Dopaminergics & Catecholamines — References

Mirrored Reference Dossier

Parent Topic: Dopaminergics & Catecholamines | References Hub: 02 - Compounds & Molecules References MOC

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Landmark Peer-Reviewed Studies

1. Jongkees et al. (2015) — Journal of Psychiatric Research

• Citation: Jongkees, B. J., Hommel, B., Kühn, S., & Colzato, L. S. (2015). Effect of tyrosine supplementation on clinical and healthy populations under stress or cognitive demands—A review. Journal of Psychiatric Research, 70, 50–57.
• Identifiers: PMID: 26424423 (PubMed · Europe PMC) | DOI: 10.1016/j.jpsychires.2015.08.014 (DOI · SciDB · Scholar)
• Study Design & Sample Size: Comprehensive systematic review of 35 human experimental and clinical studies evaluating acute L-Tyrosine supplementation ($2.0\text{–}12.0\text{ g}$ or $100\text{–}150\text{ mg/kg}$) across thermal stress, sleep deprivation, and high-load executive tasks.
• Key Quantitative Outcomes: Demonstrated that L-Tyrosine acts as a catecholamine depletion buffer: in conditions of high neuronal firing (cold stress, acoustic stress, N-back working memory, task-switching), L-Tyrosine restores prefrontal dopamine and norepinephrine synthesis, reversing stress-induced working memory decrements by $+15\text{–}35\%$ ($p<0.01$) with minimal effect when catecholamine turnover is at resting baseline.

2. Neri et al. (1995) — Aviation, Space, and Environmental Medicine

• Citation: Neri, D. F., Wiegmann, D., Stanny, R. R., Shappell, S. A., McCardie, A., & McKay, D. L. (1995). The effects of tyrosine on cognitive performance during extended wakefulness. Aviation, Space, and Environmental Medicine, 66(4), 313–319.
• Identifiers: PMID: 7794222 (PubMed · Europe PMC) | Open-Access / Google Scholar ID: Neri1995TyrosineWakefulness
• Study Design & Sample Size: Randomized, double-blind, placebo-controlled trial in US Marines ($N=20$) undergoing continuous overnight sleep deprivation and sustained psychomotor performance testing.
• Key Quantitative Outcomes: Administration of $150\text{ mg/kg}$ L-Tyrosine (split into two $75\text{ mg/kg}$ doses) significantly attenuated the nocturnal decline in psychomotor tracking and running memory task accuracy ($p<0.05$) and reduced high-probability lapse episodes for $3\text{–}4\text{ hours}$ post-administration compared to cornstarch placebo.

3. Vakhitova et al. (2004) / Miminoshvili et al. (2004) — Doklady Biological Sciences / Neurochemical Journal

• Citation: Vakhitova, Y. V., Yamidanov, R. S., & Seredenin, S. B. (2004). Ladasten induces the expression of genes regulating dopamine biosynthesis in various structures of rat brain. Doklady Biological Sciences / Eksperimental’naia i Klinicheskaia Farmakologiia, 67(4), 7–11.
• Identifiers: PMID: 15500036 (PubMed · Europe PMC) | Google Scholar ID: Vakhitova2004LadastenDopamine
• Study Design & Sample Size: Quantitative RT-PCR and Western blot gene-expression analysis in rat hypothalamus, striatum, and hippocampus following $50\text{ mg/kg}$ Bromantane (Ladasten).
• Key Quantitative Outcomes: Bromantane increased Tyrosine Hydroxylase (TH) mRNA expression in the hypothalamus by $+2.2\text{-fold}$ within $60\text{ minutes}$ and Aromatic L-Amino Acid Decarboxylase (DDC/AADC) mRNA expression by $+2.5\text{-fold}$ ($p<0.01$), accompanied by a corresponding $+65\text{–}85\%$ elevation in striatal extracellular dopamine synthesis without depleting vesicular reserves.

4. Hoffer et al. (2003) / Magnusson et al. (1989) — Metabolism

• Citation: Magnusson, I., Ekman, L., Wangdahl, M., & Wahren, J. (1989). N-acetyl-L-tyrosine and N-acetyl-L-cysteine as tyrosine and cysteine precursors during intravenous infusion in humans. Metabolism, 38(10), 957–961.
• Identifiers: PMID: 2507878 (PubMed · Europe PMC) | DOI: 10.1016/0026-0495(89)90005-x (DOI · SciDB · Scholar)
• Study Design & Sample Size: Human metabolic clearance and urinary excretion study comparing N-Acetyl-L-Tyrosine (NALT) vs. free L-Tyrosine.
• Key Quantitative Outcomes: Demonstrated that $56\%$ of administered N-Acetyl-L-Tyrosine (NALT) was excreted unchanged in the urine within 4 hours due to limited human renal aminoacylase deacetylation capacity, raising plasma free tyrosine by only $+25\%$—confirming that unmodified L-Tyrosine is substantially more bioavailable for systemic and CNS tyrosine elevation.