Glucagon-like Peptide-2 Functions as an Anorexigenic Peptide not only in the Central Nervous System but also in the Peripheral Circulation in Broiler Chicks

Abstract

Brain-gut peptides play important roles in the appetite regulatory system in mammals. Glucagon-like peptide (GLP)-1, GLP-2, and oxyntomodulin (OXM) are processed from the same precursor, proglucagon, in both brain and intestines in mammals and birds. We previously showed that intracerebroventricular administration of these three peptides significantly suppressed food intake in chicks. However, peripheral roles of chicken GLP-2 have not yet been investigated, although GLP-2 plays important roles both in central and peripheral regulation of food intake in mammals. The aim of this study is to investigate whether GLP-2 functions as an anorexigenic peptide in both brain and peripheral circulation in chicks. Intracerebroventricular administration of GLP-2 significantly suppressed food intake in chicks. Twenty-four hours of fasting significantly decreased the mRNA level of proglucagon in the medulla oblongata of chicks. These results suggest that GLP-2 functions as anorexigenic peptides in the central nervous system in chicks. In addition, intravenous administration of GLP-2 significantly suppressed food intake in chicks. Lines of evidence suggest that dietary nutrients stimulate the secretion of GLP-2 from L cells in the small intestine in chickens. These findings suggest that GLP-2 functions as both central and peripheral anorexigenic signals in chicks.

Gut Hormones and Regulation of Food Intake in Birds

“…Immunohistochemical and morphometric studies of chickens suggest that GLP-2 colocalizes with GLP-1 in the same secretory granules of L cells in the small intestine of chickens (Monir et al, 2014c;Nishimura et al, 2013). Intravascular administration of GLP-2 suppressed the food intake of chicks (Honda et al, 2015d). GLP-2 receptor mRNA is expressed in the brain and gastrointestinal tract of chickens (Richards & McMurtry, 2008;Mo et al, 2014).…”

“…Complementary DNAs of ghrelin and CCK were amplified with the primers as follows: ghrelin sense, 5′ -CCC ACA TAT AAA AAC ATA CAG CAA CA-3′ ; ghrelin antisense, 5′ -GCC TCG GCG ATG TAA TCT TG-3′ ; CCK sense, 5′ -GCG CTG CTG GCC AAG TA-3′ ; and CCK antisense, 5′ -GAC AGA GAA CCT CCC AGT GGA A-3′ . Complementary DNAs of PYY, proglucagon, and RPS17 were amplified with the primers described previously (Honda et al, 2015d, Aoki et al, 2017. This experiment was approved by the Institutional Animal Care and Use Committee (Permission number: 25-08-01) and carried out according to the Kobe University Animal Experimental Regulation.…”

Effects of Fasting and Refeeding on the mRNA levels of Insulin-like Growth Factor-binding Proteins in Chick Liver and Brain

“…cDNAs of chicken IGFBP-1, -2, -3, -4, and -5 (GenBank accession numbers: NM_001001294, NM_205359, NM_001101034, NM_204353, and XM_422069, respectively) were amplified with the following primers: IGFBP-1 sense, GT-3'. cDNA of ribosomal protein S17 (GenBank accession number: NM_204217), as an internal standard, was amplified with previously reported primers (Honda et al, 2015b). mRNA levels were quantified in duplicate using an Applied Biosystems 7300…”

Glucagon and Neuromedin U Suppress Food Intake in Broiler Chicks

“…NMU primers were purchased from FASMAC Co., Ltd. (Kanagawa, Japan). Complementary DNA of proglucagon was amplified with the primers as previously described (Honda et al, 2015b). As an internal standard, cDNA of ribosomal protein S17 (RPS17) was also amplified with the primers as previously described (Honda et al, 2015b).…”

“…Complementary DNA of proglucagon was amplified with the primers as previously described (Honda et al, 2015b). As an internal standard, cDNA of ribosomal protein S17 (RPS17) was also amplified with the primers as previously described (Honda et al, 2015b). THUNDERBIRD TM SYBR ® qPCR Mix was purchased from Toyobo Co. Ltd. (Osaka, Japan), and mRNA expression was quantified in duplicate using the Applied Biosystems 7300 Real-Time PCR system according to the supplier's recommendations.…”