In vivo effects of high phenylalanine blood levels on Na+,K+-ATPase, Mg2+-ATPase activities and biogenic amine concentrations in phenylketonuria

Protective effects of Descurainia sophia seeds extract and its fractions on pulmonary edema by untargeted urine and serum metabolomics strategy

Background: Descurainia sophia seeds (DS) is a herbal medicine in traditional Chinese medicine (TCM) for treating lung diseases. We aimed to evaluate the therapeutic effect of DS and five of its fractions upon pulmonary edema (PE) through metabolomics analysis (MA) of urine and serum samples of rats. Methods: A PE model was established by intrathoracic injection of carrageenan. Rats were pretreated with DS extract or its five fractions (polysaccharides (DS-Pol); oligosaccharides (DS-Oli); flavonoid glycosides (DS-FG); flavonoid aglycone (DS-FA); fat oil fraction (DS-FO)) for seven consecutive days. Forty-eight hours after carrageenan injection, lung tissues were subjected to histopathology. MA of urine and serum was done by ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry, respectively. Principal component analysis and orthogonal partial least squares-discriminant analysis were operated for the MA of rats and potential biomarkers related to treatment. Heatmaps and metabolic networks were constructed to explore how DS and its five fractions act against PE. Results: DS and its five fractions could all attenuate pathologic lung injury to different degrees, and DS-Oli, DS-FG, and DS-FO had a more potent effect compared with DS-Pol and DS-FA. DS-Oli, DS-FG, DS-FA, and DS-FO could regulate the metabolic profiles of PE rats, but DS-Pol was less potent. According to MA, the five fractions could improve PE to some degree due to their anti-inflammatory, immunoregulatory, and renoprotective activities by mediating the metabolism of taurine, tryptophan, and arachidonic acid. However, DS-Oli, DS-FG, and DS-FO had more important roles in edema-fluid reabsorption, and reduction of vascular leakage through regulating the metabolism of phenylalanine, sphingolipid and bile acid. Finally, heatmaps and hierarchical clustering analysis indicated DS-Oli, DS-FG, and DS-FO to be more efficacious than DS-Pol or DS-FA against PE. The five fractions of DS had a synergistic effect on PE from different aspects, thereby constituting the entire efficacy of DS. DS-Oli, DS-FG, or DS-FO could be used as an alternative to DS. Conclusion: MA combined with use of DS and its fractions provided novel insights into the mechanism of action of TCM.

Birth weight related blood concentrations of the neurotransmission amino acids glutamine plus glutamate, phenylalanine and tyrosine in full-term breastfed infants perinatally

Background The amino acids glutamine plus glutamate, phenylalanine and tyrosine are implicated in neurotransmission. We aimed to evaluate these amino acid blood concentrations in full-term breastfed infants with different birth weight (BW) perinatally. Methods Breastfed full-term infants (n = 6000, males 3000, females 3000) BW 2000-4000 g were divided into four equal groups. Both males and females Groups A, 2000-2500 g, B 2500-3000 g, C 3000-3500 g, D 3500-4000 g. Blood samples on Guthrie cards, were taken on the 3rd day of life and quantified via a liquid chromatography tandem mass spectrometry (LC-MS/MS) method. Results Glutamine plus glutamate mean values were found to be statistically significantly different between males vs. females in all the studied groups. The highest values were determined in both males and females in group D. Statistically significantly higher values of phenylalanine appeared in group D vs. other groups. Tyrosine mean values were calculated to be statistically significantly different in both sexes in group A compared to other groups. Conclusions Differences of glutamine plus glutamate, phenylalanine and tyrosine levels among full-term newborns with different BW are presented for the first time in the literature. Newborns with BW 3000-4000 g are benefited by having higher concentrations of the mentioned neurotransmission related amino acids. Neonatal screening reference values for these amino acids in relation to BW could be established, not only for preterm and low BW infants but also for full-term newborns with BW >3000 g.

