Tetrahydrobiopterin treatment reduces brain L-Phe but only partially improves serotonin in hyperphenylalaninemic ENU1/2 mice
| Autor: | Beat Thöny, Hiu Man Grisch-Chan, Ming Ying, Gabriella Allegri, Cary O. Harding, Shelley R. Winn, Tanja Scherer, Aurora Martinez, Christineh N. Sarkissian, Anahita Rassi |
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| Přispěvatelé: | University of Zurich, Thöny, Beat |
| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: |
0301 basic medicine
Serotonin medicine.medical_specialty 2716 Genetics (clinical) Tyrosine 3-Monooxygenase Phenylalanine hydroxylase Dopamine Phenylalanine 610 Medicine & health Tryptophan Hydroxylase Article Mice 03 medical and health sciences Hyperphenylalaninemia 1311 Genetics Phenylketonurias Internal medicine Genetics medicine Animals Humans Genetics (clinical) Neurotransmitter Agents biology TPH2 Tyrosine hydroxylase Chemistry Brain Phenylalanine Hydroxylase Tetrahydrobiopterin Tryptophan hydroxylase medicine.disease Biopterin Mice Mutant Strains Disease Models Animal 030104 developmental biology Endocrinology Monoamine neurotransmitter 10036 Medical Clinic biology.protein medicine.drug |
| Popis: | Hyperphenylalaninemia (HPA) caused by hepatic phenylalanine hydroxylase (PAH) deficiency has severe consequences on brain monoamine neurotransmitter metabolism. We have studied monoamine neurotransmitter status and the effect of tetrahydrobiopterin (BH4) treatment in Pahenu1/enu2 (ENU1/2) mice, a model of partial PAH deficiency. These mice exhibit elevated blood L-phenylalanine (L-Phe) concentrations similar to that of mild hyperphenylalaninemia (HPA), but brain levels of L-Phe are still ~5-fold elevated compared to wild-type. We found that brain L-tyrosine, L-tryptophan, BH4 cofactor and catecholamine concentrations, and brain tyrosine hydroxylase (TH) activity were normal in these mice but that brain serotonin, 5-hydroxyindolacetic acid (5HIAA) and 3-methoxy-4-hydroxyphenylglycol (MHPG) content, and brain TH protein, as well as tryptophan hydroxylase type 2 (TPH2) protein levels and activity were reduced in comparison to wild-type mice. Parenteral L-Phe loading conditions did not lead to significant changes in brain neurometabolite concentrations. Remarkably, enteral BH4 treatment, which normalized brain L-Phe levels in ENU1/2 mice, lead to only partial recovery of brain serotonin and 5HIAA concentrations. Furthermore, indirect evidence indicated that the GTP cyclohydrolase I (GTPCH) feedback regulatory protein (GFRP) complex may be a sensor for brain L-Phe elevation to ameliorate the toxic effects of HPA. We conclude that BH4 treatment of HPA toward systemic L-Phe lowering reverses elevated brain L-Phe content but the recovery of TPH2 protein and activity as well as serotonin levels is suboptimal, indicating that patients with mild HPA and mood problems (depression or anxiety) treated with the current diet may benefit from supplementation with BH4 and 5-OH-tryptophan. |
| Databáze: | OpenAIRE |
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