Pathophysiological aspects of neonatal anoxia and temporal expression of S100β in different brain regions

Abstract

The aim of this study was to investigate the temporal variations of S100β in the hippocampus, cerebellum and cerebral cortex of neonatal rats (Wistar strain) under anoxic conditions. Real-time PCR and western blotting techniques were used for gene expression and protein analysis. Animals were divided into two groups, a control group and an anoxic group, and further separated at different time points for analysis. After anoxia, S100β gene expression showed a significant peak in the hippocampus and cerebellum after 2 h, followed by a decline compared to the control group at other time points. The increased gene expression in these regions was also accompanied by an increase in S100β protein levels in the anoxia group, observable 4 h after injury. In contrast, S100β mRNA content in the cerebral cortex never exceeded control values at any time point. Similarly, the protein content of S100β in the cerebral cortex did not show statistically significant differences compared to control animals at any assessment time point. These results suggest that the production profile of S100β differs by brain region and developmental stage. The observed differences in vulnerability between the hippocampus, cerebellum and cerebral cortex may be attributed to their distinct developmental periods. The hippocampus and cerebellum, which develop earlier than the cerebral cortex, showed more pronounced effects in response to anoxia, which is supported by the gene expression and protein content in this study. This result reveals the brain region-dependent nature of S100β as a biomarker of brain injury.

S100B actions on glial and neuronal cells in the developing brain: an overview

“…S100B expression was first observed in the forebrain at E18 and corresponded to cells lining the ventricle ( Landry et al, 1989 ). Moreover, in male rat pups, S100β gene expression and content were reported in the hippocampus, cerebellum, and cerebral cortex at P4 ( Hamasaki et al, 2023 ). During the second postnatal week, an accumulation of S100B mRNA was observed in regions of the hippocampus, neocortex, and olfactory bulb.…”

“…More data concerning S100B distribution in rat brains is available. S100B expression at mRNA or protein levels has been reported in the midbrain, hindbrain, third ventricle, cerebellum, the pontine, facial, and motor trigeminal nuclei, and around the fourth ventricle, the forebrain, particularly, the hippocampus, neocortex, and olfactory bulb ( Van Hartesveldt et al, 1986 ; Landry et al, 1989 ; Hamasaki et al, 2023 ; Stahlke et al, 2024 ). Later, in the adult rat central nervous system (CNS), two classes of S100B positive neuron populations were described, “Persistently S100B-positive” neurons, which were firmly immunoreactive and were mainly found in the nuclei of the lower brainstem and cerebellum.…”