title: Serum S100B protein is increased in fasting rats.
abstract: BACKGROUND
  S100B is a calcium-binding protein expressed and secreted by astrocytes; serum and cerebrospinal fluid (CSF) S100B elevation has been proposed as an index of brain damage. However, other tissues are shown to produce this protein and the clinical significance of serum S100B elevation has been discussed.
  
  
  METHODS
  We investigated the levels of serum and CSF S100B in fasting Wistar rats. Animals were divided into two groups, control and fasting for 48 h, and S100B levels in serum and CSF were determined by ELISA. S100B secretion in dissociated epididymal fat cells was investigated in the presence of epinephrine.
  
  
  RESULTS
  We observed a significant >2-fold increase of S100B levels in serum of fasting rats, without changes in its CSF content. Moreover, we demonstrated in vitro epinephrine stimulated S100B release from fat cells.
  
  
  CONCLUSIONS
  Present results reinforce that extracerebral sources of S100B, particularly adipocytes, contribute to its serum levels and support the idea that caution is needed when interpreting serum S100B increase as a clinical marker of brain damage.
authors.affiliation: Dept. Bioquímica, Instituto de Ciências Básicas da Saúde, UFRGS, Porto Alegre, Brazil.
authors.forename: Cristina B O
authors.initials: CB
authors.lastname: Netto
authors.forename: Sabrina
authors.initials: S
authors.lastname: Conte
authors.forename: Marina C
authors.initials: MC
authors.lastname: Leite
authors.forename: Caroline
authors.initials: C
authors.lastname: Pires
authors.forename: Tiago L
authors.initials: TL
authors.lastname: Martins
authors.forename: Penélope
authors.initials: P
authors.lastname: Vidal
authors.forename: Mara S
authors.initials: MS
authors.lastname: Benfato
authors.forename: Roberto
authors.initials: R
authors.lastname: Giugliani
authors.forename: Carlos-Alberto
authors.initials: CA
authors.lastname: Gonçalves
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000097:blood / Q000134:cerebrospinal fluid; D001930:Brain Injuries / Q000097:blood; D002478:Cells, Cultured; D030501:Epididymal Secretory Proteins / Q000032:analysis*; D004822:Epididymis / Q000166:cytology / Q000378:metabolism; D004837:Epinephrine / Q000494:pharmacology; D005215:Fasting / Q000097:blood* / Q000134:cerebrospinal fluid*; D008297:Male; D009414:Nerve Growth Factors / Q000097:blood* / Q000134:cerebrospinal fluid*; D051381:Rats; D017208:Rats, Wistar; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins / Q000097:blood* / Q000134:cerebrospinal fluid*; D013997:Time Factors; D014662:Vasoconstrictor Agents / Q000494:pharmacology
chemical_list: D015415:Biomarkers; D030501:Epididymal Secretory Proteins; D009414:Nerve Growth Factors; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins; C579158:S100b protein, rat; D014662:Vasoconstrictor Agents; D004837:Epinephrine