Effect of Acute Tyrosine Depletion in Using a Branched Chain Amino-Acid Mixture on Dopamine Neurotransmission in the Rat Brain

BackgroundIn rats, amino acid mixtures lacking tyrosine and its precursor phenylalanine decrease the release of dopamine produced by the psychostimulant drug amphetamine. Amphetamine has been proposed as a model for clinical mania.AimsTo assess whether dietary tyrosine depletion attenuates the psychostimulant effects of methamphetamine in healthy volunteers and diminishes the severity of mania in acutely ill patients.MethodSixteen healthy volunteers received a tyrosine-free amino acid mixture and a control mixture in a double-blind crossover design 4 h before methamphetamine (0.15 mg/kg). Twenty in-patients meeting DSM–IV criteria for mania were allocated blindly and randomly to receive either the tyrosine-free mixture or the control mixture.ResultsThe tyrosine-free mixture lowered both subjective and objective measures of the psychostimulant effects of methamphetamine. Ratings of mania were lower in the patients who received the tyrosine-free mixture.ConclusionsDecreased tyrosine availability to the brain attenuates pathological increases in dopamine neurotransmission following methamphetamine administration and putatively in mania.

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Influence of Dietary Supplementation with an Amino Acid Mixture on Inflammatory Markers, Immune Status and Serum Proteome in LPS-Challenged Weaned Piglets

Animals ◽

10.3390/ani11041143 ◽

2021 ◽

Vol 11 (4) ◽

pp. 1143

Author(s):

José Prates ◽

João Freire ◽

André de Almeida ◽

Cátia Martins ◽

David Ribeiro ◽

...

Keyword(s):

Amino Acid ◽

Protein Profile ◽

Amino Acid Mixture ◽

Acid Mixture ◽

Control Group ◽

Weaned Piglets ◽

Lps Challenge ◽

Dietary Amino Acid ◽

Branched Chain ◽

Experimental Treatments

In order to investigate the effect of a dietary amino acid mixture supplementation in lipopolysaccharide (LPS)-challenged weaned piglets, twenty-seven 28-day-old (8.2 ± 1.0 kg) newly weaned piglets were randomly allocated to one of three experimental treatments for five weeks. Diet 1: a CTRL treatment. Diet 2: an LPS treatment, where piglets were intraperitoneally administered LPS (25 μg/kg) on day 7. Diet 3: an LPS+MIX treatment, where piglets were intraperitoneally administered LPS on day 7 and fed a diet supplemented with a mixture of 0.3% of arginine, branched-chain amino acids (leucine, valine, and isoleucine), and cystine (MIX). Blood samples were drawn on day 10 and day 35, and serum was analysed for selected chemical parameters and proteomics. The LPS and LPS+MIX groups exhibited an increase in haptoglobin concentrations on day 10. The LPS group showed an increased cortisol concentration, while this concentration was reduced in the LPS+MIX group compared to the control group. Similarly, the LPS+MIX group showed a decreased haptoglobin concentration on day 35 compared to the two other groups. Immunoglobulin concentrations were affected by treatments. Indeed, on day 10, the concentrations of IgG and IgM were decreased by the LPS challenge, as illustrated by the lower concentrations of these two immunoglobulins in the LPS group compared to the control group. In addition, the supplementation with the amino acid mixture in the LPS+MIX further decreased IgG and increased IgM concentrations compared to the LPS group. Although a proteomics approach did not reveal important alterations in the protein profile in response to treatments, LPS-challenged piglets had an increase in proteins linked to the immune response, when compared to piglets supplemented with the amino acid mixture. Overall, data indicate that LPS-challenged piglets supplemented with this amino acid mixture are more protected against the detrimental effects of LPS.

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