An experimental study on intra-axonal calcium overloading in ratsdiffuse axonal injury(DAI)and the therapeutic effects of calcium antagonist

Objective To explore the intra axonal overloading of calcium ions in brain diffuse axonal injury(DAI) and the therapeutic effects of Nimotop on DAI. Methods 14 SD rats were divided into injury group, treatment group(intravenous injection of Nimotop was given immediately after trauma), and control group respectively. DAI model of the rat was produced by using a head instant lateral rotation injury device. Tissues of medulla oblongata 2 24h after injury and processed for electron microscopic observation by a cytochemical technique for Ca 2+ .Results (1) In the injured rats, there were local disconnection of the myelin, lucent spaces between myelin lamellae, separation of axolemma from the myelin, peripharal accumulation of organelles, intra axonal formation of vesicles and oligomitochondria. A large number of fine calcium deposits were seen on the myelin. The severity of myelin impairement was related positively to the number of calcium deposits. Coarse calcium deposits appeared in later period after injury. Neuronal somas and microvascular endothelial cells showed a lot of vesicles and calcium deposits. Many microvilli formed in the luminal aspect of endothelium.(2) In the treatment group, the injury of myelin tended to be localized, and the axoplasm had nearly normal mitochondria in number, appearance and distribution. Few of calcium particles were deposited in axons. Vacuolation was reduced in the neuronal soma and endothelium.Conclusion In DAI there is an intra axonal overloading with Ca 2+ which is a key factor to the occurrence and development of DAI. Nimotop can alleviate DAI.