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Cicek C, Eren-Koçak E, Telkoparan-Akillilar P, Gok M, Bodur E. cAMP/PKA-CREB-BDNF signaling pathway in hippocampus of rats subjected to chemically-induced phenylketonuria. Metab Brain Dis 2022; 37:545-557. [PMID: 34800207 DOI: 10.1007/s11011-021-00865-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 10/31/2021] [Indexed: 12/13/2022]
Abstract
Phenylketonuria (PKU) is an inborn error disease in phenylalanine metabolism resulting from defects in the stages of converting phenylalanine to tyrosine. Although the pathophysiology of PKU is not elucidated yet, the toxic effect of phenylalanine on the brain causes severe mental retardation. In relation to learning and memory, the hippocampal PKA / CREB / BDNF pathway may play a role in learning deficits in PKU patients. This study aimed to investigate PKA/CREB/BDNF pathway in hippocampus of chemically induced PKU rats with regard to gender. Sprague-Dawley rat pups were randomized into two groups of both genders. To chemically induce PKU, animals received subcutaneous administration of phenylalanine (5.2 mmol / g) plus p-chlorophenylalanine, phenylalanine hydroxylase inhibitor (0.9 mmol / g); control animals received 0.9% NaCl. Injections started on the 6th day and continued until the 21st day after which locomotor activity, learning and memory were tested. In male PKU rats, locomotor activity was reduced. There were no differences in learning and memory performances of male and female PKU rats. In PKU rats, pCREB / CREB levels in males was unchanged while it decreased in females. Elevated PKA activity, BDNF levels and decreased pCREB/CREB ratio found in female PKU rats were not replicated in PKU males in which BDNF is decreased. Our results display that in this disease model a gender specific differential activation of cAMP/PKA-CREB-BDNF signaling pathway in hippocampus occurs investigation of which can help us to a better understanding of disease pathophysiology.
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Affiliation(s)
- Cigdem Cicek
- Department of Medical Biochemistry, Hacettepe University, Faculty of Medicine, 06100, Ankara, Turkey
- Department of Medical Biochemistry, Yuksek Ihtisas University, Faculty of Medicine, 06520, Ankara, Turkey
| | - Emine Eren-Koçak
- Hacettepe University, Institute of Neurological Sciences and Psychiatry, 06100, Ankara, Turkey
| | | | - Muslum Gok
- Department of Medical Biochemistry, Hacettepe University, Faculty of Medicine, 06100, Ankara, Turkey
- Department of Medical Biochemistry, Mugla Sitki Kocman University, Faculty of Medicine, 48000, Mugla, Turkey
| | - Ebru Bodur
- Department of Medical Biochemistry, Hacettepe University, Faculty of Medicine, 06100, Ankara, Turkey.
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Ren SX, Zhang B, Lin Y, Ma DS, Li H. Mechanistic evaluation of anti-arthritic activity of β-methylphenylalanine in experimental rats. Biomed Pharmacother 2019; 113:108730. [PMID: 30861411 DOI: 10.1016/j.biopha.2019.108730] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 02/20/2019] [Accepted: 02/22/2019] [Indexed: 01/21/2023] Open
Abstract
Arthritis is a common chronic joint disorder, with general symptoms including stiffness and joint pain. β-methylphenylalanine is a well-known non-proteogenic unnatural amino acid. This study analyzes the anti-arthritic activity of β-methylphenylalanine in experimental rats. The experimental groups were as follows: group I, sham; group II, control; group III, 100 mg/kg of β-methylphenylalanine; and group IV, 200 mg/kg of β-methylphenylalanine. Lipid peroxidation, glutathione peroxidase (Gpx), reduced glutathione (GSH), superoxide dismutase (SOD), catalase, prostaglandin E2 (PGE2), matrix metalloproteinase-3 (MMP-3), ceruloplasmin, zinc, copper, mRNA, and protein expression of inducible nitric oxide synthase (iNOS) and nuclear factor-kappa B (NF-κB) were determined. Supplementation with β-methylphenylalanine significantly reduced lipid peroxidation, copper, PGE2 and MMP-3 levels, whereas GSH, Gpx, catalase, SOD and zinc levels were increased. Supplementation with β-methylphenylalanine significantly reduced NF-κB mRNA expression by 26% and 47.8% in groups III and IV, respectively (P < 0.045), while iNOS mRNA expression was reduced by 14.3 and 47.6% in groups III and IV, respectively. NF-κB and iNOS protein expression increased by 160% and 120% respectively, in the control rats compared to the sham rats. However, supplementation with β-methylphenylalanine significantly reduced NF-κB protein expression by 27% and 50% in groups III and IV, respectively, while iNOS protein expression was reduced by 22.7% and 45.4% in groups III and IV, respectively. Taken together, our data show that supplementation of β-methylphenylalanine was effective against arthritis in a rat model.
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Affiliation(s)
- Shi-Xiang Ren
- Department of Orthopedics, Beijing Chaoyang Hospital Affiliated to Capital Medical University, Beijing, 100020, China
| | - Bo Zhang
- Department of Orthopedics, Beijing Chaoyang Hospital Affiliated to Capital Medical University, Beijing, 100020, China
| | - Yuan Lin
- Department of Orthopedics, Beijing Chaoyang Hospital Affiliated to Capital Medical University, Beijing, 100020, China
| | - De-Si Ma
- Department of Orthopedics, Beijing Chaoyang Hospital Affiliated to Capital Medical University, Beijing, 100020, China
| | - Huan Li
- Department of Orthopedics, The First People's Hospital of Changzhou, Jiangsu Province (The Third Affiliated Hospital of Soochow University), Changzhou City, Jiangsu Province, 213003 China.
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3
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Dienel GA, Cruz NF. Biochemical, Metabolic, and Behavioral Characteristics of Immature Chronic Hyperphenylalanemic Rats. Neurochem Res 2015. [PMID: 26224289 DOI: 10.1007/s11064-015-1678-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Phenylketonuria and hyperphenylalanemia are inborn errors in metabolism of phenylalanine arising from defects in steps to convert phenylalanine to tyrosine. Phe accumulation causes severe mental retardation that can be prevented by timely identification of affected individuals and their placement on a Phe-restricted diet. In spite of many studies in patients and animal models, the basis for acquisition of mental retardation during the critical period of brain development is not adequately understood. All animal models for human disease have advantages and limitations, and characteristics common to different models are most likely to correspond to the disorder. This study established similar levels of Phe exposure in developing rats between 3 and 16 days of age using three models to produce chronic hyperphenylalanemia, and identified changes in brain amino acid levels common to all models that persist for ~16 h of each day. In a representative model, local rates of glucose utilization (CMRglc) were determined at 25-27 days of age, and only selective changes that appeared to depend on Phe exposure were observed. CMRglc was reduced in frontal cortex and thalamus and increased in hippocampus and globus pallidus. Behavioral testing to evaluate neuromuscular competence revealed poor performance in chronically-hyperphenylalanemic rats that persisted for at least 3 weeks after cessation of Phe injections and did not occur with mild or acute hyperphenylalanemia. Thus, the abnormal amino acid environment, including hyperglycinemia, in developing rat brain is associated with selective regional changes in glucose utilization and behavioral abnormalities that are not readily reversed after they are acquired.
