Effect of cerebral ischemic preconditioning on NOS activity and NO content in the CA1 region of the hippocampus in rats / 中国病理生理杂志

ABSTRACT

AIM: To explore the role of NO in the induction of brain ischemic tolerance (BIT) by observing changes of NOS activity and NO_2-/NO_3- content following a transient cerebral ischemia. METHODS: The rat 4-vessel occluding brain ischemic model was used. 140 male Wistar rats were divided into sham, cerebral ischemic preconditioning (CIP), ischemic insult and CIP+ischemic insult groups. An occlusion of the 4 vessels for 3 min was normally used as CIP, and a relative long one for 10 min was used as ischemic insult. When CIP was followed by ischemic insult, the interval between them was 3 d. The CA1 region of the hippocampus of rats was dissected out at 0 h, 2 h, 16 h, 24 h, 36 h, 72 h and 7 d after the last time of ischemia to assay its NOS activity and NO_2-/NO_3- content. RESULTS: The NOS activity and NO_2-/NO_3- content began to increase at 16 h, peaked at 24 h and decreased to basal level at 36 h of reperfusion after CIP. The duration of the up-regulation of NOS activity and NO_2-/NO_3- content was much shorter than that of BIT, which usually takes place 1-7 d after CIP. The pattern of upregulation of the NOS activity and NO_2-/NO_3- content was similar to the CIP group, but the maximum (24 h) was much more than that in CIP group (P