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Intermittent ethanol exposure increases the number of cerebellar microglia
Jarno Riikonen1, Pia Jaatinen, Jyrki Rintala
1Tampere School of Public Health, FIN-33014 University of Tampere, Tampere, Finland.
Aims:
The number of cerebellar microglia after 5(1)/2 months of continuous or intermittent ethanol exposure was studied using the optical dissector method.
Methods:
Male Wistar rats were divided into three groups: an intermittently ethanol-exposed group, a continuously ethanol-exposed group and a control group (n = 6 in each group). The intermittently treated rats had two ethanol-withdrawal periods per week throughout the experiment. The number of microglia was measured in the anterior (folium II) and the posterior (folium X) cerebellar vermis. Tomato (Lycopersicon esculentum) lectin was used to stain the cerebellar microglia.
Results:
The volumes of folia II and X were similar in all the groups. The number of microglia increased in the molecular layer of folium II in the intermittently ethanol-exposed group compared with the continuously exposed and control groups. In the granular layer, there were no differences between the groups in the number of microglia.
Conclusions:
The results suggest that the number of cerebellar microglia increases in the anterior vermis before any ethanol-induced cerebellar atrophy is discernible. Repeated ethanol withdrawals seem to be more essential in inducing microgliosis than ethanol intoxication per se.
Insights
Repeated ethanol withdrawal, not continuous exposure, significantly increased cerebellar microglia in male Wistar rats. This microgliosis in the anterior cerebellum occurred before observable atrophy, suggesting withdrawal is key to neuroinflammation.
Area of Science:
- Neuroscience
- Toxicology
Background:
- Ethanol consumption can lead to cerebellar damage.
- The role of microglia in ethanol-induced neuroinflammation is not fully understood.
Purpose of the Study:
- To investigate the effect of continuous versus intermittent ethanol exposure on cerebellar microglia numbers.
- To determine if ethanol withdrawal or intoxication is the primary driver of microgliosis.
Main Methods:
- Male Wistar rats were exposed to ethanol continuously, intermittently, or not at all (control) for 5.5 months.
- The optical dissector method was used to quantify microglia in the anterior (folium II) and posterior (folium X) cerebellar vermis.
- Tomato lectin staining identified microglia.
Main Results:
- No significant differences in cerebellar folia volumes were observed between groups.
- Intermittent ethanol exposure led to a significant increase in microglia in the molecular layer of the anterior cerebellum (folium II) compared to continuous exposure and controls.
- Microglia numbers in the granular layer did not differ across groups.
Conclusions:
- Increased cerebellar microglia (microgliosis) in the anterior vermis may precede detectable ethanol-induced cerebellar atrophy.
- Repeated ethanol withdrawal periods appear to be a more significant factor in inducing microgliosis than ethanol intoxication itself.