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Affiliation(s)
- Gerald A Dienel
- Department of Neurology, University of Arkansas for Medical Sciences, 4301 W. Markham St., Mail Slot 500, Little Rock, AR, 72205, USA.
| | - Nancy F Cruz
- Department of Neurology, University of Arkansas for Medical Sciences, 4301 W. Markham St., Mail Slot 500, Little Rock, AR, 72205, USA
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4
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Kennedy DA, Vembu N, Fronczek FR, Devocelle M. Synthesis of mutual azo prodrugs of anti-inflammatory agents and peptides facilitated by α-aminoisobutyric acid. J Org Chem 2011; 76:9641-7. [PMID: 22026631 DOI: 10.1021/jo201358e] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Reported is the synthesis of azo mutual prodrugs of the nonsteroidal anti-inflammatory agents (NSAIDs) 4-aminophenylacetic acid (4-APAA) or 5-aminosalicylic acid (5-ASA) with peptides, including an antibiotic peptide temporin analogue modified at the amino terminal by an α-aminoisobutyric acid (Aib) residue. These prodrugs are designed for colonic delivery of two agents to treat infection and inflammation by the bacterial pathogen Clostridium difficile .
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Affiliation(s)
- David A Kennedy
- Centre for Synthesis and Chemical Biology, Department of Pharmaceutical and Medicinal Chemistry, Royal College of Surgeons in Ireland, 123 St. Stephen's Green, Dublin 2, Ireland.
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5
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Kaufman S. The phenylalanine hydroxylating system. ADVANCES IN ENZYMOLOGY AND RELATED AREAS OF MOLECULAR BIOLOGY 2006; 67:77-264. [PMID: 8322620 DOI: 10.1002/9780470123133.ch2] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- S Kaufman
- Laboratory of Neurochemistry, National Institute of Mental Health, Bethesda, MD
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Kienzle Hagen ME, Pederzolli CD, Sgaravatti AM, Bridi R, Wajner M, Wannmacher CMD, Wyse ATS, Dutra-Filho CS. Experimental hyperphenylalaninemia provokes oxidative stress in rat brain. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1586:344-52. [PMID: 11997085 DOI: 10.1016/s0925-4439(01)00112-0] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Tissue accumulation of L-phenylalanine (Phe) is the biochemical hallmark of human phenylketonuria (PKU), an inherited metabolic disorder clinically characterized by mental retardation and other neurological features. The mechanisms of brain damage observed in this disorder are poorly understood. In the present study we investigated some oxidative stress parameters in the brain of rats with experimental hyperphenylalaninemia. Chemiluminescence, total radical-trapping antioxidant potential (TRAP), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activities were measured in the brain of the animals. We observed that chemiluminescence is increased and TRAP is reduced in the brain of hyperphenylalaninemic rats. Similar data were obtained in the in vitro experiments using Phe at various concentrations. CAT activity was significantly inhibited by Phe in vitro and in vivo, whereas GSH-Px activity was reduced in vivo but not in vitro and SOD activity was not altered by any treatment. The results indicate that oxidative stress may be involved in the neuropathology of PKU. However, further studies are necessary to confirm and extend our findings to the human condition and also to determine whether an antioxidant therapy may be of benefit to these patients.
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Affiliation(s)
- Martine E Kienzle Hagen
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Faculdade de Farmácia, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600 (Anexo) 90035-003, Porto Alegre, RS, Brazil
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7
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Streck EL, Edom PT, Noriler ME, Borges LF, Pontes ZL, Parolo E, Dutra-Filho CS, Wannmacher CM, Wyse AT. Effect of phenylalanine and p-chlorophenylalanine on Na+, K+-ATPase activity in the synaptic plasma membrane from the cerebral cortex of rats. Metab Brain Dis 2000; 15:105-14. [PMID: 11092577 DOI: 10.1007/bf02679977] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Na+, K+-ATPase activity was measured in synaptic plasma membrane from cerebral cortex of Wistar rats subjected to experimental phenylketonuria, i.e., chemical hyperphenylalaninemia induced by subcutaneous administration of 5.2 micromol phenylalanine / g body weight (twice a day) plus 0.9 micromol p-chlorophenylalanine / g body weight (once a day). The treatment was performed from the 6th to the 14th postpartum day and rats were killed 12 h after the last injection. Synaptic plasma membrane from cerebral cortex was prepared by a discontinuous density sucrose gradient for Na+, K+-ATPase activity determination. The results showed that the enzyme activity was decreased by 30% in animals subjected to experimental phenylketonuria when compared to control. The in vitro effects of the drugs on Na+, K+-ATPase activity were also investigated. Phenylalanine and p-chlorophenylalanine inhibited the enzyme activity and this inhibition was reversed by alanine. In addition, competition between phenylalanine and p-chlorophenylalanine for binding to the enzyme was observed, suggesting a common binding site for these substances. Our results suggest that reduction of Na+, K+-ATPase activity may be one of the mechanisms related to the brain dysfunction observed in human PKU.
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Affiliation(s)
- E L Streck
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
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8
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Austic RE, Su CL, Strupp BJ, Levitsky DA. Effects of dietary mixtures of amino acids on fetal growth and maternal and fetal amino acid pools in experimental maternal phenylketonuria. Am J Clin Nutr 1999; 69:687-96. [PMID: 10197570 DOI: 10.1093/ajcn/69.4.687] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Branched-chain amino acids have been reported to improve fetal brain development in a rat model in which maternal phenylketonuria (PKU) is induced by the inclusion of an inhibitor of phenylalanine hydroxylase, DL-p-chlorophenylalanine, and L-phenylalanine in the diet. OBJECTIVE We studied whether a dietary mixture of several large neutral amino acids (LNAAs) would improve fetal brain growth and normalize the fetal brain amino acid profile in a rat model of maternal PKU induced by DL-alpha-methylphenylalanine (AMPhe). DESIGN Long-Evans rats were fed a basal diet or a similar diet containing 0.5% AMPhe + 3.0% L-phenylalanine (AMPhe + Phe diet) from day 11 until day 20 of gestation in experiments to test various mixtures of LNAAs. Maternal weight gains and food intakes to day 20, fetal body and brain weights at day 20, and fetal brain and fetal and maternal plasma amino acid concentrations at day 20 were measured. RESULTS Concentrations of phenylalanine and tyrosine in fetal brain and in maternal and fetal plasma were higher and fetal brain weights were lower in rats fed the AMPhe + Phe diet than in rats fed the basal diet. However, fetal brain growth was higher and concentrations of phenylalanine and tyrosine in fetal brain and in maternal and fetal plasma were lower in rats fed the AMPhe + Phe diet plus LNAAs than in rats fed the diet containing AMPhe + Phe alone. CONCLUSION LNAA supplementation of the diet improved fetal amino acid profiles and alleviated most, but not all, of the depression in fetal brain growth observed in this model of maternal PKU.
