title: Is really endogenous ghrelin a hunger signal in chickens? Association of GHSR SNPs with increase appetite, growth traits, expression and serum level of GHRL, and GH.
abstract: Chicken growth hormone secretagogue receptor (GHSR) is a receptor for ghrelin (GHRL), a peptide hormone produced by chicken proventriculus, which stimulates growth hormone (GH) release and food intake. The purpose of this study was to search for single nucleotide polymorphisms (SNPs) in exon 2 of GHSR gene and to analyze their effect on the appetite, growth traits and expression levels of GHSR, GHRL, and GH genes as well as serum levels of GH and GHRL in Mandara chicken. Two adjacent SNPs, A239G and G244A, were detected in exon 2 of GHSR gene. G244A SNP was non-synonymous mutation and led to replacement of lysine amino acid (aa) by arginine aa, while A239G SNP was synonymous mutation. The combined genotypes of A239G and G244A SNPs produced three haplotypes; GG/GG, GG/AG, AG/AG, which associated significantly (P<0.05) with growth traits (body weight, average daily gain, shank length, keel length, chest circumference) at age from >4 to 16w. Chickens with the homozygous GG/GG haplotype showed higher growth performance than other chickens. The two SNPs were also correlated with mRNA levels of GHSR and GH (in pituitary gland), and GHRL (in proventriculus and hypothalamus) as well as with serum level of GH and GHRL. Also, chickens with GG/GG haplotype showed higher mRNA and serum levels. This is the first study to demonstrate that SNPs in GHSR can increase appetite, growth traits, expression and level of GHRL, suggesting a hunger signal role for endogenous GHRL.
authors: Department of Anatomy & Embryology, Faculty of Veterinary Medicine, Kafrelsheikh University, Egypt. Electronic address: mohrizk73@yahoo.com.
authors: Mohammed Abu
authors: MA
authors: El-Magd
authors: Department of Animal Wealth Development, Veterinary Genetics & Genetic Engineering, Faculty of Veterinary Medicine, Zagazig University, Egypt.
authors: Ayman A
authors: AA
authors: Saleh
authors: Department of Animal Wealth Development, Animal Breeding and Production, Faculty of Veterinary Medicine, Zagazig University, Egypt.
authors: Tamer M
authors: TM
authors: Abdel-Hamid
authors: Department of Physiology, Faculty of Veterinary Medicine, Mansura University, Egypt.
authors: Rasha M
authors: RM
authors: Saleh
authors: Department of Animal Wealth Development, Biostatistics, Faculty of Veterinary Medicine, Zagazig University, Egypt.
authors: Mohammed A
authors: MA
authors: Afifi
mesh_terms: D000483:Alleles; D000818:Animals; D001066:Appetite / Q000235:genetics*; D001483:Base Sequence; D001947:Breeding; D002645:Chickens / Q000235:genetics* / Q000254:growth & development*; D005787:Gene Frequency; D056726:Genetic Association Studies; D056426:Genetic Loci; D054439:Ghrelin / Q000097:blood* / Q000235:genetics; D013006:Growth Hormone / Q000097:blood* / Q000235:genetics; D006239:Haplotypes / Q000235:genetics; D006815:Hunger / Q000502:physiology*; D015810:Linkage Disequilibrium / Q000235:genetics; D008297:Male; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D019655:Quantitative Trait, Heritable; D060888:Real-Time Polymerase Chain Reaction; D054440:Receptors, Ghrelin / Q000235:genetics*
chemical_list: D054439:Ghrelin; D054440:Receptors, Ghrelin; D013006:Growth Hormone
keywords: GH; GHRL; GHSR; Growth traits; Hunger signal; SNPs