Neurotransmitter amines in brain edema of a rat glioma model.

The effect of vasogenic brain edema on amine neurotransmitter concentrations was studied in rats bearing transplanted glioma C6 brain tumors. In comparison with sham-operated and nonoperated controls, the tumor-implanted animals showed significant decreases in both dopamine (DA) and norepinephrine (NE) in the hypothalamus, cortex, and striatum. Treatment with dexamethasone (DEX) tended to restore these monoamines to the levels measured in sham-operated controls. In the nonoperated controls, DEX significantly increased NE but not DA. In tumor-bearing rats there was no increase in hypothalamic or striatal water content, and DEX had no effect on the water content of these structures. However, there was a significant increase in the cortical water content, which was reduced by DEX to the control levels. The water content within the tumor was also significantly decreased by DEX. In the nonoperated controls, there was no difference in water content between DEX-treated and nontreated animals. These findings suggest that tumor-induced brain edema reduces noradrenergic and dopaminergic activities. DEX administration resulted in normalization of the water content in edematous regions and of the DA and NE concentrations, and brought about marked symptomatic improvement.