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EFFECT OF GUT PEPTIDES ON HYPOTHALAMIC mRNA CONCENTRATION AND DRY MATTER INTAKE IN RUMINANTS

Relling, Alejandro Enrique

Abstract Details

2009, Doctor of Philosophy, Ohio State University, OSU Nutrition.
A series of experiments were conducted to gain a better understanding of mechanisms involved in feed intake regulation by ruminants. Specifically, the effect of changes in metabolites and hormones concentrations on dry matter intake (DMI) and hypothalamic mRNA concentration of neuropeptide Y (NPY), agouti-related peptide (AgRP) and proopiomelanocortin (POMC) in ruminants.In chapter 3, in vitro experiments were performed to determine the effect of glucose and propionate, insulin, cholecystokinin (CCK), insulin, glucagon like peptide-1(GLP-1), and peptide YY (PYY), on sheep hypothalamic mRNA concentration for NPY, AgRP, and POMC. The incubation of sheep hypothalamus in glucose, propionate, insulin, CCK, GLP-1, or PYY did not affect the mRNA concentration for NPY, AgRP, or POMC compared with control hypothalamus. Hypothalamus incubated in glucose plus insulin media did not result in changes in mRNA for NPY or AgRP, but increased POMC mRNA concentration. In chapter4, the effect of feeding fat and restricting DMI on plasma concentrations of insulin, GLP-1, glucose-dependent insulinotropic polypeptide (GIP), CCK, ghrelin and oxyntomodulin (OXM) and the hypothalamic NPY, AgRP and POMC concentration in growing lambs were reported. Feeding wethers ad libitum increased plasma insulin, GIP and NEFA concentration and decreased hypothalamic mRNA expression of NPY and AgRP compared with feeding wethers at a restricted intake. The addition of dietary fat decreased DMI, insulin and glucose concentration and increased plasma GIP and hypothalamic mRNA concentration for NPY and AgRP. Plasma GLP-1 and CCK concentration increased for wethers fed ad libitum compared with those restricted-fed, but for those fed ad libitum, the response was greater when they had supplemental fat in the diet. Pre-feeding plasma ghrelin concentration was higher in the restricted compared with the ad libitum-fed wethers, but the concentration was similar after feeding. In Chapters 5 and 6, the effect of GLP-1 and CCK infusion at physiological doses on DMI is described. In Chapter 5, GLP-1 infusion, but not CCK, had effects on DMI and initial meal size similar to effects of feeding fat. However, in Chapter 6 the results of GLP-1 infusion do not support the results of Chapter 5. Chapter 7 described the an OXM assay validation for bovine plasma, and effects of increased abomasal supply of casein, starch, or soybean oil to the small intestine on plasma concentrations of ghrelin and OXM on days 1 and 7 of infusion. Oil and casein infusion decreased pre-feeding plasma ghrelin concentration on both days. The infusion of oil, starch or casein did not change plasma OXM concentration. The decrease in plasma ghrelin concentration due to oil infusion could be associated with a decrease in DMI; however, the decrease in ghrelin concentration due to casein infusion was not associated with a decrease in DMI, and that plasma OXM concentration is not associated with DMI. It can be concluded that GLP-1 has a role in regulating DMI, but it is not the sole factor. These experiments suggest that the interaction among hormones and metabolites are more important for the regulation of DMI in ruminants than a single factor such as GLP1.
Steven C. Loerch, PhD (Advisor)
Christopher K. Reynolds, PhD (Committee Member)
Jeffrey L Firkins, PhD (Committee Member)
Joy L. Plate, PhD (Committee Member)
Kichoon Lee, PhD (Committee Member)

Recommended Citations

Citations

  • Relling, A. E. (2009). EFFECT OF GUT PEPTIDES ON HYPOTHALAMIC mRNA CONCENTRATION AND DRY MATTER INTAKE IN RUMINANTS [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1243026530

    APA Style (7th edition)

  • Relling, Alejandro. EFFECT OF GUT PEPTIDES ON HYPOTHALAMIC mRNA CONCENTRATION AND DRY MATTER INTAKE IN RUMINANTS. 2009. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1243026530.

    MLA Style (8th edition)

  • Relling, Alejandro. "EFFECT OF GUT PEPTIDES ON HYPOTHALAMIC mRNA CONCENTRATION AND DRY MATTER INTAKE IN RUMINANTS." Doctoral dissertation, Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1243026530

    Chicago Manual of Style (17th edition)