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Glutamine synthetase in experimental meningitis: increased ratio of the subunits 3 and 2 may indicate enhanced
A V Smirnov1, H Tumani, S Henne
1Department of Neurology, University of Gottingen, Robert-Koch-Strasse 40, D-37075, Göttingen, Germany.
Abstract:
Glutamine synthetase (GS) activity is higher in the neocortex but not in the hippocampal formation of rabbit brain during Streptococcus pneumoniae meningitis compared to the respective brain region of uninfected control animals. One-dimensional polyacrylamide gel electrophoresis (1D-SDS-PAGE) revealed an apparent molecular mass (M(r)) of 44000 Dalton (Da) for GS from rabbit brain. After two-dimensional gel electrophoresis (2D-PAGE), followed by Coomassie-blue staining, GS separated into three distinct spots (S1, S2, S3). One additional spot (S4) occurred on the immunoblot. All four GS spots exhibited the same M(r) (44000 Da), but differed in their isoelectric points. Densitometric evaluation of the two-dimensional maps revealed a strong increase of optical density (OD) of S3 in the frontal cortex of infected animals. The calculated OD ratio S3/S2 in the frontal cortex from rabbits with meningitis was 1.75+/-0.68 (mean+/-standard deviation). Compared to controls (0. 85+/-0.39), this value was significantly increased (p=0.0006). In the hippocampal formation, the ratio S3/S2 was nearly unchanged during meningitis. It is suggested that the ratio S3/S2 may indicate a neuroprotective feature of rabbit brain during meningitis since neuronal apoptosis occurs only in the dentate gyrus and not in the frontal cortex.
Insights
Bacterial meningitis in rabbits increases glutamine synthetase (GS) activity in the neocortex, indicated by a specific protein spot ratio. This change may suggest a neuroprotective response in the frontal cortex during infection.
Area of Science:
- Neuroscience
- Biochemistry
- Pathology
Background:
- Streptococcus pneumoniae meningitis affects brain regions differently.
- Glutamine synthetase (GS) plays a crucial role in brain function.
- Understanding enzyme activity changes during meningitis is vital for neuroprotection research.
Purpose of the Study:
- To investigate changes in glutamine synthetase (GS) activity in specific rabbit brain regions during Streptococcus pneumoniae meningitis.
- To analyze the molecular characteristics of GS using gel electrophoresis.
- To correlate GS activity patterns with neuroprotection mechanisms.
Main Methods:
- Rabbit models of Streptococcus pneumoniae meningitis.
- One-dimensional SDS-PAGE to determine GS molecular mass.
- Two-dimensional gel electrophoresis (2D-PAGE) to separate GS isoforms.
- Densitometric analysis of 2D-PAGE maps and immunoblots.
- Statistical analysis of GS spot ratios (S3/S2) in different brain regions.
Main Results:
- Glutamine synthetase (GS) molecular mass was identified as 44000 Da.
- GS separated into four distinct spots (S1-S4) on 2D-PAGE, differing in isoelectric points.
- A significant increase in the S3/S2 spot ratio was observed in the frontal cortex of meningitis rabbits compared to controls (p=0.0006).
- The S3/S2 ratio remained unchanged in the hippocampal formation during meningitis.
Conclusions:
- Elevated glutamine synthetase (GS) activity, specifically the S3 spot, in the rabbit frontal cortex during meningitis may indicate a neuroprotective mechanism.
- The differential response of GS activity between the neocortex and hippocampal formation suggests region-specific adaptations to infection.
- The S3/S2 ratio serves as a potential biomarker for neuroprotection in the context of bacterial meningitis.