Evidence for a reduced numerical density of S100B-positive astrocytes in depression

Objective: Several very consistent clinical studies observed increased blood levels of S100B in affective disorders, as reviewed by Schroeter ML and Steiner J (2009). These elevations of S100B have been attributed to astrocytic dysfunction. However, histological data on human post mortem tissue have not been published yet. Material and Methods: To clarify this question, astrocytic and oligodendrocytic S100B-expression was analyzed by immunohistochemistry in the pyramidal layer/alveus of the hippocampus, the mediodorsal thalamic nucleus and the superior temporal cortex of 17 depressed patients and 16 controls from the Magdeburg Brain Collection. Results: The density of S100B-positive astrocytes was reduced in the pyramidal layer of the hippocampus and the superior temporal cortex of depressed patients (p<0.05), but not in the mediodorsal thalamus. No significant diagnosis related changes were detected regarding S100B-positive oligodendrocytes. Conclusion: Our histological data provide indeed evidence for a numeral reduction of S100B-positive astrocytes in depression. This is in line with observations by Rajkowska G and Miguel-Hidalgo JJ (2007), who reported reduced densities of GFAP-positive astrocytes in fronto-limbic brain regions in major depression and bipolar disorders.