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Affiliation(s)
- R E Austic
- Department of Animal Science, Cornell University, Ithaca, NY 14853, USA.
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9
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Abstract
In a genetic mouse model of human phenylketonuria we have examined the offspring of hyperphenylalaninemic mothers for the presence of cardiovascular defects, an important feature of the pathology of the human maternal phenylketonuria syndrome. Beginning at 14.5 d after conception (75% through gestation), a variety of cardiovascular defects became apparent among the progeny of the hyperphenylalaninemic females. These defects ranged from mild to serious and correlated with the maternal but not the fetal Pah genotype. Nearly all of the defects were vascular, however, whereas the most reported in humans so far have been cardiac. The predisposing biochemical condition in this mouse disease model seems to be the same as in the human disease; elevated maternal blood phenylalanine levels concentrated across the placental barrier to produce a teratogenic developmental environment. This model for congenital cardiovascular defects should enhance two related areas of research. 1) It should allow a more thorough investigation of the relationship between maternal diet and maternal phenylketonuria birth defects, and 2) it should provide an experimental tool to gain insight into the normal process of cardiovascular development.
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Affiliation(s)
- J D McDonald
- Department of Biological Sciences, Wichita State University, Kansas 67260-0026, USA
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10
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Abstract
The maternal phenylketonuria (PKU) syndrome refers to the teratogenic effects of PKU during pregnancy. These effects include mental retardation, microcephaly, congenital heart disease, and intrauterine growth retardation. In untreated pregnancies wherein the mother has classic PKU with a blood phenylalanine level > or = 1,200 microM (20 mg/dl), the frequencies of these abnormalities in offspring are exceedingly high, approaching 75-90% for microcephaly and mental retardation and 15% for congenital heart disease. There is a dose response relationship with progressively lower frequencies of these abnormalities at lower phenylalanine levels, both in the pregnancies of women with variants of PKU and in treated classic PKU pregnancies. The pathogenesis of this syndrome is unknown; it may be related to inhibition by phenylalanine of large neutral amino acid transport across the placenta or to direct toxicity of phenylalanine and/or a phenylalanine metabolite in certain fetal organs. A mouse model for PKU now exists, and studies of maternal PKU in this model are in progress. The treatment of maternal PKU consists of biochemical control through a phenylalanine restricted diet during pregnancy. The best results are obtained with diet initiation before conception or no later than the earliest weeks of pregnancy. Women with PKU and their families require much psychosocial support to meet the strict requirements of a maternal PKU pregnancy, including compliance with a difficult diet. With such compliance, however, it seems that bearing normal or near normal offspring is possible.
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Affiliation(s)
- H L Levy
- Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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11
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Wyse AT, Sarkis JJ, Cunha-Filho JS, Teixeira MV, Schetinger MR, Wajner M, Milton C, Wannmacher D. Effect of phenylalanine and its metabolites on ATP diphosphohydrolase activity in synaptosomes from rat cerebral cortex. Neurochem Res 1994; 19:1175-80. [PMID: 7824071 DOI: 10.1007/bf00965152] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The in vitro effects of phenylalanine and some of its metabolites on ATP diphosphohydrolase (apyrase, EC 3.6.1.5) activity in synaptosomes from rat cerebral cortex were investigated. The enzyme activity in synaptosomes from rats subjected to experimental hyperphenylalaninemia (alpha-methylphenylalanine plus phenylalanine) was also studied. In the in vitro studies, a biphasic effect of phenylalanine on both enzyme substrates (ATP and ADP) was observed, with maximal inhibition at 2.0 mM and maximal activation at 5.0 mM. Inhibition of the enzyme activity was not due to calcium chelation. Moreover, phenylpyruvate, when compared with phenylalanine showed opposite effects on the enzyme activity, suggesting that phenylalanine and phenylpyruvate bind to two different sites on the enzyme. The other tested phenylalanine metabolites phenyllactate, phenylacetate and phenylethylamine) had no effect on ATP diphosphohydrolase activity. In addition, we found that ATP diphosphohydrolase activity in synaptosomes from cerebral cortex of rats with chemically induced hyperphenylalaninemia was significantly enhanced by acute or chronic treatment. Since it is conceivable that ATPase-ADPase activities play an important role in neurotransmitter (ATP) metabolism, it is tempting to speculate that our results on the deleterious effects of phenylalanine and phenylpyruvate on ATP diphosphohydrolase activity may be related to the neurological dysfunction characteristics of naturally and chemically induced hyperphenylalaninemia.
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Affiliation(s)
- A T Wyse
- Departamento de Clências Fisiológicas, Fundacão Universidade do Rio Grande, RS, Brazil
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12
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Burri R, Steffen C, Stieger S, Brodbeck U, Colombo JP, Herschkowitz N. Reduced myelinogenesis and recovery in hyperphenylalaninemic rats. Correlation between brain phenylalanine levels, characteristic brain enzymes for myelination, and brain development. MOLECULAR AND CHEMICAL NEUROPATHOLOGY 1990; 13:57-69. [PMID: 2095783 DOI: 10.1007/bf03159908] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In a previous paper (Burri et al., 1990), we have shown that experimental hyperphenylalaninemia (hyper-Phe) in 3-17 d-old rats leads to reduced myelinogenesis. Such treated rats recover during a 6 w low phenylalanine (Phe) period between days 17 and 59. In order to get more detailed information about the disturbed myelinogenesis and recovery, we measured in hyper-Phe rats the developmental pattern of two brain enzymes typical for myelination, cerebroside sulfotransferase (CST), and 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNP), and other developmental parameters. Further, we correlated brain Phe levels with the brain damage in hyper-Phe rats, and we measured brain acetylcholinesterase (AChE) as a neuronal marker. Experimental hyper-Phe rats, injected between postnatal days 3 and 17 with alpha-methylphenylalanine and phenylalanine, showed a delayed age-dependent increase of CST activity, compared to that of controls. In hyper-Phe rats, CST peak activity was reached 2-4 d later, and was lower than in controls. The age-dependent decrease of the CST activity, however, started in test and control rats at the same time, at day 21. Between days 24 and 59, hyper-Phe rats had normal CST activity. CNP activity in hyper-Phe rats was lower than in controls from day 10 to 35, and recovered to normal values between days 35 and 59. Our results indicate that recovery from reduced myelinogenesis is possible after the period of fast myelination without compensatory increased CST activity. Further, the brain damage in test rats with Phe levels higher than average is more severe than in test rats with Phe levels lower than average; and there is no effect of hyperphenylalaninemia on brain neurons containing AChE.