Maternal phenylketonuria syndrome: studies in mice suggest a potential approach to a continuing problem

BackgroundUntreated phenylketonuria (PKU), one of the most common human genetic disorders, usually results in mental retardation. Although a protein-restricted artificial diet can prevent retardation, dietary compliance in adults is often poor. In pregnant PKU women, noncompliance can result in maternal PKU syndrome, where high phenylalanine (Phe) levels cause severe fetal complications. Enzyme substitution therapy using Phe ammonia lyase (PAL) corrects PKU in BTBR Phe hydroxylase (Pah^enu2) mutant mice, suggesting a potential for maternal PKU syndrome treatment in humans.MethodsWe reviewed clinical data to assess maternal PKU syndrome incidence in pregnant PKU women. We treated female PKU mice (on normal diet) with PAL, stabilizing Phe at physiological levels, and mated them to assess pregnancy outcomes.ResultsPatient records show that, unfortunately, the efficacy of diet to prevent maternal PKU syndrome has not significantly improved since the problem was first noted 40 years ago. PAL treatment of pregnant PKU mice shows that offspring of PAL-treated dams survive to adulthood, in contrast to the complete lethality seen in untreated mice, or limited survival seen in mice on a PKU diet.ConclusionPAL treatment reduced maternal PKU syndrome severity in mice and may have potential for human PKU therapy.

A Metabolomics-Based Strategy for the Mechanism Exploration of Traditional Chinese Medicine: Descurainia sophia Seeds Extract and Fractions as a Case Study

A UPLC-QTOF-MS based metabolomics research was conducted to explore potential biomarkers which would increase our understanding of the model and to assess the integral efficacy of Descurainia sophia seeds extract (DS-A). Additionally, DS-A was split into five fractions in descending order of polarity, which were utilized to illustrate the mechanism together. The 26 identified biomarkers were mainly related to disturbances in phenylalanine, tyrosine, tryptophan, purine, arginine, and proline metabolism. Furthermore, heat map, hierarchical cluster analysis (HCA), and correlation network diagram of biomarkers perturbed by modeling were all conducted. The results of heat map and HCA suggested that fat oil fraction could reverse the abnormal metabolism in the model to some extent; meanwhile the metabolic inhibitory effect produced by the other four fractions helped to relieve cardiac load and compensate the insufficient energy supplement induced by the existing heart and lung injury in model rats. Briefly, the split fractions interfered with the model from different aspects and ultimately constituted the overall effects of extract. In conclusion, the metabolomics method, combined with split fractions of extract, is a powerful approach for illustrating pathologic changes of Chinese medicine syndrome and action mechanisms of traditional Chinese medicine.

Association of common variants in PAH and LAT1 with non-syndromic cleft lip with or without cleft palate (NSCL/P) in the Polish population

BACKGROUND

Non-syndromic cleft lip with or without cleft palate (NSCL/P) is a common structural malformation with a complex and multifactorial aetiology. Associations of abnormalities in phenylalanine metabolism and orofacial clefts have been suggested.

METHODS

Eight single nucleotide polymorphisms (SNPs) of genes encoding phenylalanine hydroxylase (PAH) and large neutral l-amino acid transporter type 1 (LAT1), as well as the PAH mutation that is most common in the Polish population (rs5030858; R408W), were investigated in 263 patients with NSCL/P and 270 matched controls using high resolution melting curve analysis (HRM).

RESULTS

We found that two polymorphic variants of PAH appear to be risk factors for NSCL/P. The odds ratio (OR) for individuals with the rs7485331 A allele (AC or AA) compared to CC homozygotes was 0.616 (95% confidence interval [CI]=0.437-0.868; p=0.005) and this association remains statistically significant after multiple testing correction. The PAH rs12425434, previously associated with schizophrenia, was borderline associated with orofacial clefts. Moreover, haplotype analysis of polymorphisms in the PAH gene revealed a 4-marker combination that was significantly associated with NSCL/P. The global p-value for a haplotype comprised of SNPs rs74385331, rs12425434, rs1722392, and the mutation rs5030858 was 0.032, but this association did not survive multiple testing correction.

CONCLUSION

This study suggests the involvement of the PAH gene in the aetiology of NSCL/P in the tested population. Further replication will be required in separate cohorts to confirm the consistency of the observed association.

The effects of sapropterin on urinary monoamine metabolites in phenylketonuria

BACKGROUND

Sapropterin dihydrochloride (BH4, tetrahydrobiopterin) can lower plasma phenylalanine (Phe) concentrations for a subset of patients with phenylketonuria (PKU), an inborn error of metabolism. Studies suggest that monoamine neurotransmitter concentrations are low in PKU patients. Sapropterin functions as a cofactor for hydroxylases specific to Phe, tyrosine, and tryptophan metabolism, pathways essential for catecholamine and serotonin synthesis.

