Endocrine Abstracts

Ingested protein has a greater satiating effect than other macronutrients. The underlying mechanism is unknown, but it has been shown that protein induces greater increases in anorectic gut hormone levels than carbohydrate or fat. It was hypothesised that these effects could be mediated by specific amino acids comprising the protein. We therefore examined the effects of specific amino acids on food intake and gut hormone release. Fasted male Wistar rats received an oral gavage of water or 4000 μmol/kg L-Arginine or L-Lysine. Food intake was recorded over the following 24 hours. In a separate experiment, rats received an oral gavage of water or 4000 μmol/kg L-Arginine or L-Lysine and 30 or 60 minutes later trunk blood was collected. Plasma was analysed for Glucagon-like peptide-1-like immunoreactivity (GLP-1-IR) and Peptide YY-like immunoreactivity (PYY-IR) using radioimmunoassay. Oral administration of L-Arginine and L-Lysine significantly reduced food intake one hour after administration (P<0.05). Oral administration of L-Lysine significantly increased plasma levels of GLP-1-IR at 30 (P<0.001) and 60 (P<0.001) minutes after administration. Oral administration of L-Arginine significantly increased plasma levels of GLP-1-IR 60 minutes after administration (P<0.05). Oral administration of L-Arginine significantly increased plasma levels of PYY-IR 30 minutes after administration (P<0.005). Oral administration of L-lysine significantly increased plasma levels of PYY-IR 60 minutes after administration (P<0.001). L-Arginine and L-Lysine significantly reduced acute food intake following oral gavage in Wistar rats. These amino acids also increased plasma levels of GLP-1-IR and PYY-IR. It is possible that these amino acids mediate part of the satiating effects of protein via modulating gut hormone release.

Declaration of interest: There is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported.

Funding: Declaration of Funding: The Section is funded by grants from the MRC, BBSRC, NIHR, an Integrative Mammalian Biology (IMB) Capacity Building Award, an FP7- HEALTH- 2009- 241592 EuroCHIP grant and is supported by the NIHR Imperial Biomedical Research Centre Funding Scheme. Kevin G Murphy is supported by project grants from the NIHR and BBSRC.