Calcium Accumulation following Middle Cerebral Artery Occlusion in Stroke-Prone Spontaneously Hypertensive Rats

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Abstract
Delayed neuronal damage in the ischemic region of the rat brain following middle cerebral artery (MCA) occlusion in stroke-prone spontaneously hypertensive rats was studied. The distribution of neuronal damage was determined by 45Ca autoradiography. Accumulation of 45Ca was observed in the corpus callosum and ipsilateral cerebral cortex immediately following MCA occlusion. After 3 days of occlusion, 45Ca had accumulated in the ipsilateral pyramidal tract, the ventral posterior nucleus of the thalamus, and the lateral portion of the striatum. Significant accumulation of 45Ca was observed in the same areas after 7 and 14 days of occlusion. Next the effect of MK-801 on accumulation of 45Ca after MCA occlusion was examined using the same technique. MK-801 (0.5–10 mg/kg i.v.) or saline was administered 15 min before MCA occlusion, and volumes of accumulation of 45Ca were calculated 1 week after ischemic insults. MK-801 significantly reduced 45Ca uptake in the cortex, striatum, and thalamus. Furthermore, there was a strong statistical correlation between the volume of accumulation of 45Ca in the cortex and that in the thalamus ( r = 0.8974; p < 0.001; n = 25). We speculate that delayed neuronal damage in the corpus callosum, ipsilateral pyramidal tract, and thalamus may be caused by secondary neuronal degeneration. However, neuronal damage in the striatum, a segment not supplied by the MCA, may be related to excessive release of glutamate.