RESUMO
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.
Assuntos
Proteínas Secretadas pelo Epidídimo/análise , Jejum/sangue , Jejum/líquido cefalorraquidiano , Fatores de Crescimento Neural/sangue , Fatores de Crescimento Neural/líquido cefalorraquidiano , Proteínas S100/sangue , Proteínas S100/líquido cefalorraquidiano , Animais , Biomarcadores/sangue , Biomarcadores/líquido cefalorraquidiano , Lesões Encefálicas/sangue , Células Cultivadas , Epididimo/citologia , Epididimo/metabolismo , Epinefrina/farmacologia , Masculino , Ratos , Ratos Wistar , Subunidade beta da Proteína Ligante de Cálcio S100 , Fatores de Tempo , Vasoconstritores/farmacologiaRESUMO
1. We investigated the content of S100B protein by ELISA in three brain regions (hippocampus, cerebral cortex, and cerebellum) and in cerebrospinal fluid of rats during postnatal development as well as the content and secretion of S100B in pre- and postconfluent primary astrocyte cultures. 2. An accumulation of S100B occurred in all brain regions with similar ontogenetic pattern between second and fourth postnatal weeks. However, we observed a decrease in the cerebrospinal fluid S100B after the critical period for synaptogenesis in rodents. 3. A similar profile of cell accumulation and decrease in basal secretion was also observed during aging of astrocyte cultures. 4. These data contribute to the proposal that S100B is an important glial-derived protein during brain development and that changes in extracellular levels of S100B may be related to glial proliferation and synaptogenesis.