OBJECTIVE

The objective of this study is to determine the impact of sapropterin on monoamine neurotransmitter status in patients with PKU.

DESIGN

58 PKU subjects were provided 20 mg/kg of sapropterin for 1 month. Those who responded with at least a 15% decrease in plasma Phe received sapropterin for 1 year, while Non-responders discontinued it. After an additional 3 months, Responders who demonstrated increased Phe tolerance and decreased medical food dependence were classified as Definitive, whereas Responders unable to liberalize their diet without compromising plasma Phe control were identified as Provisional. At study visits, patients provided blood for plasma amino acids, 3-day diet records, and 12-hour urine samples analyzed for epinephrine (E), dopamine (DA), dihydroxyphenylacetate (DOPAC), homovanillic acid (HVA), 3-methoxytyramine (3MT), serotonin (5HT), and 5-hydroxyindole acetic acid (5HIAA) using HPLC with electrochemical detection.

RESULTS

Compared with healthy non-PKU controls, subjects with PKU had significantly lower baseline concentrations of DA, HVA, 3MT, 5HT, and 5HIAA (p < 0.001 for all). Medical food protein intake had a direct association with DA, HVA, 5HT, and 5HIAA during the study (p < 0.05 for all), while plasma Phe had an inverse association with these markers (p < 0.01 for all). DOPAC was also associated with plasma Phe throughout the year (p = 0.035), although not at baseline. Patients with PKU had a significant increase in HVA (p = 0.015) after 1 month of sapropterin. When stratifying by Responder and Non-Responder status, significance of HVA increase in Non-responders (p = 0.041) was confirmed, but not in Responders (p = 0.081). A declining trend in urinary 5HIAA, significant only after controlling for plasma Phe (p = 0.019), occurred for Definitive Responders during the 1-year study.

CONCLUSION

Urinary monoamine concentrations are low in patients with PKU and are influenced by oral sapropterin and medical food intake, highlighting the importance of these therapies to neurotransmitter metabolism in phenylketonuria.

Erythrocyte membrane AChE, Na(+), K(+)-ATPase and Mg(2+) ATPase activities in mothers and their premature neonates in relation to the mode of delivery

AIM

To investigate erythrocyte membrane AChE, Na(+), K(+)-ATPase and Mg(2+)-ATPase activities in mothers and their full-term or premature newborns in relation to the mode of delivery.

METHODS

Blood was obtained from mothers pre- and post-delivery and the umbilical cord (CB) of their full-term newborns: Group A₁ (n = 16) born with vaginal delivery (VD), Group B₁ (n = 14) full-terms with scheduled cesarean section (CS), Group A₂ (n = 12) prematures with VD, Group B₂ (n = 14) prematures with CS. Total Antioxidant Status (TAS) and common laboratory tests were measured with routine methods, and the membrane enzyme activities spectrophotometrically.

RESULTS

TAS was reduced in mothers post VD and in the CB whereas remained unaltered in CS mothers and their newborns. AChE and Na(+), K(+)-ATPase were increased in mothers post VD. AChE was lower in the CB of prematures than that of full-terms independently of the mode of delivery. Na(+), K(+)-ATPase activity was increased in the groups of mothers post VD and decreased in prematures. The enzyme was higher in prematures with CS than that with VD. Mg(2+)-ATPase activity was unchanged.

CONCLUSION

The increased maternal AChE and Na(+), K(+)-ATPase activities may be due to the low TAS determined post VD, whereas their decreased activities in prematures to their immaturity.

Phenylacetylglycine, a putative biomarker of phospholipidosis: Its origins and relevance to phospholipid accumulation using amiodarone treated rats as a model

