title: Altered behavior of adult obese rats by monosodium l-glutamate neonatal treatment is related to hypercorticosteronemia and activation of hypothalamic ERK1 and ERK2.
abstract: OBJECTIVE
  Obesity is a metabolic and hormonal disorder with serious social and psychological impacts. There is a close relationship among obesity, neuroendocrine homeostasis and behavioral patterns. However, few data are available in the literature regarding this subject. This study assessed behavior and memory of adult obese rats by monosodium l-glutamate (MSG) neonatal treatment or highly palatable dietary treatment.
  
  
  METHODS
  MSG obesity was induced by subcutaneous injections of MSG (4 mg/g) during the first 5 days of life (Ob-MSG); control group (C-MSG), received saline solution equimolar. Both groups were fed with commercial chow. To induce dietary obesity, 21-day-old rats were assigned to two experimental diets: highly palatable diet (Ob-Diet) and control diet (C-Diet) composed of commercial chow. Ninety-day-old animals were submitted to behavioral assessment by the open-field test and short- and long-term memory by the object recognition test. Biometric variables were obtained, the Lee index was calculated and mass of retroperitoneal and perigonadal fat pads was measured. Furthermore, an altered behavioral profile was investigated by quantification of plasmatic corticosterone, expression, and activity of hypothalamic extracellular signal-regulated kinase protein (ERK) 1 and 2.
  
  
  RESULTS
  Increased Lee index and fat pads were observed in Ob-MSG and Ob-Diet groups. Ob-MSG presented a higher level of anxiety and impaired long-term memory compared to C-MSG, while there was no difference between Ob-Diet and C-Diet. The Ob-MSG group presented a higher level of plasmatic corticosterone and increased phosphorylation of hypothalamic ERK1 and 2.
  
  
  CONCLUSIONS
  Both treatments induced obesity but only Ob-MSG showed altered behavioral parameters, which is related to increased concentration of corticosterone and hypothalamic ERK1 and 2 activation.
authors: a Laboratory of Cellular and Molecular Biology, Department of Biology , Federal University of Juiz de Fora , Juiz de Fora , Brazil.
authors: Ernesto da Silveira Goulart
authors: ED
authors: Guimarães
authors: a Laboratory of Cellular and Molecular Biology, Department of Biology , Federal University of Juiz de Fora , Juiz de Fora , Brazil.
authors: Luiz Carlos
authors: LC
authors: de Caires Júnior
authors: a Laboratory of Cellular and Molecular Biology, Department of Biology , Federal University of Juiz de Fora , Juiz de Fora , Brazil.
authors: Camila Manso
authors: CM
authors: Musso
authors: a Laboratory of Cellular and Molecular Biology, Department of Biology , Federal University of Juiz de Fora , Juiz de Fora , Brazil.
authors: Mariana
authors: M
authors: Macedo de Almeida
authors: b Laboratory of Physiology, Department of Physiology , Federal University of Juiz de Fora , Juiz de Fora , Brazil.
authors: Cássio Francisco
authors: CF
authors: Gonçalves
authors: b Laboratory of Physiology, Department of Physiology , Federal University of Juiz de Fora , Juiz de Fora , Brazil.
authors: Klaus Grossi
authors: KG
authors: Pettersen
authors: b Laboratory of Physiology, Department of Physiology , Federal University of Juiz de Fora , Juiz de Fora , Brazil.
authors: Santiago Tavares
authors: ST
authors: Paes
authors: a Laboratory of Cellular and Molecular Biology, Department of Biology , Federal University of Juiz de Fora , Juiz de Fora , Brazil.
authors: Raúl Marcel
authors: RM
authors: González Garcia
authors: c Department of Cell Biology , State University of Maringá , Maringá , Brazil.
authors: Paulo Cesar
authors: PC
authors: de Freitas Mathias
authors: c Department of Cell Biology , State University of Maringá , Maringá , Brazil.
authors: Rosana
authors: R
authors: Torrezan
authors: b Laboratory of Physiology, Department of Physiology , Federal University of Juiz de Fora , Juiz de Fora , Brazil.
authors: Carlos Alberto
authors: CA
authors: Mourao-Júnior
authors: b Laboratory of Physiology, Department of Physiology , Federal University of Juiz de Fora , Juiz de Fora , Brazil.
authors: Ana Eliza
authors: AE
authors: Andreazzi
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001522:Behavior, Animal / Q000187:drug effects; D003345:Corticosterone / Q000819:agonists / Q000097:blood*; D004195:Disease Models, Animal; D004789:Enzyme Activation / Q000187:drug effects; D007031:Hypothalamus / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008297:Male; D000069077:Memory Consolidation / Q000187:drug effects; D057567:Memory, Long-Term / Q000187:drug effects; D008570:Memory, Short-Term / Q000187:drug effects; D019950:Mitogen-Activated Protein Kinase 1 / Q000737:chemistry / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000737:chemistry / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000819:agonists / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D009765:Obesity / Q000097:blood / Q000139:chemically induced / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D011897:Random Allocation; D017208:Rats, Wistar; D012970:Sodium Glutamate / Q000633:toxicity
chemical_list: D009419:Nerve Tissue Proteins; C535149:Mapk1 protein, rat; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D012970:Sodium Glutamate; D003345:Corticosterone
keywords: Behavior; Highly palatable diet; Memory; Monosodium l-glutamate; Obesity; Rat