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Affiliation(s)
- R Burri
- University of Berne, Department of Pediatrics, Switzerland
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13
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Strupp BJ, Himmelstein S, Bunsey M, Levitsky DA, Kesler M. Cognitive profile of rats exposed to lactational hyperphenylalaninemia: correspondence with human mental retardation. Dev Psychobiol 1990; 23:195-214. [PMID: 2379759 DOI: 10.1002/dev.420230302] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The present study was designed to provide further information on the enduring cognitive effects of experimental phenylketonuria (PKU) in rats, produced by the administration of alpha-methylphenylalanine and phenylalanine on postnatal days 3-21. These rats evidenced: (1) impaired learning set formation, (2) stimulus perseveration, particularly after an error, and (3) difficulty in utilizing the less salient features of their environment in mastering discrimination problems. In contrast, long-term memory function and the ability to form simple associations did not differ from controls. This pattern of intact and impaired cognitive functions bears remarkable similarity to that of mentally retarded humans and neonatally hyperphenylalaninemic rhesus monkeys, thus affirming the use of rats to study mental retardation. In addition, possible reasons for the mildness of the impairments commonly observed in animal models of severe mental retardation syndromes are discussed. We suggest that transfer of learning paradigms that assess the animal's ability to use information acquired in other problems are more likely to uncover significant cognitive impairments in such models than are procedures that test only the animals' ability to solve a single problem.
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Affiliation(s)
- B J Strupp
- Department of Psychology, Cornell University, Ithaca, New York 14853
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Gehrmann J, Schott K, Neuhoff V. Biochemical and developmental features of experimental phenylketonuria induced by L-ethionine in suckling rats. BIOCHEMICAL MEDICINE AND METABOLIC BIOLOGY 1989; 41:201-11. [PMID: 2742800 DOI: 10.1016/0885-4505(89)90027-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Suckling rats were injected subcutaneously with doses of L-ethionine (0.1 mumole/g body wt) at intervals of 12 hr. In the latter group, phenylalanine hydroxylase was effectively inhibited in vivo resulting in hyperphenylalaninemia and phenylketonuria. Due to the well-known sex-specific differences in L-ethionine metabolism female rats were much more affected by chronic administration of L-ethionine. The underlying mechanism of enzyme inhibition by ethionine could be disturbed protein synthesis and impaired protein phosphorylation, which was suggested by pronounced decreases in ATP content in liver. In the high dosage group depletions mainly of the branched-chain amino acids and lysine occurred in serum and brain, whereas the concentrations of methionine and tryptophan were increased. Tyrosine tended to be decreased in the course of hyperphenylalaninemia. Hyperphenylalaninemia and other resulting amino acid imbalances obviously impaired brain development during the early postnatal period. Concomitantly with reductions in protein concentrations, the activity of cathepsin D, a major intralysosomal acid proteinase, was increased in brain, suggesting also higher protein catabolism in brain. Side effects of this treatment, however, were higher mortality, loss of body weight, and a general impression of delayed development, resembling a state of undernutrition to some extent. These obvious side effects of ethionine limit the usefulness of ethionine as a suitable model for classic phenylketonuria in suckling rats.
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Affiliation(s)
- J Gehrmann
- Max-Planck Institut für Experimentelle Medizin, Forschungsstelle Neurochemie, Göttingen, Federal Republic of Germany
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Matsuo K, Hommes FA. The development of the muscarinic acetylcholine receptor in normal and hyperphenylalaninemic rat cerebrum. Neurochem Res 1988; 13:867-70. [PMID: 3226469 DOI: 10.1007/bf00970755] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The effect of hyperphenylalaninemia on the development of the muscarinic acetylcholine receptor in rat cerebrum has been studied. Rats were subjected to the hyperphenylalaninemic regimen as of 5 days of age. A gradual and steady decrease in the number of binding sites for L-[3H]quinuclidinylbenzilate was observed, with the white matter more affected than the gray matter. A return to normal blood phenylalanine levels after the age of 21 days does not lead to an increase in this number of binding sites.
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Affiliation(s)
- K Matsuo
- Department of Cell and Molecular Biology, Medical College of Georgia, Augusta 30912-2100
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Sato T, Imura E, Murata A, Minami S, Okabe T, Ohno I. Effects of maternal phenylalanine or tyrosine hydroxylase inhibition on postnatal maturation of catecholamine and amino acid metabolism in rats. ACTA PAEDIATRICA JAPONICA : OVERSEAS EDITION 1988; 30:56-62. [PMID: 2906779 DOI: 10.1111/j.1442-200x.1988.tb02497.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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17
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Bode VC, McDonald JD, Guenet JL, Simon D. hph-1: a mouse mutant with hereditary hyperphenylalaninemia induced by ethylnitrosourea mutagenesis. Genetics 1988; 118:299-305. [PMID: 3360305 PMCID: PMC1203282 DOI: 10.1093/genetics/118.2.299] [Citation(s) in RCA: 64] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Ethylnitrosourea mutagenesis of spermatogonial stem cells and a three-generation breeding scheme were used to screen for recessive mutations that cause defects in phenylalanine metabolism leading to elevated serum levels of this amino acid. This paper describes the isolation of such a mutation, hph-1, causing a heritable hyperphenylalaninemia in the neonate and weanling and an inability to effectively clear a phenylalanine challenge in the adult. Micro-pedigree analysis of the original mutant mouse and data obtained from crosses of affected and unaffected animals indicate that the mutation segregates in an autosomal recessive manner. An interspecies mouse backcross mapping experiment places the mutant gene locus on mouse chromosome 14 very near Np-1 and a backcross experiment with a conventional inbred mouse strain involving a nearby locus confirms the chromosome 14 assignment. The initial symptomatology of the mutant phenotype suggests this mutant may represent a useful animal model for the study of hyperphenylalaninemia in man.
