Dietary macronutrient composition affects hypothalamic appetite regulation in chicks.
OBJECTIVE
The objective was to determine the effects of high-protein and high-fat diets, and fasting and refeeding, on appetite regulation in chicks.


METHODS
Day of hatch chicks were fed one of four diets: basal, high protein (25% crude protein), and 15 and 30% high fat (15 and 30% metabolizable energy derived from soybean oil, respectively), and assigned to one of three treatments at 4 days: (1) access to feed, (2) 3 hours of fasting, or (3) fasting followed by 1 hour of refeeding. The hypothalamus was collected, total RNA isolated, and mRNA abundance measured.


RESULTS
Food intake was reduced in chicks fed the high-protein and high-fat diets. Agouti-related peptide, neuropeptide Y (NPY), NPY receptors 1, 2, and 5, melanocortin receptors 3 and 4 (MC3R and 4R, respectively), mesotocin, corticotropin-releasing factor (CRF), and CRF receptor sub-type 2 (CRFR2) mRNAs were greatest in chicks that consumed the basal diet. Refeeding was associated with increased MC3R mRNA in the high-protein diet group. CRFR2 mRNA was increased by fasting and refeeding in chicks that consumed the high-protein diet.


CONCLUSIONS
Food intake and hypothalamic gene expression of some important appetite-associated factors were reduced in chicks fed the high-protein or high-fat diets. Fasting and refeeding accentuated several differences and results suggest that the CRF and melanocortin pathways are involved.
a Department of Animal and Poultry Sciences , Virginia Tech , 175 West Campus Drive, Blacksburg , VA 24061 , USA.
Betty R
BR
McConn
a Department of Animal and Poultry Sciences , Virginia Tech , 175 West Campus Drive, Blacksburg , VA 24061 , USA.
Justin
J
Matias
a Department of Animal and Poultry Sciences , Virginia Tech , 175 West Campus Drive, Blacksburg , VA 24061 , USA.
Guoqing
G
Wang
a Department of Animal and Poultry Sciences , Virginia Tech , 175 West Campus Drive, Blacksburg , VA 24061 , USA.
Mark A
MA
Cline
a Department of Animal and Poultry Sciences , Virginia Tech , 175 West Campus Drive, Blacksburg , VA 24061 , USA.
Elizabeth R
ER
Gilbert
D000818:Animals; D001066:Appetite; D001069:Appetite Regulation; D001835:Body Weight; D002645:Chickens; D059305:Diet, High-Fat; D000073600:Diet, High-Protein; D005215:Fasting; D005786:Gene Expression Regulation; D007031:Hypothalamus / Q000502:physiology*; D009478:Neuropeptide Y / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D044104:Receptor, Melanocortin, Type 3 / Q000235:genetics / Q000378:metabolism; D044105:Receptor, Melanocortin, Type 4 / Q000235:genetics / Q000378:metabolism; D018019:Receptors, Corticotropin-Releasing Hormone / Q000235:genetics / Q000378:metabolism; D017476:Receptors, Neuropeptide Y / Q000235:genetics / Q000378:metabolism
C101531:CRF receptor type 2; D009478:Neuropeptide Y; D012333:RNA, Messenger; D044104:Receptor, Melanocortin, Type 3; D044105:Receptor, Melanocortin, Type 4; D018019:Receptors, Corticotropin-Releasing Hormone; D017476:Receptors, Neuropeptide Y
Appetite; Chick; Diet; Hypothalamus; mRNA