Levels of Tyrosine and Tryptophan in the Plasma and Brain of Spontaneously Hypertensive Rats

Osumi, Yoshitsugu; Tanaka, Chikako; Takaori, Shuji

doi:10.1254/jjp.24.715

Cited by 18 publications

(5 citation statements)

References 14 publications

(7 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Osumi et al. (15) showed that blood pressure fell in SHR rats that consumed a diet supplemented with 1% L-tyrosine. The authors concluded, however, that the tyrosine effect "cannot be attributed to noradrenaline formed from tyrosine" (15).…”

Section: Discussionmentioning

confidence: 99%

“…(15) showed that blood pressure fell in SHR rats that consumed a diet supplemented with 1% L-tyrosine. The authors concluded, however, that the tyrosine effect "cannot be attributed to noradrenaline formed from tyrosine" (15). Shalita and Dikstein (16) suggested a possible false transmitter mechanism by which tyrosine might prevent the development of hypertension in rats treated with deoxycorticosterone acetate and salt.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Tyrosine administration reduces blood pressure and enhances brain norepinephrine release in spontaneously hypertensive rats.

Sved¹,

Fernstrom²,

Wurtman³

1979

Proc. Natl. Acad. Sci. U.S.A.

145

View full text Add to dashboard Cite

Administration of L-tyrosine to normotensive or spontaneously hypertensive rats reduces blood pressure. The effect is maximal within 2 hr of injection. In spontaneously hypertensive rats, a dose of 50 mg/kg, intraperitoneally, reduces blood pressure by about 12 mm Hg (1 mm Hg = 1.33 X 102 pascals); a dose of 200 mg/kg produces the maximal effect, a reduction of about 40 mm Hg. Tryptophan injection (225 mg/kg) also lowers blood pressure in spontaneously hypertensive rats, but only by about half as much as an equivalent dose of tyrosine.Other amino acids tested (leucine, isoleucine, valine, alanine, arginine, and aspartate) do not affect blood pressure. Tyrosine injection appears to reduce blood pressure via an action within the central nervous system, since the effect can be blocked by co-administering other large neutral amino acids that reduce tyrosine's uptake into the brain. That tyrosine's antihypertensive action is mediated by an acceleration in norepinephrine or epinephrine release within the central nervous system is suggested by the concurrent increase that its injection produces in brain levels of methoxyhydroxyphenylethylglycol sulfate. Norepinephrine (NE) and possibly epinephrine release by nerve terminals in the mammalian central nervous system (CNS) modifies blood pressure. Depending on the locus, NE release can either increase or decrease blood pressure (1, 2). In the brain stem, stimulation of a-adrenergic receptors lowers blood pressure. The antihypertensive action of several drugs (e.g., clonidine and methyldopa) has been attributed to their ability to stimulate these brain-stem receptors (1). Epinephrine-containing neurons are also present in brain-stem regions involved in blood pressure regulation (3, 4). Thus, they may release their transmitter onto these same a receptors and thereby influence blood pressure.The synthesis and release of NE (or possibly epinephrine) in the rat brain are influenced by the availability of the precursor amino acid, tyrosine. Thus, tyrosine administration, which raises brain tyrosine levels, stimulates dopa accumulation in rats pretreated with R04-4602 (an inhibitor of aromatic L-aminoacid decarboxylase); the injection of other large neutral amino acids, which lowers brain tyrosine levels, diminishes dopa formation (5-7). Tyrosine injection also increases brain levels of methoxyhydroxyphenylethylglycol sulfate ref. 8), indicating that NE and epinephrine release might be enhanced by precursor administration. If stimulation of central a receptors can lower blood pressure and if tyrosine administration does enhance the release of NE (or perhaps epinephrine) from CNS nerve terminals, then tyrosine injection might also lower blood pressure. The studies described below have tested this hypothesis. (10) after isolation of the metabolite on QAE-Sephadex columns. Serum and brain tyrosine levels were also estimated fluorimetrically by the method of Waalkes and Udenfriend (11). Amino acids (L-form, free base; obtained from standard commercial suppliers), dissolve...

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Tyrosine administration reduces blood pressure and enhances brain norepinephrine release in spontaneously hypertensive rats.

Sved¹,

Fernstrom²,

Wurtman³

1979

Proc. Natl. Acad. Sci. U.S.A.

