Effect of Alcohol Injections on the Blood-Brain Barrier

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Abstract
Ethyl alcohol was injected into the left common carotid artery of 21 adult rabbits: 7 received 2 ml of a 30% alcohol solution and were killed at various intervals (1-52 hours) after the injection: 8 received 2ml of alcohol solutions varying between 7.5 and 45% and were allowed to survive 2 hours; and 6 received between 4 and 10 ml of a 30% alcohol solution and were killed 2 hours later. Radioautographic technique with radioactive iodinated bovine albumin as indicator was used to study the changes of the cerebral vascular permeability. The healthy cerebral blood vessels of a control rabbit and of the right control cerebral hemispheres of all rabbits in the present experiments were impermeable to albumin molecules and to trypan blue particles. Injection of 2 ml of 7.5% alcohol increased the cerebral vascular permeability to albumin molecules and to trypan blue particles. This increase was enhanced with higher concentrations of alcohol and reached a maximum with 30% alcohol. An amount of 10 ml of alcohol at a concentration higher than 45% caused the death of rabbits after injection. The increased permeability after alcohol injection did not last long. Following intracarotid injection of 2 ml of 30% alcohol, the radioactivity seen in the radioautographs was very intense after 1 hour, attained a peak after 2 hours, declined after 3 hours and became very weak after 6 hours. No radioactivity was detectable 52 hours after the alcohol injection. The radioactivity or blue tinge was very pronounced in the thalamus, hypothalamus and amygdaloid nuclei, but less in the cerebral cortex. Spread of radioactivity to the opposite cerebral hemisphere was observed along the corpus callosum, hippocampal formation and massa intermedia. No histopathological changes which could account for the over-all increase in the cerebral vascular permeability were observed in the cerebral blood capillaries or in the brain tissue. The mechanism underlying the effect of alcohol on the cerebral vascular permeability is discussed. Data obtained from the present investigation favor the hypothesis that alcohol influences the neuronal metabolism which, in turn, causes the alteration of the blood-brain barrier. A comparison of the alcohol concentrations in blood necessary for changes in the cerebral vascular permeability was made between man and rabbit. This comparison indicates that the blood brain barrier in man might be altered, at alcohol concentrations of about 0.2% before he could experience stupor or coma following the drinking of alcohol.

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