Skeletal muscle wasting occurs in adult rats under chronic treatment with paracetamol when glutathione-dependent detoxification is highly activated (original) (raw)
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British Journal of Nutrition
Cysteine (Cys), a conditionally indispensable amino acid, is required for the detoxification of paracetamol (acetaminophen, N-acetyl-para-aminophenol, 4-hydroxy-acetanilide, APAP), a drug of widespread use in older persons. We recently reported that repeated APAP cures could worsen sarcopenia in old rats, likely to be due to the impairment of Cys/GSH homoeostasis. The aim of the study was to evaluate whether a dietary Cys supplementation during APAP cures could improve Cys/GSH homoeostasis and thus preserve skeletal muscle. Male 21·5-month-old Wistar rats received three 2-week-long cures of APAP (1 % of diet) alone or with extra Cys (0·5 % of diet), intercalated with washout periods of 2 weeks (APAP and APAP–Cys groups, respectively). They were compared with untreated control rats (CT group). CT and APAP–Cys groups were pair-fed to the APAP group. Dietary Cys supplementation was efficient to prevent increase in liver mass (P<0·0001), decrease in liver GSH (P<0·0001), increase ...
AGE, 2012
Sulfur amino acids are determinant for the detoxification of paracetamol (N-acetyl-p-aminophenol) through sulfate and glutathione conjugations. Long-term paracetamol treatment is common in the elderly, despite a potential cysteine/glutathione defi-ciency. Detoxification could occur at the expense of anti-oxidative defenses and whole body protein stores in elderly. We tested how older persons satisfy the extra demand in sulfur amino acids induced by longterm paracetamol treatment, focusing on metabolic and nutritional aspects. Effects of 3 g/day paracetamol for 14 days on fasting blood glutathione, plasma amino acids and sulfate, urinary paracetamol metabolites, and urinary metabolomic were studied in independently living older persons (five women, five men, mean (±SEM) age 74±1 years). Dietary intakes were recorded before and at the end of the treatment and ingested sulfur amino acids were evaluated. Fasting blood glutathione, plasma amino acids, and sulfate were unchanged. Urinary nitrogen excretion supported a preservation of whole body proteins, but large-scale urinary metabolomic analysis revealed an oxidation of some sulfur-containing compounds. Dietary protein intake was 13% higher at the end than before paracetamol treatment. Final sulfur amino acid intake reached 37 mg/kg/day. The increase in sulfur amino acid intake corresponded to half of the sulfur excreted in urinary paracetamol conjugates. In conclusion, older persons accommodated to long-term paracetamol treatment by increasing dietary protein intake without any mobilization of body proteins, but with decreased anti-oxidative defenses. The extra demand in sulfur amino acids led to a consumption far above the corresponding population-safe recommendation.
The Journal of nutrition, 2002
In liver, cysteine dioxygenase (CDO), cysteinesulfinate decarboxylase (CSD), and gamma-glutamylcysteine synthetase (GCS) play important regulatory roles in the metabolism of cysteine to sulfate, taurine and glutathione. Because glutathione is released by the liver and degraded by peripheral tissues that express gamma-glutamyl transpeptidase, some peripheral tissues may be exposed to relatively high concentrations of cysteine. Rats were fed diets that contained low, moderate or high concentrations of protein or supplemental cysteine or methionine for 2 wk, and CDO, CSD and GCS activities, concentrations and mRNA levels and the concentrations of cysteine, taurine and glutathione were measured in liver, kidney, lung and brain. All three enzymes in liver responded to the differences in dietary protein or sulfur amino acid levels, but only CSD in kidney and none of the three enzymes in lung and brain responded. Renal CSD activity was twice as much in rats fed the low protein diet as in r...
Skeletal muscle protein loss due to D-penicillamine results from reduced protein synthesis
The International Journal of Biochemistry & Cell Biology, 2001
Reports in the literature indicate that the trifunctional amino acid D-penicillamine (D-P) induces a variety of muscle abnormalities, although the mechanisms are unknown. We hypothesised that defects may also arise due to the effects of D-P on rates of protein synthesis, possibly via changes in muscle metal composition. Male Wistar rats were injected with D-P at doses of 50 and 500 mg/kg body weight, i.p. Rats designated as controls were injected with 0.15 mol/l NaCl. After 24 h, there were reductions in muscle protein contents, protein synthetic capacities (RNA:protein ratio), fractional rates of protein synthesis, synthesis rates per unit RNA and synthesis rates per unit DNA in skeletal muscles of D-P treated rats. There were no statistically significant differences between the responses of the muscles containing a predominance of either Type I (represented by the soleus) or Type II (represented by the plantaris) fibres. In general, intracellular amino acids were not significantly affected by D-P treatment. Changes in muscle metals included significant reductions in copper, iron and manganese, without alterations in zinc or magnesium. In liver D-P reduced copper and iron though zinc, manganese and magnesium were unaffected. These effects of D-P on muscle may have been direct, as plasma indices of liver (activities of alkaline phosphatase and alanine aminotransferase) and kidney (urea, creatinine and electrolytes) damage were not significantly altered by D-P treatment. Plasma levels of corticosterone, insulin and free T 3 were also not significantly affected by D-P treatment. Muscle protein carbonyl concentrations, an index of free radical activity, were similarly unaffected. This is the first report of reduced rates of muscle protein synthesis in D-P treatment. Our data suggests that the reduced rates of muscle protein synthesis may contribute to, or reflect, the muscle abnormalities observed in patients undergoing D-P treatment.
