Skeletal muscle expression of LDH and monocarboxylate transporters in growing rats submitted to protein malnutrition.
BACKGROUND
In different circumstances such as infant malnutrition, old age or chronic disease, decline of muscular strength, particularly anaerobic power, is shown. In this context, our laboratory, has demonstrated a decrease in anaerobic glycolytic power in pre-pubertal Bolivian children living at low and high altitude and suffering from marginal protein malnutrition.


OBJECTIVE
To bring molecular support to the relationship between protein malnutrition and anaerobic glycolytic metabolism, we studied the impact of prolonged protein malnutrition on lactate metabolism in different muscles of growing rats. Lactate dehydrogenase (LDH), monocarboxylate transporters (MCT1, MCT4) and membrane protein CD147 were chosen as specific markers of anaerobic glycolytic metabolism.


METHODS
Two groups of 10 weaning male rats were fed for 10 weeks either ad libitum with a well-balanced diet containing 18% protein or an isocaloric-diet containing 8% protein. LDH activity and mRNA amounts of LDH isoforms, MCT, CD147 were measured.


RESULTS
Protein deprivation during rat growth induced a decrease of LDH specific activity in skeletal muscles (mean value of -41%), accompanied by isoform distribution modifications in soleus, but not in glycolytic muscles (extensor digitorum longus (EDL) or plantaris). A reduction in mRNA amounts encoding the LDH A and B subunits was observed in EDL. A decrease in LDH B mRNA amounts was monitored in plantaris, whereas no modification in both LDH isoform mRNA quantities was observed in soleus. MCT1 mRNA quantities were decreased in EDL but MCT4 mRNA quantities remained stable. CD147 mRNA amounts were unchanged except for EDL with a 42% increase.


CONCLUSIONS
The global decreases of LDH activity, LDH and MCT gene expressions in growing rat skeletal muscles support the observed alterations of lactate metabolism associated with lowered muscular anaerobic performances in protein malnutrition.
Jouaville
Lionel F
LF
Faculté de Médecine, Laboratoire Inter-Universitaire de Biologie de l'Activité Physique et Sportive, 28 place Henri Dunant, 63001, Clermont-Ferrand, France. physio.sport@u-clermont1.fr
Fellmann
Nicole
N
Coudert
Jean
J
Clottes
Eric
E
D000818:Animals; D004044:Dietary Proteins / Q000008:administration & dosage* / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D000860:Hypoxia / Q000235:genetics / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D027501:Monocarboxylic Acid Transporters / Q000378:metabolism*; D009124:Muscle Proteins / Q000096:biosynthesis* / Q000378:metabolism; D018482:Muscle, Skeletal / Q000201:enzymology / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism; D020033:Protein Isoforms; D012333:RNA, Messenger / Q000378:metabolism; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D027981:Symporters / Q000378:metabolism; D000099233:Monocarboxylate Transport Protein 1
D004044:Dietary Proteins; D007770:L-Lactate Dehydrogenase; D008565:Membrane Proteins; D027501:Monocarboxylic Acid Transporters; D009124:Muscle Proteins; D010100:Oxygen; D020033:Protein Isoforms; D012333:RNA, Messenger; D027981:Symporters; D000099233:Monocarboxylate Transport Protein 1; C516342:Slc16a3 protein, rat