Effects of heat exposure on Akt/S6K1 signaling and expression of genes related to protein and energy metabolism in chicken (Gallus gallus) pectoralis major muscle.
In order to improve understanding of the heat-induced changes in muscle growth, we determined the expression of genes related to protein and energy metabolism in the pectoralis major muscle of chickens. We also explored the protein kinase B (PKB also called Akt)/p70 S6 kinase (S6K1)/S6 pathway that mediates anabolic signals thereby regulating metabolism and hypertrophic/atrophic balance. Four-week-old chickens were exposed to 32 or 22 degrees C for 1 week. Chickens from both groups were then fasted for 16 h or left fed, and submitted to an oral administration of glucose-arginine to induce an anabolic response (30-min treatment) or left untreated. High ambient temperature and the associated decrease in feed intake modified the expression of certain energy-related genes (e.g. -40% for PGC-1alpha) and protein metabolism (e.g. about +80% for atrogin-1), but the expression of several muscle metabolism-related genes considered here was unchanged. The capacity for muscle protein synthesis, i.e. RNA/protein ratio, was reduced in warm conditions (approximately -20%). Slightly lower activation of S6 induced by glucose-arginine treatment was found at 32 degrees C compared to 22 degrees C, which might indicate somewhat lower efficiency of mRNA translation. Analysis of glucose/insulin balance suggested changes in glucose metabolism under heat exposure. However, this remains to be characterized.
Boussaid-Om Ezzine
S
S
INRA, UR83 Recherches Avicoles, F-37380 Nouzilly, France.
Everaert
N
N
Métayer-Coustard
S
S
Rideau
N
N
Berri
C
C
Joubert
R
R
Temim
S
S
Collin
A
A
Tesseraud
S
S
D000818:Animals; D030161:Avian Proteins / Q000235:genetics / Q000378:metabolism*; D001786:Blood Glucose / Q000032:analysis; D002645:Chickens / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D004734:Energy Metabolism; D015870:Gene Expression; D006358:Hot Temperature; D007328:Insulin / Q000097:blood; D008297:Male; D010369:Pectoralis Muscles / Q000254:growth & development / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism*; D015398:Signal Transduction
D030161:Avian Proteins; D001786:Blood Glucose; D007328:Insulin; D051057:Proto-Oncogene Proteins c-akt; D038762:Ribosomal Protein S6 Kinases, 70-kDa