Intra-axonal overloading of calcium ion in rat diffuse axonal injury and therapeutic effect of calcium antagonist / 中华创伤杂志(英文版)

ABSTRACT

OBJECTIVE: Exploring the intra-axonal overloading of calcium ion (Ca(2+)) in brain diffuse axonal injury (DAI) and the therapeutic effect of calcium antagonist(Nimotop) on DAI. METHODS: Fourteen SD rats were divided into injury group, treatment group and control group. The DAI model of rats was produced by using a head-instant-axial-rotation device. Tissues from the medulla oblongata of rats were taken 2-24 h post-injury and processed for electron microscopic observation by a cytochemical technique for calcium ion. RESULTS: In the injured rats there was evidence of local disruption of myelin sheath,lucent spaces between myelin sheath lamellae, separation of axolemma from the inner layer of myelin sheath, peripheral accumulation of organellae, intra-axonal formation of vacuoles and reduction of mitochondria. A large number of fine calcium deposits were seen on the affected myelin sheath. The severity of the myelin sheath lesion was related positively to the number of calcium deposits on it. In the later post-injury period the coarse calcium particles appeared within the damaged axon. Neuronal somas and microvascular endotheliums showed a lot of vacuoles and some fine calcium deposits. Many microvilli formed on the luminal aspect of endothelium. In the treatment group myelin sheath tended to be injured locally, and axoplasmic mitochondria were nearly normal in number, structure, and distribution. Few calcium deposits were found in axons. Vacuolization was obviously reduced in neuronal soma and endothelium. CONCLUSIONS: In DAI there exists an intra-axonal overloading of calcium ion, which is a key factor to the occurrence and development of DAI. Early use of Nimotop can alleviate DAI.