Journal Article

l-phenylalanine modulates gut hormone release and glucose tolerance, and suppresses food intake through the calcium-sensing receptor in rodents

Amarsi, R, Gonzalez-Abuin, N, Sargent, P R, Cao, Y, Moolla, A, Johnson, R, Jomard, A, Bloom, S R, Akalestou, E, Murphy, K G, Amin, A, Norton, M, Gray, G W, Spreckley, E, Malik, Z, Kinsey-Jones, J S, Alamshah, A, Ramgulam, A, Saleh, K

2017

Overview

Objective: High-protein diets (HPDs) are associated with greater satiety and weight loss than diets rich in other macronutrients. The exact mechanisms by which HPDs exert their effects are unclear. However, evidence suggests that the sensing of amino acids produced as a result of protein digestion may have a role in appetite regulation and satiety. We investigated the effects of l -phenylalanine (L-Phe) on food intake and glucose homeostasis in rodents. Methods: We investigated the effects of the aromatic amino-acid and calcium-sensing receptor (CaSR) agonist l -phenylalanine (L-Phe) on food intake and the release of the gastrointestinal (GI) hormones peptide YY (PYY), glucagon-like peptide-1 (GLP-1) and ghrelin in rodents, and the role of the CaSR in mediating these effects in vitro and in vivo. We also examined the effect of oral l -Phe administration on glucose tolerance in rats. Results: Oral administration of l -Phe acutely reduced food intake in rats and mice, and chronically reduced food intake and body weight in diet-induced obese mice. Ileal l -Phe also reduced food intake in rats. l -Phe stimulated GLP-1 and PYY release, and reduced plasma ghrelin, and also stimulated insulin release and improved glucose tolerance in rats. Pharmacological blockade of the CaSR attenuated the anorectic effect of intra-ileal l -Phe in rats, and l -Phe-induced GLP-1 release from STC-1 and primary L cells was attenuated by CaSR blockade. Conclusions: l -Phe reduced food intake, stimulated GLP-1 and PYY release, and reduced plasma ghrelin in rodents. Our data provide evidence that the anorectic effects of l -Phe are mediated via the CaSR, and suggest that l -Phe and the CaSR system in the GI tract may have therapeutic utility in the treatment of obesity and diabetes. Further work is required to determine the physiological role of the CaSR in protein sensing in the gut, and the role of this system in humans.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 631/443 / 631/443/319/1488/393 / 64/60 / 96/106 / Amino acids / Animals / Appetite / Appetite Depressants - administration & dosage / Appetite Depressants - pharmacology / Appetite Regulation - drug effects / Body weight / Body weight loss / Calcium / Calcium-sensing receptors / Diabetes mellitus / Diet / Digestive system / Disease Models, Animal / Eating - drug effects / Energy Metabolism / Epidemiology / Food / Food intake / Gastrointestinal Hormones - metabolism / Gastrointestinal tract / Ghrelin / Glucagon / Glucagon-like peptide 1 / Glucose / Glucose Intolerance / Glucose tolerance / Health Promotion and Disease Prevention / Homeostasis / Hormone release / Hormones / Insulin / Internal Medicine / L cells / Male / Medicine / Medicine & Public Health / Metabolic Diseases / Mice / Mice, Inbred C57BL / Obesity / Oral administration / Original / original-article / Phenylalanine / Phenylalanine - administration & dosage / Phenylalanine - pharmacology / Physiological aspects / Proteins / Public Health / Rats / Rats, Wistar / Receptors / Receptors, Calcium-Sensing - metabolism / Receptors, Gastrointestinal Hormone - metabolism / Reducing diets / Rodentia / Rodents / Satiation - drug effects / Satiety / Weight loss