Hepatic cysteine sulphinic acid decarboxylase depletion and defective taurine metabolism in a rat partial nephrectomy model of chronic kidney disease

• Published in: BMC nephrology Vol. 22; no. 1; p. 250
• Main Authors: Abbasian, Nima, Ghaderi-Najafabadi, Maryam, Watson, Emma, Brown, Jeremy, Yu Si, Li, Bursnall, Debbie, Pawluczyk, Izabella, Seymour, Anne-Marie, Bevington, Alan
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 05-07-2021; BioMed Central; BMC
• Subjects: Amino acid metabolism; Amino acids; Animals; Biosynthesis; Body weight; Carboxy-Lyases - metabolism; Care and treatment; Chronic kidney disease; Chronic kidney failure; Creatinine; Cysteine dioxygenase; Cysteine Dioxygenase - metabolism; Cysteine sulphinic acid decarboxylase; Decarboxylases; Deficiency diseases; Diet; Dietary Supplements; Disease Models, Animal; End-stage renal disease; Enzymes; Glutamine; Glutamine - administration & dosage; Health aspects; Humans; Kidney diseases; L-glutamine; Liver; Liver - enzymology; Liver - metabolism; Male; Metabolism; Muscle, Skeletal - metabolism; Musculoskeletal system; Nephrectomy; Nephrology; Plasma; Protein biosynthesis; Proteins; Proteinuria; Rats; Rats, Sprague-Dawley; Renal Insufficiency, Chronic - diet therapy; Renal Insufficiency, Chronic - metabolism; RNA, Messenger - metabolism; Skeletal muscle; Statistical analysis; Sulfur; Sulphinoalanine decarboxylase; Surgery; Taurine; Taurine - biosynthesis; Taurine - metabolism; Testing; Urine; Vascular diseases; United Kingdom; United Kingdom > UK; Cysteine sulphinic acid decarboxylase; Taurine; Chronic kidney disease; L-glutamine; Sulphinoalanine decarboxylase
• ISSN: 1471-2369; 1471-2369
• DOI: 10.1186/s12882-021-02442-7

Taurine depletion occurs in patients with end-stage chronic kidney disease (CKD). In contrast, in the absence of CKD, plasma taurine is reported to increase following dietary L-glutamine supplementation. This study tested the hypothesis that taurine biosynthesis decreases in a rat CKD model, but is rectified by L-glutamine supplementation.
CKD was induced by partial nephrectomy in male Sprague-Dawley rats, followed 2 weeks later by 2 weeks of 12% w/w L-glutamine supplemented diet (designated NxT) or control diet (NxC). Sham-operated control rats (S) received control diet.
Taurine concentration in plasma, liver and skeletal muscle was not depleted, but steady-state urinary taurine excretion (a measure of whole-body taurine biosynthesis) was strongly suppressed (28.3 ± 8.7 in NxC rats versus 78.5 ± 7.6 μmol/24 h in S, P < 0.05), accompanied by reduced taurine clearance (NxC 0.14 ± 0.05 versus 0.70 ± 0.11 ml/min/Kg body weight in S, P < 0.05). Hepatic expression of mRNAs encoding key enzymes of taurine biosynthesis (cysteine sulphinic acid decarboxylase (CSAD) and cysteine dioxygenase (CDO)) showed no statistically significant response to CKD (mean relative expression of CSAD and CDO in NxC versus S was 0.91 ± 0.18 and 0.87 ± 0.14 respectively). Expression of CDO protein was also unaffected. However, CSAD protein decreased strongly in NxC livers (45.0 ± 16.8% of that in S livers, P < 0.005). L-glutamine supplementation failed to rectify taurine biosynthesis or CSAD protein expression, but worsened CKD (proteinuria in NxT 12.5 ± 1.2 versus 6.7 ± 1.5 mg/24 h in NxC, P < 0.05).
In CKD, hepatic CSAD is depleted and taurine biosynthesis impaired. This is important in view of taurine's reported protective effect against cardio-vascular disease - the leading cause of death in human CKD.