Lysine mediation of avian neuroendocrine food regulation

Ashley C Payne, Tennessee State University


Obesity, which is influenced partly by food intake, is a nationwide health problem projected to increase in the future. Hypothalamic food intake mechanisms are involved metabolically and neurologically via two peptide hormones Leptin and Ghrelin, and the amino acid, Glutamate, which can result enzymatically from lysine metabolism. Our hypothesis is lysine homeostasis mediates regulation of feed intake and performance characteristics via the brain-liver axis through glutamate sensing.. The main objectives were to examine the effects of lysine homeostasis in avian food regulation and performance characteristics; and to correlate these with neuroendocrine signaling. Four dietary treatments of Lysine (0.86%, 0.92%, 1.10% control ration, and 1.22%) were fed to 432 French Guinea fowl (GF). A total of 60 one day-old keets were weighed and randomly assigned to the dietary treatments. At 4 and 8 weeks of age (WOA) 28 and 32 birds, respectively were randomly selected, weighed and euthanatized. The duodenum, liver, pancreas, brain and adipose tissue were excised and snap frozen in liquid nitrogen and stored at -80°C until use. Ribonucleic Acid (RNA) was collected using the RNeasy© RNA extraction kit. Lysine at 0.80% hindered growth, caused poor development of some digestive organs and high mortality in GF. Glutamate has a correlation with leptin, and at low levels of lysine causes changes in food regulation. This is evidenced in expression of both brain glutamate and leptin receptors at the lowest level of lysine (0.86%). The fold change for the liver glutamate metabotropic receptor I was significantly lower at 0.86 and 0.92% compared to the other treatments. Expression of the Glutamate Metabotropic Receptor I in the brain was significantly higher (P<0.05) at 0.86% and 0.92% lysine when compared to the control (1.10%) and birds fed diets 1.22% lysine. The Glutamate ionotropic receptor displayed high expression at the highest lysine concentration. Ghrelin levels were variable in the brain; and ghrelin receptor expression in the brain was higher in 0.86 and 0.92% than in other treatments. Further research to ascertain the signaling pathways regulating food intake in the brain-liver axis has yet to be done. Key words: lysine, glutamate ionotropic receptor, glutamate metabotropic receptor I, leptin, ghrelin, French guinea fowl, food regulation, obesity, and hypothalamus

Subject Area

Genetics|Cellular biology|Animal sciences

Recommended Citation

Ashley C Payne, "Lysine mediation of avian neuroendocrine food regulation" (2014). ETD Collection for Tennessee State University. Paper AAI1557685.