Lacto‐ghrestatin, a novel bovine milk‐derived peptide, suppresses ghrelin secretion

Abstract

Ghrelin, an endogenous peptide isolated from the stomach, is known to stimulate food intake after peripheral administration. We found that the enzymatic digest of β-lactoglobulin decreases ghrelin secretion from the ghrelin-producing cell line MGN3-1. The peptides present in the digest were comprehensively analyzed using the nanoLC-OrbitrapMS. Among them, we identified that the nonapeptide LIVTQTMKG, corresponding to β-lactoglobulin(1-9), suppresses ghrelin secretion from MGN3-1 cells. We named LIVTQTMKG 'lacto-ghrestatin'. We found that lacto-ghrestatin decreases intracellular cAMP levels and mRNA expression levels of ghrelin production-related genes in MGN3-1 cells. Orally administered lacto-ghrestatin decreases plasma ghrelin levels and food intake in fasted mice. Lacto-ghrestatin is the first food-derived peptide to suppress ghrelin secretion in vitro and in vivo.

Comprehensive analysis of a dipeptide library to identify ghrelin release‐modulating peptides

“…BCAAs are known to activate the mammalian target of rapamycin (mTOR) pathway , but LI evoked G i signaling in MGN3‐1 cells. We previously reported that the milk‐derived nonapeptide LIVTQTMKG, termed ‘lacto‐ghrestatin’, suppresses ghrelin secretion . LI is the N‐terminal dipeptide of lacto‐ghrestatin.…”

“…Acylated ghrelin concentrations in culture media of MGN3‐1 cells were measured as described previously . In brief, MGN3‐1 cells were incubated with test agents dissolved in DMEM (100 μL per each well) containing 50 μ m sodium octanoate at 37 °C for 4 h. The dipeptide library was tested at the concentration of 1 m m in Figs and S1.…”

“…Intracellular cAMP and Ca 2+ levels were measured as described previously . For cAMP measurement, MGN3‐1 cells were incubated with test agents dissolved in Krebs‐Ringer‐HEPES buffer (110 m m NaCl, 5 m m KCl, 1.8 m m CaCl 2 , 1 m m MgCl 2 , 55 m m sucrose, 25 m m glucose, 10 m m HEPES, pH 7.4) containing 500 μ m 3‐isobutyl‐1‐methylxanthine at 37 °C for 30 min.…”

“…In vivo ghrelin secretion and food intake experiments were performed as previously described with slight modification . In brief, 10‐ to 11‐week‐old male ddY mice (Japan SLC, Shizuoka, Japan) were deprived of food pellets for 18 h in the case of fasting conditions.…”

“…Several amino acids, glucose, and fatty acids were reported to affect ghrelin secretion . Recently, our group identified ghrelin release‐modulating peptides from enzymatic digests of food proteins . However, the structural characteristics of peptides which can modulate ghrelin secretion are unknown.…”