The Changes In Myocardial Energy Metabolism And PPAR-α Expression In The Acute Period Following High-level Spinal Cord Injury

Objective To investigate the changes in myocardial energy metabolism andmyocardial PPAR-α expression in myocardial injury induced by high-levelspinal cord injury (SCI), clarifying whether myocardial injury after SCI isrelated to the changes of energy metabolism of myocardial cells and myocardialPPAR-α expression.Methods Healthy adult male Sprague-Dawley (SD) rats (n=60) weighing250-300g were subjected to C7SCI injury by Allen’s method at6,12,24,48hor72h after SCI(SCI groups, respectively;6rats/group/time point)and shamoperation groups(TS groups, respectively;6rats/group/time point). After thesuccess of the modeling, the abdominal aorta was exposed, and arterial blood(~2ml) was sampled by scalp needle expiration and stored in refrigerated tubes,determinating levels of creatine kinase (CK), creatine kinase isoenzyme(CK-MB). Myocardial tissues from the right apical structures were collectedusing ophthalmic scissors, to detect myocardial ATP, AMP, ADP content of thewith organization High performance liquid chromatograph, using transmissionelectron microscopy to observe the morphological characteristics of myocardialcells and to detect the changes of myocardial free fatty acid, lactic acid, ATP,and the ATP atpase; simultaneously, to detect PPAR alpha mRNA expressionwith real-time fluorescent quantitative PCR, and to detect detection of myocardial tissue PPAR alpha protein with Western blot.Results （1） The serum CK and CK-MB levels in SCI group rats weresignificantly higher than those of the sham operation group rats at all timepoints (P <0.05);The serum CK and CK-MB levels in SCI group rats at6hbegan to rise, began to fall, is still higher than at72h in TS group.（2） Transmission electron microscopy results have showed myocardial cellsexhibited normal nucleus and nucleolus regions, cardiac myofibrils werearranged in neat rows, sarcomeres were clear, and the mitochondrial membranewas intact in the sham operation group.In SCI groups,changes in myocardialapoptotic morphology were readily apparent, including highly coiled chromatinin the nucleus (marginalization), high degrees of nuclear chromatin condensation,and apparent cavitation in many vacuolar structures. Furthermore, there were alarge number of broken myocardial filaments, indicating significant myocardialcell damage.（3）Energy substrate metabolism and atpase of test results:①The weight ofATP in SCI group rats were significantly lower than those of the TS group rats atall time points (P <0.05), the weight of ATP in SCI group rats was lowest at12h.②Myocardial Na+-K+-ATP enzyme and Ca2+-Mg2+-ATP enzyme levels in SCIgroup rats were significantly lower than those of the TS group rats at all timepoints (P <0.05),and began to decline at SCI6h, the lowest at SCI24h (P <0.05), began to rise after SCI48h, but were still lower than control group at SCI72h (P <0.05).③Results of free fatty acid and lactic acid: Free fatty acid andlactic acid in SCI group rats were significantly lower than those of the TS grouprats at all time points (P <0.05), and began to rise after SCI12h, reached thehighest at SCI24h (P <0.05), began to decline after48h, but were still higher than that of TS group at SCI72h (P <0.05).（4）PPAR alpha mRNA expression quantity in SCI group rats were significantlylower than those of the TS group rats at all time points (P <0.05). PPAR alphamRNA expression quantity in SCI group rats was lowest at SCI12h (P <0.05),and higher than other time point(P <0.05), but still lower than TS group(P <0.05). PPAR alpha protein content in SCI group rats were significantlylower than those of the TS group rats at all time points (P <0.05). PPAR alphaprotein content in SCI group rats was lowest at SCI12h (P <0.05),and higherthan other time point(P <0.05), but still lower than TS group (P <0.05).Conclusion After high-level spinal cord injury,the serum CK and CK-MBlevels rase, Myocardial Na+-K+-ATP enzyme levels and Ca2+-Mg2+-ATP enzymelevels were lower, the content of free fatty acid and lactic acid began to fall in6hafter injury, until24h after injury, but the injury after48h began to rise,72h isstill on the rise,and PPAR alpha expression was down-regulation.The studiesdemonstrate that decrease of myocardial energy metabolism rats and expressionof myocardial PPAR alpha after SCI is associated with myocardial injury afterSCI, and is probably one of the mechanisms of myocardial injury after SCI.