Resumo

S100B is a calcium binding protein mainly expressed and secreted by astrocytes in the central nervous system and has been described as a marker of astroglial activation, measured in cerebrospinal fluid (CSF) and serum. However, adipocytes contribute to the serum levels of this protein. Thus, it is important to know the factors that influence the apparent compartmentalization of this protein between serum and cerebrospinal fluid (CSF) to understanding the significance of changes. Our objective was to evaluate serum and CSF levels of S100B in response to acute stimulation with lipopolysaccharide (LPS) injected centrally or peripherally. Anesthetized adult wistar rats received 10 µL ICV of 2.5 ug/uL LPS or phosphate-buffered saline (control). CSF, collected by cisterna magna puncture, as well as blood, collected by intracardiac puncture, at 30 min or 24 h after. S100B content was measured by ELISA. A significant increase in CSF S100B was observed in 30 min (205%, p=0.009, n=5) and in 24 h (301%, p=0.003, n=5) after ICV LPS administration, without significant changes in S100B serum content. Interestingly, when rats received IP LPS (250 ug/Kg body) they also exhibited an increase in CSF S100B in 30 min (250%, p=0.04, n=5), but not in 24 h, and again no significant changes in serum S100B were observed when compared with controls that received phosphate-buffered saline. Our results suggest a brain specific LPS-induced release of S100B, i.e., peripheral immune cells stimulated by LPS did not release or cause a detectable S100B release from potential extra-cerebral sources of S100B (e.g. adipocytes).Together, these data contribute to our understanding of the effect of LPS on astrocytes, particularly on S100B secretion and help us to interpret cerebrospinal fluid and serum changes of this protein in brain inflammatory disorders.