Immunocontent and secretion of S100B in astrocyte cultures from different brain regions in relation to morphology

Abstract

Primary astrocyte cultures prepared from neonatal hippocampus, cerebral cortex and cerebellum were morphologically distinct. Cells from hippocampus and cortex were almost entirely protoplasmic, whereas cerebellar astrocytes had many processes; in the absence of serum these differences were accentuated. We compared the immunocontent and secretion of the mitogenic protein S100B in these cultures. Immunocontent was 2.5 times higher in cerebellar astrocytes than in hippocampal or cortical astrocytes. Cells from all three regions secreted S100B under basal conditions, but the secretion rate was higher in cerebellar astrocytes. Secretion depended on protein synthesis and was increased by incubation with forskolin or lysophosphatidic acid in mechanisms which were additive. The stellate morphology induced by forskolin was reversed by lysophosphatidic acid in hippocampal but not in cerebellar cultures, suggesting that S100B secretion was not associated with a process-bearing phenotype of astrocytes. ß

Serum S100B is increased during early treatment with antipsychotics and in deficit schizophrenia

“…Because particularly typical antipsychotics act via D 2 receptors (Kapur and Seeman, 2001), they may trigger elevations of the intracellular messenger cyclic adenosine 3V ,5V -monophosphate (cAMP) (Siegel et al, 1999). Astrocytes in turn may secrete S100B, induced for instance by the cAMP regulatory element (Zimmer et al, 1995;Pinto et al, 2000). This hypothesis may explain the higher serum levels of S100B in medicated patients in comparison with unmedicated patients and healthy controls in our study, particularly because the majority of patients received typical antipsychotics.…”

“…Thus, the data suggest that antipsychotics increase serum concentrations of S100B. Astrocytes may actively secrete S100B (Pinto et al, 2000) and possess D 2 receptors, at least in specific brain regions (Khan et al, 2001). Because particularly typical antipsychotics act via D 2 receptors (Kapur and Seeman, 2001), they may trigger elevations of the intracellular messenger cyclic adenosine 3V ,5V -monophosphate (cAMP) (Siegel et al, 1999).…”

“…Whether S100B serum levels are elevated due to damage to the brain, particularly astrocytes (Abdul-Khaliq et al, 1999, and a subsequent disruption of the astrocytically supported blood -brain barrier (Schroeter et al, 1999(Schroeter et al, , 2001, or by the active secretion of S100B by astrocytes (Pinto et al, 2000), has to be clarified by further studies.…”

“…Each monomer has a molecular weight of approximately 10 kDa. S100B regulates cell shape, energy metabolism, contraction, cell-to-cell communication, intracellular signal transduction, cell growth (Zimmer et al, 1995), 0920- and can be released by astrocytes (Pinto et al, 2000). Interestingly, the effects of extracellular S100B depend on its concentration (Schäfer and Heizmann, 1996).…”

Distinct Genetic Signatures among Pilocytic Astrocytomas Relate to Their Brain Region Origin

“…The detection of a genetic signature specific to cerebellar versus neocortical astrocytes and neural stem cells suggests that morphologically indistinguishable glia and stem cells from different brain regions are unique. In this regard, numerous studies have shown that cerebellar and neocortical astrocytes have different biological and electrophysiologic properties (42)(43)(44)(45). For example, neocortical astrocytes exhibit increased ATP/ADP hydrolysis (46), as well as increased serotonin and glutamate uptake (47), relative to astrocytes from the cerebellum.…”