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Effects of glucose, propionate and splanchnic hormones on neuropeptide mRNA concentrations in the ovine hypothalamus
Author(s) -
Relling A. E.,
Lee K.,
Loerch S. C.,
Reynolds C. K.
Publication year - 2012
Publication title -
journal of animal physiology and animal nutrition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.651
H-Index - 56
eISSN - 1439-0396
pISSN - 0931-2439
DOI - 10.1111/j.1439-0396.2011.01192.x
Subject(s) - endocrinology , medicine , peptide yy , hypothalamus , insulin , propionate , neuropeptide y receptor , hormone , chemistry , appetite , biology , neuropeptide , receptor , biochemistry
Summary The capacity for glucose, propionate or hormones of splanchnic origin to influence appetite by directly regulating the expression of neuropeptides in the feeding centres of the hypothalamus of the ruminant is not described. Therefore, our objective was to measure the direct effect of metabolites (glucose and propionate) or hormones [insulin, cholecystokinin (CCK), glucagon‐like peptide‐1 (GLP‐1) and polypeptide YY (PYY)] on hypothalamic mRNA concentrations for neuropeptide Y (NPY), agouti‐related peptide (AgRP) and proopiomelanocortin (POMC) following in vitro incubation. Hypothalamic tissue from 4‐ to 5‐month‐old 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 m m glucose or DMEM with the following additions: 10 m m glucose, 1 m m propionate, 1 n m insulin, 120 p m GLP‐1, 100 p m PYY, 80 p m CCK or 10 m m glucose plus 1 n m insulin. The abundance of mRNA for NPY, AgRP and POMC was measured using quantitative reverse transcriptase PCR. Fisher’s protected LSD test was used to compare changes in relative mRNA concentrations for the hypothalamus incubated in the control media vs. the rest of the treatments. The media containing glucose plus insulin increased POMC mRNA concentration (p < 0.05), but did not affect NPY or AgRP mRNA concentration. There were no effects observed for the other treatments (p > 0.20). Results of the present study are consistent with the concept that effects of propionate on feed intake in ruminants is not mediated through direct effects on the hypothalamus, and that insulin is required for an effect of glucose on hypothalamic POMC expression.