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Affiliation(s)
- V C Bode
- Division of Biology, Kansas State University, Manhattan 66506
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18
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Abstract
Pregnant rats were given a diet supplemented with 0.5% alpha-methyl-phenylalanine and 3% phenylalanine from the 12th day of gestation to term. Compared to unsupplemented controls, maternal serum phenylalanine was elevated 8-10-fold. Experimental litters did not differ from controls in number of offspring, birth weight, or subsequent growth on an unsupplemented diet. At 8 weeks of age, animals were tested for latent learning on a 4-arm maze, and at 10 weeks, they were tested for observational learning with littermates in a food preference paradigm. In both tests, experimental animals did learn, but significantly less than controls. The data suggest that maternal hyperphenylalaninemia, induced as a model for the inborn error, phenylketonuria, can lead to learning deficits later in the lives of offspring.
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Affiliation(s)
- D Sadava
- Joint Science Department, Claremont Colleges, California 91711
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19
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Greengard O, Wolfe J. Cerebral serotonin regulation by phenylalanine analogues and during hyperphenylalaninemia. Biochem Pharmacol 1987; 36:965-70. [PMID: 2436623 DOI: 10.1016/0006-2952(87)90192-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Severe hyperphenylalaninemia induced in infant rats by 3 days of treatment with p-chlorophenylalanine (p-cl phe) plus phenylalanine (phe) did not lower the tryptophan concentration of the brain, and the cerebral serotonin (5-HT) deficiency was attributable entirely to the known suppression to tryptophan hydroxylase (TPH) by p-cl phe. The decrease in 5-HT and 5-hydroxyindoleacetic acid (5-HIAA) was thus no more pronounced than in rats which, treated with p-cl phe alone, were devoid of hyperphenylalaninemia. Suppression of TPH was found to also underlie the decrease in cerebral 5-HT caused by treatment with alpha-methylphenylalanine (alpha-mephe) alone: a 22% loss of midbrain TPH activity was detectable 24 hr after an injection only, reverted toward the normal during the next 2 days, and was clearly unrelated to the weak competitive inhibition of the enzyme by alpha-mephe in vitro. However, alpha-mephe (unlike p-cl phe), when administered together with phe, did not suppress TPH, nor did it counterbalance the reduction of cerebral tryptophan uptake by excess phe. Thus the 5-HT diminution in the rat model of phenylketonuria produced by treatment with alpha-mephe plus phe was attributable to hyperphenylalaninemia and the inhibition of tryptophan transport to the brain. Injection of tryptophan was found to restore the cerebral 5-HT level in the face of persistently severe hyperphenylalaninemia.
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20
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McChesney R, Isaacs CE, Greengard O. Cerebral glycine content and phosphoserine phosphatase activity in hyperaminoacidemias. Neurochem Res 1987; 12:289-95. [PMID: 3035402 DOI: 10.1007/bf00972139] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Chronic hyperphenylalaninemia maintained with the aid of a suppressor of phenylalanine hydroxylase, alpha-methylphenylalanine, increases the glycine concentration and the phosphoserine phosphatase activity of the developing rat brain but not that of liver or kidney. Similar increases occur after daily injections with large doses of phenylalanine alone, while tyrosine, isoleucine, alanine, proline, and threonine, were without effect. Treatment with methionine, which increases the phosphoserine phosphatase activity of the brain and lowered that of liver and kidney, left the cerebral glycine level unchanged. When varying the degrees of gestational or early postnatal hyperphenylalaninemia, a significant linear correlation was found between the developing brains' phosphoserine phosphatase and glycine concentration. Observations on the uptake of injected glycine and its decline further indicate that coordinated rises in the brain's phosphoserine phosphatase and glycine content associated with experimental hyperphenylalaninemia denote a direct impact of phenylalanine on the intracellular pathway of glycine synthesis in immature animals.
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Ledley FD, Woo SL. P-chlorophenylalanine does not inhibit production of recombinant human phenylalanine hydroxylase in NIH3T3 cells or E. coli. Biochem Biophys Res Commun 1987; 142:302-8. [PMID: 2949745 DOI: 10.1016/0006-291x(87)90273-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
P-chlorophenylalanine is an irreversible inhibitor of rat phenylalanine hydroxylase in vivo and in rat hepatoma cells and is frequently administered to rodents to create an animal model for phenylketonuria. We investigated the effect of p-chlorophenylalanine on production of human phenylalanine hydroxylase in human hepatoma cells and cells transformed with the recombinant human phenylalanine hydroxylase gene. P-chlorophenylalanine inhibited production of the human enzyme in human hepatoma cells and transformed mouse hepatoma cells but had no effect on the production of the enzyme in transformed NIH3T3 cells or in E. coli. Thus, phenylalanine hydroxylase inhibition does not result from a simple interaction between the drug and enzyme.
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22
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Rao DN, Kaufman S. Purification and state of activation of rat kidney phenylalanine hydroxylase. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(19)84462-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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23
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Hirano S, Takagi Y, Kanamatsu T, Nakai K. Effects of hyperphenylalaninemia in the fetal stage on the postnatal development of fetal rat brain. Neurochem Res 1985; 10:1071-81. [PMID: 2997643 DOI: 10.1007/bf00965882] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The effect of exposure at different prenatal stages to maternal hyperphenylalaninemia (HyPhe) on the somatic and neurological development of fetuses in rats was studied, with special respect to the change of relevant enzyme activities in the brain. While evident somatic damage was found only in the fetuses exposed to maternal HyPhe at a last stage of gestation, distinct mental retardation seemingly due to some irreversible damage to the brain was observed in all the treated fetuses regardless of the timing of exposure, and a significantly reduced activity of 2', 3'-cyclic nucleotide 3'-phosphohydrolase (CNPase), a marker enzyme of myelin, was confirmed in the mantle region of the brain.
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Lewis SA, Lyon IC, Elliott RB. Outcome of pregnancy in the rat with mild hyperphenylalaninaemia and hypertyrosinaemia: implications for the management of "human maternal PKU". J Inherit Metab Dis 1985; 8:113-7. [PMID: 3939586 DOI: 10.1007/bf01819292] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
In attempting to determine the effects of mildly elevated maternal phenylalanine (Phe) blood levels on the developing fetal rat brain, a dietary supplement of Phe was given, under taste cover of Aspartame. Phe and tyrosine (Tyr) levels were mildly elevated throughout pregnancy without evidence of malnutrition. Mild hyperphenylalaninaemia with concurrent hypertyrosinaemia induced in rats prior to conception resulted in microcephaly and lasting behavioural problems in the offspring, specifically hyperactivity and learning difficulties. Dams fed Tyr to produce Tyr levels equivalent to the Phe-fed animals showed only the learning difficulties among the offspring. alpha-Methyl Phe, a Phe hydroxylase inhibitor, fed in conjunction with Phe, at the level relevant to these experiments, resulted in raised Tyr levels and does not provide a better method of determining whether mildly elevated maternal Phe levels alone, or Phe and Tyr in combination, cause the abnormality found in the offspring of Phe-supplemented dams. Therapeutic addition of Tyr to diets of mothers with even mild hyperphenylalaninaemia should be approached with caution as mild co-elevation of Phe and Tyr in the fetus may be harmful. In the face of such a possible therapeutic dilemma alternatives, such as dietary additions of other essential amino acids to limit fetal brain damage, need to be explored.
