CONCURRENT REGISTRATION OF EEG RESPONSES CATECHOLAMINE UPTAKE AND TRYPAN BLUE STAINING IN CHEMICAL BLOOD-BRAIN-BARRIER DAMAGE

On rabbits depleted of endogenous monoamines through reserpine treatment, unilateral chemical injury of the BBB was produced under continous EEG registration. Catecholamines in various doses were given intravenously in order to reveal any response in the EEG as well as the accumulation of catecholamines in nerve terminals and non-terminal axons as seen in freeze-dried sections under the fluorescence microscope. In the same sections intravenously given trypan blue could be concominatly determined due to its red fluorescence, distinctly contrasting to the green colour of the accumulated monoamines. EEG effects following monoamine injections were seen in 2 of the 5 rabbits studied with EEG recording. They appeared as bursts of low spike potentials on the BBB-damaged side resembling the EEG changes often preceding the high voltage paroxysmal activity evoked by pencillin. Comparison with the action of released endogenous monoamines on specific receptor sites was discussed as background for this EEG response. In general, the most extensive monoamine uptake took place in areas with minimal trypan blue staining while areas characterized by abundant trypan blue staining, especially of cell bodies, showed no or very few monoamine-concentrating axons. A strong monoamine fluorescence in capillary pericytes was sometimes seen in very mild BBB-damaged regions, a finding suggesting that the chemical injury here was restricted to the endothelium proper. © 1969 Springer-Verlag.