Effects of glucose, propionate, insulin and gut peptides on

RELLING A.E.; LEE K.; LOERCH S.C.; REYNOLDS C.K.

Denver, Colorado

Congreso; JAM 2010; 2010

american dairy science asociation and american society of animal science

The effects of glucose, propionate, or hormones of splanchnic origin on appetite regulating neuropeptides in the hypothalamus of ruminants have not been described. Therefore, the objective of the present study was to measure the effect in vitro of glucose, propionate, insulin, cholecystokinin (CCK), glucagon-like peptide-1 (GLP-1), or polypeptide YY (PYY) on hypothalamic mRNA concentrations for neuropeptide Y (NPY), agouti-related peptide (AgRP), and proopiomelanocortin (POMC). In an incomplete block design, hypothalamic tissue from market lambs was obtained at slaughter and immediately incubated in culture media for 2 h at 36°C. Treatments included a control Dulbecco’s Modified Eagle Medium (DMEM) containing 1 mM glucose (n=8) or DMEM with the following additions: 10 mM glucose (n=8), 1 mM propionate (n=4), 1 nM insulin (n=4), 120 pM GLP-1 (n=4), 100 pM PYY (n=4), 80 pMM glucose (n=8) or DMEM with the following additions: 10 mM glucose (n=8), 1 mM propionate (n=4), 1 nM insulin (n=4), 120 pM GLP-1 (n=4), 100 pM PYY (n=4), 80 pMM glucose (n=8), 1 mM propionate (n=4), 1 nM insulin (n=4), 120 pM GLP-1 (n=4), 100 pM PYY (n=4), 80 pMM insulin (n=4), 120 pM GLP-1 (n=4), 100 pM PYY (n=4), 80 pM CCK (n=4), or 10 mM glucose plus 1 nM insulin (n=4). The abundance of mRNA for NPY, AgRP, and POMC was measured using quantitative reverse transcriptase PCR, and normalized to peptidylprolyl isomerase B mRNA expression in the same sample. Dunnett’s mean separation was performed to compare treatment means to the control using mixed model procedures testing the random effects of lamb and block, andM glucose plus 1 nM insulin (n=4). The abundance of mRNA for NPY, AgRP, and POMC was measured using quantitative reverse transcriptase PCR, and normalized to peptidylprolyl isomerase B mRNA expression in the same sample. Dunnett’s mean separation was performed to compare treatment means to the control using mixed model procedures testing the random effects of lamb and block, and the fixed effects of treatment. There was a 4-fold increase in POMC mRNA concentration for the media containing glucose plus insulin (P < 0.05), but NPY or AgRP mRNA concentration was not affected. There were no effects observed for the other treatments (P > 0.20). Results of the present study suggest insulin is required for effects of glucose on hypothalamic POMC expression in sheep. Therefore, it is likely that the effect on the neuropeptides that regulate dry matter intake are due to additive effects of multiple signals, not solely changes in single hormone and metabolite concentrations.P < 0.05), but NPY or AgRP mRNA concentration was not affected. There were no effects observed for the other treatments (P > 0.20). Results of the present study suggest insulin is required for effects of glucose on hypothalamic POMC expression in sheep. Therefore, it is likely that the effect on the neuropeptides that regulate dry matter intake are due to additive effects of multiple signals, not solely changes in single hormone and metabolite concentrations.P > 0.20). Results of the present study suggest insulin is required for effects of glucose on hypothalamic POMC expression in sheep. Therefore, it is likely that the effect on the neuropeptides that regulate dry matter intake are due to additive effects of multiple signals, not solely changes in single hormone and metabolite concentrations.