Blood‐Brain Barrier Alteration after Experimental Cold Injury of the Rabbit Brain, Indicated by Penicillin G in EEG and by Dye Tests

Abstract

I.'lodmark, S. Blood-brain barrier alteiatiori after experimental cold injuv of the rabbit brain, indicated by penicillin G in EGG and by dye tests. Acta physiol. scand. 1965.63.225-235. -Two previous known methods to indicate blood-brain barrier alterationsintravital dye tests and EEG test after drug activationwere applied in parallel in 25 short-or long-term experiments on cold-induced cerebral lesions in the rabbit. The method of cold application was a modification of that of Hass and Taylor, supplemented by a recording of the extradural temperature. A new type of permanent electrode for EEG recording is described. In 19 of 20 animals in which a structure-deranging lesion was induced, a concomitant blood-brain barrier alteration could be demonstrated. In 11 of these 19 expts. a complete correlation of the two methods of barrier indication was obtained (8 animals inconsistent results). In 6 animals in which no blood-brain barrier alteration was induced a concordance of negative results with the two methods was also seen. Three to four days was the maximum duration of blood-brain barrier damage noted among the 13 animals in which the tendency to restitution of barrier function was studied. The results are in conformity with those of previous investigators and seem to justify the use of normally-barred EEG activating drugs such as penicillin, as detectors of blood-brain barrier alteration. These drugs seem particularly suitable for iterative studies in living animals. By means of a method for study of the interrelation between EEG and blood-brain barrier phenomena (Flodmark and Steinwall 1962) the reversibility of some chemically induced blood-brain barrier alteration as primarily shown by Broman and Olsson (1948) has recently been confirmed (Flodmark and Steinwall 1963 b). A similar tendency to restitution of a concomitant blood-brain barrier alteration in physically induced structure-deranging cerebral lesions has been demonstrated in previous investigations by means of different acidic dye indicators (Broman et al. 1949, Bakay et al. 1956, Klatzo rt al. 1958, 1961, Astrom et al. 1961 or by means of normally-barred EEG-activating drugs (Gonsette 1956). 225

Electroconvulsive shock impedes the learning of taste aversions: Absence of blood-brain-barrier involvement

“…The brains of dye-pretreated rats (dye-ECS) did not stain in contrast to nondye-pretreated rats (saline-ECS) following posttest injection oftrypan blue, thus indicating that permeability of the BBB of dye-EC~ animals might not have been appreciably altered by ECS. Trypan blue is unable to pass from blood to brain under normal barrier conditions but can pass with any impairment of the BBB (Steinwall, 1961;Flodmark, 1965). The present data suggest that permeability changes in the BBB are probably not significant determinants in the mechanism of ECS-induced impairment in the learning of taste aversions.…”

“…After concussion (Aird, Strait, Zealear, & Hrenoff, 1952), cold-induced localized cerebra! lesion (Flodmark, 1965), and ECS (Aird et al, 1956a;Aird, 1958), the systemic penetration of the brain by drugs with only limited access to it under normal barrier conditions was found to be increased, suggesting that the BBB mechanism was disturbed. In all cases, altered CNS physiology was indicated by the development of EEG dysrhythmias.…”

EEG monitoring of focal lesions of the blood-brain barrier

“…Therefore, when IV penicillin is administered to a normal animal, since it is relatively excluded by the BBB, the effect on the EEG is limited to synchronous spike wave discharge (Remler 1973) which can be suppressed by pentobarbital. He went on to correlate this EEG monitoring with other BBB monitors such as dye injection (Flodmark 1965b, Flodmark et al 1969 demonstrating the method's basic accuracy. The presence or absence of this spike focus is established by EEG recording.…”

“…He extended this work to human pathology of gliomas and other BBB lesions. He went on to correlate this EEG monitoring with other BBB monitors such as dye injection (Flodmark 1965b, Flodmark et al 1969 demonstrating the method's basic accuracy.…”