A combination of simvastatin and low-protein diet increases renal 2-oxoglutarate dehydrogenase activity in rats

Mitochondrial 2-oxoglutarate dehydrogenase complex (2-OGDH) that consists of multiple copies of 3 catalytic subunits (E1, E2, E3) is a regulatory enzyme of tricarboxylic acid cycle. 2-OGDH together with branched chain α-ketoacid dehydrogenase (BCKDH) and pyruvate dehydrogenase (PDH) belongs to the 2-oxoacid dehydrogenases family. It was shown that in protein-restricted rats simvastatin stimulated liver BCKDH, whereas it exerted no effect on BCKDH in rats fed a standard diet. We hypothesized that combination of simvastatin and low-protein diet could have an impact on renal 2-OGDH. The purpose of the study was to determine the effect of combination of simvastatin and low-protein diet on renal 2-OGDH in rats. Simvastatin (80 mg/kg b.wt/day) or the vehicle (0.3% methylcellulose) were administered orally (for 14 days) to rats fed low-protein (8% protein) or standard (23% protein) diet. 2-OGDH activity, protein levels and mRNA levels for E1 and E2 subunits were determined. In addition, serum creatinine level was measured. Results: The combination of simvastatin and low-protein diet elicited the increase of renal 2-OGDH activity that corresponded to the increase of E1 protein, but not of E1 mRNA level. In contrast, simvastatin treatment did not affect 2-OGDH activity, nor protein and mRNA levels of E1 in rats fed standard diet. Serum creatinine levels were not changed upon simvastatin administration in any group. In conclusion, the results of present study indicate that combination of simvastatin and low-protein diet induces stimulation of renal 2-OGDH complex probably at post-transcriptional level.