Plasma Levels of Amino Acids Correlate With Motor Fluctuations in Parkinsonism

Pincus, Jonathan H.; Barry, Kathryn

doi:10.1001/archneur.1987.00520220012007

Cited by 67 publications

(62 citation statements)

References 19 publications

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“…Data were shown by the numbers of rotations (mean + sem) or % ratio between the 2 trials (mean + sere). *p < 0.05 compared with control group the fluctuations of L-dopa effects in parkinsonian patients (Nutt et al, 1984;Juncos et al, 1987;Pincus and Barry, 1987b;Eriksson et al, 1988;Carter et al, 1989;Frankel et al, 1989). Positron emission tomography in a healthy human showed that the brain uptake of L-[lSF]fluorodopa was inhibited by amino acids (Leenders et al, 1986).…”

Section: Discussionmentioning

confidence: 99%

Rotations induced by L-dopa in parkinsonian rats are reduced by an ingestion of amino acids

Mizuta

Kuno

1993

J Neural Transm Gen Sect

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We studied the effect of amino acid load on L-dopa-induced rotational behavior in rats with unilateral lesion of the nigrostriatal pathway. Pretreatment of rats with an ingestion of high concentration of amino acids significantly reduced the number of rotations induced by subcutaneously injected L-dopa. These results provide the experimental basis for clinical observations that dietary protein affects the response to L-dopa in parkinsonian patients.

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Section: Discussionmentioning

confidence: 99%

Rotations induced by L-dopa in parkinsonian rats are reduced by an ingestion of amino acids

Mizuta

Kuno

1993

J Neural Transm Gen Sect

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“…The patients with marked rigidity and akinesia (Cases 9 and 10) did not respond to the treatment. Large neutral amino acids (LNAAs)are known to compete with levodopa for transport across the blood-brain barrier (13). The BCAAs,valine, leucine and isoleucine, belong to this category of amino acids.…”

Section: Discussionmentioning

confidence: 99%

Branched-Chain Amino Acid Therapy for Spinocerebellar Degeneration: A Pilot Clinical Crossover Trial.

et al. 1999

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Object: The potential effects of branched-chain amino acids (BCAAs)on spinocerebellar degeneration (SCD) were explored in eleven patients. Methods: The patients received 200 ml of BCAA-rich solution, 2 mg of thyrotropin-releasing hormone (TRH; protirelin), or a placebo daily for 7 days each in a random order. An SCDscore was used to quantify the severity of symptoms. Patients: Eleven patients with SCD(7 male, 4 female; mean age 60±ll; mean disease duration 5.5 years) participated in this study. Results: The meanSCDscore of the eleven patients improved significantly by the BCAAtreatment compared with the baseline. The conditions of five of the eleven patients (45 %) were clearly improved by the BCAAtreatment. All of the responders manifested predominantly cerebellar symptoms, but no prominent parkinsonian symptoms. Two patients with marked rigidity and akinesia did not respond to the treatment. Conclusion: Weconcluded that BCAAsdo have a beneficial effect on functional improvement in patients with SCD, and that further large scale studies are needed. (Internal Medicine 38: 401-406, 1999)

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“…This means that levodopa and LNAAs share the same carrier in the gut and in the brain, and that levodopa competes with other dietetic LNAAs in this phase of its pharmacokinetics. The competition occurs mainly in the brain capillary endothelial cell (the BBB) and can block levodopa entry in the brain, even if blood concentrations of the drug are adequate (Pincus & Barry, 1987c). As a result, the effectiveness of levodopa-based drugs is strictly influenced by diet, particularly by its protein content.…”

Section: Diet and Levodopamentioning

confidence: 99%

“…Therefore, although limiting the protein intake significantly improves the motor disabilities and the sensitivity to levodopa in some patients by reducing LNAA plasma levels, a high-protein diet can cause a dramatic worsening of motor performance in the same patients (Berry et al, 1991;Pincus & Barry, 1987a, 1987b, 1987cWajsbort, 1977). In fact, as we have seen previously, motor performance correlated with LNAA, not with levodopa, absorption, and blood concentrations (Carter et al, 1989;Tsui et al, 1989).…”

Section: Levodopa and Dietary Proteinmentioning

confidence: 99%