title: Monosodium Glutamate Dietary Consumption Decreases Pancreatic β-Cell Mass in Adult Wistar Rats.
abstract: BACKGROUND
  The amount of dietary monosodium glutamate (MSG) is increasing worldwide, in parallel with the epidemics of metabolic syndrome. Parenteral administration of MSG to rodents induces obesity, hyperglycemia, hyperlipidemia, insulin resistance, and type 2 diabetes. However, the impact of dietary MSG is still being debated. We investigated the morphological and functional effects of prolonged MSG consumption on rat glucose metabolism and on pancreatic islet histology.
  
  
  METHODS
  Eighty adult male Wistar rats were randomly subdivided into 4 groups, and test rats in each group were supplemented with MSG for a different duration (1, 3, 6, or 9 months, n=20 for each group). All rats were fed ad libitum with a standard rat chow and water. Ten test rats in each group were provided MSG 2 mg/g body weight/day in drinking water and the 10 remaining rats in each group served as non-MSG treated controls. Oral glucose tolerance tests (OGTT) were performed and serum insulin measured at 9 months. Animals were sacrificed at 1, 3, 6, or 9 months to examine the histopathology of pancreatic islets.
  
  
  RESULTS
  MSG-treated rats had significantly lower pancreatic β-cell mass at 1, 6 and 9 months of study. Islet hemorrhages increased with age in all groups and fibrosis was significantly more frequent in MSG-treated rats at 1 and 3 months. Serum insulin levels and glucose tolerance in MSG-treated and untreated rats were similar at all time points we investigated.
  
  
  CONCLUSIONS
  Daily MSG dietary consumption was associated with reduced pancreatic β-cell mass and enhanced hemorrhages and fibrosis, but did not affect glucose homeostasis. We speculate that high dietary MSG intake may exert a negative effect on the pancreas and such effect might become functionally significant in the presence or susceptibility to diabetes or NaCl; future experiments will take these crucial cofactors into account.
authors.affiliation: Department of Biochemistry, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.
authors.forename: Piyanard
authors.initials: P
authors.lastname: Boonnate
authors.affiliation: Department of Pathology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.
authors.forename: Sakda
authors.initials: S
authors.lastname: Waraasawapati
authors.affiliation: Department of Anatomy, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.
authors.forename: Wiphawi
authors.initials: W
authors.lastname: Hipkaeo
authors.affiliation: Department of Biochemistry, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.
authors.forename: Supattra
authors.initials: S
authors.lastname: Pethlert
authors.affiliation: Department of Biochemistry, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.
authors.forename: Amod
authors.initials: A
authors.lastname: Sharma
authors.affiliation: Rheumatology and Clinical Immunology, Humanitas Clinical and Research Center, Milan, Italy; Rheumatology, Allergy, and Clinical Immunology, University of California Davis, Davis, California, United States of America.
authors.forename: Carlo
authors.initials: C
authors.lastname: Selmi
authors.affiliation: Department of Biochemistry, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.
authors.forename: Vitoon
authors.initials: V
authors.lastname: Prasongwattana
authors.affiliation: Department of Biochemistry, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.
authors.forename: Ubon
authors.initials: U
authors.lastname: Cha'on
mesh_terms: D000818:Animals; D001786:Blood Glucose; D001835:Body Weight; D004032:Diet; D005951:Glucose Tolerance Test; D007328:Insulin / Q000378:metabolism; D050417:Insulin-Secreting Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D007515:Islets of Langerhans / Q000166:cytology / Q000378:metabolism / Q000473:pathology; D008297:Male; D009929:Organ Size / Q000187:drug effects; D051381:Rats; D012970:Sodium Glutamate / Q000008:administration & dosage*; D013997:Time Factors
chemical_list: D001786:Blood Glucose; D007328:Insulin; D012970:Sodium Glutamate