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.

Eating for 3.8 × 1013: Examining the Impact of Diet and Nutrition on the Microbiota-Gut-Brain Axis Through the Lens of Microbial Endocrinology

“…For example, intestinal microbial-produced free lysine and threonine has been detected in human plasma (152). Lysine was recently shown to play an important function in avian neuroendocrine regulation of food intake, however, a role for the microbiota was not investigated (153). Amino acids are precursors to several microbial-derived neuroendocrine molecules, including the biogenic amines agmatine, derived from lysine; cadaverine, derived from arginine; and putrescine, derived from ornithine (154).…”

Effectiveness of Rice Germ Supplementation on Body Composition, Metabolic Parameters, Satiating Capacity, and Amino Acid Profiles in Obese Postmenopausal Women: A Randomized, Controlled Clinical Pilot Trial

“…Lysine, the precursor to metabolic glutamate, can mediate food intake by way of a neuronal and glutamate sensing mechanism through the liver [57][58][59]. In our focus on satiety, Haber's means over time showed a clear improvement in the feeling of satiety for the supplemented women compared to the placebo group.…”

Transcriptome Analysis and Expression of Selected Cationic Amino Acid Transporters in the Liver of Broiler Chicken Fed Diets with Varying Concentrations of Lysine

“…Similar studies by Nasr and Kheiri [ 3 ], Bhogoju et al [ 5 ], Khwatenge et al [ 6 ], Kerr et al [ 40 ] and Corzo et al [ 41 ] have confirmed this effect of lysine on the growth performance of birds. The reduction in feed intake may likely be due to the birds experiencing satiety effects, hence reducing growth [ 4 , 11 ]. This may be explained by the mediation of lysine via neuroendocrine food regulation.…”

“…This may be explained by the mediation of lysine via neuroendocrine food regulation. Recent studies have shown that dietary lysine concentration may influence signaling pathways that regulate food intake via the brain–liver axis by the neuroendocrine system [ 6 , 11 ].…”

“…These two routes converge ultimately at the α-aminoadipic semialdehyde level [ 10 ]. Therefore, the liver plays an important role, including in the sensing of other amino acids [ 11 ]. Amino acid transporters such as cationic amino acid transporters (CATs) play an important role in the sensing of amino acid levels, both directly as initiators of nutrient signaling and indirectly as regulators of external amino acid access to intracellular receptor/signaling mechanisms [ 12 ].…”