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Greengard O, Brass CA. Developmental changes of cerebral phenylalanine uptake from severely elevated blood levels. Neurochem Res 1984; 9:837-48. [PMID: 6541764 DOI: 10.1007/bf00965670] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Brain phenylalanine concentrations at plasma levels raised to that in phenylketonuric subjects were studied in rats from fetal through postnatal life. Suppression of the hepatic phenylalanine hydroxylase with alpha methylphenylalanine, and injections of age-adjusted doses of phenylalanine on the next day, assured the persistence of the same elevation of plasma levels for at least four hours prior to assay. The net phenylalanine uptake determined under these conditions underwent several-fold decreases between the fourth day and the end of the suckling period, and by about the age of 30 days it was as low as in adulthood. The development of transport properties studied here could contribute to the change with age in the vulnerability of the brain to the same degree of hyperphenylalaninemia and, since the cerebral phenylalanine uptake may decrease to non-damaging levels during childhood, it is pertinent to defining the age at which the rigorous diet of phenylketonurics might be safely relaxed.
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Johnson RC, Shah SN. Effect of hyperphenylalaninemia induced during suckling on brain DNA metabolism in rat pups. Neurochem Res 1984; 9:517-28. [PMID: 6235457 DOI: 10.1007/bf00964378] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
We studied DNA metabolism (synthesis and degradation) in brain to investigate the effect of hyperphenylalaninemia induced in rats by treatment with PCPA or alpha MPA plus PHE during suckling (4th-20th days of postnatal age) on cell proliferation and naturally occurring cell death. The incorporation of 14C in DNA as percent of total radioactivity in the tissue, 30 min after administration of [14C]thymidine served as a measure of DNA synthesis in vivo, and the amount of radioactivity recovered in DNA as percent of total 14C in the tissues of 21 day old rats, injected with [14C]thymidine on 2nd day after birth, indicated the turnover (degradation) of DNA. The results showed that the DNA content of cerebellum as well as cerebrum was reduced by treatment with PCPA plus PHE, while treatment with alpha MPA plus PHE had no effect on DNA content in cerebellum but reduced the levels in cerebrum. Treatment with PCPA or alpha MPA plus PHE reduced the synthesis of DNA in cerebrum of 11 day old rats but not in 21 day old rats, and the treatments did not affect DNA synthesis in cerebellum of either 11 or 21 day old rats. The turnover (degradation) of DNA was increased in both cerebellum and cerebrum from rats treated with PCPA plus PHE but alpha MPA plus PHE treatment did not alter the DNA turnover either in cerebellum or in cerebrum. The activity of acid DNase was reduced in both cerebellum and cerebrum from 11 as well as 21 day old rats treated with PCPA plus PHE, but the enzyme activity was not altered in the tissues from rats of both ages treated with alpha MPA plus PHE. The data thus indicate that in rats treated with PCPA plus PHE the reduction in cerebral DNA levels occurs due to reduced synthesis and/or increased turnover (degradation) of DNA but that the reduction in cerebellar DNA may occur only as a result of increased turnover (degradation), and that in rats treated with alpha MPA plus PHE the reduction in cerebral DNA must occur due to reduced synthesis. This suggests that treatment of rats with PCPA plus PHE during suckling inhibits cell proliferation and/or increases naturally occurring cell death in both cerebellum and cerebrum while treatment with alpha MPA plus PHE inhibits only cell proliferation and in cerebrum alone.
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Abstract
Experimental phenylketonuria was induced in male rats by daily injections of alpha-methylphenylalanine and phenylalanine on postnatal Days 3-31. Beginning at 8 weeks of age, the animals were subjected to a test of observational learning followed by a test of latent learning (two tests of "advantageous" learning). The animals subjected to the PKU treatment early in life showed significant learning deficits in both tests. The importance of these studies lies in the fact that unlike conventional tests of learning, tests of advantageous learning are sensitive to the kinds of biological insults which cause mental retardation in humans. This differential sensitivity evident in studies of animal models of cognitive pathology is analogized to the areas of dysfunction which characterize human mental retardation. Suggestions for the development of appropriate models of intellectual development are made.
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Taylor EH, Hommes FA. Effect of experimental hyperphenylalaninemia on myelin metabolism at later stages of brain development. Int J Neurosci 1983; 20:217-27. [PMID: 6686838 DOI: 10.3109/00207458308986575] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Myelination is the most important process in postnatal maturation of the nervous system and during this period the growing infant passes through a "vulnerable period" during which irreversible brain damage can occur if the neonate is subjected to a potential neurotoxin. This study was undertaken to investigate the mechanisms by which chronic hyperphenylalaninemia interferes with myelin metabolism, beyond the neonatal period of rapid myelination, at a time when myelin continues to accumulate. Rats of 25 days of age were placed on a hyperphenylalanimenia (HyPhe) inducing diet of 5% phenylalanine plus 0.4% alpha-methylphenylalanine (alpha MP) at 25 days of age to approximate plasma phenylalanine levels of an untreated human PKU patient (1.5 mM). The HyPhe group exhibited approximately a 15% decrease in the amount of myelin protein throughout the 70 days of the study. The rate of incorporation of 3H-lysine into both TCA precipitable whole brain proteins or myelin proteins did not vary from the HyPhe group and a weight matched control group (WMC). Therefore, this loss of myelin could not be attributed to a hypo-myelination. The turnover of whole brain proteins also was unaffected by the HyPhe treatment; however, the turnover of myelin proteins in the HyPhe group was dramatically different (t 1/2 = 3 days) from that of the WMC group (t 1/2 = 36 days) or a group treated with only alpha MP (t 1/2 = 26 days).
