Effect of Blood Glucose Level on Infarct Volume in Transient Cerebral Ischemia in Rats

ABSTRACT

In order to find out the effect of blood glucose on the ischemic brain injury, the authors studied the relationship between the blood glucose level and the infarct volume in a focal cerebral ischemia-reperfusion model in a series of 60 adult rats. The experimental animals were divided into 4 groups of 15 rats rats in group I were allowed free access to food until ischemic insults rats in group II were fasted for 24 hours prior to ischemic insult rats in group III were fed but received intraperitoneal injection of 1.7unit/kg of insulin 50 minutes before the onset of ischemia and rats in group IV were fed and received intraperitoneal injection of 2g/kg of 50% glucose during ischemia. The ischemia was made through unilateral occlusion of the middle cerebral artery(MCA) by inserting a 16mm length of 4-0 nylon surgical thread through the internal carotid artery as well as occlusion of both common carotid arteries(CCA) using nontraumatic aneurysm clips. Reperfusion was induced by pulling the thread that occluded the MCA as well as removing the aneurysm clips from both of the CCAs. Each group was further divided into a(2 hour), b(4 hour), and c(6 hour) subgroups of 5 rats according to the duration of ischemia. All animal were killed 3 hours after reperfusion, and infarct volume determined by triphenyltetrazolium chloride was calculated by a computer image software. The results showed that rats of glucose loaded during ischemia(group IV) developed the highest blood glucose levels during ischemia and post-ischemia and the largest infarct volume among groups. The rats which were fed until ischemic insult(group I) developed higher blood glucose levels and larger infarct volume than those developed in group II and III. The rats of group III developed higher blood glucose levels and larger infarct volume than group II. According to our data, lowering the blood glucose level by fasting or intraperitoneal injection of insulin reduced the infarct volme in model of transient focal cerebral ischemia. These results suggest that maintenance of low level of blood glucose during early phase of cerebral infarction may reduce volume of infarction and neurological sequelae.