neurosurgery & Psychiatry
- Publisher
- BMJ
- Published
- 1989-04-01
- Volume
- 52
- Issue
- 4
- Pages
- 481-487
- ISSN
- 0022-3050 (ISSN-L)
- PMC
- PMC1032296
- OpenAlex
- W2104961238
- Cited by
- 49
- References
- 32
- Citations by year
- 2026: 1 · 2024: 2 · 2023: 1 · 2021: 1 · 2019: 1 · 2018: 2 · 2017: 2 · 2016: 2 · 2015: 3 · 2014: 4 · 2012: 1
- FWCI
- 0.76
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- Journal of Neurology Neurosurgery & Psychiatry (publishedVersion)
- PubMed Central (publishedVersion)
- PubMed (publishedVersion)
- HighWire Press Open Archive (submittedVersion)
- Funders
- National Institutes of Health
- National Institute of Neurological Disorders and Stroke (R01NS21062-04, R01NS021062)
- National Center for Research Resources (RR-00334)
- Topics
- Health Sciences › Medicine › Neurology › Parkinson's Disease Mechanisms and Treatments
- Health Sciences › Medicine › Neurology › Neurological disorders and treatments
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Clinical Biochemistry › Metabolism and Genetic Disorders
- Keywords
- large neutral amino acids, levodopa, Parkinson's disease, hospital food, amino acid competition, minimum effective concentration
- MeSH terms
- Adult, Aged, Amino Acids, Blood-Brain Barrier, Circadian Rhythm, Feeding Behavior, Female, Humans, Levodopa, Male, Middle Aged, Parkinson Disease, Prognosis
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