Acetylcholine and experimental brain injury

✓ Anesthetized dogs were subjected to a blow directly on the cerebral cortical surface. As measured by perfusion studies via push-pull cannulae, at the site of trauma within 20 min there was a significant increase in acetylcholine (ACh) released from the cerebral cortical cells, which rose progressively until a plateau was reached in about 1 hour. Concomitantly, ACh appeared within the cerebrospinal fluid (CSF) within 40 min after the injury. In addition, as monitored by the ACh liberation, the injured cells were apparently unable to respond functionally to a subcortical stimulus for several hours after the trauma. These studies support the hypothesis that ACh is released from the mechanically damaged cells, and then subsequently leaks into the CSF. The evidence suggests that a cholinergic factor may be significant in brain injury.