Dietary sulfur amino acid effects on fasting plasma cysteine/cystine redox potential in humans
Nutrition, 2011
Objective-Oxidation of plasma cysteine/cystine (Cys/CySS) redox potential (E h CySS) has been associated with risk factors for cardiovascular disease in humans. Cys and CySS are derived from dietary sulfur amino acids (SAA), but the specific effects of SAA depletion and repletion on Cys/ CySS redox indices are unknown. The present study examined the effect of dietary SAA intake level on free Cys, free CySS and E h CySS in human plasma under fasting conditions. Research Methods and Procedures-Healthy individuals aged 18-36 y (n=13) were equilibrated to foods providing the RDA for SAA and then fed chemically defined diets without SAA (0 mg•kg −1 •d −1 ; n=13) followed by SAA at levels approximating the mean (56 mg•kg −1 •d −1 ; n=8) or 99th percentile (117 mg•kg −1 •d −1 ; n=5) intake levels of Americans. Fasting plasma samples were collected daily during 4-d study periods and analyzed for free Cys, free CySS and the E h CySS. Results-The SAA-free diet significantly (p<0.05) decreased plasma free Cys concentrations and oxidized E h CySS values after 4 days of SAA depletion. With SAA repletion at 56 mg•kg −1 •d − 1 , plasma free Cys increased significantly and values for E h CySS became more reducing. Administration of a diet providing a higher dose of SAA (117 mg•kg −1 •d −1) resulted in a significantly higher level of free Cys and a more reducing E h CySS. Conclusions-These results show that free Cys and Cys/CySS redox potential (E h CySS) in fasting plasma are affected by dietary SAA intake level in humans. Significant changes occur slowly over 4 days with insufficient SAA intake, but rapidly (after 1 day) with repletion.
Toxicology Letters, 1992
Since plasma reduced glutathione (GSH) seems to reflect liver GSH content, we have assessed plasma GSH in patients using paracetamol daily. In these patients a significant lower plasma GSH concentration was found with respect to controls. After the i.v. administration of GSH free plasma cysteine was 12 fold higher than in basal condition and all the pattern of plasma thiol groups was modified. This work suggests that the possible protective effect of GSH administration is due to the availability of plasma thiol compounds that enter the cell rather than GSH itself.
Age-related changes in glutathione availability and skeletal muscle carbonyl content in healthy rats
Experimental Gerontology, 2004
The free radical theory of aging proposes that oxidative stress plays a key role in the aging process. By altering muscle protein degradation rates, it could accelerate the age-related loss of muscle proteins. Glutathione (GSH), one of the main body antioxidants, could prevent this phenomenon, but its concentration decreases during aging. Our aims were to have a better understanding of the mechanisms of the agerelated decrease in glutathione availability and of the links with sarcopenia. Male Wistar rats aged 6, 9, 12, 15, 19, 22, 25 and 28 months ðn ¼ 6 per age) were used to measure plasma and skeletal muscle protein carbonyl content, plasma total and free cyst(e)ine content, liver and muscle glutathione content as well as liver GSSG reductase, GSH peroxidase, GSH transferase and g glutamyl cysteine synthetase (GCS) activities. Although tissue glutathione content decreased with age, the other markers of oxidative stress were little changed during aging. In particular, muscle protein carbonyl content was unchanged. Variations in glutathione availability were not explained by cyst(e)ine availability but depended on g GCS activity. The stability of skeletal muscle carbonyl content during aging suggests a very efficient degradation of oxidized proteins in muscle. q
The Journal of Toxicological Sciences, 2003
L-Buthionine (S,R)-sulfoximine (BSO), an inhibitor of glutathione (GSH) synthesis, was administered to mice via drinking water for 14 days in order to establish an animal model with continuously depleted levels of GSH. No toxicity was observed at 20 mM BSO, even though a significant decrease in liver weight was observed at 30 mM BSO. GSH levels in the liver, kidney, brain, lung, heart, spleen, pancreas, small intestine, large intestine, skeletal muscle, plasma and blood cells from mice given 20 mM of BSO were all less than those from the control mice continuously throughout a 24-hr period. The ratios of the GSH levels to that of the control were 46.4% and 16.7% in the liver and kidney, respectively, suggesting a decrease in GSH conjugation activity in vivo by GSH depletion. Liver cytochrome P450 content and UDP-glucuronosyltransferase activity to p-nitrophenol were not influenced by the BSO dosing. To confirm the adequacy of this GSH-depletion model, 0.125 or 0.25% of acetaminophen (APAP) was administered via diet to this model for 14 days. Nine out of the ten mice given both 20 mM BSO and 0.25% APAP died on Day 2, and remarkable necrosis was observed in the hepatocytes and renal tubular epithelium. Moreover, focal necrosis of hepatocytes with proliferation of fibroblasts was observed on Day 15 in some mice coadministered 20 mM BSO and 0.125% APAP. However, no toxicity was observed in mice given APAP alone. Based on these results, a mouse given 20 mM of BSO via drinking water for 14 days was concluded to be an animal model with continuously depleted levels of GSH in various organs without toxicity. This model shows high susceptibility to toxicity induced by chemicals which are metabolized to electrophilic and reactive metabolite(s), such as APAP.