title: Lysine mediation of neuroendocrine food regulation in guinea fowl.
abstract: In poultry, obesity is partly influenced by food intake, and is increasingly becoming a nationwide problem. Hypothalamic food intake mechanisms are involved metabolically and neurologically via two peptide hormones, leptin and ghrelin, and the amino acid glutamate, which is enzymatically derived from lysine metabolism. We hypothesize that lysine homeostasis mediates regulation of feed intake and performance characteristics via the brain-liver axis through glutamate sensing. The objective was to examine the effects of lysine homeostasis in avian food regulation and performance through neuroendocrine signaling. One-day-old male French Guinea fowl (GF) keets (n = 270) were weighed and randomly assigned to 5 dietary treatments (0.80%, 0.86%, 0.92%, 1.10% control, and 1.22% lysine) in 3 replicates. At 4 and 8 wk of age 20% of experimental birds were randomly selected, weighed and euthanatized. The liver, pancreas, and hypothalamus were excised, snap frozen in liquid nitrogen and stored at -80°C until use. Tissue mRNA was extracted and cDNA synthesized for qPCR assays. Lysine at 0.80 and 0.86% hindered growth, development of digestive organs, expression of brain and liver glutamate and leptin receptors, and caused high mortality in GF. The fold change for metabotropic glutamate receptor I was lower (P < 0.05) in liver and higher in brain at 0.86 and 0.92% than the control (1.10%) and 1.22% lysine. The 1.22% lysine exhibited highest expression of ionotropic glutamate receptor, while brain ghrelin receptor expression was highest at 0.86 and 0.92% lysine. Therefore, dietary lysine concentration may influence signaling pathways regulating food intake in brain-liver axis via glutamate synthesis.
authors.affiliation: College of Agricultural, Human and Natural Sciences, Tennessee State University, 3500 John A. Merritt Blvd., Nashville, Tennessee 37209-1561.
authors.forename: A
authors.initials: A
authors.lastname: Payne
authors.affiliation: College of Agricultural, Human and Natural Sciences, Tennessee State University, 3500 John A. Merritt Blvd., Nashville, Tennessee 37209-1561.
authors.forename: X
authors.initials: X
authors.lastname: Wang
authors.affiliation: College of Agricultural, Human and Natural Sciences, Tennessee State University, 3500 John A. Merritt Blvd., Nashville, Tennessee 37209-1561.
authors.forename: M T
authors.initials: MT
authors.lastname: Ivy
authors.affiliation: College of Agricultural, Human and Natural Sciences, Tennessee State University, 3500 John A. Merritt Blvd., Nashville, Tennessee 37209-1561.
authors.forename: A
authors.initials: A
authors.lastname: Stewart
authors.affiliation: College of Agricultural, Human and Natural Sciences, Tennessee State University, 3500 John A. Merritt Blvd., Nashville, Tennessee 37209-1561.
authors.forename: K
authors.initials: K
authors.lastname: Nelson
authors.affiliation: College of Agricultural, Human and Natural Sciences, Tennessee State University, 3500 John A. Merritt Blvd., Nashville, Tennessee 37209-1561.
authors.forename: C
authors.initials: C
authors.lastname: Darris
authors.affiliation: College of Agricultural, Human and Natural Sciences, Tennessee State University, 3500 John A. Merritt Blvd., Nashville, Tennessee 37209-1561 snahashon@tnstate.edu.
authors.forename: S N
authors.initials: SN
authors.lastname: Nahashon
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000818:Animals; D004032:Diet / Q000662:veterinary; D019587:Dietary Supplements / Q000032:analysis; D005247:Feeding Behavior; D046094:Galliformes / Q000254:growth & development / Q000502:physiology*; D018698:Glutamic Acid / Q000378:metabolism*; D006706:Homeostasis; D007031:Hypothalamus / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008239:Lysine / Q000378:metabolism*; D008297:Male; D009490:Neurosecretory Systems / Q000378:metabolism*; D011897:Random Allocation; D015398:Signal Transduction
chemical_list: D018698:Glutamic Acid; D008239:Lysine
keywords: glutamate; guinea fowl; leptin and ghrelin; lysine food regulation; obesity