Amiodarone was given to male Sprague-Dawley rats at a dose of 150 mg kg(-1) day(-1) for 7 consecutive days to induce phospholipidosis in the lungs of treated rats. Amiodarone was given alone or concurrently with phenobarbitone. Animals given amiodarone had raised total phospholipid in serum, lung and lymphocytes, and elevated lyso(bis)phosphatidic acid (LBPA) in all tissues. Urinary and plasma phenylacetylglycine (PAG) and hepatic portal:aortal phenylacetate (PA) ratio were increased, whereas hepatic phenylalanine hydroxylase (PAH) activity and plasma phenylalanine:tyrosine ratio were not affected. Phenobarbitone treatment increased hepatic total P450 content and induced 7-pentoxyresorufin O-dealkylatian (PROD) activity, as expected, but had no effect on any other biochemical parameter. Plasma amiodarone concentration was reduced in rats co-administered both drugs and phospholipid accumulation in target tissues was attenuated compared with rats treated with amiodarone alone. However, phenobarbitone co-administration failed to alter the magnitude of response with regards to urinary PAG excretion and plasma concentration of its precursors after amiodarone treatment. Increased intestinal absorption of PAG precursors probably resulted in the raised urinary PAG after amiodarone treatment. Urinary PAG correlated weakly with serum, lymphocyte and lung phospholipids. However, urinary PAG excretion was similar in rats dosed solely with amiodarone or in combination with phenobarbitone, despite the fact that the degree of phospholipid accumulation was far less in rats given the combined treatment. Nevertheless, urinary PAG was raised only in animals exhibiting abnormal phospholipid accumulation in target tissues and may thus be useful as a surrogate biomarker for phospholipidosis.

The in vivo and in vitro effects of L-carnitine supplementation on the erythrocyte membrane acetylcholinesterase, Na+, K+-ATPase and Mg2+-ATPase activities in basketball players

BACKGROUND

We investigated whether the activities of erythrocyte membrane acetylcholinesterase (AChE), Na+, K+-ATPase and Mg2+-ATPase are modulated in basketball players pre- vs. post-forced training with or without L-carnitine (L-C) supplementation.

METHODS

Blood was obtained from 10 male players pre-game (group A) and post-game (group B) and after 1 month L-C supplementation (2 g/24 h orally) pre-training (group C) and post-training (group D). Lactate, pyruvate and total antioxidant status (TAS) were measured with commercial kits, catecholamines with HPLC and the enzyme activities spectrophotometrically.

RESULTS

Lactate, pyruvate, AChE, Na+, K+-ATPase and catecholamines were increased (p<0.001) and TAS was decreased (p<0.001) in group B. In contrast, TAS remained unaltered and the all enzyme activities were reduced (p<0.001) in group D at the same time of study. Mg2+-ATPase activity remained unchanged. In vitro incubation of the modulated AChE and Na+, K+-ATPase with L-C (25 microM) from group B and group D resulted in a non-significant reduction of the enzymes in group B and complete restoration of their activities in group D.

CONCLUSIONS

The increase of AChE and Na+, K+-ATPase activities may be due to the elevation of catecholamines in group B. Carnitine utilization by the muscles during training may result in a reduction of the enzyme activities (group D). The latter is supported by the recovery of the enzyme activities after incubation of the membranes from group D with L-C.

Reduced cerebral fluoro-L-dopamine uptake in adult patients suffering from phenylketonuria

Deficiency of phenylalanine hydroxylase activity in phenylketonuria (PKU) causes an excess of phenylalanine (Phe) throughout the body, predicting impaired synthesis of catecholamines in the brain. To test this hypothesis, we used positron emission tomography (PET) to measure the utilization of 6-[18F]fluoro-L-DOPA [corrected] (FDOPA) in the brain of adult patients suffering from PKU and in healthy controls. Dynamic 2-h long FDOPA emission recordings were obtained in seven adult PKU patients (five females, two males; age: 21 to 27 years) with elevated serum Phe levels, but lacking neurologic deficits. Seven age-matched, healthy volunteers were imaged under identical conditions. The utilization of FDOPA in striatum was calculated by linear graphical analysis (k3S, min(-1)), with cerebellum serving as a nonbinding reference region. The time to peak activity in all brain time-radioactivity curves was substantially delayed in the PKU patients relative to the control group. The mean magnitude of k3S in the striatum of the PKU patients (0.0052+/-0.0004 min(-1)) was significantly lower than in the control group (0.0088+/-0.0009 min(-1)) (P<0.001). There was no significant correlation between individual serum Phe levels and k3S. The unidirectional clearance of FDOPA to brain was impaired in adult patients suffering from PKU, presumably reflecting the competitive inhibition of the large neutral amino acid carrier by Phe. Assuming this competition to be spatially uniform, the relationship between striatum and cerebellum time-activity curves additionally suggests inhibition of DOPA efflux, possibly also due to competition from Phe. The linear graphical analysis shows reduced k3S in striatum, indicating reduced DOPA decarboxylase activity.