145

View full text Add to dashboard Cite

show abstract

“…When compared with previous publications that involve the electrochemical detection of aromatic amino acids at electrodes modified with conductive polymers and/or ZnO nanostructures [ 46 , 47 , 48 , 49 , 50 ], it can be observed that similar limits or detection are achieved. Nonetheless, considering that the plasma levels of both amino acids are in the range of 10 to 100 µM [ 51 , 52 , 53 ], it can be concluded that the mSPE (2% PANI and 0.04% ZnO nanowires) can be successfully utilized for the simultaneous detection of Tyr and Trp in real media.…”

Section: Resultsmentioning

confidence: 99%

Carbon Inks-Based Screen-Printed Electrodes for Qualitative Analysis of Amino Acids

Enache

Enculescu

Bunea

et al. 2023

IJMS

View full text Add to dashboard Cite

Due to the great significance of amino acids, a substantial number of research studies has been directed toward the development of effective and reliable platforms for their evaluation, detection, and identification. In order to support these studies, a new electrochemical platform based on PANI/ZnO nanowires’ modified carbon inks screen-printed electrodes was developed for qualitative analysis of electroactive amino acids, with emphasis on tyrosine (Tyr) and tryptophan (Trp). A comparative investigation of the carbon ink before and after modification with the PANI/ZnO was performed by scanning electron microscopy and by Raman spectroscopy, confirming the presence of PANI and ZnO nanowires. Electrochemical investigations by cyclic voltammetry and electrochemical impedance spectroscopy have shown a higher charge-transfer rate constant, which is reflected into lower charge-transfer resistance and higher capacitance values for the PANI/ZnO modified ink when compared to the simple carbon screen-printed electrode. In order to demonstrate the electrochemical performances of the PANI/ZnO nanowires’ modified carbon inks screen-printed electrodes for amino acids analysis, differential pulse voltammograms were obtained in individual and mixed solutions of electroactive amino acids. It has been shown that the PANI/ZnO nanowires’ modified carbon inks screen-printed electrodes allowed for tyrosine and tryptophan a peak separation of more than 100 mV, enabling their screening and identification in mixed solutions, which is essential for the electrochemical analysis of proteins within the proteomics research field.

show abstract

“…Other studies have shown that a diet containing 1% Ltyrosine can also lower blood pressure in spontaneously hypertensive rats (68).…”

Section: Benefits Of Tyrosine Supplementationmentioning

confidence: 92%

Supplemental tyrosine and vigilance performance in a normoxic hypobaric environment

Maresh¹

2001

PsycEXTRA Dataset

View full text Add to dashboard Cite

The public re(jortii.g burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection o; rnfo'rnation. including suggestions for reducing the burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Exposure to stress results in a decrease in mental performance resulting from a depletion of catecholamines. This decrease can result in an increase in error rates, decreased decision making ability, mental confusion, and an overall decrease in cognitive performance. Previous studies have shown that supplemental tyrosine prevents the normal decrease due to stress.Tyrosine works by increasing the catecholamine precursor.Nine subjects were exposed to a 3-hour protocol for 4 different exposures. During each exposure, the following Stressors were used: 1) hypobaric environment (for two of the four exposures); 2) immobilization; 3) prolonged inactivity; 4) behavioral and psychophysiological testing; 5) cool temperatures and low humidity; and 6) 71 dB(A) chamber environment. Subjects completed computerized vigilance and cognitive tests and a mood questionnaire, each separated by a period of inactivity. Prior to exposure, subjects ingested either 100 mg/kg body weight of a placebo or tyrosine.Supplemental tyrosine improved response time in all of the tests where it was recorded, with all except one being significant. Motor function and overall mood also significantly improved with the use of tyrosine. As expected, no measurement showed a significant improvement in performance with supplemental oxygen alone. The use of supplemental tyrosine did not significantly improve cognitive performance. Results of the contrast sensitivity taskswere not as conclusive and no improvement was found in visual temporal acuity. and physical performance. The less control the individual has over these stresses, the greater the decrement. The decrease in performance, particularly mental performance, results from a depletion of catecholamines within the brain. This decrease, especially in norepinephrine, leads to alterations in normal brain function and an increase in error rates, decreased decision making ability, mental confusion, and an overall decrease in cognitive performance. All of these are compounded the longer the individual is unable to remove the stress. Previous studies involving rats and humans have shown that supplemental tyrosine (levels above normal dietary intake) prevent the normal decrease in performance in stressed individuals. Tyrosine, the initial precursor in catecholamine synthesis, works by increasing the availability of the precursor and thereby slowing the rate of norepinephrine depletion.Nine healthy subjects from the Colorado State University community were exposed to a 3-hour protocol that w...

show abstract

Levels of Tyrosine and Tryptophan in the Plasma and Brain of Spontaneously Hypertensive Rats

Cited by 18 publications

References 14 publications

Tyrosine administration reduces blood pressure and enhances brain norepinephrine release in spontaneously hypertensive rats.

Tyrosine administration reduces blood pressure and enhances brain norepinephrine release in spontaneously hypertensive rats.

Carbon Inks-Based Screen-Printed Electrodes for Qualitative Analysis of Amino Acids

Supplemental tyrosine and vigilance performance in a normoxic hypobaric environment

Contact Info

Product

Resources

About