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Brass CA, Greengard O. Modulation of cerebral catecholamine concentrations during hyperphenylalaninaemia. Biochem J 1982; 208:765-71. [PMID: 7165732 PMCID: PMC1154029 DOI: 10.1042/bj2080765] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Hyperphenylalaninaemia induced by daily injections of alpha-methylphenylalanine plus phenylalanine caused 20-40% decreases in cerebral dopamine (3,4-dihydroxyphenethylamine) and noradrenaline in 7- and 11-day-old rats. alpha-Methylphenylalanine alone as well as phenylalanine alone caused cerebral dopamine depletion. However, the effects were not additive, in that the depletion caused by alpha-methylphenylalanine was greater, not less, than that after treatment with both it and phenylalanine. Increased concentrations of tyrosine in the brain, owing to administered or endogenously formed tyrosine, could overcome the effect of excess phenylalanine on cerebral dopamine content. The fact that the inhibition of tyrosine hydroxylase by phenylalanine (or alpha-methylphenylalanine) in vitro was overcome by tyrosine concentrations similar to those effective in vivo further implicates the tyrosine hydroxylase inhibition as the mechanism underlying the dopamine depletion in hyperphenylalaninaemia. These results provide a theoretical basis for elevation, by tyrosine supplementation, of the cerebral phenylalanine/tyrosine ratio as a possible treatment modality for phenylketonuria.
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Binek-Singer P, Johnson TC. The effects of chronic hyperphenylalaninaemia on mouse brain protein synthesis can be prevented by other amino acids. Biochem J 1982; 206:407-14. [PMID: 7150251 PMCID: PMC1158598 DOI: 10.1042/bj2060407] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
A prolonged elevation in the concentrations of circulating phenylalanine was maintained in newborn mice by daily injections of phenylalanine and a phenylalanine hydroxylase inhibitor, alpha-methylphenylalanine. The result of this chronic hyperphenylalaninaemia was an accumulation of vacant or inactive monoribosomes that persisted for 18 h of each day. An elongation assay in vitro with brain postmitochondrial supernatants demonstrated that, in addition, there was an equally prolonged decrease in the rates of polypeptide-chain elongation by the remaining brain polyribosomes. Analyses of the free amino acid composition in the brains of hyperphenylalaninaemic mice showed a loss of several amino acids from the brain, particularly the large, neutral amino acids, which are co- or counter-transported across plasma membranes with phenylalanine. When a mixture of these amino acids (leucine, isoleucine, valine, threonine, tryptophan, tyrosine, methionine) was injected into hyperphenylalaninaemic mice, there was an immediate cessation of monoribosome accumulation in the brain and there was no inhibition of the rates of polypeptide-chain elongation. Although the concentrations of the large, neutral amino acids in the brain were partially preserved by treatment of hyperphenylalaninaemic mice with the amino acid mixture, the elevated concentrations of phenylalanine remained unaltered. The amino acid mixture had no detectable effect on brain protein synthesis in the absence of the hyperphenylalaninaemic condition.
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Inborn Errors of Metabolism. Clin Biochem 1982. [DOI: 10.1016/b978-0-12-657102-8.50013-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Binek PA, Johnson TC, Kelly CJ. Effect of alpha-methylphenylalanine and phenylalanine on brain polyribosomes and protein synthesis. J Neurochem 1981; 36:1476-84. [PMID: 7264644 DOI: 10.1111/j.1471-4159.1981.tb00589.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
A chronic hyperphenylalanemia was effectively produced in developing mice by daily administrations of phenylalanine (2 mg/g body wt) and a phenylalanine hydroxylase inhibitor alpha-methyl-D,L-phenylalanine (0.43 mg/g body wt). The presence of alpha-methylphenylalanine in newborn mice inhibited 65-70% of hepatic phenylalanine hydroxylase activity within 12 h. Since this maximum inhibition persisted for 24 h or longer, decreased enzyme activity was maintained by daily administrations. Whereas concentrations of phenylalanine increased approximately 40-fold in both plasma and brain following injection of alpha-methylphenylalanine and phenylalanine, plasma levels of tyrosine were not altered significantly. Concomitant with changes in phenylalanine concentrations we observed the brain polyribosomes' disaggregation, which reached a maximum 3 h after injection and persisted as long as 18 h. Polyribosomes did not become refractory to as many as 10 daily injections of alpha-methylphenylalanine and phenylalanine. In addition to polyribosome disaggregation, chronic hyperphenylalanemia reduced the rates of polypeptide chain elongation on polyribosomes isolated from brain homogenates.
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Abstract
The amino acid content of three tissues was measured in 10-day-old rats made hyperphenylalaninemic from age 3 to 10 days by daily injection of phenylalanine plus alpha-methylphenylalanine to inhibit phenylalanine hydroxylase (PAH). At 12 h after the last injection, the concentrations of alanine, valine, methionine, isoleucine, and leucine in the cerebral hemispheres were depressed by 25-50%, whereas that of glycine was elevated 2.3-fold. In the spinal cord, the levels of phosphoserine, methionine, and leucine were decreased by 40-50%, and those of serine and threonine increased by 50%. Tyrosine and phenylalanine concentrations were high in all tissues, 2-3 and 15-30 times normal, respectively; of the amino acids investigated, they were the only ones changed in the liver. Cerebral hyperglycinemia was also produced by chronic treatment with phenylalanine plus p-chlorophenylalanine to inhibit PAH, but not by acute (12 h) hyperphenylalaninemia. An increase in cerebral phosphoserine phosphatase activity was greater in rats treated with phenylalanine plus PAH inhibitor than with inhibitor alone. The content of brain glycine normally declines with age from birth to 15 days; this decrease was prevented by chronic hyperphenylalaninemia. Attempts to reduce the cerebral glycine content of the hyperphenylalaninemic rats were unsuccessful. However, one of the therapeutic protocols, methionine loading, may be useful because it increased the methionine and decreased the phenylalanine contents in the brain.
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Isaacs CE, Greengard O. The effect of hyperphenylalaninaemia on glycine metabolism in developing rat brain. Biochem J 1980; 192:441-8. [PMID: 6112983 PMCID: PMC1162358 DOI: 10.1042/bj1920441] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The brains of 3--16-day-old rats that were rendered hyperphenylalaninaemic by daily injections of alpha-methylphenylalanine plus phenylalanine were subjected to biochemical analysis. Fluctuations throughout the treatment period in the concentrations of branched-chain amino acids, methionine and serotonin were in agreement with the known interference of excess plasma phenylalanine with transport. The glycine content, however, became abnormal only by day 5, remained so through the treatment, and the elevation was equally apparent at 4, 8 or 24 h after the last daily injections. On the last day of treatment there were small increases in the taurine, glutamate, aspartate and 4-aminobutyrate concentrations, attributable mainly to the diencephalon or brain stem. After day 3 of treatment there were persistent elevations in the specific activity of phosphoserine phosphatase and glycine synthase (but not serine hydroxymethyltransferase) of the brain in each of the regions analysed. The observations indicate that chronic hyperphenylalaninaemia interferes with the normal regulation of intracerebral glycine metabolism during a critical period of early postnatal development, and suggest that the resulting excess in this amino acid (particularly marked in the cortex) contributes to the behavioural abnormalities that these animals exhibit in later life.
