Gut Hormones and Regulation of Food Intake in Birds

Abstract

Gut hormones act as appetite regulatory hormones in mammals. For example, the hunger hormone ghrelin, which is released from the stomach before food intake, stimulates appetite. In contrast, satiety hormones such as cholecystokinin, glucagon-like peptide-1, and peptide YY, which are released from the intestines after food intake, suppress appetite. The effects of these peptides on food intake have been shown to be similar in both mammals and fishes. However, evidence suggests that the physiological roles of these gut hormones may be different between birds and other vertebrates. This review summarizes the current information on the roles of gut hormones in the regulation of food intake in birds, especially in chickens.

Keywords: brain; chicken; gut hormones; hypothalamus; intestine.

Fig. 1.

Comparison of the mRNA levels of ghrelin, cholecystokinin (CCK), peptide YY (PYY) and proglucagon in the gastrointestinal tract of 8-day-old broiler chicks. Real-time PCR analysis was performed to quantify the mRNA levels of the gut hormones. The mRNA levels of ribosomal protein S17 (RPS17) were also analyzed as the internal standard. Values represent the mean±SEM of four birds. Different letters above each bar denote statistical significance (P<0.05, Tukey-Kramer test). 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.