title: Postprandial insulin action relies on meal composition and hepatic parasympathetics: dependency on glucose and amino acids: Meal, parasympathetics & insulin action.
abstract: Insulin sensitivity (IS) increases following a meal. Meal composition affects postprandial glucose disposal but still remains unclear which nutrients and mechanisms are involved. We hypothesized that gut-absorbed glucose and amino acids stimulate hepatic parasympathetic nerves, potentiating insulin action. Male Sprague-Dawley rats were 24 h fasted and anesthetized. Two series of experiments were performed. (A) IS was assessed before and after liquid test meal administration (10 ml.kg(-1), intraenteric): glucose + amino acids + lipids (GAL, n=6); glucose (n=5); amino acids (n=5); lipids (n=3); glucose + amino acids (GA, n=9); amino acids + lipids (n=3); and glucose + lipids (n=4). (B) Separately, fasted animals were submitted to hepatic parasympathetic denervation (DEN); IS was assessed before and after GAL (n=4) or GA administration (n=4). (A) Both GAL and GA induced significant insulin sensitization. GAL increased IS from 97.9±6.2 mg glucose/kg bw (fasting) to 225.4±18.3 mg glucose/kg bw (P<0.001; 143.6±26.0% potentiation of IS); GA increased IS from 109.0±6.6 to 240.4±18.0 mg glucose/kg bw (P<0.001; 123.1±13.4% potentiation). None of the other meals potentiated IS. (B) GAL and GA did not induce a significant insulin sensitization in DEN animal. To achieve maximal insulin sensitization following a meal, it is required that gut-absorbed glucose and amino acids trigger a vagal reflex that involves hepatic parasympathetic nerves.
authors.affiliation: CEDOC, NOVA Medical School/Faculdade de Ciências Médicas (NMS/FCM), Universidade Nova de Lisboa, Lisbon, Portugal; Department of Physiology, NOVA Medical School/Faculdade de Ciências Médicas (NMS/FCM), Universidade Nova de Lisboa, Lisbon, Portugal.
authors.forename: Ricardo A
authors.initials: RA
authors.lastname: Afonso
authors.affiliation: CEDOC, NOVA Medical School/Faculdade de Ciências Médicas (NMS/FCM), Universidade Nova de Lisboa, Lisbon, Portugal; APDP-Diabetes Portugal, Educationand Research Centre (APDP-ERC), Lisbon, Portugal.
authors.forename: Joana M
authors.initials: JM
authors.lastname: Gaspar
authors.affiliation: CEDOC, NOVA Medical School/Faculdade de Ciências Médicas (NMS/FCM), Universidade Nova de Lisboa, Lisbon, Portugal.
authors.forename: Iva
authors.initials: I
authors.lastname: Lamarão
authors.affiliation: Department of Pharmacology & Therapeutics, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada.
authors.forename: W Wayne
authors.initials: WW
authors.lastname: Lautt
authors.affiliation: CEDOC, NOVA Medical School/Faculdade de Ciências Médicas (NMS/FCM), Universidade Nova de Lisboa, Lisbon, Portugal; Department of Physiology, NOVA Medical School/Faculdade de Ciências Médicas (NMS/FCM), Universidade Nova de Lisboa, Lisbon, Portugal; APDP-Diabetes Portugal, Educationand Research Centre (APDP-ERC), Lisbon, Portugal. Electronic address: paula.macedo@fcm.unl.pt.
authors.forename: M Paula
authors.initials: MP
authors.lastname: Macedo
mesh_terms: D000596:Amino Acids / Q000008:administration & dosage*; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D005502:Food; D005947:Glucose / Q000008:administration & dosage*; D054795:Incretins / Q000097:blood; D007328:Insulin / Q000097:blood / Q000502:physiology*; D007333:Insulin Resistance / Q000502:physiology*; D008099:Liver / Q000187:drug effects* / Q000502:physiology; D010277:Parasympathomimetics / Q000008:administration & dosage*; D019518:Postprandial Period; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000596:Amino Acids; D001786:Blood Glucose; D054795:Incretins; D007328:Insulin; D010277:Parasympathomimetics; D005947:Glucose
keywords: Glucose; Insulin action; Insulin sensitivity; Meal composition; Nutritional modulation of insulin sensitivity; Parasympathetic nerves; Protein intake