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Glick SD, Greengard O. Exaggerated cerebral lateralization in rats after early postnatal hyperphenylalaninemia. Brain Res 1980. [DOI: 10.1016/s0006-8993(80)80054-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Johnson RC, Shah SN. Effects of alpha-methylphenylalanine plus phenylalanine treatment during development on myelin in rat brain. Neurochem Res 1980; 5:709-18. [PMID: 7422057 DOI: 10.1007/bf00964709] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The effects of hyperphenylalaninemia induced by treatment with alpha-methylphenylalanine (MPA) plus phenylalanine (PHE) on body and brain weight, on myelin and synaptosome formation, and on the lipids and fatty acids of myelin were studied in rats. The administraton of MPA (2.4 mumol/g body wt) plus PHE (2.6 mumol/g body wt) for 25 and 35 days beginning on the fifth postnatal day did not affect brain development. On doubling the dosage of PHE, body and brain weights and myelin yields were significantly lowered. The lipid composition of myelin from the brains of treated animals was largely unaffected; however, the concentration of sulfatides ws significantly reduced. Unsaturated fatty acid levels in myelin from hyperphenylalaninemic rat brains were reduced while long-chain fatty acids were unaffected. We conclude that as in hyperphenylalaninemia induced by other methods, MPA + PHE treatment impairs body and brain growth, reduces myelin formation, and causes inhibition of fatty acid desaturation in the brain.
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Wen GY, Wisniewski HM, Shek JW, Loo YH, Fulton TR. Neuropathology of phenylacetate poisoning in rats: an experimental model of phenylketonuria. Ann Neurol 1980; 7:557-66. [PMID: 7192068 DOI: 10.1002/ana.410070609] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Results of this investigation indicate that the suckling rat treated with phenylacetate should be a useful new model for studying the pathogenesis of phenylketonuria and neuronal development. Both cerebellar and retinal neurons of postnatally treated rats are vulnerable to the adverse effects of phenylacetate. Morphological changes observed in the cerebellum, retina, and optic nerve of treated animals during the fourth to twenty-first days of life consist of regional reduction in the size of cerebellar vermis lobules IV, V, VIa, and IX, 35 to 40% reduction in thickness of the molecular layer, accumulation of cerebellar external granular cells and retinal neuroblastic cells, fewer parallel fibers in the cerebellar cortex, and fewer myelinated axons in the optic nerve.
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Lane JD, Neuhoff V. Phenylketonuria: clinical and experimental considerations revealed by the use of animal models. THE SCIENCE OF NATURE - NATURWISSENSCHAFTEN 1980; 67:227-33. [PMID: 6446685 DOI: 10.1007/bf01054531] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Phenylketonuria is a genetic defect that leads to imbecility, if the diagnosis is not made directly after birth. Since the development of imbecility can be almost totally halted by suitable dietary treatment, phenylketonuria is of more interest to neurochemists than to clinicians. This genetic defect is not known to occur in aminals. It is therefore necessary to develop suitable models for neurochemical analysis. Most successful is the simultaneous application to developing rats of alpha-methyl-phenylalanine (an inhibitor of phenylalanine hydroxylase), together with phenylalanine. With this treatment it is possible to induce changes in the central nervous system which are surprisingly similar to those found in patients with phenylketonuria. This model is therefore of great importance in the analyses of the disturbances of metabolism, which finally causes the severe defects in normal brain function.
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Figlewicz DA, Druse MJ. Experimental hyperphenylalaninemia: effect on central nervous system myelin subfractions. Exp Neurol 1980; 67:315-29. [PMID: 7349991 DOI: 10.1016/0014-4886(80)90232-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Lane JD, Schöne B, Langenbeck U, Neuhoff V. Characterization of experimental phenylketonuria. Augmentation of hyperphenylalaninemia with alpha-methylphenylalanine and p-chlorophenylalanine. BIOCHIMICA ET BIOPHYSICA ACTA 1980; 627:144-56. [PMID: 6444271 DOI: 10.1016/0304-4165(80)90316-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Phenylalanine in conjunction with p-chlorophenylalanine or alpha-methylphenylalanine was administered to suckling rats to induce hyperphenylalaninemia reminiscent of untreated phenylketonuria, and developmental parameters were monitored. The experimental model utilizing p-chlorophenylalanine was found to be unsatisfactory, in that the drug had general deleterious effects on growth, numerous side effects including increased mortality, and affected brain levels of biogenic monoamine neurotransmitters. The model utilizing alpha-methylphenylalanine was relatively free from nonspecific effects and thus, changes observed in the animals were attributable to experimental phenylketonuria. The latter animals had slightly decreased body and brain weights, and exhibited grossly elevated serum phenylalanine and urinary excretion of phenylketone metabolites. Hyperphenylalaninemia produced greatly disrupted brain amino acids at 10 days of age (prior to the formalization of the blood-brain barrier and specific transport systems) which was limited by 30 days of age to changes in glycine, gamma-aminobutyric acid and the aliphatic and aromatic amino acids which compete for uptake in the brain by a common carrier. These animals also exhibited a myelin deficit and changes in proteins from isolated nerve cell preparations. Mature animals which had daily treatment up to 60 days of age exhibited a long-term learning impairment. These observations are consistent with many aspects of the clinical picture of untreated phenylketonuric patients, and suggest that this animal model will be beneficial in studying the disease.
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Luttges MW, Gerren RA. Postnatal alpha-methylphenylalanine treatment effects on adult mouse locomotor activity and avoidance learning. Pharmacol Biochem Behav 1979; 11:493-8. [PMID: 531071 DOI: 10.1016/0091-3057(79)90031-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Neonatal mice were injected for five days with a combination of alpha-methylphenylalanine and phenylalanine to determine the influences of excess phenylalanine during development upon the behavior of these mice as adults. Spontaneous activity, bolus production, passive avoidance learning, simple active avoidance learning and complex active avoidance learning were tested in mice treated at two different postnatal periods. The results show that the treatments during development produced adult behavioral alterations compared to controls. The effects were most pronounced in mice treated in the postnatal period immediately after birth. The behavioral effects can be summarized as increased emotionality and generalized, stimulus-induced activity as well as decreased passive avoidance performance and complex active avoidance performance. These behavioral deficits are consistent with those usually reported in various models of human phenylketonuria.
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Del Valle JA, Greengard O. Isoenzyme composition of hepatic phenylalanine hydroxylase in developing rats after treatment with cortisol, alpha-methylphenylalanine and p-chlorophenylalanine in vivo. BIOCHEMICAL MEDICINE 1978; 20:247-55. [PMID: 153746 DOI: 10.1016/0006-2944(78)90071-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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