Therapeutic efficacy of dl-α-lipoic acid on cyclosporine A induced renal alterations

The present study was designed to evaluate the possible beneficial effect of lipoic acid in preventing the renal damage induced by cyclosporine A in rats. Male albino rats of Wistar strain were divided into four groups and treated as follows. Two groups received cyclosporine A by oral gavage (25 mg/kg/body weight) for 21 days to induce nephrotoxicity, one of which simultaneously received lipoic acid treatment (20 mg/kg body weight) for 21 days. A vehicle (olive oil) and a lipoic acid drug control were also included. Cyclosporine A induced renal damage was evident from the decreased activities of tissue marker enzymes (alkaline phosphatase, acid phosphatase, lactate dehydrogenase, aspartate transaminase and alanine transaminase) and decreased activities of ATPases (Na+, K+-ATPase, Ca2+-ATPase and Mg2+ ATPase). An apparent increase in the levels of serum constituents (urea, uric acid and creatinine) and urinary marker enzymes (N-acetyl-beta-D-glucosaminidase, beta-glucosidase, beta-galactosidase, cathepsin-D and gamma-glutamyl transpeptidase) along with significant decline in creatinine clearance were seen in the cyclosporine treated rats, which was reversed upon treatment with lipoic acid. Ultrastructural observations were also in agreement with the above abnormal changes. Lipoic acid effectively reverted these abnormal biochemical changes and minimized the morphological lesions in renal tissue. Hence, this study clearly exemplifies that lipoic acid might be an ideal choice against cyclosporine A induced cellular abnormalities.

l-Cysteine and glutathione restore the reduction of rat hippocampal Na+, K+-ATPase activity induced by aspartame metabolites

Studies have implicated aspartame (ASP) ingestion in neurological problems. The aim of this study was to evaluate hippocampal Na(+),K(+)-ATPase and Mg(2+)-ATPase activities after incubation with ASP or each of ASP metabolites, phenylalanine (Phe), methanol (MeOH) and aspartic acid (asp) separately. Suckling rat hippocampal homogenates or pure Na(+),K(+)-ATPase were incubated with ASP metabolites. Na(+),K(+)-ATPase and Mg(2+)-ATPase activities were measured spectrophotometrically. Incubation of hippocampal or pure Na(+),K(+)-ATPase with ASP concentrations (expected in the cerebrospinal fluid (CSF)) after ASP consumption of 34, 150 or 200mg/kg resulted in hippocampal enzyme activity reduction of 26%, 50% or 59%, respectively, whereas pure enzyme was remarkably stimulated. Moreover, incubation with hippocampal homogenate of each one of the corresponding in the CSF ASP metabolites related to the intake of common, high/abuse doses of the sweetener, inhibited Na(+),K(+)-ATPase, while pure enzyme was activated. Hippocampal Mg(2+)-ATPase remained unaltered. Addition of l-cysteine (cys) or reduced glutathione (GSH) in ASP mixtures, related with high/toxic doses of the sweetener, completely or partially restored the inactivated membrane Na(+),K(+)-ATPase, whereas the activated pure enzyme activity returned to normal. CSF concentrations of ASP metabolites related to common, abuse/toxic doses of the additive significantly reduced rat hippocampal Na(+),K(+)-ATPase activity, whereas pure enzyme was activated. Cys or GSH completely or partially restored both enzyme activities.

Differential effects of phenylalanine on Rac1, Cdc42, and RhoA expression and activity in cultured cortical neurons

Phenylketonuria (PKU) is characterized by a high concentration of phenylalanine, which can lead to mental retardation. One of the characteristic pathologic changes in untreated phenylketonuria patients is a reduction in the number of axons, dendrites, and synapses in the brain. This is thought to be due to the toxic effects of phenylalanine and/or its metabolites, however, the underlying mechanism remains unclear. In this study, we observed that phenylalanine reduced the number of dendrites and dendritic spines in cultured neurons. We further demonstrated that phenylalanine down-regulated Rac1, Cdc42, and RhoA mRNA and protein expression. Pull-down assays indicated that phenylalanine caused a decrease in Rac1/Cdc42 activity but increased RhoA activity. Expression of a dominant negative RhoA or treatment with a Rho-associated kinase specific inhibitor, Y-27632, partly inhibited the phenylalanine-induced decrease in dendrite numbers. In conclusion, we have demonstrated that phenylalanine affects the expression and activity of Rac1, Cdc42, and RhoA. Furthermore, RhoA signaling is involved in the inhibitory effect of phenylalanine on dendritic branching. These results may provide an important insight into the molecular mechanism underlying phenylalanine-induced abnormalities of dendrites, specifically in phenylketonuria neuronal injury.

