Rice protein hydrolysates stimulate GLP-1 secretion, reduce GLP-1 degradation, and lower the glycemic response in rats

Yuki Ishikawa, Tohru Hira, Daisuke Inoue, Yukikazu Harada, Hiroyuki Hashimoto, Mikio Fujii, Motoni Kadowaki, Hiroshi Hara

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

Rice has historically been consumed in Asia as a major source of carbohydrates, however, little is known regarding the functional roles of rice proteins as dietary factors. In the present study, we investigated whether peptides derived from rice proteins could stimulate GLP-1 secretion, which results in reducing glycemia via the incretin effect in normal rats. Hydrolysates were prepared from the protein fraction of rice endosperm or rice bran, and the effects of these hydrolysates on GLP-1 secretion were examined in a murine enteroendocrine cell line GLUTag. Plasma was collected after oral administration of the rice protein hydrolysates, under anesthesia, or during glucose tolerance tests in rats. In anesthetized rats, plasma dipeptidyl peptidase-IV (DPP-IV) activity was measured after ileal administration of the rice protein hydrolysates. GLP-1 secretion from GLUTag cells was potently stimulated by the rice protein hydrolysates, especially by the peptic digest of rice endosperm protein (REPH) and that of rice bran protein (RBPH). Oral administration of REPH or RBPH elevated plasma GLP-1 concentrations, which resulted in the reduction of glycemia under the intraperitoneal glucose tolerance test. In addition, the plasma DPP-IV activity was attenuated after ileal administration of REPH or RBPH, which resulted in a higher ratio of intact (active) GLP-1 to total GLP-1 in the plasma. These results demonstrate that rice proteins exert potent stimulatory effects on GLP-1 secretion, which could contribute to the reduction of postprandial glycemia. The inhibitory effect of these peptides on the plasma DPP-IV activity may potentiate the incretin effect of GLP-1.

Original languageEnglish
Pages (from-to)2525-2534
Number of pages10
JournalFood and Function
Volume6
Issue number8
DOIs
Publication statusPublished - Aug 1 2015
Externally publishedYes

Fingerprint

glucagon-like peptide 1
Protein Hydrolysates
rice protein
Glucagon-Like Peptide 1
protein hydrolysates
secretion
degradation
rats
Dipeptidyl Peptidase 4
blood glucose
secretin
rice bran
hydrolysates
rice
Incretins
oral administration
endosperm
Endosperm
Glucose Tolerance Test
Proteins

All Science Journal Classification (ASJC) codes

  • Food Science

Cite this

Rice protein hydrolysates stimulate GLP-1 secretion, reduce GLP-1 degradation, and lower the glycemic response in rats. / Ishikawa, Yuki; Hira, Tohru; Inoue, Daisuke; Harada, Yukikazu; Hashimoto, Hiroyuki; Fujii, Mikio; Kadowaki, Motoni; Hara, Hiroshi.

In: Food and Function, Vol. 6, No. 8, 01.08.2015, p. 2525-2534.

Research output: Contribution to journalArticle

Ishikawa, Y, Hira, T, Inoue, D, Harada, Y, Hashimoto, H, Fujii, M, Kadowaki, M & Hara, H 2015, 'Rice protein hydrolysates stimulate GLP-1 secretion, reduce GLP-1 degradation, and lower the glycemic response in rats', Food and Function, vol. 6, no. 8, pp. 2525-2534. https://doi.org/10.1039/c4fo01054j
Ishikawa, Yuki ; Hira, Tohru ; Inoue, Daisuke ; Harada, Yukikazu ; Hashimoto, Hiroyuki ; Fujii, Mikio ; Kadowaki, Motoni ; Hara, Hiroshi. / Rice protein hydrolysates stimulate GLP-1 secretion, reduce GLP-1 degradation, and lower the glycemic response in rats. In: Food and Function. 2015 ; Vol. 6, No. 8. pp. 2525-2534.
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