title: Effects of tonic immobility (TI) and corticosterone (CORT) on energy status and protein metabolism in pectoralis major muscle of broiler chickens.
abstract: Tonic immobility (TI), which can be divided into short (STI) or long (LTI) duration, is a character related to fear. Our previous study has demonstrated LTI phenotype and chronic corticosterone (CORT) administration retarded growth of breast muscle in broiler chickens. In order to investigate the mechanism behind the negative effects of LTI and CORT on growth, the level of mRNA transcription of several key genes linked to energy and protein metabolism was measured in muscle. LTI broilers showed lower levels of ATP, energy charge (EC) (p<0.01), and lower muscle glycogen content (p<0.05) but higher level of ADP (p = 0.08) than STI birds. CORT treatment elevated EC level (p<0.05) and reduced liver glycogen content (p<0.05). Real-time PCR results showed that STI chickens had higher mRNA expression of PPAR α (p = 0.06) and AMPK α (p = 0.09) than LTI. CORT significantly down-regulated α-enolase mRNA expression in breast muscle compared to control (p<0.05). Neither TI nor CORT altered gene expression in Akt/mTOR/p70s6k cascade pathway in muscle (p > 0.05). However, western blot results showed that LTI chickens exhibited higher protein content of total Akt (p = 0.05) and phosphorylated Akt (p = 0.06) than STI. CORT treatment decreased the total protein content of Akt (p = 0.09) and p70s6k (p = 0.08). These results suggest that the retardation of muscle growth by LTI and chronic CORT administration parallels a strong alternation in energy status but slight changes of Akt/mTOR/p70s6k cascade, indicating that a decrease in muscle growth induced by LTI and CORT might not be mediated through mTOR-dependent signaling pathways.
authors.affiliation: Key Laboratory of Animal Physiology and Biochemistry, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Yujing
authors.initials: Y
authors.lastname: Duan
authors.affiliation: Key Laboratory of Animal Physiology and Biochemistry, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Wenyan
authors.initials: W
authors.lastname: Fu
authors.affiliation: Key Laboratory of Animal Physiology and Biochemistry, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Song
authors.initials: S
authors.lastname: Wang
authors.affiliation: Key Laboratory of Animal Physiology and Biochemistry, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China. Electronic address: niyingdong@njau.edu.cn.
authors.forename: Yingdong
authors.initials: Y
authors.lastname: Ni
authors.affiliation: Key Laboratory of Animal Physiology and Biochemistry, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Ruqian
authors.initials: R
authors.lastname: Zhao
mesh_terms: D000227:Adenine Nucleotides / Q000378:metabolism; D000818:Animals; D030161:Avian Proteins / Q000235:genetics / Q000378:metabolism*; D002645:Chickens / Q000378:metabolism*; D003345:Corticosterone / Q000502:physiology*; D004734:Energy Metabolism; D015870:Gene Expression; D006003:Glycogen / Q000378:metabolism; D046353:Immobility Response, Tonic; D008099:Liver / Q000378:metabolism; D010369:Pectoralis Muscles / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism
chemical_list: D000227:Adenine Nucleotides; D030161:Avian Proteins; D006003:Glycogen; D051057:Proto-Oncogene Proteins c-akt; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D058570:TOR Serine-Threonine Kinases; D003345:Corticosterone
keywords: ADP; AMP; AMP-activated protein kinase alpha; AMPK α; ATP; Akt; Atrogin-1; Broilers; CORT; Corticosterone; EC; Energy status; HPLC; LTI; MuRF1; PMC; PPAR α; Pectoralis major muscle; Protein metabolism; STI; TI; Tonic immobility; adenosine diphosphate; adenosine monophosphate; adenosine triphosphate; corticosterone; energy charge; high performance liquid chromatography; long tonic immobility; mTOR; mammalian target of rapamycin; muscle RING finger-1; muscle atrophy F box; p70s6k; pectoralis major muscle; peroxisome proliferator-activated receptor alpha; ribosomal protein S6 kinase; serine/threonine protein kinase B; short tonic immobility; tonic immobility