An in vivo and in vitro study of erythrocyte membrane acetylcholinesterase, (Na+, K+)-ATPase and Mg2+-ATPase activities in basketball players on α-tocopherol supplementation. The role of l-carnitine

BACKGROUND & AIMS

Vitamin E (alpha-tocopherol, alpha-Te) and carnitine reduce lipid peroxidation. THE AIM WAS TO: To investigate the erythrocyte membrane acetylcholinesterase (AChE), Na+, K+-ATPase and Mg2+-ATPase activities in basketball players with or without alpha-Te supplementation, before and after training. In vitro, we aimed to find out any additional effect of L-carnitine (L-C) on the modulated enzyme activities.

SUBJECTS AND METHODS

Blood was obtained from 10 players before (group A), after exercise (group B) and after 1 month on alpha-Te (200 mg/24 h orally) supplementation before (group C) and after the game (group D). Lactate, pyruvate, muscle enzyme activities and total antioxidant status (TAS) were measured with commercial kits. Catecholamines and alpha-Te were determined with HPLC methods and membrane enzyme activities spectrophotometrically.

RESULTS

Lactate, pyruvate, muscle enzymes and catecholamine levels were increased (P<0.001) in all groups after training. Alpha-Te levels and Mg2+-ATPase activity remained unaltered before and after exercise. TAS was decreased in the groups after the game. AChE activity was increased in group B (P<0.01) and decreased in group D (P<0.01). After the exercise, Na+, K+-ATPase activity was increased in group B and remained unaltered in group D. In vitro incubation of membranes from group D with L-C resulted in a partially restoration of the membrane AChE activity, whereas Na+, K+-ATPase and Mg2+-ATPase activities were found unchanged.

CONCLUSIONS

Alpha-Te supplementation in basketball players results in an increase of TAS and AChE activity, whereas the other enzyme activities were found unchanged. L-C addition may restore AChE activity, which was modulated by training in players on alpha-Te.

L-Cysteine supplementation prevents exercise-induced alterations in human erythrocyte membrane acetylcholinesterase and Na+,K+-ATPase activities

BACKGROUND

L-Cysteine (L-Cys) is implicated in the reduction of free radical production. The aim of this study was to investigate whether L-Cys supplementation prevents modulation of the activities of erythrocyte membrane acetylcholinesterase (AChE), Na(+),K(+)-ATPase and Mg(2+)-ATPase induced by free radicals in basketball players during training.

METHODS

Blood was obtained from 10 basketball male players before (group A) and after a game (group B) and after 1 week of L-Cys (0.5 g/24 h orally) supplementation before (group C) and after training (group D). Lactate, pyruvate and total antioxidant status (TAS) were measured using commercial kits and the enzyme activities were determined spectrophotometrically.

RESULTS

Both lactate and pyruvate levels remarkably increased after exercise. In contrast, TAS levels significantly decreased in group B, increased in group C and then declined (group D), reaching those of group A. AChE activity was statistically increased post-exercise (3.98+/-0.04 Delta OD/min x mg protein) compared with pre-training (2.90+/-0.05 Delta OD/min x mg protein, p<0.01). Na(+),K(+)-ATPase activity was also higher post-exercise (1.27+/-0.05 micromol Pi/h x mg protein) than that pre-exercise (0.58+/-0.04 micromol Pi/h x mg protein, p<0.001). When the players were supplemented with L-Cys, both AChE and Na(+),K(+)-ATPase activities remained unaltered post-exercise. Mg(2+)-ATPase activities were unchanged in all groups studied.

CONCLUSIONS

L-Cys supplementation may protect the enzyme activities studied against stimulation induced by free radical production during training in athletes by ameliorating their total antioxidant capacity.

