Layer and broiler chicks exhibit similar hypothalamic expression of orexigenic neuropeptides but distinct expression of genes related to energy homeostasis and obesity.
Layer and broiler chickens demonstrate striking differences in body weight and body composition. However, the mechanism underlying such difference is elusive. Hypothalamus-pituitary-adrenal (HPA) axis regulates energy homeostasis and body size in mammals, but information in birds is scarce. Here we test the hypothesis that such breed difference is more associated with hypothalamic expression of genes related to HPA axis, rather than orexigenic neuropeptides. Broiler chicks exhibit significantly higher body weight and food intake at day (D) 7 posthatching, but the food intake relative to body weight gain was actually lower. No breed differences were observed for hypothalamic expression of neuropeptide Y (NPY), agouti-related protein (AGRP), proopiomelanocortin (POMC), orexin (ORX), leptin receptor (LEPR), acetyl-CoA carboxylase (ACC) or fatty acid synthase (FAS). However, broiler chicks expressed significantly higher glucocorticoid receptor (GR) mRNA (P<0.05) and protein (P<0.01) in hypothalamus compared to layer chicks, which is associated with lower corticotropin-releasing hormone (CRH) mRNA (P<0.05) yet higher accumulation of CRH peptide in hypothalamus, suggesting an augmented GR-mediated negative feedback regulation of CRH transcription and release in broiler chicks. Furthermore, fat mass and obesity associated (FTO) gene was also more highly expressed in hypothalamus of broiler chicks (P<0.05). These results suggest that the genes related to energy homeostasis and obesity, such as GR, CRH and FTO, rather than orexigenic neuropeptides, are impacted by the genetic selection practices and play a role in breed-specific body weight setpoint regulation in the chicken.
Key Laboratory of Animal Physiology and Biochemistry, Nanjing Agricultural University, Nanjing 210095, PR China.
Lixia
L
Yuan
Yingdong
Y
Ni
Stephan
S
Barth
Yufeng
Y
Wang
Roland
R
Grossmann
Ruqian
R
Zhao
D000071516:Alpha-Ketoglutarate-Dependent Dioxygenase FTO; D000818:Animals; D001069:Appetite Regulation / Q000235:genetics*; D001835:Body Weight / Q000235:genetics; D002645:Chickens / Q000033:anatomy & histology / Q000235:genetics* / Q000378:metabolism*; D003346:Corticotropin-Releasing Hormone / Q000235:genetics / Q000378:metabolism; D004734:Energy Metabolism / Q000235:genetics*; D005246:Feedback / Q000502:physiology; D005786:Gene Expression Regulation / Q000235:genetics; D006706:Homeostasis / Q000235:genetics; D007031:Hypothalamus / Q000166:cytology / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D008297:Male; D006899:Mixed Function Oxygenases; D009479:Neuropeptides / Q000235:genetics* / Q000378:metabolism; D009765:Obesity / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D000068797:Orexins; D007652:Oxo-Acid-Lyases / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D011965:Receptors, Glucocorticoid / Q000235:genetics / Q000378:metabolism; D013045:Species Specificity
D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D000068797:Orexins; D012333:RNA, Messenger; D011965:Receptors, Glucocorticoid; D003346:Corticotropin-Releasing Hormone; D006899:Mixed Function Oxygenases; C524916:FTO protein, mouse; D000071516:Alpha-Ketoglutarate-Dependent Dioxygenase FTO; D007652:Oxo-Acid-Lyases