Lupeol and its ester inhibit alteration of myocardial permeability in cyclophosphamide administered rats

Cyclophosphamide (CP), an alkylating agent widely used in cancer chemotherapy causes cardiac membrane damage. Lupeol, a pentacyclic triterpene, isolated from Crataeva nurvala stem bark and its ester, lupeol linoleate possess a wide range of medicinal properties. The effect of lupeol and its ester was evaluated in CP induced alterations in cardiac electrolytes in rats. Male albino rats of Wistar strain were categorized into 6 groups. Group I served as control. Rats in groups II, V and VI were injected intraperitoneally with a single dose of CP (200 mg/kg body weight) dissolved in saline. CP treated groups V and VI received lupeol and lupeol linoleate (50 mg/kg body weight) respectively, dissolved in olive oil for 10 days by oral gavage. At the end of the experimental period, urinary risk factors, activities of ATPases and electrolytes were measured using standard procedures. CP administered rats showed a significant decrease (P < 0.001) in the activities of ATPases. It was associated with significant alterations (P < 0.001) of electrolytes both in serum and cardiac tissue. The levels of urea, uric acid and creatinine were also significantly (P < 0.001) altered in the serum and urine. Lupeol and its ester showed reversal of the above alterations induced by CP. These findings demonstrate that the supplementation with lupeol and its ester could preserve membrane permeability, highlighting their protective effect against CP induced cardiotoxicity.

The effect of L-cysteine and glutathione on inhibition of Na+, K+-ATPase activity by aspartame metabolites in human erythrocyte membrane

BACKGROUND

Reports have implicated Aspartame (N-L-a-aspartyl-L-phenylalanine methyl ester, ASP) in neurological problems.

AIM

To evaluate Na(+), K(+)-ATPase activities in human erythrocyte membranes after incubation with the ASP metabolites, phenylalanine (Phe), methanol (MeOH) and aspartic acid (Asp).

METHODS

Erythrocyte membranes were obtained from 12 healthy individuals and were incubated at 37 degrees C for 1 h with the sum or each of the ASP metabolites separately, which are commonly measured in blood after ASP ingestion. Na(+), K(+)-ATPase and Mg(2+)-ATPase activities were measured spectrophotometrically.

RESULTS

Membrane Mg(2+)-ATPase activity was not altered. The sum of ASP metabolite concentrations corresponding to 34, 150 or 200 mg/kg of the sweetener ingestion resulted in an inhibition of the membrane Na(+), K(+)-ATPase by -30, -40, -48%, respectively. MeOH concentrations of 0.14, 0.60 or 0.80 mM decreased the enzyme activity by -25, -38, -43%, respectively. Asp concentrations of 2.80, 7.60 or 10.0 mM inhibited membrane Na(+), K(+)-ATPase by -26, -40, -46%, respectively. Phe concentrations of 0.14, 0.35 or 0.50 mM reduced the enzyme activity by -24, -44, -48%, respectively. Preincubation with L-cysteine or reduced glutathione (GSH) completely or partially restored the inhibited membrane Na(+), K(+)-ATPase activity by high or toxic ASP metabolite concentrations.

CONCLUSIONS

Low concentrations of ASP metabolites had no effect on Na(+), K(+)-ATPase activity. High or abuse concentrations of ASP hydrolysis products significantly decreased the membrane enzyme activity, which was completely or partially prevented by L-cysteine or reduced GSH.

Study on cardioactive effects of brazilein

Brazilein (6a,7-dihydro-3,6a,10-trihydroxy-benz[b]indeno[1,2-d]pyran-9(6H)-one) is a compound obtained in a large amount from Caesalpinia sappan ethanol extracts with a high purity of about 98%. In isolated cardiac tissues, we found that brazilein exhibited a positive inotropic action in a concentration-dependent manner with little effect on heart rate and coronary perfusion. To study its possible mode of action, isolated rat hearts were treated with propranolol. This treatment did not alter the cardiotonic effect of brazilein, suggesting that this effect does not involve stimulation of beta-adrenoceptors. On the other hand, an analysis of the interaction between Na(+),K(+)-ATPase and brazilein was carried out. Albino guinea pig erythrocytes (mainly alpha1-Na(+),K(+)-ATPase isoforms) enriched with Na(+),K(+)-ATPase isoforms were utilized to compare the inhibition promoted by brazilein with that of classical inhibitors such as the cardiac glycoside deslanoside. Analysis of inhibition curves revealed that unlike deslanoside, brazilein had a relatively low affinity for erythrocyte isoforms and failed to completely inhibit the Na(+),K(+)-ATPase activity. The extent of the maximum inhibition rate was about 50%. The inhibitory effect of brazilein was not antagonized by 10 mmol/l K(+), as observed with deslanoside. Electrocardiogram research in vivo showed that brazilein did not induce the ventricular arrhythmias observed with deslanoside, suggesting that brazilein might have a less adverse effect and higher therapeutic index than cardiac glycosides. In light of all the above-mentioned observations, it can be concluded that brazilein, a molecule with a non-steroidal skeleton, produced its positive inotropic effect through inhibiting Na(+),K(+)-ATPase and could thus serve as a structural paradigm to develop new inotropic drugs.

Cytoprotective role of DL-α-Lipoic acid in cyclophosphamide induced myocardial toxicity

Cyclophosphamide (CP), a potent antitumor drug is known to cause severe cardiotoxicity. The present study is aimed at evaluating the cardioprotective role of lipoic acid in CP induced toxicity. Male albino rats of Wistar strain were divided into four groups and treated as follows: Group I served as control, Group II received a single dose of CP (200 mg/kg b.wt., i.p.), Group III received lipoic acid (25 mg/kg b.wt., orally) for 10 days, Group IV received CP immediately followed by lipoic acid for 10 days. In CP administered rats, the activities of tissue marker enzymes (creatine phosphokinase, lactate dehydrogenase, aspartate transaminase and alanine transaminase) were significantly (p<0.001) reduced, ATPases suffered loss in enzyme activity and thiols were depleted. Histopathological observations were also in agreement with the above abnormal changes. Lipoic acid effectively reverted these abnormal biochemical changes and minimized the histopathological lesions in heart. These observations highlight the protective role of lipoic acid in CP induced cardiac injury.

A study of gene expression profiles of cultured embryonic rat neurons induced by phenylalanine

To have more insight into the mechanism of neuronal injury in phenylketonuria (PKU) patients, gene expression profiles were studied in cell culture of embryonic rat cortical neurons induced by phenylalanine. Randomly chose cortical cultured for 3 days were treated by 0.9-mM phenylalanine for 12 h. Control group of the same batch was treated with the same volume of medium. Total RNA was extracted and hybridized with the Affymetrix gene chip U34 according to the protocol provided by the Affymetrix Company. Real-time PCR was used to further confirm the result. We found that the hybridization signals of 167 genes were increased among the total 1323 probes plotted on the chip. The 167 increased genes could be functionally categorized into signal transduction, neuron related, cytoskeleton, metabolism, ion channels, transcription factors, cytokines, and apoptosis related. Signals of seven probes were decreased, which accounted to 0.5% of the total number. A series of genes that were not reported previously were upregulated by phenylalanine, including Ca2+/calmodulin-dependent protein kinase, Brain type II (CaMK II), ras, P38, L-voltage dependent calcium channel, some genes related to vesicle formation and transmitter release, some glutamate receptor subunits and glutamate transporters. According to the gene expression profiles, it is likely that multiprocesses are involved in the neuronal injury induced by phenylalanine, such as the activation on of the NMDR-Ca2+-CaMK II-Ras-P38 axis, the abnormality in neurotransmitter release. Our study also suggests that the excitatory neurotransmitter glutamate may play a role in the neural pathology of PKU.

Platelet serotonin concentrations in PKU patients under dietary control and tetrahydrobiopterin treatment

Tetrahydrobiopterin (BH4) supplementation has been applied in PKU treatment, resulting in successful control of blood phenylalanine (Phe) concentrations. We evaluated serotonin status in PKU patients under classical dietary treatment (n = 40) and in a group of 11 PKU patients under BH4 treatment, both during a 6-month period. Platelet serotonin values were significantly lower in PKU patients under dietary treatment when compared with controls. A negative correlation was observed between plasma Phe and platelet serotonin concentrations (r = -0.367, p = 0.017) in PKU patients. Platelet serotonin concentration increased significantly after both 1 and 6 months of BH4 therapy when compared with baseline conditions (Wilcoxon test: p = 0.013 and p = 0.021, respectively), while no differences were observed when comparing plasma Phe concentrations at the different points. Our results indicate that PKU patients under classical treatment have decreased platelet serotonin concentrations, probably owing to continued high Phe values, while BH4 supplementation restored platelet serotonin values.